METHODS AND SYSTEMS FOR DETERMINING CIRCULATING TUMOR DNA FRACTION IN A PATIENT SAMPLE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of United States Provisional Patent Application Serial No. 63/389,733, filed July 15, 2022, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present disclosure relates generally to methods and systems for analyzing genomic profiling data, and more specifically to methods and systems for determining the fraction of tumor DNA in a sample obtained from a subject (e.g., a patient) using genomic profiling data.

BACKGROUND

[0003] The analysis of genomic profiling data obtained by sequencing DNA extracted from a patient sample for the purpose of disease diagnosis or prognosis often requires one to estimate the fraction of tumor DNA present in the sample. For liquid biopsy-based techniques in particular, accurate assessment of the amount of circulating tumor DNA (ctDNA) in patient plasma (or other liquid biopsy samples) can be essential. Plasma ctDNA content serves as an important quality control (QC) metric for the assay, and also serves as a biomarker for disease diagnosis, disease prognosis, and disease monitoring purposes. The fraction of ctDNA present in the total amount of cell-free DNA (cfDNA) isolated from a sample can be estimated, for example, by detecting the level of tumor aneuploidy represented in the cfDNA. However, due to the characteristics of the cfDNA present in liquid biopsy samples, and the inherently low levels of cfDNA that are often present in liquid biopsy samples, the evidence for tumor aneuploidy can be either absent or below detectable levels for many samples. Thus, improved methods for determining ctDNA fraction in liquid biopsy samples will be required to improve the diagnostic, prognostic, and disease monitoring performance of liquid biopsy-based techniques and thereby accelerate their adoption rate and impact on improved healthcare outcomes. BRIEF SUMMARY OF THE INVENTION

[0004] Disclosed herein are methods and systems that can provide more accurate assessment of tumor DNA content in biopsy samples in general, and in particular, more accurate assessment of circulating tumor DNA content in cell-free DNA samples collected from patient plasma or other liquid biopsy samples. The methods described herein overcome the problem encountered with existing tumor aneuploidy-based methods for estimating tumor DNA fraction when there is no detectable aneuploidy signal by leveraging alternative signals, e.g., signals associated with the presence of somatic short variants, to infer tumor DNA fraction (e.g., ctDNA fraction). The approach is based on: (i) a derived physical relationship between the allele frequency of variants (e.g., somatic short variants) and tumor content that’s dictated by the copy number state of the genomic location(s) of the variant(s) and a tumor average ploidy, and (ii) access to an extensive database collection of patient genomic profile data.

[0005] Briefly, variants (e.g., somatic short variants) are identified in a sample (e.g., a biopsy sample, a liquid biopsy sample, or a plasma sample) based on sequence read data derived from the sample and their allele frequencies are quantified. An empirical distribution of all possible sample tumor DNA fraction values given the observed somatic short variant allele frequencies can then be generated using (i) the formula that describes the physical relationship between somatic variant allele frequency and tumor DNA fraction for given copy number states of the variant genomic locations and a given tumor average ploidy, and (ii) by leveraging historical patient data that comprises known copy number and tumor ploidy profiles. A model, such as a probability density model (e.g., a non-parametric probability density model), can then be fitted to the empirical distribution of tumor DNA fraction values, and an estimate of tumor DNA fraction for the sample can be derived from the model along with upper and lower bounds for the estimate based on a desired confidence interval.

[0006] The disclosed methods achieve more accurate assessment of tumor DNA content than existing short variant allele frequency (VAF)-based methods by accounting for the influence of copy number and tumor average ploidy on variant allele frequency (VAF), thus providing an estimate that more closely reflects the true tumor DNA fraction of a sample. [0007] Disclosed herein are methods comprising: providing a plurality of nucleic acid molecules obtained from a sample from a subject; ligating one or more adapters onto one or more nucleic acid molecules from the plurality of nucleic acid molecules; amplifying the one or more ligated nucleic acid molecules from the plurality of nucleic acid molecules; capturing amplified nucleic acid molecules from the amplified nucleic acid molecules; sequencing, by a sequencer, the captured nucleic acid molecules to obtain a plurality of sequence reads that represent the captured nucleic acid molecules; receiving, at one or more processors, sequence read data for the plurality of sequence reads; determining, using the one or more processors, a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generating, using the one or more processors, an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fitting, using the one or more processors, a model to the empirical distribution of tumor DNA fraction values; and determining a tumor DNA fraction for the sample based on the model.

[0008] In some embodiments, the method further comprises determining a confidence interval for the tumor DNA fraction based on the model. In some embodiments, the one or more variants comprise one or more somatic short variants. In some embodiments, the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

[0009] In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. [0010] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

[0011] In some embodiments, the plurality of historical subject samples comprise solid biopsy samples, liquid biopsy samples, or any combination thereof. In some embodiments, the plurality of historical subject samples comprises cancer samples. In some embodiments, the plurality of historical subject samples comprises samples for a single type of cancer. In some embodiments, the plurality of historical subject samples comprises samples for multiple types of cancer.

[0012] In some embodiments, the plurality of historical subject samples comprise acute lymphoblastic leukemia (Philadelphia chromosome positive) samples, acute lymphoblastic leukemia (precursor B-cell) samples, acute myeloid leukemia (FLT3+) samples, acute myeloid leukemia (with an IDH2 mutation) samples, anaplastic large cell lymphoma samples, basal cell carcinoma samples, B-cell chronic lymphocytic leukemia samples, bladder cancer samples, breast cancer (HER2 overexpressed/amplified) samples, breast cancer (HER2+) samples, breast cancer (HR+, HER2-) samples, cervical cancer samples, cholangiocarcinoma samples, chronic lymphocytic leukemia samples, chronic lymphocytic leukemia (with 17p deletion) samples, chronic myelogenous leukemia samples, chronic myelogenous leukemia (Philadelphia chromosome positive) samples, classical Hodgkin lymphoma samples, colorectal cancer samples, colorectal cancer (dMMR and MSI-H) samples, colorectal cancer (KRAS wild type) samples, cryopyrin-associated periodic syndrome samples, cutaneous T-cell lymphoma samples, dermatofibrosarcoma protuberans samples, diffuse large B-cell lymphoma samples, fallopian tube cancer samples, follicular B-cell non-Hodgkin lymphoma samples, follicular lymphoma samples, gastric cancer samples, gastric cancer (HER2+) samples, gastroesophageal junction (GEJ) adenocarcinoma samples, gastrointestinal stromal tumor samples, gastrointestinal stromal tumor (KIT+) samples, giant cell tumor of the bone samples, glioblastoma samples, granulomatosis with polyangiitis samples, head and neck squamous cell carcinoma samples, hepatocellular carcinoma samples, Hodgkin lymphoma samples, juvenile idiopathic arthritis samples, lupus erythematosus samples, mantle cell lymphoma samples, medullary thyroid cancer samples, melanoma samples, melanoma samples with a BRAF V600 mutation, melanoma samples with a BRAF V600E or V600K mutation, Merkel cell carcinoma samples, multicentric Castleman's disease samples, multiple hematologic malignancy samples including Philadelphia chromosome-positive AEE and CME, multiple myeloma samples, myelofibrosis samples, nonHodgkin’s lymphoma samples, nonresectable subependymal giant cell astrocytoma samples associated with tuberous sclerosis, non-small cell lung cancer samples, non-small cell lung cancer (AEK+) samples, non-small cell lung cancer (PD-E1+) samples, non-small cell lung cancer (with AEK fusion or ROS1 gene alteration) samples, non-small cell lung cancer (with BRAF V600E mutation) samples, non-small cell lung cancer samples (with an EGFR exon 19 deletion or exon 21 substitution (E858R) mutation), non-small cell lung cancer samples (with an EGFR T790M mutation), ovarian cancer samples, ovarian cancer samples (with a BRCA mutation), pancreatic cancer samples, pancreatic cancer samples, gastrointestinal cancer samples, lung origin neuroendocrine tumor samples, pediatric neuroblastoma samples, peripheral T-cell lymphoma samples, peritoneal cancer samples, prostate cancer samples, renal cell carcinoma samples, rheumatoid arthritis samples, small lymphocytic lymphoma samples, soft tissue sarcoma samples, solid tumor (MSI-H/dMMR) samples, squamous cell cancer samples of the head and neck, squamous non-small cell lung cancer samples, thyroid cancer samples, thyroid carcinoma samples, urothelial cancer samples, urothelial carcinoma samples, Waldenstrom's macroglobulinemia samples, or any combination thereof.

[0013] In some embodiments, the model is parametric probability density model. In some embodiments, the model is a non-parametric probability density model. In some embodiments, the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction. In some embodiments, the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values. [0014] In some embodiments, the sample comprises DNA extracted from a blood sample, a plasma sample, a cerebrospinal fluid sample, a pleural effusion fluid sample, a sputum sample, a stool sample, a urine sample, or a saliva sample.

[0015] In some embodiments, the subject is suspected of having or is determined to have cancer. In some embodiments, the cancer is acute lymphoblastic leukemia (Philadelphia chromosome positive), acute lymphoblastic leukemia (precursor B-cell), acute myeloid leukemia (FLT3+), acute myeloid leukemia (with an IDH2 mutation), anaplastic large cell lymphoma, basal cell carcinoma, B-cell chronic lymphocytic leukemia, bladder cancer, breast cancer (HER2 overexpressed/amplified), breast cancer (HER2+), breast cancer (HR+, HER2-), cervical cancer, cholangiocarcinoma, chronic lymphocytic leukemia, chronic lymphocytic leukemia (with 17p deletion), chronic myelogenous leukemia, chronic myelogenous leukemia (Philadelphia chromosome positive), classical Hodgkin lymphoma, colorectal cancer, colorectal cancer (dMMR/MSI-H), colorectal cancer (KRAS wild type), cryopyrin-associated periodic syndrome, a cutaneous T-cell lymphoma, dermatofibrosarcoma protuberans, a diffuse large B-cell lymphoma, fallopian tube cancer, a follicular B-cell non-Hodgkin lymphoma, a follicular lymphoma, gastric cancer, gastric cancer (HER2+), gastroesophageal junction (GEJ) adenocarcinoma, a gastrointestinal stromal tumor, a gastrointestinal stromal tumor (KIT+), a giant cell tumor of the bone, a glioblastoma, granulomatosis with polyangiitis, a head and neck squamous cell carcinoma, a hepatocellular carcinoma, Hodgkin lymphoma, juvenile idiopathic arthritis, lupus erythematosus, a mantle cell lymphoma, medullary thyroid cancer, melanoma, a melanoma with a BRAF V600 mutation, a melanoma with a BRAF V600E or V600K mutation, Merkel cell carcinoma, multicentric Castleman's disease, multiple hematologic malignancies including Philadelphia chromosome-positive ALL and CML, multiple myeloma, myelofibrosis, a non-Hodgkin’ s lymphoma, a nonresectable subependymal giant cell astrocytoma associated with tuberous sclerosis, a non-small cell lung cancer, a non-small cell lung cancer (ALK+), a non-small cell lung cancer (PD-L1+), a non-small cell lung cancer (with ALK fusion or ROS1 gene alteration), a non-small cell lung cancer (with BRAF V600E mutation), a non-small cell lung cancer (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutations), a non- small cell lung cancer (with an EGFR T790M mutation), ovarian cancer, ovarian cancer (with a BRCA mutation), pancreatic cancer, a pancreatic, gastrointestinal, or lung origin neuroendocrine tumor, a pediatric neuroblastoma, a peripheral T-cell lymphoma, peritoneal cancer, prostate cancer, a renal cell carcinoma, rheumatoid arthritis, a small lymphocytic lymphoma, a soft tissue sarcoma, a solid tumor (MSI-H/dMMR), a squamous cell cancer of the head and neck, a squamous non-small cell lung cancer, thyroid cancer, a thyroid carcinoma, urothelial cancer, a urothelial carcinoma, or Waldenstrom's macroglobulinemia.

[0016] In some embodiments, the method further comprises treating the subject with an anticancer therapy. In some embodiments, the anti-cancer therapy comprises a targeted anti-cancer therapy. In some embodiments, the targeted anti-cancer therapy comprises abemaciclib (Verzenio), abiraterone acetate (Zytiga), acalabrutinib (Calquence), ado-trastuzumab emtansine (Kadcyla), afatinib dimaleate (Gilotrif), aldesleukin (Proleukin), alectinib (Alecensa), alemtuzumab (Campath), alitretinoin (Panretin), alpelisib (Piqray), amivantamab-vmjw (Rybrevant), anastrozole (Arimidex), apalutamide (Erleada), asciminib hydrochloride (Scemblix), atezolizumab (Tecentriq), avapritinib (Ayvakit), avelumab (Bavencio), axicabtagene ciloleucel (Yescarta), axitinib (Inlyta), belantamab mafodotin-blmf (Blenrep), belimumab (Benlysta), belinostat (Beleodaq), belzutifan (Welireg), bevacizumab (Avastin), bexarotene (Targretin), binimetinib (Mektovi), blinatumomab (Blincyto), bortezomib (Velcade), bosutinib (Bosulif), brentuximab vedotin (Adcetris), brexucabtagene autoleucel (Tecartus), brigatinib (Alunbrig), cabazitaxel (Jevtana), cabozantinib (Cabometyx), cabozantinib (Cabometyx, Cometriq), canakinumab (Haris), capmatinib hydrochloride (Tabrecta), carfilzomib (Kyprolis), cemiplimab-rwlc (Libtayo), ceritinib (LDK378/Zykadia), cetuximab (Erbitux), cobimetinib (Cotellic), copanlisib hydrochloride (Aliqopa), crizotinib (Xalkori), dabrafenib (Tafinlar), dacomitinib (Vizimpro), daratumumab (Darzalex), daratumumab and hyaluronidase-fihj (Darzalex Faspro), darolutamide (Nubeqa), dasatinib (Sprycel), denileukin diftitox (Ontak), denosumab (Xgeva), dinutuximab (Unituxin), dostarlimab-gxly (Jemperli), durvalumab (Imfinzi), duvelisib (Copiktra), elotuzumab (Empliciti), enasidenib mesylate (Idhifa), encorafenib (Braftovi), enfortumab vedotin-ejfv (Padcev), entrectinib (Rozlytrek), enzalutamide (Xtandi), erdafitinib (Balversa), erlotinib (Tarceva), everolimus (Afinitor), exemestane (Aromasin), fam-trastuzumab deruxtecan-nxki (Enhertu), fedratinib hydrochloride (Inrebic), fulvestrant (Faslodex), gefitinib (Iressa), gemtuzumab ozogamicin (Mylotarg), gilteritinib (Xospata), glasdegib maleate (Daurismo), hyaluronidase-zzxf (Phesgo), ibrutinib (Imbruvica), ibritumomab tiuxetan (Zevalin), idecabtagene vicleucel (Abecma), idelalisib (Zydelig), imatinib mesylate (Gleevec), infigratinib phosphate (Truseltiq), inotuzumab ozogamicin (Besponsa), iobenguane 1131 (Azedra), ipilimumab (Yervoy), isatuximab-irfc (Sarclisa), ivosidenib (Tibsovo), ixazomib citrate (Ninlaro), lanreotide acetate (Somatuline Depot), lapatinib (Tykerb), larotrectinib sulfate (Vitrakvi), lenvatinib mesylate (Lenvima), letrozole (Femara), lisocabtagene maraleucel (Breyanzi), loncastuximab tesirine-lpyl (Zynlonta), lorlatinib (Lorbrena), lutetium Lu 177-dotatate (Lutathera), margetuximab-cmkb (Margenza), midostaurin (Rydapt), mobocertinib succinate (Exkivity), mogamulizumab-kpkc (Poteligeo), moxetumomab pasudotox-tdfk (Lumoxiti), naxitamab-gqgk (Danyelza), necitumumab (Portrazza), neratinib maleate (Nerlynx), nilotinib (Tasigna), niraparib tosylate monohydrate (Zejula), nivolumab (Opdivo), obinutuzumab (Gazyva), ofatumumab (Arzerra), olaparib (Lynparza), olaratumab (Lartruvo), osimertinib (Tagrisso), palbociclib (Ibrance), panitumumab (Vectibix), panobinostat (Farydak), pazopanib (Votrient), pembrolizumab (Keytruda), pemigatinib (Pemazyre), pertuzumab (Perjeta), pexidartinib hydrochloride (Turalio), polatuzumab vedotin-piiq (Polivy), ponatinib hydrochloride (Iclusig), pralatrexate (Folotyn), pralsetinib (Gavreto), radium 223 dichloride (Xofigo), ramucirumab (Cyramza), regorafenib (Stivarga), ribociclib (Kisqali), ripretinib (Qinlock), rituximab (Rituxan), rituximab and hyaluronidase human (Rituxan Hycela), romidepsin (Istodax), rucaparib camsylate (Rubraca), ruxolitinib phosphate (Jakafi), sacituzumab govitecan-hziy (Trodelvy), seliciclib, selinexor (Xpovio), selpercatinib (Retevmo), selumetinib sulfate (Koselugo), siltuximab (Sylvant), sipuleucel-T (Provenge), sirolimus protein-bound particles (Fyarro), sonidegib (Odomzo), sorafenib (Nexavar), sotorasib (Lumakras), sunitinib (Sutent), tafasitamab-cxix (Monjuvi), tagraxofusp-erzs (Elzonris), talazoparib tosylate (Talzenna), tamoxifen (Nolvadex), tazemetostat hydrobromide (Tazverik), tebentafusp-tebn (Kimmtrak), temsirolimus (Torisel), tepotinib hydrochloride (Tepmetko), tisagenlecleucel (Kymriah), tisotumab vedotin-tftv (Tivdak), tocilizumab (Actemra), tofacitinib (Xeljanz), tositumomab (Bexxar), trametinib (Mekinist), trastuzumab (Herceptin), tretinoin (Vesanoid), tivozanib hydrochloride (Fotivda), toremifene (Fareston), tucatinib (Tukysa), umbralisib tosylate (Ukoniq), vandetanib (Caprelsa), vemurafenib (Zelboraf), venetoclax (Venclexta), vismodegib (Erivedge), vorinostat (Zolinza), zanubrutinib (Brukinsa), ziv-aflibercept (Zaltrap), or any combination thereof. [0017] In some embodiments, the method further comprises obtaining the sample from the subject. In some embodiments, the sample comprises a tissue biopsy sample, a liquid biopsy sample, or a normal control. In some embodiments, the sample is a liquid biopsy sample and comprises blood, plasma, cerebrospinal fluid, sputum, stool, urine, or saliva. In some embodiments, the sample is a liquid biopsy sample and comprises circulating tumor cells (CTCs). In some embodiments, the sample is a liquid biopsy sample and comprises cell-free DNA (cfDNA), circulating tumor DNA (ctDNA), or any combination thereof. In some embodiments, the plurality of nucleic acid molecules comprises a mixture of tumor nucleic acid molecules and non-tumor nucleic acid molecules. In some embodiments, the tumor nucleic acid molecules are derived from a tumor portion of a heterogeneous tissue biopsy sample, and the non-tumor nucleic acid molecules are derived from a normal portion of the heterogeneous tissue biopsy sample. In some embodiments, the sample comprises a liquid biopsy sample, and wherein the tumor nucleic acid molecules are derived from a circulating tumor DNA (ctDNA) fraction of the liquid biopsy sample, and the non-tumor nucleic acid molecules are derived from a non- tumor, cell-free DNA (cfDNA) fraction of the liquid biopsy sample.

[0018] In some embodiments, the one or more adapters comprise amplification primers, flow cell adaptor sequences, substrate adapter sequences, or sample index sequences. In some embodiments, the captured nucleic acid molecules are captured from the amplified nucleic acid molecules by hybridization to one or more bait molecules. In some embodiments, the one or more bait molecules comprise one or more nucleic acid molecules, each comprising a region that is complementary to a region of a captured nucleic acid molecule. In some embodiments, amplifying nucleic acid molecules comprises performing a polymerase chain reaction (PCR) amplification technique, a non-PCR amplification technique, or an isothermal amplification technique. In some embodiments, the sequencing comprises use of a massively parallel sequencing (MPS) technique, whole genome sequencing (WGS), whole exome sequencing, targeted sequencing, direct sequencing, or Sanger sequencing technique. In some embodiments, the sequencing comprises massively parallel sequencing, and the massively parallel sequencing technique comprises next generation sequencing (NGS). In some embodiments, the sequencer comprises a next generation sequencer. [0019] In some embodiments, one or more of the plurality of sequencing reads overlap one or more gene loci within one or more subgenomic intervals in the sample. In some embodiments, the one or more gene loci comprises between 10 and 20 loci, between 10 and 40 loci, between 10 and 60 loci, between 10 and 80 loci, between 10 and 100 loci, between 10 and 150 loci, between 10 and 200 loci, between 10 and 250 loci, between 10 and 300 loci, between 10 and 350 loci, between 10 and 400 loci, between 10 and 450 loci, between 10 and 500 loci, between 20 and 40 loci, between 20 and 60 loci, between 20 and 80 loci, between 20 and 100 loci, between 20 and 150 loci, between 20 and 200 loci, between 20 and 250 loci, between 20 and 300 loci, between 20 and 350 loci, between 20 and 400 loci, between 20 and 500 loci, between 40 and 60 loci, between 40 and 80 loci, between 40 and 100 loci, between 40 and 150 loci, between 40 and 200 loci, between 40 and 250 loci, between 40 and 300 loci, between 40 and 350 loci, between 40 and 400 loci, between 40 and 500 loci, between 60 and 80 loci, between 60 and 100 loci, between 60 and 150 loci, between 60 and 200 loci, between 60 and 250 loci, between 60 and 300 loci, between 60 and 350 loci, between 60 and 400 loci, between 60 and 500 loci, between 80 and 100 loci, between 80 and 150 loci, between 80 and 200 loci, between 80 and 250 loci, between 80 and 300 loci, between 80 and 350 loci, between 80 and 400 loci, between 80 and 500 loci, between 100 and 150 loci, between 100 and 200 loci, between 100 and 250 loci, between 100 and 300 loci, between 100 and 350 loci, between 100 and 400 loci, between 100 and 500 loci, between 150 and 200 loci, between 150 and 250 loci, between 150 and 300 loci, between 150 and 350 loci, between 150 and 400 loci, between 150 and 500 loci, between 200 and 250 loci, between 200 and 300 loci, between 200 and 350 loci, between 200 and 400 loci, between 200 and 500 loci, between 250 and 300 loci, between 250 and 350 loci, between 250 and 400 loci, between 250 and 500 loci, between 300 and 350 loci, between 300 and 400 loci, between 300 and 500 loci, between 350 and 400 loci, between 350 and 500 loci, or between 400 and 500 loci.

[0020] In some embodiments, the one or more gene loci comprise ABL1, ACVR1B, AKT1, AKT2, AKT3, ALK, ALOX12B, AMER1, APC, AR, ARAF, ARFRP1, ARID1A, ASXL1, ATM, ATR, ATRX, AURKA, AURKB, AXIN1, AXL, BAP1, BARD1, BCL2, BCL2L1, BCL2L2, BCL6, BCOR, BCORL1, BCR, BRAF, BRCA1, BRCA2, BRD4, BRIP1, BTG1, BTG2, BTK, CALR, CARD11, CASP8, CBFB, CBL, CCND1, CCND2, CCND3, CCNE1, CD22, CD274, CD70, CD74, CD79A, CD79B, CDC73, CDH1, CDK12, CDK4, CDK6, CDK8, CDKN1A, CDKN1B, CDKN2A, CDKN2B, CDKN2C, CEBPA, CHEK1, CHEK2, CIC, CREBBP, CRKL, CSF1R, CSF3R, CTCF, CTNNA1, CTNNB1, CUL3, CUL4A, CXCR4, CYP17A1, DAXX, DDR1, DDR2, DIS3, DNMT3A, D0T1L, EED, EGFR, EMSY (Cllorf30), EP300, EPHA3, EPHB1, EPHB4, ERBB2, ERBB3, ERBB4, ERCC4, ERG, ERRFI1, ESRI, ETV4, ETV5, ETV6, EWSR1, EZH2, EZR, FAM46C, FANCA, FANCC, FANCG, FANCL, FAS, FBXW7, FGF10, FGF12, FGF14, FGF19, FGF23, FGF3, FGF4, FGF6, FGFR1, FGFR2, FGFR3, FGFR4, FH, FECN, FET1, FET3, FOXE2, FUBP1, GABRA6, GAT A3, GATA4, GATA6, GID4 (C17orf39), GNA11, GNA13, GNAQ, GNAS, GRM3, GSK3B, H3F3A, HDAC1, HGF, HNF1A, HRAS, HSD3B1, ID3, IDH1, IDH2, IGF1R, IKBKE, IKZF1, INPP4B, IRF2, IRF4, IRS2, JAK1, JAK2, JAK3, JUN, KDM5A, KDM5C, KDM6A, KDR, KEAP1, KEF, KIT, KLHL6, KMT2A (MLL), KMT2D (MLL2), KRAS, ETK, LYN, MAF, MAP2K1, MAP2K2, MAP2K4, MAP3K1, MAP3K13, MAPK1, MCL1, MDM2, MDM4, MED12, MEF2B, MEN1, MERTK, MET, MITF, MKNK1, MLH1, MPL, MRE11A, MSH2, MSH3, MSH6, MST1R, MTAP, MTOR, MUTYH, MYB, MYC, MYCL, MYCN, MYD88, NBN, NF1, NF2, NFE2L2, NFKBIA, NKX2-1, NOTCH1, NOTCH2, NOTCH3, NPM1, NRAS, NT5C2, NTRK1, NTRK2, NTRK3, NUTM1, P2RY8, PALB2, PARK2, PARP1, PARP2, PARP3, PAX5, PBRM1, PDCD1, PDCD1LG2, PDGFRA, PDGFRB, PDK1, PIK3C2B, PIK3C2G, PIK3CA, PIK3CB, PIK3R1, PIM1, PMS2, POLDI, POLE, PPARG, PPP2R1A, PPP2R2A, PRDM1, PRKAR1A, PRKCI, PTCHI, PTEN, PTPN11, PTPRO, QKI, RAC1, RAD21, RAD51, RAD51B, RAD51C, RAD51D, RAD52, RAD54L, RAFI, RARA, RBI, RBM10, REL, RET, RICTOR, RNF43, ROS1, RPTOR, RSPO2, SDC4, SDHA, SDHB, SDHC, SDHD, SETD2, SF3B1, SGK1, SLC34A2, SMAD2, SMAD4, SMARCA4, SMARCB1, SMO, SNCAIP, SOCS1, SOX2, SOX9, SPEN, SPOP, SRC, STAG2, STAT3, STK11, SUFU, SYK, TBX3, TEK, TERC, TERT, TET2, TGFBR2, TIPARP, TMPRSS2, TNFAIP3, TNFRSF14, TP53, TSC1, TSC2, TYRO3, U2AF1, VEGFA, VHL, WHSCI, WHSC1L1, WT1, XPO1, XRCC2, ZNF217, ZNF703, or any combination thereof.

[0021] In some embodiments, the one or more gene loci comprise ABL, ALK, ALL, B4GALNT1, BAFF, BCL2, BRAF, BRCA, BTK, CD19, CD20, CD3, CD30, CD319, CD38, CD52, CDK4, CDK6, CML, CRACC, CS1, CTLA-4, dMMR, EGFR, ERBB1, ERBB2, FGFR1- 3, FLT3, GD2, HDAC, HER1, HER2, HR, IDH2, IL-ip, IL-6, IL-6R, JAK1, JAK2, JAK3, KIT, KRAS, MEK, MET, MSLH, mTOR, PARP, PD-1, PDGFR, PDGFRa, PDGFRp, PD-L1, PI3K5, PIGF, PTCH, RAF, RANKL, RET, ROS1, SLAMF7, VEGF, VEGFA, VEGFB, or any combination thereof.

[0022] In some embodiments, the method further comprising generating, by the one or more processors, a report indicating the determined tumor DNA fraction of the sample. In some embodiments, the method further comprises transmitting the report to a healthcare provider. Oln some embodiments, the report is transmitted via a computer network or a peer-to-peer connection.

[0023] Disclosed herein are methods for determining a tumor DNA fraction for a cell-free DNA sample from a subject, the methods comprising: receiving, at one or more processors, sequence read data for a plurality of sequence reads derived from the cell-free DNA (cfDNA) sample from the subject; determining, using the one or more processors, a variant allele frequency (VAF) for one or more variants detected in the cfDNA sample based on the sequence read data; generating, using the one or more processors, an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fitting, using the one or more processors, a model to the empirical distribution of tumor DNA fraction values; and determining a tumor DNA fraction for the cfDNA sample based on the model.

[0024] In some embodiments, the method further comprises determining a confidence interval for the tumor DNA fraction based on the model. In some embodiments, the one or more variants comprise one or more short variants. In some embodiments, the one or more short variants comprise one or more somatic short variants. In some embodiments, the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

[0025] In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the cfDNA sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the cfDNA sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the cfDNA sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the cfDNA sample from the subject that comprise known driver mutations. In some embodiments, tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

[0026] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples.

[0027] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants. [0028] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations comprising: a first equation that equates tumor DNA fraction to a product of tumor purity and tumor average ploidy, divided by a sum of the product of tumor purity and tumor average ploidy and a product of two times a quantity of one minus tumor purity; and a second equation that equates somatic VAF to a product of tumor purity and a variant allele number for each of the one or more variants, divided by a sum of a product of tumor purity and copy number at a genomic location of the one or more variants and a product of two times a quantity of one minus tumor purity, to eliminate tumor purity and derive a relationship that equates tumor DNA fraction to tumor average ploidy divided by a quantity equal to tumor average ploidy minus the copy number at a genomic location of the one or more variants plus a ratio of variant allele number for the one or more variants to somatic VAF for each of the one or more variants.

[0029] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations: pif tumor DNA fraction = — - - — - - -

~ ^J pif + 2(l - p) pV Somatic VAF = — — — — - r C + 2(l - ) to eliminate p and obtain a relationship between tumor DNA fraction and somatic VAF described by: where p is a tumor purity, yr is an tumor average ploidy, C is the copy number at a genomic location of the one or more variants, and V is a variant allele number for each of the one or more variants.

[0030] In some embodiments, the plurality of historical subject samples comprises solid biopsy samples, liquid biopsy samples, or any combination thereof. In some embodiments, the plurality of historical subject samples comprises cancer samples. In some embodiments, the plurality of historical subject samples comprises samples for a single type of cancer. In some embodiments, the plurality of historical subject samples comprises samples for multiple types of cancer.

[0031] In some embodiments, the plurality of historical subject samples comprise bladder cancer samples, breast cancer samples, colorectal cancer samples, endometrial cancer samples, kidney cancer samples, leukemia samples, liver cancer samples, lung cancer samples, melanoma samples, non-Hodgkin lymphoma samples, pancreatic cancer samples, prostate cancer samples, thyroid cancer samples, or any combination thereof.

[0032] In some embodiments, the plurality of historical subject samples comprise acute lymphoblastic leukemia (Philadelphia chromosome positive) samples, acute lymphoblastic leukemia (precursor B-cell) samples, acute myeloid leukemia (FLT3+) samples, acute myeloid leukemia (with an IDH2 mutation) samples, anaplastic large cell lymphoma samples, basal cell carcinoma samples, B-cell chronic lymphocytic leukemia samples, bladder cancer samples, breast cancer (HER2 overexpressed/amplified) samples, breast cancer (HER2+) samples, breast cancer (HR+, HER2-) samples, cervical cancer samples, cholangiocarcinoma samples, chronic lymphocytic leukemia samples, chronic lymphocytic leukemia (with 17p deletion) samples, chronic myelogenous leukemia samples, chronic myelogenous leukemia (Philadelphia chromosome positive) samples, classical Hodgkin lymphoma samples, colorectal cancer samples, colorectal cancer (dMMR and MSI-H) samples, colorectal cancer (KRAS wild type) samples, cryopyrin-associated periodic syndrome samples, cutaneous T-cell lymphoma samples, dermatofibrosarcoma protuberans samples, diffuse large B-cell lymphoma samples, fallopian tube cancer samples, follicular B-cell non-Hodgkin lymphoma samples, follicular lymphoma samples, gastric cancer samples, gastric cancer (HER2+) samples, gastroesophageal junction (GEJ) adenocarcinoma samples, gastrointestinal stromal tumor samples, gastrointestinal stromal tumor (KIT+) samples, giant cell tumor of the bone samples, glioblastoma samples, granulomatosis with polyangiitis samples, head and neck squamous cell carcinoma samples, hepatocellular carcinoma samples, Hodgkin lymphoma samples, juvenile idiopathic arthritis samples, lupus erythematosus samples, mantle cell lymphoma samples, medullary thyroid cancer samples, melanoma samples, melanoma samples with a BRAF V600 mutation, melanoma samples with a BRAF V600E or V600K mutation, Merkel cell carcinoma samples, multicentric Castleman's disease samples, multiple hematologic malignancy samples including Philadelphia chromosome-positive ALL and CML, multiple myeloma samples, myelofibrosis samples, nonHodgkin’s lymphoma samples, nonresectable subependymal giant cell astrocytoma samples associated with tuberous sclerosis, non-small cell lung cancer samples, non-small cell lung cancer (ALK+) samples, non-small cell lung cancer (PD-L1+) samples, non-small cell lung cancer (with ALK fusion or ROS1 gene alteration) samples, non-small cell lung cancer (with BRAF V600E mutation) samples, non-small cell lung cancer samples (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutation), non-small cell lung cancer samples (with an EGFR T790M mutation), ovarian cancer samples, ovarian cancer samples (with a BRCA mutation), pancreatic cancer samples, pancreatic cancer samples, gastrointestinal cancer samples, lung origin neuroendocrine tumor samples, pediatric neuroblastoma samples, peripheral T-cell lymphoma samples, peritoneal cancer samples, prostate cancer samples, renal cell carcinoma samples, rheumatoid arthritis samples, small lymphocytic lymphoma samples, soft tissue sarcoma samples, solid tumor (MSLH/dMMR) samples, squamous cell cancer samples of the head and neck, squamous non-small cell lung cancer samples, thyroid cancer samples, thyroid carcinoma samples, urothelial cancer samples, urothelial carcinoma samples, Waldenstrom's macroglobulinemia samples, or any combination thereof.

[0033] In some embodiments, the model is a parametric probability density model. In some embodiments, the model is a non-parametric probability density model. In some embodiments, the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction. In some embodiments, the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values. [0034] In some embodiments, the cfDNA sample comprises DNA extracted from a blood sample, a plasma sample, a cerebrospinal fluid sample, a pleural effusion fluid sample, a sputum sample, a stool sample, a urine sample, or a saliva sample.

[0035] Also disclosed herein are methods for determining a tumor DNA fraction for a sample from a subject, the methods comprising: receiving, at one or more processors, sequence read data for a plurality of sequence reads derived from the sample from the subject; determining, using the one or more processors, a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generating, using the one or more processors, an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fitting, using the one or more processors, a model to the empirical distribution of tumor DNA fraction values; and determining a tumor DNA fraction for the sample based on the model.

[0036] In some embodiments, the method further comprises determining a confidence interval for the tumor DNA fraction based on the model. In some embodiments, the one or more variants comprise one or more short variants. In some embodiments, the one or more short variants comprise one or more somatic short variants. In some embodiments, the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

[0037] In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject. In some embodiments, the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject. In some embodiments, the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations. In some embodiments, the tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

[0038] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

[0039] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations comprising: a first equation that equates tumor DNA fraction to a product of tumor purity and tumor average ploidy, divided by a sum of the product of tumor purity and tumor average ploidy and a product of two times a quantity of one minus tumor purity; and a second equation that equates somatic VAF to a product of tumor purity and a variant allele number for each of the one or more variants, divided by a sum of a product of tumor purity and copy number at a genomic location of the one or more variants and a product of two times a quantity of one minus tumor purity, to eliminate tumor purity and derive a relationship that equates tumor DNA fraction to tumor average ploidy divided by a quantity equal to tumor average ploidy minus the copy number at a genomic location of the one or more variants plus a ratio of variant allele number for the one or more variants to somatic VAF for each of the one or more variants.

[0040] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations: F

Somatic VAF = - - - r pC + 2(1 - p) to eliminate p and obtain a relationship between tumor DNA fraction and somatic VAF described by: where p is a tumor purity, y is an tumor average ploidy, C is the copy number at a genomic location of the one or more variants, and V is a variant allele number for each of the one or more variants.

[0041] In some embodiments, the plurality of historical subject samples comprise solid biopsy samples, liquid biopsy samples, or any combination thereof. In some embodiments, the plurality of historical subject samples comprises cancer samples. In some embodiments, the plurality of historical subject samples comprises samples for a single type of cancer. In some embodiments, the plurality of historical subject samples comprises samples for multiple types of cancer.

[0042] In some embodiments, the plurality of historical subject samples comprise bladder cancer samples, breast cancer samples, colorectal cancer samples, endometrial cancer samples, kidney cancer samples, leukemia samples, liver cancer samples, lung cancer samples, melanoma samples, non-Hodgkin lymphoma samples, pancreatic cancer samples, prostate cancer samples, thyroid cancer samples, or any combination thereof.

[0043] In some embodiments, the plurality of historical subject samples comprise acute lymphoblastic leukemia (Philadelphia chromosome positive) samples, acute lymphoblastic leukemia (precursor B-cell) samples, acute myeloid leukemia (FLT3+) samples, acute myeloid leukemia (with an IDH2 mutation) samples, anaplastic large cell lymphoma samples, basal cell carcinoma samples, B-cell chronic lymphocytic leukemia samples, bladder cancer samples, breast cancer (HER2 overexpressed/amplified) samples, breast cancer (HER2+) samples, breast cancer (HR+, HER2-) samples, cervical cancer samples, cholangiocarcinoma samples, chronic lymphocytic leukemia samples, chronic lymphocytic leukemia (with 17p deletion) samples, chronic myelogenous leukemia samples, chronic myelogenous leukemia (Philadelphia chromosome positive) samples, classical Hodgkin lymphoma samples, colorectal cancer samples, colorectal cancer (dMMR and MSI-H) samples, colorectal cancer (KRAS wild type) samples, cryopyrin-associated periodic syndrome samples, cutaneous T-cell lymphoma samples, dermatofibrosarcoma protuberans samples, diffuse large B-cell lymphoma samples, fallopian tube cancer samples, follicular B-cell non-Hodgkin lymphoma samples, follicular lymphoma samples, gastric cancer samples, gastric cancer (HER2+) samples, gastroesophageal junction (GEJ) adenocarcinoma samples, gastrointestinal stromal tumor samples, gastrointestinal stromal tumor (KIT+) samples, giant cell tumor of the bone samples, glioblastoma samples, granulomatosis with polyangiitis samples, head and neck squamous cell carcinoma samples, hepatocellular carcinoma samples, Hodgkin lymphoma samples, juvenile idiopathic arthritis samples, lupus erythematosus samples, mantle cell lymphoma samples, medullary thyroid cancer samples, melanoma samples, melanoma samples with a BRAF V600 mutation, melanoma samples with a BRAF V600E or V600K mutation, Merkel cell carcinoma samples, multicentric Castleman's disease samples, multiple hematologic malignancy samples including Philadelphia chromosome-positive ALL and CML, multiple myeloma samples, myelofibrosis samples, nonHodgkin’s lymphoma samples, nonresectable subependymal giant cell astrocytoma samples associated with tuberous sclerosis, non-small cell lung cancer samples, non-small cell lung cancer (ALK+) samples, non-small cell lung cancer (PD-L1+) samples, non-small cell lung cancer (with ALK fusion or ROS1 gene alteration) samples, non-small cell lung cancer (with BRAF V600E mutation) samples, non-small cell lung cancer samples (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutation), non-small cell lung cancer samples (with an EGFR T790M mutation), ovarian cancer samples, ovarian cancer samples (with a BRCA mutation), pancreatic cancer samples, pancreatic cancer samples, gastrointestinal cancer samples, lung origin neuroendocrine tumor samples, pediatric neuroblastoma samples, peripheral T-cell lymphoma samples, peritoneal cancer samples, prostate cancer samples, renal cell carcinoma samples, rheumatoid arthritis samples, small lymphocytic lymphoma samples, soft tissue sarcoma samples, solid tumor (MSI-H/dMMR) samples, squamous cell cancer samples of the head and neck, squamous non-small cell lung cancer samples, thyroid cancer samples, thyroid carcinoma samples, urothelial cancer samples, urothelial carcinoma samples, Waldenstrom's macroglobulinemia samples, or any combination thereof.

[0044] In some embodiments, the model is a parametric probability density model. In some embodiments, the model is a non-parametric probability density model. In some embodiments, the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction. In some embodiments, the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

[0045] In some embodiments, the sample comprises DNA extracted from a blood sample, a plasma sample, a cerebrospinal fluid sample, a pleural effusion fluid sample, a sputum sample, a stool sample, a urine sample, or a saliva sample.

[0046] In some embodiments, the determination of tumor DNA fraction is used to diagnose or confirm a diagnosis of disease in the subject. In some embodiments, the disease is cancer. In some embodiments, the cancer is acute lymphoblastic leukemia (Philadelphia chromosome positive), acute lymphoblastic leukemia (precursor B-cell), acute myeloid leukemia (FLT3+), acute myeloid leukemia (with an IDH2 mutation), anaplastic large cell lymphoma, basal cell carcinoma, B-cell chronic lymphocytic leukemia, bladder cancer, breast cancer (HER2 overexpressed/amplified), breast cancer (HER2+), breast cancer (HR+, HER2-), cervical cancer, cholangiocarcinoma, chronic lymphocytic leukemia, chronic lymphocytic leukemia (with 17p deletion), chronic myelogenous leukemia, chronic myelogenous leukemia (Philadelphia chromosome positive), classical Hodgkin lymphoma, colorectal cancer, colorectal cancer (dMMR/MSI-H), colorectal cancer (KRAS wild type), cryopyrin-associated periodic syndrome, a cutaneous T-cell lymphoma, dermatofibrosarcoma protuberans, a diffuse large B-cell lymphoma, fallopian tube cancer, a follicular B-cell non-Hodgkin lymphoma, a follicular lymphoma, gastric cancer, gastric cancer (HER2+), gastroesophageal junction (GEJ) adenocarcinoma, a gastrointestinal stromal tumor, a gastrointestinal stromal tumor (KIT+), a giant cell tumor of the bone, a glioblastoma, granulomatosis with polyangiitis, a head and neck squamous cell carcinoma, a hepatocellular carcinoma, Hodgkin lymphoma, juvenile idiopathic arthritis, lupus erythematosus, a mantle cell lymphoma, medullary thyroid cancer, melanoma, a melanoma with a BRAF V600 mutation, a melanoma with a BRAF V600E or V600K mutation, Merkel cell carcinoma, multicentric Castleman's disease, multiple hematologic malignancies including Philadelphia chromosome-positive ALL and CML, multiple myeloma, myelofibrosis, a non-Hodgkin’ s lymphoma, a nonresectable subependymal giant cell astrocytoma associated with tuberous sclerosis, a non-small cell lung cancer, a non-small cell lung cancer (ALK+), a non-small cell lung cancer (PD-L1+), a non-small cell lung cancer (with ALK fusion or ROS1 gene alteration), a non-small cell lung cancer (with BRAF V600E mutation), a non-small cell lung cancer (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutations), a non- small cell lung cancer (with an EGFR T790M mutation), ovarian cancer, ovarian cancer (with a BRCA mutation), pancreatic cancer, a pancreatic, gastrointestinal, or lung origin neuroendocrine tumor, a pediatric neuroblastoma, a peripheral T-cell lymphoma, peritoneal cancer, prostate cancer, a renal cell carcinoma, rheumatoid arthritis, a small lymphocytic lymphoma, a soft tissue sarcoma, a solid tumor (MSLH/dMMR), a squamous cell cancer of the head and neck, a squamous non-small cell lung cancer, thyroid cancer, a thyroid carcinoma, urothelial cancer, a urothelial carcinoma, or Waldenstrom's macroglobulinemia.

[0047] In some embodiments, the method further comprises selecting an anti-cancer therapy to administer to the subject based on the determination of tumor DNA fraction. In some embodiments, the method further comprises determining an effective amount of an anti-cancer therapy to administer to the subject based on the determination of tumor DNA fraction. In some embodiments, the method further comprises administering the anti-cancer therapy to the subject based on the determination of tumor DNA fraction. In some embodiments, the anti-cancer therapy comprises chemotherapy, radiation therapy, immunotherapy, a targeted therapy, or surgery.

[0048] Also disclosed herein are methods for diagnosing a disease, the methods comprising: diagnosing that a subject has the disease based on a determination of tumor DNA fraction for a sample from the subject, wherein tumor DNA fraction is determined according to any of the methods described herein.

[0049] Disclosed herein are methods of selecting an anti-cancer therapy, the methods comprising: responsive to determining tumor DNA fraction for a sample from a subject, selecting an anti-cancer therapy for the subject, wherein tumor DNA fraction is determined according to any of the methods described herein.

[0050] Disclosed herein are methods of treating a cancer in a subject, comprising: responsive to determining tumor DNA fraction for a sample from the subject, administering an effective amount of an anti-cancer therapy to the subject, wherein tumor DNA fraction is determined according to any of the methods described herein.

[0051] Disclosed herein are methods for determining a prognosis for a subject having cancer comprising: determining tumor DNA fraction for a sample from the subject, and determining a prognosis for the subject based on the tumor DNA fraction, wherein tumor DNA fraction is determined according to any of the methods described herein.

[0052] Disclosed herein are methods for assessing molecular residual disease (MRD), the methods comprising: determining tumor DNA fraction for a sample from the subject, and assessing molecular residual disease (MRD) for the subject based on the tumor DNA fraction, wherein tumor DNA fraction is determined according to any of the methods described herein.

[0053] Disclosed herein are methods for monitoring cancer progression or recurrence in a subject, the methods comprising: determining a first tumor DNA fraction in a first sample obtained from the subject at a first time point according to any of the methods described herein; determining a second tumor DNA fraction in a second sample obtained from the subject at a second time point; and comparing the first tumor DNA fraction to the second tumor DNA fraction, thereby monitoring the cancer progression or recurrence. In some embodiments, the second tumor DNA fraction for the second sample is determined according to any of the methods described herein. In some embodiments, the method further comprises selecting an anti-cancer therapy for the subject in response to the cancer progression. In some embodiments, the method further comprises administering an anti-cancer therapy to the subject in response to the cancer progression. In some embodiments, the method further comprises adjusting an anti-cancer therapy for the subject in response to the cancer progression. In some embodiments, the method further comprises adjusting a dosage of the anti-cancer therapy or selecting a different anticancer therapy in response to the cancer progression. In some embodiments, the method further comprises administering the adjusted anti-cancer therapy to the subject. In some embodiments, the first time point is before the subject has been administered an anti-cancer therapy, and wherein the second time point is after the subject has been administered the anti-cancer therapy. In some embodiments, the subject has a cancer, is at risk of having a cancer, is being routine tested for cancer, or is suspected of having a cancer. In some embodiments, the cancer is a solid tumor. In some embodiments, the cancer is a hematological cancer. In some embodiments, the anti-cancer therapy comprises chemotherapy, radiation therapy, immunotherapy, a targeted therapy, or surgery.

[0054] In some embodiments, the method further comprises determining, identifying, or applying the value of tumor DNA fraction for the sample as a diagnostic value associated with the sample. In some embodiments, the method further comprises generating a genomic profile for the subject based on the determination of tumor DNA fraction. In some embodiments, the genomic profile for the subject further comprises results from a comprehensive genomic profiling (CGP) test, a gene expression profiling test, a cancer hotspot panel test, a DNA methylation test, a DNA fragmentation test, an RNA fragmentation test, or any combination thereof. In some embodiments, the genomic profile for the subject further comprises results from a nucleic acid sequencing-based test. In some embodiments, the method further comprisies selecting an anti-cancer therapy, administering an anti-cancer therapy, or applying an anti-cancer therapy to the subject based on the generated genomic profile. In some embodiments, the determination of tumor DNA fraction for the sample is used in making suggested treatment decisions for the subject. In some embodiments, the determination of tumor DNA fraction for the sample is used in applying or administering a treatment to the subject. [0055] Disclosed herein are systems comprising: one or more processors; and a memory communicatively coupled to the one or more processors and configured to store instructions that, when executed by the one or more processors, cause the system to: receive sequence read data for a plurality of sequence reads derived from a sample from a subject; determine a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generate an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fit a model to the empirical distribution of tumor DNA fraction values; and determine a tumor DNA fraction for the sample based on the model.

[0056] In some embodiments, the system further comprises instructions for determining a confidence interval for the tumor DNA fraction based on the model. In some embodiments, the one or more variants comprise one or more short variants. In some embodiments, the one or more short variants comprise one or more somatic short variants. In some embodiments, the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

[0057] In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations. In some embodiments, tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

[0058] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

[0059] In some embodiments, the model is a parametric probability density model. In some embodiments, the model is a non-parametric probability density model. In some embodiments, the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction. In some embodiments, the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

[0060] Aldo disclosed herein are non-transitory computer-readable storage media storing one or more programs, the one or more programs comprising instructions, which when executed by one or more processors of a system, cause the system to: receive sequence read data for a plurality of sequence reads derived from a sample from a subject; determine a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generate an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fit a model to the empirical distribution of tumor DNA fraction values; and determine a tumor DNA fraction for the sample based on the model.

[0061] In some embodiments, the non-transitory computer-readable storage medium further comprises instructions for determining a confidence interval for the tumor DNA fraction based on the model. In some embodiments, the one or more variants comprise one or more short variants. In some embodiments, the one or more short variants comprise one or more somatic short variants. In some embodiments, the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

[0062] In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some embodiments, tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject. In some embodiments, the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject. In some embodiments, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations. In some embodiments, tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

[0063] In some embodiments, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

[0064] In some embodiments, the model is a parametric probability density model. In some embodiments, the model is a non-parametric probability density model. In some embodiments, the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction. In some embodiments, the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

INCORPORATION BY REFERENCE

[0065] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference in its entirety. In the event of a conflict between a term herein and a term in an incorporated reference, the term herein controls.

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Various aspects of the disclosed methods, devices, and systems are set forth with particularity in the appended claims. A better understanding of the features and advantages of the disclosed methods, devices, and systems will be obtained by reference to the following detailed description of illustrative embodiments and the accompanying drawings, of which:

[0067] FIG. 1 provides a non-limiting example of a process flowchart for determining a ctDNA fraction for a sample.

[0068] FIG. 2 depicts an exemplary computing device or system in accordance with one embodiment of the present disclosure.

[0069] FIG. 3 depicts an exemplary computer system or computer network in accordance with one embodiment of the present disclosure. [0070] FIG. 4 provides a non-limiting example of a plot of simulated data for variant allele frequency as a function of ctDNA fraction for different copy numbers.

[0071] FIG. 5 provides non-limiting examples of plots of simulated data for variant allele frequency as a function of ctDNA fraction for different copy numbers (z.e., the same plots that are overlaid in FIG. 4; reproduced here for easier visualization). Upper left panel: simulated data plotted for the case that copy number = 1. Upper right panel: simulated data plotted for the case that copy number = 2. Lower left panel: simulated data plotted for the case that copy number = 3. Lower right panel: simulated data plotted for the case that copy number = 4.

[0072] FIG. 6 provides a non-limiting example of a plot of variant allele frequency as a function of ctDNA fraction calculated from patient sample data for different copy numbers.

[0073] FIG. 7 provides non-limiting examples of plots of variant allele frequency as a function of ctDNA fraction calculated from patient sample data for different copy numbers (z.e., the same plots that are overlaid in FIG. 6; reproduced here for easier visualization). Upper left panel: simulated data plotted for the case that copy number = 1. Upper right panel: simulated data plotted for the case that copy number = 2. Lower left panel: simulated data plotted for the case that copy number = 3. Lower right panel: simulated data plotted for the case that copy number = 4.

[0074] FIG. 8 provides a non-limiting example of a probability density plot as a function of possible ctDNA fraction values in a sample for a given value of observed maximum somatic VAF.

DETAILED DESCRIPTION

[0075] Disclosed herein are methods and systems that can provide more accurate assessment of tumor DNA content in biopsy samples in general, and in particular, more accurate assessment of circulating tumor DNA content in cell-free DNA samples collected from patient plasma or other liquid biopsy samples. The methods described herein overcome the problem encountered with existing tumor aneuploidy-based methods for estimating tumor DNA fraction when there is no detectable aneuploidy signal by leveraging alternative signals, e.g., signals associated with the presence of somatic short variants, to infer tumor DNA fraction (e.g., ctDNA fraction). The approach is based on: (i) a derived physical relationship between the allele frequency of variants (e.g., somatic short variants) and tumor content that’s dictated by the copy number state of the genomic location(s) of the variant(s) and a tumor average ploidy, and (ii) access to an extensive database collection of patient genomic profile data.

[0076] Briefly, variants (e.g., somatic short variants) are identified in a sample (e.g., a biopsy sample, a liquid biopsy sample, or a plasma sample) based on sequence read data derived from the sample and their allele frequencies are quantified. An empirical distribution of all possible sample tumor DNA fraction values given the observed somatic short variant allele frequencies can then be generated using (i) the formula that describes the physical relationship between somatic variant allele frequency and tumor DNA fraction for given copy number states of the variant genomic locations and a given tumor average ploidy, and (ii) by leveraging historical patient data that comprises known copy number and tumor ploidy profiles. A model, such as a probability density model (e.g., a non-parametric probability density model)), can then be fitted to the empirical distribution of tumor DNA fraction values, and an estimate of tumor DNA fraction for the sample can be derived from the model along with upper and lower bounds for the estimate based on a desired confidence interval.

[0077] In some instances, for example, methods are described that comprise receiving sequence read data for a plurality of sequence reads derived from the sample from the subject; determining a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generating an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fitting a model to the empirical distribution of tumor DNA fraction values; and determining a tumor DNA fraction for the sample based on the model. In some instances, the disclosed methods are computer-implemented methods.

[0078] In some instances, the method further comprises determining a confidence interval for the tumor DNA fraction based on the model. In some instances, the one or more variants comprise one or more short variants (e.g., one or more somatic short variants). In some instances, the one or more short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP). [0079] In some instances, generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some instances, generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

[0080] In some instances, tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the sample from the subject. In some instances, tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject. In some instances, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject. In some instances, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations. In some instances, tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject. In some instances, tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants. [0081] In some instances, the model is a non-parametric probability density model. In some instances, the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction. In some instances, the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

[0082] The disclosed methods achieve more accurate assessment of tumor DNA content than existing VAF-based methods by accounting for the influence of copy number and tumor average ploidy on variant allele frequency (VAF), thus providing an estimate that more closely reflects the true tumor DNA fraction of a sample.

Definitions

[0083] Unless otherwise defined, all of the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art in the field to which this disclosure belongs.

[0084] As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Any reference to “or” herein is intended to encompass “and/or” unless otherwise stated.

[0085] “About” and “approximately” shall generally mean an acceptable degree of error for the quantity measured given the nature or precision of the measurements. Exemplary degrees of error are within 20 percent (%), typically, within 10%, and more typically, within 5% of a given value or range of values.

[0086] As used herein, the terms "comprising" (and any form or variant of comprising, such as "comprise" and "comprises"), "having" (and any form or variant of having, such as "have" and "has"), "including" (and any form or variant of including, such as "includes" and "include"), or "containing" (and any form or variant of containing, such as "contains" and "contain"), are inclusive or open-ended and do not exclude additional, un-recited additives, components, integers, elements, or method steps. [0087] As used herein, the terms “individual,” “patient,” or “subject” are used interchangeably and refer to any single animal, e.g., a mammal (including such non-human animals as, for example, dogs, cats, horses, rabbits, zoo animals, cows, pigs, sheep, and non-human primates) for which treatment is desired. In particular embodiments, the individual, patient, or subject herein is a human.

[0088] The terms “cancer” and “tumor” are used interchangeably herein. These terms refer to the presence of cells possessing characteristics typical of cancer-causing cells, such as uncontrolled proliferation, immortality, metastatic potential, rapid growth and proliferation rate, and certain characteristic morphological features. Cancer cells are often in the form of a tumor, but such cells can exist alone within an animal, or can be a non-tumorigenic cancer cell, such as a leukemia cell. These terms include a solid tumor, a soft tissue tumor, or a metastatic lesion. As used herein, the term “cancer” includes premalignant, as well as malignant cancers.

[0089] As used herein, “treatment” (and grammatical variations thereof such as “treat” or “treating”) refers to clinical intervention (e.g., administration of an anti-cancer agent or anticancer therapy) in an attempt to alter the natural course of the individual being treated, and can be performed either for prophylaxis or during the course of clinical pathology. Desirable effects of treatment include, but are not limited to, preventing occurrence or recurrence of disease, alleviation of symptoms, diminishment of any direct or indirect pathological consequences of the disease, preventing metastasis, decreasing the rate of disease progression, amelioration or palliation of the disease state, and remission or improved prognosis.

[0090] As used herein, the term “subgenomic interval” (or “subgenomic sequence interval”) refers to a portion of a genomic sequence.

[0091] As used herein, the term "subject interval" refers to a subgenomic interval or an expressed subgenomic interval (e.g., the transcribed sequence of a subgenomic interval).

[0092] As used herein, the terms “variant sequence” or “variant” are used interchangeably and refer to a modified nucleic acid sequence relative to a corresponding “normal” or “wild-type” sequence. In some instances, a variant sequence may be a “short variant sequence” (or “short variant”), i.e., a variant sequence of less than about 50 base pairs in length. [0093] The terms “allele frequency” and “allele fraction” are used interchangeably herein and refer to the fraction of sequence reads corresponding to a particular allele relative to the total number of sequence reads for a genomic locus.

[0094] The terms “variant allele frequency” and “variant allele fraction” are used interchangeably herein and refer to the fraction of sequence reads corresponding to a particular variant allele relative to the total number of sequence reads for a genomic locus.

[0095] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

Methods for determining tumor DNA fraction

[0096] The methods described herein can provide more accurate assessment of tumor DNA content in biopsy samples in general, and in particular, more accurate assessment of circulating tumor DNA content in cell-free DNA samples collected from patient plasma or other liquid biopsy samples. Briefly, variants (e.g., somatic short variants) are identified in a sample (e.g., a biopsy sample, a liquid biopsy sample, or a plasma sample) based on sequence read data derived from the sample and their allele frequencies are quantified. An empirical distribution of all possible sample tumor DNA fraction values given the observed somatic short variant allele frequencies can then be generated using (i) a formula that describes the physical relationship between somatic variant allele frequency and tumor DNA fraction for given copy number states of the variant genomic locations and a given tumor average ploidy, and (ii) by leveraging historical patient data that comprises known copy number and tumor ploidy profiles. A model, such as a probability density model (e.g., a non-parametric probability density model)), can then be fitted to the empirical distribution of tumor DNA fraction values, and an estimate of tumor DNA fraction for the sample can be derived from the model along with upper and lower bounds for the estimate based on a desired confidence interval.

[0097] FIG. 1 provides a non-limiting example of a flowchart for a process 100 for determining a tumor DNA fraction (e.g., a ctDNA fraction) for a sample. Process 100 can be performed, for example, using one or more electronic devices implementing a software platform. In some examples, process 100 is performed using a client-server system, and the blocks of process 100 are divided up in any manner between the server and a client device. In other examples, the blocks of process 100 are divided up between the server and multiple client devices. Thus, while portions of process 100 are described herein as being performed by particular devices of a clientserver system, it will be appreciated that process 100 is not so limited. In other examples, process 100 is performed using only a client device or only multiple client devices. In process 100, some blocks are, optionally, combined, the order of some blocks is, optionally, changed, and some blocks are, optionally, omitted. In some examples, additional steps may be performed in combination with the process 100. Accordingly, the operations as illustrated (and described in greater detail below) are exemplary by nature and, as such, should not be viewed as limiting.

[0098] At step 102 in FIG. 1, sequence read data is received for a plurality of sequence reads obtained by extracting nucleic acids (e.g., DNA) from a sample and sequencing the nucleic acids. In some instances, the sample may comprise a tissue sample, a solid biopsy sample, a liquid biopsy sample, or any combination thereof. In some instances, the sample may comprise DNA extracted from a blood sample, a plasma sample, a cerebrospinal fluid sample, a pleural effusion fluid sample, a sputum sample, a stool sample, a urine sample, or a saliva sample. In some instances, the sample may comprise circulating free DNA (cfDNA). In some instances, the sample may comprise circulating tumor DNA (ctDNA).

[0099] At step 104 in FIG. 1, a variant allele frequency (VAF) is determined for one or more variants detected in the sample based on the sequence read data. In some instances, the one or more variants may comprise one or more short variants, one or more rearrangement events, or any combination thereof. In some instances, the one or more short variants comprise one or more somatic short variants. In some instances, the one or more short variants (e.g., one or more short somatic variants) may be variants that are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

[0100] In some instances, the one or more variants may comprise variants in the ABL1, ACVR1B, AKT1, AKT2, AKT3, ALK, ALOX12B, AMER1, APC, AR, ARAF, ARFRP1, ARID1A, ASXL1, ATM, ATR, ATRX, AURKA, AURKB, AXIN1, AXL, BAP1, BARD1, BCL2, BCL2L1, BCL2L2, BCL6, BCOR, BCORL1, BCR, BRAF, BRCA1, BRCA2, BRD4, BRIP1, BTG1, BTG2, BTK, CALR, CARD11, CASP8, CBFB, CBL, CCND1, CCND2, CCND3, CCNE1, CD22, CD274, CD70, CD74, CD79A, CD79B, CDC73, CDH1, CDK12, CDK4, CDK6, CDK8, CDKN1A, CDKN1B, CDKN2A, CDKN2B, CDKN2C, CEBPA, CHEK1, CHEK2, CIC, CREBBP, CRKL, CSF1R, CSF3R, CTCF, CTNNA1, CTNNB1, CUL3, CUL4A, CXCR4, CYP17A1, DAXX, DDR1, DDR2, DIS3, DNMT3A, D0T1L, EED, EGFR, EMSY (Cllorf30), EP300, EPHA3, EPHB1, EPHB4, ERBB2, ERBB3, ERBB4, ERCC4, ERG, ERRFI1, ESRI, ETV4, ETV5, ETV6, EWSR1, EZH2, EZR, FAM46C, FANCA, FANCC, FANCG, FANCL, FAS, FBXW7, FGF10, FGF12, FGF14, FGF19, FGF23, FGF3, FGF4, FGF6, FGFR1, FGFR2, FGFR3, FGFR4, FH, FECN, FET1, FET3, FOXE2, FUBP1, GABRA6, GATA3, GATA4, GATA6, GID4 (C17orf39), GNA11, GNA13, GNAQ, GNAS, GRM3, GSK3B, H3F3A, HDAC1, HGF, HNF1A, HRAS, HSD3B1, ID3, IDH1, IDH2, IGF1R, IKBKE, IKZF1, INPP4B, IRF2, IRF4, IRS2, JAK1, JAK2, JAK3, JUN, KDM5A, KDM5C, KDM6A, KDR, KEAP1, KEF, KIT, KLHL6, KMT2A (MLL), KMT2D (MLL2), KRAS, ETK, LYN, MAF, MAP2K1, MAP2K2, MAP2K4, MAP3K1, MAP3K13, MAPK1, MCL1, MDM2, MDM4, MED12, MEF2B, MEN1, MERTK, MET, MITF, MKNK1, MLH1, MPL, MRE11A, MSH2, MSH3, MSH6, MST1R, MTAP, MTOR, MUTYH, MYB, MYC, MYCL, MYCN, MYD88, NBN, NF1, NF2, NFE2L2, NFKBIA, NKX2-1, NOTCH1, NOTCH2, NOTCH3, NPM1, NRAS, NT5C2, NTRK1, NTRK2, NTRK3, NUTM1, P2RY8, PALB2, PARK2, PARP1, PARP2, PARP3, PAX5, PBRM1, PDCD1, PDCD1LG2, PDGFRA, PDGFRB, PDK1, PIK3C2B, PIK3C2G, PIK3CA, PIK3CB, PIK3R1, PIM1, PMS2, POLDI, POLE, PPARG, PPP2R1A, PPP2R2A, PRDM1, PRKAR1A, PRKCI, PTCHI, PTEN, PTPN11, PTPRO, QKI, RAC1, RAD21, RAD51, RAD51B, RAD51C, RAD51D, RAD52, RAD54L, RAFI, RARA, RBI, RBM10, REL, RET, RICTOR, RNF43, ROS1, RPTOR, RSPO2, SDC4, SDHA, SDHB, SDHC, SDHD, SETD2, SF3B1, SGK1, SLC34A2, SMAD2, SMAD4, SMARCA4, SMARCB1, SMO, SNCAIP, SOCS1, SOX2, SOX9, SPEN, SPOP, SRC, STAG2, STAT3, STK11, SUFU, SYK, TBX3, TEK, TERC, TERT, TET2, TGFBR2, TIPARP, TMPRSS2, TNFAIP3, TNFRSF14, TP53, TSC1, TSC2, TYRO3, U2AF1, VEGFA, VHL, WHSCI, WHSC1L1, WT1, XPO1, XRCC2, ZNF217, or ZNF703 gene locus, or any combination thereof.

[0101] In some instances, the one or more variants may comprise variants in the ABL, ALK, ALL, B4GALNT1, BAFF, BCL2, BRAF, BRCA, BTK, CD19, CD20, CD3, CD30, CD319, CD38, CD52, CDK4, CDK6, CML, CRACC, CS1, CTLA-4, dMMR, EGFR, ERBB1, ERBB2, FGFR1-3, FLT3, GD2, HDAC, HER1, HER2, HR, IDH2, IL-ip, IL-6, IL-6R, JAK1, JAK2, JAK3, KIT, KRAS, MEK, MET, MSLH, mTOR, PARP, PD-1, PDGFR, PDGFRa, PDGFRp, PD-L1, PI3K5, PIGF, PTCH, RAF, RANKL, RET, ROS1, SLAMF7, VEGF, VEGFA, or VEGFB gene locus, or any combination thereof.

[0102] At step 106 in FIG. 1, an empirical distribution of tumor DNA fraction values (e.g., ctDNA fraction values) as a function of the VAF(s) determined for the one or more variants is generated based on, e.g., historical data for a plurality of subjects (e.g., patients) that comprise known copy number and tumor ploidy profiles.

[0103] In some instances, generating the empirical distribution of tumor DNA fraction values may comprise calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. In some instances, generating the empirical distribution of tumor DNA fraction values may comprise pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. The term “substantially the same” in this context refers to the situation where the known and determined values of VAF differ by less than about 10%, less than about 8%, less than about 6%, less than about 4%, less than about 2%, less than about 1%, or less than about 0.5%.

[0104] In some instances, tumor DNA fraction values may be calculated or selected for a variant that exhibits the highest VAF in the sample from the subject. In some instances, tumor DNA fraction values may be calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject (e.g., the 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 variants that exhibit the highest rank-ordered VAFs in the sample). In some instances, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject (e.g., a predetermined set comprising 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 variants). In some instances, tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations (e.g., a predetermined set comprising 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 variants comprising known driver mutations). In some instances, tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

[0105] In some instances, e.g., if more than one variant is used to determine tumor DNA fraction, one may cluster variants according to their VAFs using, e.g., an unsupervised clustering algorithm such as an unsupervised K-means clustering algorithm, a hierarchical clustering algorithm, or a Gaussian mixture model clustering algorithm, etc. The center of each identified cluster (e.g., the mean of all VAF values in the cluster) may then represent a VAF corresponding to a particular copy number. If there is only one cluster identified, one can use the center of the cluster as the value of VAF used to generate the distribution of possible tumor DNA fractions. If more than one cluster is identified, one may apply a set of rules to select one of the clusters that likely represents the diploid (z.e., copy number = 2) state, and then use center of the diploid cluster as the value of VAF used to generate the distribution of possible tumor DNA fractions.

[0106] In some instances, tumor DNA fraction values may be calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

[0107] In some instances, tumor DNA fraction values may be calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations comprising: a first equation that equates tumor DNA fraction to a product of tumor purity and tumor average ploidy, divided by a sum of the product of tumor purity and tumor average ploidy and a product of two times a quantity of one minus tumor purity; and a second equation that equates somatic VAF to a product of tumor purity and a variant allele number for each of the one or more variants, divided by a sum of a product of tumor purity and copy number at a genomic location of the one or more variants and a product of two times a quantity of one minus tumor purity, to eliminate tumor purity and derive a relationship that equates tumor DNA fraction to tumor average ploidy divided by a quantity equal to tumor average ploidy minus the copy number at a genomic location of the one or more variants plus a ratio of variant allele number for the one or more variants to somatic VAF for each of the one or more variants.

[0108] In some instances, tumor DNA fraction values may be calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations consisting of: and

Somatic VAF = - — - (2) pC+2(l-p) ^{v 7} to eliminate p and obtain a relationship between tumor DNA fraction and somatic VAF described by the relation: where p is a tumor purity, is an tumor average ploidy, C is the copy number at a genomic location of the one or more variants, and V is a variant allele number for each of the one or more variants.

[0109] In some instances, the plurality of historical subject samples (e.g., patient samples) may comprise solid biopsy samples, liquid biopsy samples, or any combination thereof. In some instances, the plurality of historical subject samples may comprise cancer samples. In some instances, the plurality of historical subject samples may comprise samples for a single type of cancer. In some instances, the plurality of historical subject samples may comprise samples for multiple types of cancer.

[0110] In some instances, the plurality of historical subject samples (e.g., patient samples) may comprise bladder cancer samples, breast cancer samples, colorectal cancer samples, endometrial cancer samples, kidney cancer samples, leukemia samples, liver cancer samples, lung cancer samples, melanoma samples, non-Hodgkin lymphoma samples, pancreatic cancer samples, prostate cancer samples, thyroid cancer samples, or any combination thereof.

[0111] In some instances, the plurality of historical subject samples (e.g., patient samples) may comprise acute lymphoblastic leukemia (Philadelphia chromosome positive) samples, acute lymphoblastic leukemia (precursor B-cell) samples, acute myeloid leukemia (FLT3+) samples, acute myeloid leukemia (with an IDH2 mutation) samples, anaplastic large cell lymphoma samples, basal cell carcinoma samples, B-cell chronic lymphocytic leukemia samples, bladder cancer samples, breast cancer (HER2 overexpressed/amplified) samples, breast cancer (HER2+) samples, breast cancer (HR+, HER2-) samples, cervical cancer samples, cholangiocarcinoma samples, chronic lymphocytic leukemia samples, chronic lymphocytic leukemia (with 17p deletion) samples, chronic myelogenous leukemia samples, chronic myelogenous leukemia (Philadelphia chromosome positive) samples, classical Hodgkin lymphoma samples, colorectal cancer samples, colorectal cancer (dMMR and MSI-H) samples, colorectal cancer (KRAS wild type) samples, cryopyrin-associated periodic syndrome samples, cutaneous T-cell lymphoma samples, dermatofibrosarcoma protuberans samples, diffuse large B-cell lymphoma samples, fallopian tube cancer samples, follicular B-cell non-Hodgkin lymphoma samples, follicular lymphoma samples, gastric cancer samples, gastric cancer (HER2+) samples, gastroesophageal junction (GEJ) adenocarcinoma samples, gastrointestinal stromal tumor samples, gastrointestinal stromal tumor (KIT+) samples, giant cell tumor of the bone samples, glioblastoma samples, granulomatosis with polyangiitis samples, head and neck squamous cell carcinoma samples, hepatocellular carcinoma samples, Hodgkin lymphoma samples, juvenile idiopathic arthritis samples, lupus erythematosus samples, mantle cell lymphoma samples, medullary thyroid cancer samples, melanoma samples, melanoma samples with a BRAF V600 mutation, melanoma samples with a BRAF V600E or V600K mutation, Merkel cell carcinoma samples, multicentric Castleman's disease samples, multiple hematologic malignancy samples including Philadelphia chromosome-positive ALL and CML, multiple myeloma samples, myelofibrosis samples, nonHodgkin’s lymphoma samples, nonresectable subependymal giant cell astrocytoma samples associated with tuberous sclerosis, non-small cell lung cancer samples, non-small cell lung cancer (ALK+) samples, non-small cell lung cancer (PD-L1+) samples, non-small cell lung cancer (with ALK fusion or ROS1 gene alteration) samples, non-small cell lung cancer (with BRAF V600E mutation) samples, non-small cell lung cancer samples (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutation), non-small cell lung cancer samples (with an EGFR T790M mutation), ovarian cancer samples, ovarian cancer samples (with a BRCA mutation), pancreatic cancer samples, pancreatic cancer samples, gastrointestinal cancer samples, lung origin neuroendocrine tumor samples, pediatric neuroblastoma samples, peripheral T-cell lymphoma samples, peritoneal cancer samples, prostate cancer samples, renal cell carcinoma samples, rheumatoid arthritis samples, small lymphocytic lymphoma samples, soft tissue sarcoma samples, solid tumor (MSLH/dMMR) samples, squamous cell cancer samples of the head and neck, squamous non-small cell lung cancer samples, thyroid cancer samples, thyroid carcinoma samples, urothelial cancer samples, urothelial carcinoma samples, Waldenstrom's macroglobulinemia samples, or any combination thereof.

[0112] At step 108 in FIG. 1, a model is fit to the empirical distribution of tumor DNA fraction values. In some instances, the model may be a probability density model. In some instances, the model may be a parametric probability density model. In some instances, the model may be a non-parametric probability density model.

[0113] At step 110 in FIG. 1, a value of tumor DNA fraction (e.g., ctDNA fraction) is determined for the sample based on the model. In some instances, the method may further comprise determining a confidence interval for the tumor DNA fraction based on the model. In some instances, the determined tumor DNA fraction for the sample may be a most probable tumor DNA fraction. In some instances, the determined tumor DNA fraction for the cfDNA sample may be the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values. [0114] In some instances, confidence intervals may be determined for the tumor DNA fraction (e.g., ctDNA fraction) based on the model. For example, a confidence interval may be calculated as the determined mean value of tumor DNA fraction (e.g., the estimated value) plus or minus a measure of the variation in that estimate (e.g., a value proportional to the standard deviation), and provides a range of tumor DNA fraction values within which one expects the determined value of tumor DNA fraction to fall with a specified level of confidence if the determination is repeated. As a non-limiting example, the confidence interval for data which follows a normal distribution is given by:

CI = X + Z^= (4) where CI is the confidence interval (e.g., 95%), X is the mean value of tumor DNA fraction determined based on the plurality of historic samples, Z is the critical value of the z-distribution (e.g., Z = 1.96 for a 95% confidence level), s is the standard deviation of tumor DNA fraction determined based on the plurality of historical samples, and N is the number of samples in the plurality of historical samples. In some instances, confidence intervals may be determined for confidence levels of, e.g., 90%, 95%, 98%, or 99%.

Methods of use

[0115] In some instances, the disclosed methods may further comprise one or more of the steps of: (i) obtaining the sample from the subject (e.g., a subject suspected of having or determined to have cancer), (ii) extracting nucleic acid molecules (e.g., a mixture of tumor nucleic acid molecules and non-tumor nucleic acid molecules) from the sample, (iii) ligating one or more adapters to the nucleic acid molecules extracted from the sample (e.g., one or more amplification primers, flow cell adaptor sequences, substrate adapter sequences, or sample index sequences), (iv) amplifying the nucleic acid molecules (e.g., using a polymerase chain reaction (PCR) amplification technique, a non-PCR amplification technique, or an isothermal amplification technique), (v) capturing nucleic acid molecules from the amplified nucleic acid molecules (e.g., by hybridization to one or more bait molecules, where the bait molecules each comprise one or more nucleic acid molecules that each comprising a region that is complementary to a region of a captured nucleic acid molecule), (vi) sequencing the nucleic acid molecules extracted from the sample (or library proxies derived therefrom) using, e.g., a next-generation (massively parallel) sequencing technique, a whole genome sequencing (WGS) technique, a whole exome sequencing technique, a targeted sequencing technique, a direct sequencing technique, or a Sanger sequencing technique) using, e.g., a next-generation (massively parallel) sequencer, and (vii) generating, displaying, transmitting, and/or delivering a report (e.g., an electronic, webbased, or paper report) to the subject (or patient), a caregiver, a healthcare provider, a physician, an oncologist, an electronic medical record system, a hospital, a clinic, a third-party payer, an insurance company, or a government office. In some instances, the report comprises output from the methods described herein. In some instances, all or a portion of the report may be displayed in the graphical user interface of an online or web-based healthcare portal. In some instances, the report is transmitted via a computer network or peer-to-peer connection.

[0116] The disclosed methods may be used with any of a variety of samples. For example, in some instances, the sample may comprise a tissue biopsy sample, a liquid biopsy sample, or a normal control. In some instances, the sample may be a liquid biopsy sample and may comprise blood, plasma, cerebrospinal fluid, sputum, stool, urine, or saliva. In some instances, the sample may be a liquid biopsy sample and may comprise circulating tumor cells (CTCs). In some instances, the sample may be a liquid biopsy sample and may comprise cell-free DNA (cfDNA), circulating tumor DNA (ctDNA), or any combination thereof.

[0117] In some instances, the nucleic acid molecules extracted from a sample may comprise a mixture of tumor nucleic acid molecules and non-tumor nucleic acid molecules. In some instances, the tumor nucleic acid molecules may be derived from a tumor portion of a heterogeneous tissue biopsy sample, and the non-tumor nucleic acid molecules may be derived from a normal portion of the heterogeneous tissue biopsy sample. In some instances, the sample may comprise a liquid biopsy sample, and the tumor nucleic acid molecules may be derived from a circulating tumor DNA (ctDNA) fraction of the liquid biopsy sample while the non-tumor nucleic acid molecules may be derived from a non-tumor, cell-free DNA (cfDNA) fraction of the liquid biopsy sample.

[0118] In some instances, the disclosed methods for determining tumor DNA fraction (e.g., ctDNA fraction) may be used to diagnose (or as part of a diagnosis of) the presence of disease or other condition (e.g., cancer, genetic disorders (such as Down Syndrome and Fragile X), neurological disorders, or any other disease type where detection of variants, e.g., copy number alternations, are relevant to diagnosing, treating, or predicting said disease) in a subject (e.g., a patient). In some instances, the disclosed methods may be applicable to diagnosis of any of a variety of cancers as described elsewhere herein.

[0119] In some instances, the disclosed methods for determining tumor DNA fraction (e.g., ctDNA fraction) may be used to select a subject (e.g., a patient) for a clinical trial based on the determined tumor DNA fraction. In some instances, patient selection for clinical trials based on, e.g., determination of tumor DNA fraction, may accelerate the development of targeted therapies and improve the healthcare outcomes for treatment decisions.

[0120] In some instances, the disclosed methods for determining tumor DNA fraction (e.g., ctDNA fraction) may be used to select an appropriate therapy or treatment (e.g., an anti-cancer therapy or anti-cancer treatment) for a subject. In some instances, for example, the anti-cancer therapy or treatment may comprise use of a poly (ADP-ribose) polymerase inhibitor (PARPi), a platinum compound, chemotherapy, radiation therapy, a targeted therapy (e.g., immunotherapy), surgery, or any combination thereof.

[0121] In some instances, the targeted therapy (or anti-cancer target therapy) may comprise abemaciclib (Verzenio), abiraterone acetate (Zytiga), acalabrutinib (Calquence), ado-trastuzumab emtansine (Kadcyla), afatinib dimaleate (Gilotrif), aldesleukin (Proleukin), alectinib (Alecensa), alemtuzumab (Campath), alitretinoin (Panretin), alpelisib (Piqray), amivantamab-vmjw (Rybrevant), anastrozole (Arimidex), apalutamide (Erleada), asciminib hydrochloride (Scemblix), atezolizumab (Tecentriq), avapritinib (Ayvakit), avelumab (Bavencio), axicabtagene ciloleucel (Yescarta), axitinib (Inlyta), belantamab mafodotin-blmf (Blenrep), belimumab (Benlysta), belinostat (Beleodaq), belzutifan (Welireg), bevacizumab (Avastin), bexarotene (Targretin), binimetinib (Mektovi), blinatumomab (Blincyto), bortezomib (Velcade), bosutinib (Bosulif), brentuximab vedotin (Adcetris), brexucabtagene autoleucel (Tecartus), brigatinib (Alunbrig), cabazitaxel (Jevtana), cabozantinib (Cabometyx), cabozantinib (Cabometyx, Cometriq), canakinumab (Haris), capmatinib hydrochloride (Tabrecta), carfilzomib (Kyprolis), cemiplimab-rwlc (Libtayo), ceritinib (LDK378/Zykadia), cetuximab (Erbitux), cobimetinib (Cotellic), copanlisib hydrochloride (Aliqopa), crizotinib (Xalkori), dabrafenib (Tafinlar), dacomitinib (Vizimpro), daratumumab (Darzalex), daratumumab and hyaluronidase-fihj (Darzalex Faspro), darolutamide (Nubeqa), dasatinib (Sprycel), denileukin diftitox (Ontak), denosumab (Xgeva), dinutuximab (Unituxin), dostarlimab-gxly (Jemperli), durvalumab (Imfinzi), duvelisib (Copiktra), elotuzumab (Empliciti), enasidenib mesylate (Idhifa), encorafenib (Braftovi), enfortumab vedotin-ejfv (Padcev), entrectinib (Rozlytrek), enzalutamide (Xtandi), erdafitinib (Balversa), erlotinib (Tarceva), everolimus (Afinitor), exemestane (Aromasin), fam-trastuzumab deruxtecan-nxki (Enhertu), fedratinib hydrochloride (Inrebic), fulvestrant (Faslodex), gefitinib (Iressa), gemtuzumab ozogamicin (Mylotarg), gilteritinib (Xospata), glasdegib maleate (Daurismo), hyaluronidase-zzxf (Phesgo), ibrutinib (Imbruvica), ibritumomab tiuxetan (Zevalin), idecabtagene vicleucel (Abecma), idelalisib (Zydelig), imatinib mesylate (Gleevec), infigratinib phosphate (Truseltiq), inotuzumab ozogamicin (Besponsa), iobenguane 1131 (Azedra), ipilimumab (Yervoy), isatuximab-irfc (Sarclisa), ivosidenib (Tibsovo), ixazomib citrate (Ninlaro), lanreotide acetate (Somatuline Depot), lapatinib (Tykerb), larotrectinib sulfate (Vitrakvi), lenvatinib mesylate (Lenvima), letrozole (Femara), lisocabtagene maraleucel (Breyanzi), loncastuximab tesirine-lpyl (Zynlonta), lorlatinib (Lorbrena), lutetium Lu 177-dotatate (Lutathera), margetuximab-cmkb (Margenza), midostaurin (Rydapt), mobocertinib succinate (Exkivity), mogamulizumab-kpkc (Poteligeo), moxetumomab pasudotox-tdfk (Lumoxiti), naxitamab-gqgk (Danyelza), necitumumab (Portrazza), neratinib maleate (Nerlynx), nilotinib (Tasigna), niraparib tosylate monohydrate (Zejula), nivolumab (Opdivo), obinutuzumab (Gazyva), ofatumumab (Arzerra), olaparib (Lynparza), olaratumab (Lartruvo), osimertinib (Tagrisso), palbociclib (Ibrance), panitumumab (Vectibix), panobinostat (Farydak), pazopanib (Votrient), pembrolizumab (Keytruda), pemigatinib (Pemazyre), pertuzumab (Perjeta), pexidartinib hydrochloride (Turalio), polatuzumab vedotin-piiq (Polivy), ponatinib hydrochloride (Iclusig), pralatrexate (Folotyn), pralsetinib (Gavreto), radium 223 dichloride (Xofigo), ramucirumab (Cyramza), regorafenib (Stivarga), ribociclib (Kisqali), ripretinib (Qinlock), rituximab (Rituxan), rituximab and hyaluronidase human (Rituxan Hycela), romidepsin (Istodax), rucaparib camsylate (Rubraca), ruxolitinib phosphate (Jakafi), sacituzumab govitecan-hziy (Trodelvy), seliciclib, selinexor (Xpovio), selpercatinib (Retevmo), selumetinib sulfate (Koselugo), siltuximab (Sylvant), sipuleucel-T (Provenge), sirolimus protein-bound particles (Fyarro), sonidegib (Odomzo), sorafenib (Nexavar), sotorasib (Lumakras), sunitinib (Sutent), tafasitamab-cxix (Monjuvi), tagraxofusp-erzs (Elzonris), talazoparib tosylate (Talzenna), tamoxifen (Nolvadex), tazemetostat hydrobromide (Tazverik), tebentafusp-tebn (Kimmtrak), temsirolimus (Torisel), tepotinib hydrochloride (Tepmetko), tisagenlecleucel (Kymriah), tisotumab vedotin-tftv (Tivdak), tocilizumab (Actemra), tofacitinib (Xeljanz), tositumomab (Bexxar), trametinib (Mekinist), trastuzumab (Herceptin), tretinoin (Vesanoid), tivozanib hydrochloride (Fotivda), toremifene (Fareston), tucatinib (Tukysa), umbralisib tosylate (Ukoniq), vandetanib (Caprelsa), vemurafenib (Zelboraf), venetoclax (Venclexta), vismodegib (Erivedge), vorinostat (Zolinza), zanubrutinib (Brukinsa), ziv-aflibercept (Zaltrap), or any combination thereof.

[0122] In some instances, the disclosed methods for determining tumor DNA fraction (e.g., ctDNA fraction) may be used in treating a disease (e.g., a cancer) in a subject. For example, in response to determining tumor DNA fraction for a sample from the subject using any of the methods disclosed herein, an effective amount of an anti-cancer therapy or anti-cancer treatment may be administered to the subject.

[0123] In some instances, the disclosed methods for determining tumor DNA fraction (e.g., ctDNA fraction) may be used for monitoring disease progression or recurrence (e.g., cancer or tumor progression or recurrence) in a subject. For example, in some instances, the methods may be used to determine tumor DNA fraction in a first sample obtained from the subject at a first time point, and used to determine tumor DNA fraction in a second sample obtained from the subject at a second time point, where comparison of the first determination of tumor DNA fraction and the second determination of tumor DNA fraction allows one to monitor disease progression or recurrence. In some instances, the first time point is chosen before the subject has been administered a therapy or treatment, and the second time point is chosen after the subject has been administered the therapy or treatment.

[0124] In some instances, the disclosed methods may be used for adjusting a therapy or treatment (e.g., an anti-cancer treatment or anti-cancer therapy) for a subject, e.g., by adjusting a treatment dose and/or selecting a different treatment in response to a change in the determination of tumor DNA fraction (e.g., ctDNA fraction).

[0125] In some instances, the value of tumor DNA fraction (e.g., ctDNA fraction) determined using the disclosed methods may be used as a prognostic or diagnostic indicator associated with the sample. For example, in some instances, the prognostic or diagnostic indicator may comprise an indicator of the presence of a disease (e.g., cancer) in the sample, an indicator of the probability that a disease (e.g., cancer) is present in the sample, an indicator of the probability that the subject from which the sample was derived will develop a disease (e.g., cancer) (z.e., a risk factor), or an indicator of the likelihood that the subject from which the sample was derived will respond to a particular therapy or treatment.

[0126] In some instances, the disclosed methods for determining tumor DNA fraction (e.g., ctDNA fraction) may be implemented as part of a genomic profiling process that comprises identification of the presence of variant sequences at one or more gene loci in a sample derived from a subject as part of detecting, monitoring, predicting a risk factor, or selecting a treatment for a particular disease, e.g., cancer. In some instances, the variant panel selected for genomic profiling may comprise the detection of variant sequences at a selected set of gene loci. In some instances, the variant panel selected for genomic profiling may comprise detection of variant sequences at a number of gene loci through comprehensive genomic profiling (CGP), which is a next-generation sequencing (NGS) approach used to assess hundreds of genes (including relevant cancer biomarkers) in a single assay. Inclusion of the disclosed methods for determining tumor DNA fraction as part of a genomic profiling process (or inclusion of the output from the disclosed methods for determining tumor DNA fraction as part of the genomic profile of the subject) can improve the validity of, e.g., disease detection calls and treatment decisions, made on the basis of the genomic profile by, for example, independently confirming the tumor DNA fraction in a given patient sample.

[0127] In some instances, a genomic profile may comprise information on the presence of genes (or variant sequences thereof), copy number variations, epigenetic traits, proteins (or modifications thereof), and/or other biomarkers in an individual’s genome and/or proteome, as well as information on the individual’s corresponding phenotypic traits and the interaction between genetic or genomic traits, phenotypic traits, and environmental factors.

[0128] In some instances, a genomic profile for the subject may comprise results from a comprehensive genomic profiling (CGP) test, a nucleic acid sequencing-based test, a gene expression profiling test, a cancer hotspot panel test, a DNA methylation test, a DNA fragmentation test, an RNA fragmentation test, or any combination thereof.

[0129] In some instances, the method can further include administering or applying a treatment or therapy (e.g., an anti-cancer agent, anti-cancer treatment, or anti-cancer therapy) to the subject based on the generated genomic profile. An anti-cancer agent or anti-cancer treatment may refer to a compound that is effective in the treatment of cancer cells. Examples of anti-cancer agents or anti-cancer therapies include, but not limited to, alkylating agents, antimetabolites, natural products, hormones, chemotherapy, radiation therapy, immunotherapy, surgery, or a therapy configured to target a defect in a specific cell signaling pathway, e.g., a defect in a DNA mismatch repair (MMR) pathway.

Samples

[0130] The disclosed methods and systems may be used with any of a variety of samples (also referred to herein as specimens) comprising nucleic acids (e.g., DNA or RNA) that are collected from a subject (e.g., a patient). Examples of a sample include, but are not limited to, a tumor sample, a tissue sample, a biopsy sample (e.g., a tissue biopsy, a liquid biopsy, or both), a blood sample (e.g., a peripheral whole blood sample), a blood plasma sample, a blood serum sample, a lymph sample, a saliva sample, a sputum sample, a urine sample, a gynecological fluid sample, a circulating tumor cell (CTC) sample, a cerebral spinal fluid (CSF) sample, a pericardial fluid sample, a pleural fluid sample, an ascites (peritoneal fluid) sample, a feces (or stool) sample, or other body fluid, secretion, and/or excretion sample (or cell sample derived therefrom). In certain instances, the sample may be frozen sample or a formalin-fixed paraffin-embedded (FFPE) sample.

[0131] In some instances, the sample may be collected by tissue resection (e.g., surgical resection), needle biopsy, bone marrow biopsy, bone marrow aspiration, skin biopsy, endoscopic biopsy, fine needle aspiration, oral swab, nasal swab, vaginal swab or a cytology smear, scrapings, washings or lavages (such as a ductal lavage or bronchoalveolar lavage), etc.

[0132] In some instances, the sample is a liquid biopsy sample, and may comprise, e.g., whole blood, blood plasma, blood serum, urine, stool, sputum, saliva, or cerebrospinal fluid. In some instances, the sample may be a liquid biopsy sample and may comprise circulating tumor cells (CTCs). In some instances, the sample may be a liquid biopsy sample and may comprise cell- free DNA (cfDNA), circulating tumor DNA (ctDNA), or any combination thereof.

[0133] In some instances, the sample may comprise one or more premalignant or malignant cells. Premalignant, as used herein, refers to a cell or tissue that is not yet malignant but is poised to become malignant. In certain instances, the sample may be acquired from a solid tumor, a soft tissue tumor, or a metastatic lesion. In certain instances, the sample may be acquired from a hematologic malignancy or pre-malignancy. In other instances, the sample may comprise a tissue or cells from a surgical margin. In certain instances, the sample may comprise tumor-infiltrating lymphocytes. In some instances, the sample may comprise one or more non- malignant cells. In some instances, the sample may be, or is part of, a primary tumor or a metastasis (e.g., a metastasis biopsy sample). In some instances, the sample may be obtained from a site (e.g., a tumor site) with the highest percentage of tumor (e.g., tumor cells) as compared to adjacent sites (e.g., sites adjacent to the tumor). In some instances, the sample may be obtained from a site (e.g., a tumor site) with the largest tumor focus (e.g., the largest number of tumor cells as visualized under a microscope) as compared to adjacent sites (e.g., sites adjacent to the tumor).

[0134] In some instances, the disclosed methods may further comprise analyzing a primary control (e.g., a normal tissue sample). In some instances, the disclosed methods may further comprise determining if a primary control is available and, if so, isolating a control nucleic acid (e.g., DNA) from said primary control. In some instances, the sample may comprise any normal control (e.g., a normal adjacent tissue (NAT)) if no primary control is available. In some instances, the sample may be or may comprise histologically normal tissue. In some instances, the method includes evaluating a sample, e.g., a histologically normal sample (e.g., from a surgical tissue margin) using the methods described herein. In some instances, the disclosed methods may further comprise acquiring a sub-sample enriched for non-tumor cells, e.g., by macro-dissecting non-tumor tissue from said NAT in a sample not accompanied by a primary control. In some instances, the disclosed methods may further comprise determining that no primary control and no NAT is available, and marking said sample for analysis without a matched control. [0135] In some instances, samples obtained from histologically normal tissues (e.g., otherwise histologically normal surgical tissue margins) may still comprise a genetic alteration such as a variant sequence as described herein. The methods may thus further comprise re-classifying a sample based on the presence of the detected genetic alteration. In some instances, multiple samples (e.g., from different subjects) are processed simultaneously.

[0136] The disclosed methods and systems may be applied to the analysis of nucleic acids extracted from any of variety of tissue samples (or disease states thereof), e.g., solid tissue samples, soft tissue samples, metastatic lesions, or liquid biopsy samples. Examples of tissues include, but are not limited to, connective tissue, muscle tissue, nervous tissue, epithelial tissue, and blood. Tissue samples may be collected from any of the organs within an animal or human body. Examples of human organs include, but are not limited to, the brain, heart, lungs, liver, kidneys, pancreas, spleen, thyroid, mammary glands, uterus, prostate, large intestine, small intestine, bladder, bone, skin, etc.

[0137] In some instances, the nucleic acids extracted from the sample may comprise deoxyribonucleic acid (DNA) molecules. Examples of DNA that may be suitable for analysis by the disclosed methods include, but are not limited to, genomic DNA or fragments thereof, mitochondrial DNA or fragments thereof, cell-free DNA (cfDNA), and circulating tumor DNA (ctDNA). Cell-free DNA (cfDNA) is comprised of fragments of DNA that are released from normal and/or cancerous cells during apoptosis and necrosis, and circulate in the blood stream and/or accumulate in other bodily fluids. Circulating tumor DNA (ctDNA) is comprised of fragments of DNA that are released from cancerous cells and tumors that circulate in the blood stream and/or accumulate in other bodily fluids.

[0138] In some instances, DNA is extracted from nucleated cells from the sample. In some instances, a sample may have a low nucleated cellularity, e.g., when the sample is comprised mainly of erythrocytes, lesional cells that contain excessive cytoplasm, or tissue with fibrosis. In some instances, a sample with low nucleated cellularity may require more, e.g., greater, tissue volume for DNA extraction.

[0139] In some instances, the nucleic acids extracted from the sample may comprise ribonucleic acid (RNA) molecules. Examples of RNA that may be suitable for analysis by the disclosed methods include, but are not limited to, total cellular RNA, total cellular RNA after depletion of certain abundant RNA sequences (e.g., ribosomal RNAs), cell-free RNA (cfRNA), messenger RNA (mRNA) or fragments thereof, the poly(A)-tailed mRNA fraction of the total RNA, ribosomal RNA (rRNA) or fragments thereof, transfer RNA (tRNA) or fragments thereof, and mitochondrial RNA or fragments thereof. In some instances, RNA may be extracted from the sample and converted to complementary DNA (cDNA) using, e.g., a reverse transcription reaction. In some instances, the cDNA is produced by random-primed cDNA synthesis methods. In other instances, the cDNA synthesis is initiated at the poly(A) tail of mature mRNAs by priming with oligo(dT)-containing oligonucleotides. Methods for depletion, poly(A) enrichment, and cDNA synthesis are well known to those of skill in the art.

[0140] In some instances, the sample may comprise a tumor content (e.g., comprising tumor cells or tumor cell nuclei), or a non-tumor content (e.g., immune cells, fibroblasts, and other nontumor cells). In some instances, the tumor content of the sample may constitute a sample metric. In some instances, the sample may comprise a tumor content of at least 5-50%, 10-40%, 15-25%, or 20-30% tumor cell nuclei. In some instances, the sample may comprise a tumor content of at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, or at least 50% tumor cell nuclei. In some instances, the percent tumor cell nuclei (e.g., sample fraction) is determined (e.g., calculated) by dividing the number of tumor cells in the sample by the total number of all cells within the sample that have nuclei. In some instances, for example when the sample is a liver sample comprising hepatocytes, a different tumor content calculation may be required due to the presence of hepatocytes having nuclei with twice, or more than twice, the DNA content of other, e.g., non-hepatocyte, somatic cell nuclei. In some instances, the sensitivity of detection of a genetic alteration, e.g., a variant sequence, or a determination of, e.g., micro satellite instability, may depend on the tumor content of the sample. For example, a sample having a lower tumor content can result in lower sensitivity of detection for a given size sample.

[0141] In some instances, as noted above, the sample comprises nucleic acid (e.g., DNA, RNA (or a cDNA derived from the RNA), or both), e.g., from a tumor or from normal tissue. In certain instances, the sample may further comprise a non-nucleic acid component, e.g., cells, protein, carbohydrate, or lipid, e.g., from the tumor or normal tissue. Subjects

[0142] In some instances, the sample is obtained (e.g., collected) from a subject (e.g., patient) with a condition or disease (e.g., a hyperproliferative disease or a non-cancer indication) or suspected of having the condition or disease. In some instances, the hyperproliferative disease is a cancer. In some instances, the cancer is a solid tumor or a metastatic form thereof. In some instances, the cancer is a hematological cancer, e.g., a leukemia or lymphoma.

[0143] In some instances, the subject has a cancer or is at risk of having a cancer. For example, in some instances, the subject has a genetic predisposition to a cancer (e.g., having a genetic mutation that increases his or her baseline risk for developing a cancer). In some instances, the subject has been exposed to an environmental perturbation (e.g., radiation or a chemical) that increases his or her risk for developing a cancer. In some instances, the subject is in need of being monitored for development of a cancer. In some instances, the subject is in need of being monitored for cancer progression or regression, e.g., after being treated with an anti-cancer therapy (or anti-cancer treatment). In some instances, the subject is in need of being monitored for relapse of cancer. In some instances, the subject is in need of being monitored for minimum residual disease (MRD). In some instances, the subject has been, or is being treated, for cancer. In some instances, the subject has not been treated with an anti-cancer therapy (or anti-cancer treatment).

[0144] In some instances, the subject (e.g., a patient) is being treated, or has been previously treated, with one or more targeted therapies. In some instances, e.g., for a patient who has been previously treated with a targeted therapy, a post-targeted therapy sample (e.g., specimen) is obtained (e.g., collected). In some instances, the post-targeted therapy sample is a sample obtained after the completion of the targeted therapy.

[0145] In some instances, the patient has not been previously treated with a targeted therapy. In some instances, e.g., for a patient who has not been previously treated with a targeted therapy, the sample comprises a resection, e.g., an original resection, or a resection following recurrence (e.g., following a disease recurrence post-therapy). Cancers

[0146] In some instances, the sample is acquired from a subject having a cancer. Exemplary cancers include, but are not limited to, B cell cancer (e.g., multiple myeloma), melanomas, breast cancer, lung cancer (such as non-small cell lung carcinoma or NSCLC), bronchus cancer, colorectal cancer, prostate cancer, pancreatic cancer, stomach cancer, ovarian cancer, urinary bladder cancer, brain or central nervous system cancer, peripheral nervous system cancer, esophageal cancer, cervical cancer, uterine or endometrial cancer, cancer of the oral cavity or pharynx, liver cancer, kidney cancer, testicular cancer, biliary tract cancer, small bowel or appendix cancer, salivary gland cancer, thyroid gland cancer, adrenal gland cancer, osteosarcoma, chondrosarcoma, cancer of hematological tissues, adenocarcinomas, inflammatory myofibroblastic tumors, gastrointestinal stromal tumor (GIST), colon cancer, multiple myeloma (MM), myelodysplastic syndrome (MDS), myeloproliferative disorder (MPD), acute lymphocytic leukemia (ALL), acute myelocytic leukemia (AML), chronic myelocytic leukemia (CML), chronic lymphocytic leukemia (CLL), polycythemia Vera, Hodgkin lymphoma, nonHodgkin lymphoma (NHL), soft-tissue sarcoma, fibrosarcoma, myxosarcoma, liposarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endothelio sarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilms' tumor, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, meningioma, neuroblastoma, retinoblastoma, follicular lymphoma, diffuse large B-cell lymphoma, mantle cell lymphoma, hepatocellular carcinoma, thyroid cancer, gastric cancer, head and neck cancer, small cell cancers, essential thrombocythemia, agnogenic myeloid metaplasia, hypereosinophilic syndrome, systemic mastocytosis, familiar hypereosinophilia, chronic eosinophilic leukemia, neuroendocrine cancers, carcinoid tumors, and the like.

[0147] In some instances, the cancer comprises acute lymphoblastic leukemia (Philadelphia chromosome positive), acute lymphoblastic leukemia (precursor B-cell), acute myeloid leukemia (FLT3+), acute myeloid leukemia (with an IDH2 mutation), anaplastic large cell lymphoma, basal cell carcinoma, B-cell chronic lymphocytic leukemia, bladder cancer, breast cancer (HER2 overexpressed/amplified), breast cancer (HER2+), breast cancer (HR+, HER2-), cervical cancer, cholangiocarcinoma, chronic lymphocytic leukemia, chronic lymphocytic leukemia (with 17p deletion), chronic myelogenous leukemia, chronic myelogenous leukemia (Philadelphia chromosome positive), classical Hodgkin lymphoma, colorectal cancer, colorectal cancer (dMMR and MSI-H), colorectal cancer (KRAS wild type), cryopyrin-associated periodic syndrome, a cutaneous T-cell lymphoma, dermato fibrosarcoma protuberans, a diffuse large B- cell lymphoma, fallopian tube cancer, a follicular B-cell non-Hodgkin lymphoma, a follicular lymphoma, gastric cancer, gastric cancer (HER2+), a gastroesophageal junction (GEJ) adenocarcinoma, a gastrointestinal stromal tumor, a gastrointestinal stromal tumor (KIT+), a giant cell tumor of the bone, a glioblastoma, granulomatosis with polyangiitis, a head and neck squamous cell carcinoma, a hepatocellular carcinoma, Hodgkin lymphoma, juvenile idiopathic arthritis, lupus erythematosus, a mantle cell lymphoma, medullary thyroid cancer, melanoma, a melanoma with a BRAF V600 mutation, a melanoma with a BRAF V600E or V600K mutation, Merkel cell carcinoma, multicentric Castleman's disease, multiple hematologic malignancies including Philadelphia chromosome-positive ALL and CML, multiple myeloma, myelofibrosis, a non-Hodgkin’ s lymphoma, a nonresectable subependymal giant cell astrocytoma associated with tuberous sclerosis, a non-small cell lung cancer, a non-small cell lung cancer (ALK+), a non-small cell lung cancer (PD-L1+), a non-small cell lung cancer (with ALK fusion or ROS1 gene alteration), a non-small cell lung cancer (with BRAF V600E mutation), a non-small cell lung cancer (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutations), a non- small cell lung cancer (with an EGFR T790M mutation), ovarian cancer, ovarian cancer (with a BRCA mutation), pancreatic cancer, a pancreatic, gastrointestinal, or lung origin neuroendocrine tumor, a pediatric neuroblastoma, a peripheral T-cell lymphoma, peritoneal cancer, prostate cancer, a renal cell carcinoma, rheumatoid arthritis, a small lymphocytic lymphoma, a soft tissue sarcoma, a solid tumor (MSLH/dMMR), a squamous cell cancer of the head and neck, a squamous non-small cell lung cancer, thyroid cancer, a thyroid carcinoma, urothelial cancer, a urothelial carcinoma, or Waldenstrom's macroglobulinemia. [0148] In some instances, the cancer is a hematologic malignancy (or premaligancy). As used herein, a hematologic malignancy refers to a tumor of the hematopoietic or lymphoid tissues, e.g., a tumor that affects blood, bone marrow, or lymph nodes. Exemplary hematologic malignancies include, but are not limited to, leukemia (e.g., acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), hairy cell leukemia, acute monocytic leukemia (AMoL), chronic myelomonocytic leukemia (CMML), juvenile myelomonocytic leukemia (JMML), or large granular lymphocytic leukemia), lymphoma (e.g., AIDS-related lymphoma, cutaneous T-cell lymphoma, Hodgkin lymphoma (e.g., classical Hodgkin lymphoma or nodular lymphocyte- predominant Hodgkin lymphoma), mycosis fungoides, non-Hodgkin lymphoma (e.g., B-cell non-Hodgkin lymphoma (e.g., Burkitt lymphoma, small lymphocytic lymphoma (CLL/SLL), diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B -lymphoblastic lymphoma, or mantle cell lymphoma) or T-cell non-Hodgkin lymphoma (mycosis fungoides, anaplastic large cell lymphoma, or precursor T-lymphoblastic lymphoma)), primary central nervous system lymphoma, Sezary syndrome, Waldenstrom macroglobulinemia), chronic myeloproliferative neoplasm, Langerhans cell histiocytosis, multiple myeloma/plasma cell neoplasm, myelodysplastic syndrome, or myelodysplastic/myeloproliferative neoplasm.

Nucleic acid extraction and processing

[0149] DNA or RNA may be extracted from tissue samples, biopsy samples, blood samples, or other bodily fluid samples using any of a variety of techniques known to those of skill in the art (see, e.g., Example 1 of International Patent Application Publication No. WO 2012/092426; Tan, et al. (2009), “DNA, RNA, and Protein Extraction: The Past and The Present”, J. Biomed. Biotech. 2009:574398; the technical literature for the Maxwell® 16 LEV Blood DNA Kit (Promega Corporation, Madison, WI); and the Maxwell 16 Buccal Swab LEV DNA Purification Kit Technical Manual (Promega Literature #TM333, January 1, 2011, Promega Corporation, Madison, WI)). Protocols for RNA isolation are disclosed in, e.g., the Maxwell® 16 Total RNA Purification Kit Technical Bulletin (Promega Literature #TB351, August 2009, Promega Corporation, Madison, WI). [0150] A typical DNA extraction procedure, for example, comprises (i) collection of the fluid sample, cell sample, or tissue sample from which DNA is to be extracted, (ii) disruption of cell membranes (z.e., cell lysis), if necessary, to release DNA and other cytoplasmic components, (iii) treatment of the fluid sample or lysed sample with a concentrated salt solution to precipitate proteins, lipids, and RNA, followed by centrifugation to separate out the precipitated proteins, lipids, and RNA, and (iv) purification of DNA from the supernatant to remove detergents, proteins, salts, or other reagents used during the cell membrane lysis step.

[0151] Disruption of cell membranes may be performed using a variety of mechanical shear (e.g., by passing through a French press or fine needle) or ultrasonic disruption techniques. The cell lysis step often comprises the use of detergents and surfactants to solubilize lipids the cellular and nuclear membranes. In some instances, the lysis step may further comprise use of proteases to break down protein, and/or the use of an RNase for digestion of RNA in the sample.

[0152] Examples of suitable techniques for DNA purification include, but are not limited to, (i) precipitation in ice-cold ethanol or isopropanol, followed by centrifugation (precipitation of DNA may be enhanced by increasing ionic strength, e.g., by addition of sodium acetate), (ii) phenol-chloroform extraction, followed by centrifugation to separate the aqueous phase containing the nucleic acid from the organic phase containing denatured protein, and (iii) solid phase chromatography where the nucleic acids adsorb to the solid phase (e.g., silica or other) depending on the pH and salt concentration of the buffer.

[0153] In some instances, cellular and histone proteins bound to the DNA may be removed either by adding a protease or by having precipitated the proteins with sodium or ammonium acetate, or through extraction with a phenol-chloroform mixture prior to a DNA precipitation step.

[0154] In some instances, DNA may be extracted using any of a variety of suitable commercial DNA extraction and purification kits. Examples include, but are not limited to, the QIAamp (for isolation of genomic DNA from human samples) and DNAeasy (for isolation of genomic DNA from animal or plant samples) kits from Qiagen (Germantown, MD) or the Maxwell® and ReliaPrep™ series of kits from Promega (Madison, WI). [0155] As noted above, in some instances the sample may comprise a formalin-fixed (also known as formaldehyde-fixed, or paraformaldehyde-fixed), paraffin-embedded (FFPE) tissue preparation. For example, the FFPE sample may be a tissue sample embedded in a matrix, e.g., an FFPE block. Methods to isolate nucleic acids (e.g., DNA) from formaldehyde- or paraformaldehyde-fixed, paraffin-embedded (FFPE) tissues are disclosed in, e.g., Cronin, et al., (2004) Am J Pathol. 164(l):35-42; Masuda, et al., (1999) Nucleic Acids Res. 27(22): 4436-4443; Specht, et al., (2001) Am J Pathol. 158(2):419-429; the Ambion RecoverAll™ Total Nucleic Acid Isolation Protocol (Ambion, Cat. No. AM1975, September 2008); the Maxwell® 16 FFPE Plus LEV DNA Purification Kit Technical Manual (Promega Literature #TM349, February 2011); the E.Z.N.A.® FFPE DNA Kit Handbook (OMEGA bio-tek, Norcross, GA, product numbers D3399-00, D3399-01, and D3399-02, June 2009); and the QIAamp® DNA FFPE Tissue Handbook (Qiagen, Cat. No. 37625, October 2007). For example, the RecoverAll™ Total Nucleic Acid Isolation Kit uses xylene at elevated temperatures to solubilize paraffin- embedded samples and a glass-fiber filter to capture nucleic acids. The Maxwell® 16 FFPE Plus LEV DNA Purification Kit is used with the Maxwell® 16 Instrument for purification of genomic DNA from 1 to 10 pm sections of FFPE tissue. DNA is purified using silica-clad paramagnetic particles (PMPs), and eluted in low elution volume. The E.Z.N.A.® FFPE DNA Kit uses a spin column and buffer system for isolation of genomic DNA. QIAamp® DNA FFPE Tissue Kit uses QIAamp® DNA Micro technology for purification of genomic and mitochondrial DNA.

[0156] In some instances, the disclosed methods may further comprise determining or acquiring a yield value for the nucleic acid extracted from the sample and comparing the determined value to a reference value. For example, if the determined or acquired value is less than the reference value, the nucleic acids may be amplified prior to proceeding with library construction. In some instances, the disclosed methods may further comprise determining or acquiring a value for the size (or average size) of nucleic acid fragments in the sample, and comparing the determined or acquired value to a reference value, e.g., a size (or average size) of at least 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 base pairs (bps). In some instances, one or more parameters described herein may be adjusted or selected in response to this determination.

[0157] After isolation, the nucleic acids are typically dissolved in a slightly alkaline buffer, e.g., Tris-EDTA (TE) buffer, or in ultra-pure water. In some instances, the isolated nucleic acids (e.g., genomic DNA) may be fragmented or sheared by using any of a variety of techniques known to those of skill in the art. For example, genomic DNA can be fragmented by physical shearing methods, enzymatic cleavage methods, chemical cleavage methods, and other methods known to those of skill in the art. Methods for DNA shearing are described in Example 4 in International Patent Application Publication No. WO 2012/092426. In some instances, alternatives to DNA shearing methods can be used to avoid a ligation step during library preparation.

Library preparation

[0158] In some instances, the nucleic acids isolated from the sample may be used to construct a library (e.g., a nucleic acid library as described herein). In some instances, the nucleic acids are fragmented using any of the methods described above, optionally subjected to repair of chain end damage, and optionally ligated to synthetic adapters, primers, and/or barcodes (e.g., amplification primers, sequencing adapters, flow cell adapters, substrate adapters, sample barcodes or indexes, and/or unique molecular identifier sequences), size-selected (e.g., by preparative gel electrophoresis), and/or amplified (e.g., using PCR, a non-PCR amplification technique, or an isothermal amplification technique). In some instances, the fragmented and adapter-ligated group of nucleic acids is used without explicit size selection or amplification prior to hybridization-based selection of target sequences. In some instances, the nucleic acid is amplified by any of a variety of specific or non-specific nucleic acid amplification methods known to those of skill in the art. In some instances, the nucleic acids are amplified, e.g., by a whole-genome amplification method such as random-primed strand-displacement amplification. Examples of nucleic acid library preparation techniques for next-generation sequencing are described in, e.g., van Dijk, et al. (2014), Exp. Cell Research 322: 12 - 20, and Illumina’s genomic DNA sample preparation kit.

[0159] In some instances, the resulting nucleic acid library may contain all or substantially all of the complexity of the genome. The term “substantially all” in this context refers to the possibility that there can in practice be some unwanted loss of genome complexity during the initial steps of the procedure. The methods described herein also are useful in cases where the nucleic acid library comprises a portion of the genome, e.g., where the complexity of the genome is reduced by design. In some instances, any selected portion of the genome can be used with a method described herein. For example, in certain embodiments, the entire exome or a subset thereof is isolated. In some instances, the library may include at least 95%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, or 5% of the genomic DNA. In some instances, the library may consist of cDNA copies of genomic DNA that includes copies of at least 95%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, or 5% of the genomic DNA. In certain instances, the amount of nucleic acid used to generate the nucleic acid library may be less than 5 micrograms, less than 1 microgram, less than 500 ng, less than 200 ng, less than 100 ng, less than 50 ng, less than 10 ng, less than 5 ng, or less than 1 ng.

[0160] In some instances, a library (e.g., a nucleic acid library) includes a collection of nucleic acid molecules. As described herein, the nucleic acid molecules of the library can include a target nucleic acid molecule (e.g., a tumor nucleic acid molecule, a reference nucleic acid molecule and/or a control nucleic acid molecule; also referred to herein as a first, second and/or third nucleic acid molecule, respectively). The nucleic acid molecules of the library can be from a single subject or individual. In some instances, a library can comprise nucleic acid molecules derived from more than one subject (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30 or more subjects). For example, two or more libraries from different subjects can be combined to form a library having nucleic acid molecules from more than one subject (where the nucleic acid molecules derived from each subject are optionally ligated to a unique sample barcode corresponding to a specific subject). In some instances, the subject is a human having, or at risk of having, a cancer or tumor.

[0161] In some instances, the library (or a portion thereof) may comprise one or more subgenomic intervals. In some instances, a subgenomic interval can be a single nucleotide position, e.g., a nucleotide position for which a variant at the position is associated (positively or negatively) with a tumor phenotype. In some instances, a subgenomic interval comprises more than one nucleotide position. Such instances include sequences of at least 2, 5, 10, 50, 100, 150, 250, or more than 250 nucleotide positions in length. Subgenomic intervals can comprise, e.g., one or more entire genes (or portions thereof), one or more exons or coding sequences (or portions thereof), one or more introns (or portion thereof), one or more microsatellite region (or portions thereof), or any combination thereof. A subgenomic interval can comprise all or a part of a fragment of a naturally occurring nucleic acid molecule, e.g., a genomic DNA molecule. For example, a subgenomic interval can correspond to a fragment of genomic DNA which is subjected to a sequencing reaction. In some instances, a subgenomic interval is a continuous sequence from a genomic source. In some instances, a subgenomic interval includes sequences that are not contiguous in the genome, e.g., subgenomic intervals in cDNA can include exonexonjunctions formed as a result of splicing. In some instances, the subgenomic interval comprises a tumor nucleic acid molecule. In some instances, the subgenomic interval comprises a non-tumor nucleic acid molecule.

Targeting gene loci for analysis

[0162] The methods described herein can be used in combination with, or as part of, a method for evaluating a plurality or set of subject intervals (e.g., target sequences), e.g., from a set of genomic loci (e.g., gene loci or fragments thereof), as described herein.

[0163] In some instances, the set of genomic loci evaluated by the disclosed methods comprises a plurality of, e.g., genes, which in mutant form, are associated with an effect on cell division, growth or survival, or are associated with a cancer, e.g., a cancer described herein.

[0164] In some instances, the set of gene loci evaluated by the disclosed methods comprises at least 1, at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, or more than 100 gene loci.

[0165] In some instances, the selected gene loci (also referred to herein as target gene loci or target sequences), or fragments thereof, may include subject intervals comprising non-coding sequences, coding sequences, intragenic regions, or intergenic regions of the subject genome. For example, the subject intervals can include a non-coding sequence or fragment thereof (e.g., a promoter sequence, enhancer sequence, 5’ untranslated region (5’ UTR), 3’ untranslated region (3’ UTR), or a fragment thereof), a coding sequence of fragment thereof, an exon sequence or fragment thereof, an intron sequence or a fragment thereof. Target capture reagents

[0166] The methods described herein may comprise contacting a nucleic acid library with a plurality of target capture reagents in order to select and capture a plurality of specific target sequences (e.g., gene sequences or fragments thereof) for analysis. In some instances, a target capture reagent (z.e., a molecule which can bind to and thereby allow capture of a target molecule) is used to select the subject intervals to be analyzed. For example, a target capture reagent can be a bait molecule, e.g., a nucleic acid molecule (e.g., a DNA molecule or RNA molecule) which can hybridize to (z.e., is complementary to) a target molecule, and thereby allows capture of the target nucleic acid. In some instances, the target capture reagent, e.g., a bait molecule (or bait sequence), is a capture oligonucleotide (or capture probe). In some instances, the target nucleic acid is a genomic DNA molecule, an RNA molecule, a cDNA molecule derived from an RNA molecule, a microsatellite DNA sequence, and the like. In some instances, the target capture reagent is suitable for solution-phase hybridization to the target. In some instances, the target capture reagent is suitable for solid-phase hybridization to the target. In some instances, the target capture reagent is suitable for both solution-phase and solid-phase hybridization to the target. The design and construction of target capture reagents is described in more detail in, e.g., International Patent Application Publication No. WO 2020/236941, the entire content of which is incorporated herein by reference.

[0167] The methods described herein provide for optimized sequencing of a large number of genomic loci (e.g., genes or gene products (e.g., mRNA), micro satellite loci, etc.) from samples (e.g., cancerous tissue specimens, liquid biopsy samples, and the like) from one or more subjects by the appropriate selection of target capture reagents to select the target nucleic acid molecules to be sequenced. In some instances, a target capture reagent may hybridize to a specific target locus, e.g., a specific target gene locus or fragment thereof. In some instances, a target capture reagent may hybridize to a specific group of target loci, e.g., a specific group of gene loci or fragments thereof. In some instances, a plurality of target capture reagents comprising a mix of target- specific and/or group- specific target capture reagents may be used.

[0168] In some instances, the number of target capture reagents (e.g., bait molecules) in the plurality of target capture reagents (e.g., a bait set) contacted with a nucleic acid library to capture a plurality of target sequences for nucleic acid sequencing is greater than 10, greater than 50, greater than 100, greater than 200, greater than 300, greater than 400, greater than 500, greater than 600, greater than 700, greater than 800, greater than 900, greater than 1,000, greater than 1,250, greater than 1,500, greater than 1,750, greater than 2,000, greater than 3,000, greater than 4,000, greater than 5,000, greater than 10,000, greater than 25,000, or greater than 50,000.

[0169] In some instances, the overall length of the target capture reagent sequence can be between about 70 nucleotides and 1000 nucleotides. In one instance, the target capture reagent length is between about 100 and 300 nucleotides, 110 and 200 nucleotides, or 120 and 170 nucleotides, in length. In addition to those mentioned above, intermediate oligonucleotide lengths of about 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 300, 400, 500, 600, 700, 800, and 900 nucleotides in length can be used in the methods described herein. In some embodiments, oligonucleotides of about 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, or 230 bases can be used.

[0170] In some instances, each target capture reagent sequence can include: (i) a target- specific capture sequence (e.g., a gene locus or micro satellite locus-specific complementary sequence), (ii) an adapter, primer, barcode, and/or unique molecular identifier sequence, and (iii) universal tails on one or both ends. As used herein, the term "target capture reagent" can refer to the targetspecific target capture sequence or to the entire target capture reagent oligonucleotide including the target- specific target capture sequence.

[0171] In some instances, the target- specific capture sequences in the target capture reagents are between about 40 nucleotides and 1000 nucleotides in length. In some instances, the targetspecific capture sequence is between about 70 nucleotides and 300 nucleotides in length. In some instances, the target- specific sequence is between about 100 nucleotides and 200 nucleotides in length. In yet other instances, the target- specific sequence is between about 120 nucleotides and 170 nucleotides in length, typically 120 nucleotides in length. Intermediate lengths in addition to those mentioned above also can be used in the methods described herein, such as target-specific sequences of about 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 300, 400, 500, 600, 700, 800, and 900 nucleotides in length, as well as target- specific sequences of lengths between the above-mentioned lengths. [0172] In some instances, the target capture reagent may be designed to select a subject interval containing one or more rearrangements, e.g., an intron containing a genomic rearrangement. In such instances, the target capture reagent is designed such that repetitive sequences are masked to increase the selection efficiency. In those instances where the rearrangement has a known juncture sequence, complementary target capture reagents can be designed to recognize the juncture sequence to increase the selection efficiency.

[0173] In some instances, the disclosed methods may comprise the use of target capture reagents designed to capture two or more different target categories, each category having a different target capture reagent design strategy. In some instances, the hybridization-based capture methods and target capture reagent compositions disclosed herein may provide for the capture and homogeneous coverage of a set of target sequences, while minimizing coverage of genomic sequences outside of the targeted set of sequences. In some instances, the target sequences may include the entire exome of genomic DNA or a selected subset thereof. In some instances, the target sequences may include, e.g., a large chromosomal region (e.g., a whole chromosome arm). The methods and compositions disclosed herein provide different target capture reagents for achieving different sequencing depths and patterns of coverage for complex sets of target nucleic acid sequences.

[0174] Typically, DNA molecules are used as target capture reagent sequences, although RNA molecules can also be used. In some instances, a DNA molecule target capture reagent can be single stranded DNA (ssDNA) or double- stranded DNA (dsDNA). In some instances, an RNA- DNA duplex is more stable than a DNA-DNA duplex and therefore provides for potentially better capture of nucleic acids.

[0175] In some instances, the disclosed methods comprise providing a selected set of nucleic acid molecules (e.g., a library catch) captured from one or more nucleic acid libraries. For example, the method may comprise: providing one or a plurality of nucleic acid libraries, each comprising a plurality of nucleic acid molecules (e.g., a plurality of target nucleic acid molecules and/or reference nucleic acid molecules) extracted from one or more samples from one or more subjects; contacting the one or a plurality of libraries (e.g., in a solution-based hybridization reaction) with one, two, three, four, five, or more than five pluralities of target capture reagents (e.g., oligonucleotide target capture reagents) to form a hybridization mixture comprising a plurality of target capture reagent/nucleic acid molecule hybrids; separating the plurality of target capture reagent/nucleic acid molecule hybrids from said hybridization mixture, e.g., by contacting said hybridization mixture with a binding entity that allows for separation of said plurality of target capture reagent/nucleic acid molecule hybrids from the hybridization mixture, thereby providing a library catch (e.g., a selected or enriched subgroup of nucleic acid molecules from the one or a plurality of libraries).

[0176] In some instances, the disclosed methods may further comprise amplifying the library catch (e.g., by performing PCR). In other instances, the library catch is not amplified.

[0177] In some instances, the target capture reagents can be part of a kit which can optionally comprise instructions, standards, buffers or enzymes or other reagents.

Hybridization conditions

[0178] As noted above, the methods disclosed herein may include the step of contacting the library (e.g., the nucleic acid library) with a plurality of target capture reagents to provide a selected library target nucleic acid sequences (i.e., the library catch). The contacting step can be effected in, e.g., solution-based hybridization. In some instances, the method includes repeating the hybridization step for one or more additional rounds of solution-based hybridization. In some instances, the method further includes subjecting the library catch to one or more additional rounds of solution-based hybridization with the same or a different collection of target capture reagents.

[0179] In some instances, the contacting step is effected using a solid support, e.g., an array. Suitable solid supports for hybridization are described in, e.g., Albert, T.J. et al. (2007) Nat. Methods 4(11):903-5; Hodges, E. et al. (2007) Nat. Genet. 39(12): 1522-7; and Okou, D.T. et al. (2007) Nat. Methods 4(11 ):907-9, the contents of which are incorporated herein by reference in their entireties.

[0180] Hybridization methods that can be adapted for use in the methods herein are described in the art, e.g., as described in International Patent Application Publication No. WO 2012/092426. Methods for hybridizing target capture reagents to a plurality of target nucleic acids are described in more detail in, e.g., International Patent Application Publication No. WO 2020/236941, the entire content of which is incorporated herein by reference.

Sequencing methods

[0181] The methods and systems disclosed herein can be used in combination with, or as part of, a method or system for sequencing nucleic acids (e.g., a next-generation sequencing system) to generate a plurality of sequence reads that overlap one or more gene loci within a subgenomic interval in the sample and thereby determine, e.g., gene allele sequences at a plurality of gene loci. “Next-generation sequencing” (or “NGS”) as used herein may also be referred to as “massively parallel sequencing” (or “MPS”), and refers to any sequencing method that determines the nucleotide sequence of either individual nucleic acid molecules (e.g., as in single molecule sequencing) or clonally expanded proxies for individual nucleic acid molecules in a high throughput fashion (e.g., wherein greater than 10 ³ , 10 ⁴ , 10 ⁵ or more than 10 ⁵ molecules are sequenced simultaneously).

[0182] Next-generation sequencing methods are known in the art, and are described in, e.g., Metzker, M. (2010) Nature Biotechnology Reviews 11:31-46, which is incorporated herein by reference. Other examples of sequencing methods suitable for use when implementing the methods and systems disclosed herein are described in, e.g., International Patent Application Publication No. WO 2012/092426. In some instances, the sequencing may comprise, for example, whole genome sequencing (WGS), whole exome sequencing, targeted sequencing, or direct sequencing. In some instances, sequencing may be performed using, e.g., Sanger sequencing. In some instances, the sequencing may comprise a paired-end sequencing technique that allows both ends of a fragment to be sequenced and generates high-quality, alignable sequence data for detection of, e.g., genomic rearrangements, repetitive sequence elements, gene fusions, and novel transcripts.

[0183] The disclosed methods and systems may be implemented using sequencing platforms such as the Roche 454, Illumina Solexa, ABI-SOLiD, ION Torrent, Complete Genomics, Pacific Bioscience, Helicos, and/or the Polonator platform. In some instances, sequencing may comprise Illumina MiSeq sequencing. In some instances, sequencing may comprise Illumina HiSeq sequencing. In some instances, sequencing may comprise Illumina NovaSeq sequencing. Optimized methods for sequencing a large number of target genomic loci in nucleic acids extracted from a sample are described in more detail in, e.g., International Patent Application Publication No. WO 2020/236941, the entire content of which is incorporated herein by reference.

[0184] In certain instances, the disclosed methods comprise one or more of the steps of: (a) acquiring a library comprising a plurality of normal and/or tumor nucleic acid molecules from a sample; (b) simultaneously or sequentially contacting the library with one, two, three, four, five, or more than five pluralities of target capture reagents under conditions that allow hybridization of the target capture reagents to the target nucleic acid molecules, thereby providing a selected set of captured normal and/or tumor nucleic acid molecules (z.e., a library catch); (c) separating the selected subset of the nucleic acid molecules (e.g., the library catch) from the hybridization mixture, e.g., by contacting the hybridization mixture with a binding entity that allows for separation of the target capture reagent/nucleic acid molecule hybrids from the hybridization mixture, (d) sequencing the library catch to acquiring a plurality of reads (e.g., sequence reads) that overlap one or more subject intervals (e.g., one or more target sequences) from said library catch that may comprise a mutation (or alteration), e.g., a variant sequence comprising a somatic mutation or germline mutation; (e) aligning said sequence reads using an alignment method as described elsewhere herein; and/or (f) assigning a nucleotide value for a nucleotide position in the subject interval (e.g., calling a mutation using, e.g., a Bayesian method or other method described herein) from one or more sequence reads of the plurality.

[0185] In some instances, acquiring sequence reads for one or more subject intervals may comprise sequencing at least 1, at least 5, at least 10, at least 20, at least 30, at least 40, at least 50, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 450, at least 500, at least 550, at least 600, at least 650, at least 700, at least 750, at least 800, at least 850, at least 900, at least 950, at least 1,000, at least 1,250, at least 1,500, at least 1,750, at least 2,000, at least 2,250, at least 2,500, at least 2,750, at least 3,000, at least 3,500, at least 4,000, at least 4,500, or at least 5,000 loci, e.g., genomic loci, gene loci, microsatellite loci, etc. In some instances, acquiring a sequence read for one or more subject intervals may comprise sequencing a subject interval for any number of loci within the range described in this paragraph, e.g., for at least 2,850 gene loci. [0186] In some instances, acquiring a sequence read for one or more subject intervals comprises sequencing a subject interval with a sequencing method that provides a sequence read length (or average sequence read length) of at least 20 bases, at least 30 bases, at least 40 bases, at least 50 bases, at least 60 bases, at least 70 bases, at least 80 bases, at least 90 bases, at least 100 bases, at least 120 bases, at least 140 bases, at least 160 bases, at least 180 bases, at least 200 bases, at least 220 bases, at least 240 bases, at least 260 bases, at least 280 bases, at least 300 bases, at least 320 bases, at least 340 bases, at least 360 bases, at least 380 bases, or at least 400 bases. In some instances, acquiring a sequence read for the one or more subject intervals may comprise sequencing a subject interval with a sequencing method that provides a sequence read length (or average sequence read length) of any number of bases within the range described in this paragraph, e.g., a sequence read length (or average sequence read length) of 56 bases.

[0187] In some instances, acquiring a sequence read for one or more subject intervals may comprise sequencing with at least lOOx or more coverage (or depth) on average. In some instances, acquiring a sequence read for one or more subject intervals may comprise sequencing with at least lOOx, at least 150x, at least 200x, at least 250x, at least 500x, at least 750x, at least l,000x, at least 1,500 x, at least 2,000x, at least 2,500x, at least 3,000x, at least 3,500x, at least 4,000x, at least 4,500x, at least 5,000x, at least 5,500x, or at least 6,000x or more coverage (or depth) on average. In some instances, acquiring a sequence read for one or more subject intervals may comprise sequencing with an average coverage (or depth) having any value within the range of values described in this paragraph, e.g., at least 160x.

[0188] In some instances, acquiring a read for the one or more subject intervals comprises sequencing with an average sequencing depth having any value ranging from at least lOOx to at least 6,000x for greater than about 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99% of the gene loci sequenced. For example, in some instances acquiring a read for the subject interval comprises sequencing with an average sequencing depth of at least 125x for at least 99% of the gene loci sequenced. As another example, in some instances acquiring a read for the subject interval comprises sequencing with an average sequencing depth of at least 4,100x for at least 95% of the gene loci sequenced. [0189] In some instances, the relative abundance of a nucleic acid species in the library can be estimated by counting the relative number of occurrences of their cognate sequences (e.g., the number of sequence reads for a given cognate sequence) in the data generated by the sequencing experiment.

[0190] In some instances, the disclosed methods and systems provide nucleotide sequences for a set of subject intervals (e.g., gene loci), as described herein. In certain instances, the sequences are provided without using a method that includes a matched normal control (e.g., a wild-type control) and/or a matched tumor control (e.g., primary versus metastatic).

[0191] In some instances, the level of sequencing depth as used herein (e.g., an X-fold level of sequencing depth) refers to the number of reads (e.g., unique reads) obtained after detection and removal of duplicate reads (e.g., PCR duplicate reads). In other instances, duplicate reads are evaluated, e.g., to support detection of copy number alteration (CNAs).

Alignment

[0192] Alignment is the process of matching a read with a location, e.g., a genomic location or locus. In some instances, NGS reads may be aligned to a known reference sequence (e.g., a wild-type sequence). In some instances, NGS reads may be assembled de novo. Methods of sequence alignment for NGS reads are described in, e.g., Trapnell, C. and Salzberg, S.L. Nature Biotech., 2009, 27:455-457. Examples of de novo sequence assemblies are described in, e.g., Warren R., et al., Bioinformatics, 2007, 23:500-501; Butler, J. et al., Genome Res., 2008, 18:810-820; and Zerbino, D.R. and Birney, E., Genome Res., 2008, 18:821-829. Optimization of sequence alignment is described in the art, e.g., as set out in International Patent Application Publication No. WO 2012/092426. Additional description of sequence alignment methods is provided in, e.g., International Patent Application Publication No. WO 2020/236941, the entire content of which is incorporated herein by reference.

[0193] Misalignment (e.g., the placement of base-pairs from a short read at incorrect locations in the genome), e.g., misalignment of reads due to sequence context (e.g., the presence of repetitive sequence) around an actual cancer mutation can lead to reduction in sensitivity of mutation detection, can lead to a reduction in sensitivity of mutation detection, as reads for the alternate allele may be shifted off the histogram peak of alternate allele reads. Other examples of sequence context that may cause misalignment include short-tandem repeats, interspersed repeats, low complexity regions, insertions - deletions (indels), and paralogs. If the problematic sequence context occurs where no actual mutation is present, misalignment may introduce artifactual reads of “mutated” alleles by placing reads of actual reference genome base sequences at the wrong location. Because mutation-calling algorithms for multigene analysis should be sensitive to even low-abundance mutations, sequence misalignments may increase false positive discovery rates and/or reduce specificity.

[0194] In some instances, the methods and systems disclosed herein may integrate the use of multiple, individually-tuned, alignment methods or algorithms to optimize base-calling performance in sequencing methods, particularly in methods that rely on massively parallel sequencing (MPS) of a large number of diverse genetic events at a large number of diverse genomic loci. In some instances, the disclosed methods and systems may comprise the use of one or more global alignment algorithms. In some instances, the disclosed methods and systems may comprise the use of one or more local alignment algorithms. Examples of alignment algorithms that may be used include, but are not limited to, the Burrows-Wheeler Alignment (BWA) software bundle (see, e.g., Li, et al. (2009), “Fast and Accurate Short Read Alignment with Burrows-Wheeler Transform”, Bioinformatics 25: 1754-60; Li, et al. (2010), Fast and Accurate Long-Read Alignment with Burrows-Wheeler Transform”, Bioinformatics epub.

PMID: 20080505), the Smith- Waterman algorithm (see, e.g., Smith, et al. (1981), "Identification of Common Molecular Subsequences", J. Molecular Biology 147(1): 195-197), the Striped Smith- Waterman algorithm (see, e.g., Farrar (2007), “Striped Smith-Waterman Speeds Database Searches Six Times Over Other SIMD Implementations”, Bioinformatics 23(2): 156-161), the Needleman-Wunsch algorithm (Needleman, et al. (1970) "A General Method Applicable to the Search for Similarities in the Amino Acid Sequence of Two Proteins", J. Molecular Biology 48(3):443-53), or any combination thereof.

[0195] In some instances, the methods and systems disclosed herein may also comprise the use of a sequence assembly algorithm, e.g., the Arachne sequence assembly algorithm (see, e.g., Batzoglou, et al. (2002), “ARACHNE: A Whole-Genome Shotgun Assembler”, Genome Res. 12: 177-189). [0196] In some instances, the alignment method used to analyze sequence reads is not individually customized or tuned for detection of different variants (e.g., point mutations, insertions, deletions, and the like) at different genomic loci. In some instances, different alignment methods are used to analyze reads that are individually customized or tuned for detection of at least a subset of the different variants detected at different genomic loci. In some instances, different alignment methods are used to analyze reads that are individually customized or tuned to detect each different variant at different genomic loci. In some instances, tuning can be a function of one or more of: (i) the genetic locus (e.g., gene loci, micro satellite locus, or other subject interval) being sequenced, (ii) the tumor type associated with the sample, (iii) the variant being sequenced, or (iv) a characteristic of the sample or the subject. The selection or use of alignment conditions that are individually tuned to a number of specific subject intervals to be sequenced allows optimization of speed, sensitivity, and specificity. The method is particularly effective when the alignment of reads for a relatively large number of diverse subject intervals are optimized. In some instances, the method includes the use of an alignment method optimized for rearrangements in combination with other alignment methods optimized for subject intervals not associated with rearrangements.

[0197] In some instances, the methods disclosed herein further comprise selecting or using an alignment method for analyzing, e.g., aligning, a sequence read, wherein said alignment method is a function of, is selected responsive to, or is optimized for, one or more of: (i) tumor type, e.g., the tumor type in the sample; (ii) the location (e.g., a gene locus) of the subject interval being sequenced; (iii) the type of variant (e.g., a point mutation, insertion, deletion, substitution, copy number variation (CNV), rearrangement, or fusion) in the subject interval being sequenced; (iv) the site (e.g., nucleotide position) being analyzed; (v) the type of sample (e.g., a sample described herein); and/or (vi) adjacent sequence(s) in or near the subject interval being evaluated (e.g., according to the expected propensity thereof for misalignment of the subject interval due to, e.g., the presence of repeated sequences in or near the subject interval).

[0198] In some instances, the methods disclosed herein allow for the rapid and efficient alignment of troublesome reads, e.g., a read having a rearrangement. Thus, in some instances where a read for a subject interval comprises a nucleotide position with a rearrangement, e.g., a translocation, the method can comprise using an alignment method that is appropriately tuned and that includes: (i) selecting a rearrangement reference sequence for alignment with a read, wherein said rearrangement reference sequence aligns with a rearrangement (in some instances, the reference sequence is not identical to the genomic rearrangement); and (ii) comparing, e.g., aligning, a read with said rearrangement reference sequence.

[0199] In some instances, alternative methods may be used to align troublesome reads. These methods are particularly effective when the alignment of reads for a relatively large number of diverse subject intervals is optimized. By way of example, a method of analyzing a sample can comprise: (i) performing a comparison (e.g., an alignment comparison) of a read using a first set of parameters (e.g., using a first mapping algorithm, or by comparison with a first reference sequence), and determining if said read meets a first alignment criterion (e.g., the read can be aligned with said first reference sequence, e.g., with less than a specific number of mismatches); (ii) if said read fails to meet the first alignment criterion, performing a second alignment comparison using a second set of parameters, (e.g., using a second mapping algorithm, or by comparison with a second reference sequence); and (iii) optionally, determining if said read meets said second criterion (e.g., the read can be aligned with said second reference sequence, e.g., with less than a specific number of mismatches), wherein said second set of parameters comprises use of, e.g., said second reference sequence, which, compared with said first set of parameters, is more likely to result in an alignment with a read for a variant (e.g., a rearrangement, insertion, deletion, or translocation).

[0200] In some instances, the alignment of sequence reads in the disclosed methods may be combined with a mutation calling method as described elsewhere herein. As discussed herein, reduced sensitivity for detecting actual mutations may be addressed by evaluating the quality of alignments (manually or in an automated fashion) around expected mutation sites in the genes or genomic loci (e.g., gene loci) being analyzed. In some instances, the sites to be evaluated can be obtained from databases of the human genome (e.g., the HG19 human reference genome) or cancer mutations (e.g., COSMIC). Regions that are identified as problematic can be remedied with the use of an algorithm selected to give better performance in the relevant sequence context, e.g., by alignment optimization (or re-alignment) using slower, but more accurate alignment algorithms such as Smith- Waterman alignment. In cases where general alignment algorithms cannot remedy the problem, customized alignment approaches may be created by, e.g., adjustment of maximum difference mismatch penalty parameters for genes with a high likelihood of containing substitutions; adjusting specific mismatch penalty parameters based on specific mutation types that are common in certain tumor types (e.g. C- T in melanoma); or adjusting specific mismatch penalty parameters based on specific mutation types that are common in certain sample types e.g. substitutions that are common in FFPE).

[0201] Reduced specificity (increased false positive rate) in the evaluated subject intervals due to misalignment can be assessed by manual or automated examination of all mutation calls in the sequencing data. Those regions found to be prone to spurious mutation calls due to misalignment can be subjected to alignment remedies as discussed above. In cases where no algorithmic remedy is found possible, “mutations” from the problem regions can be classified or screened out from the panel of targeted loci.

Mutation calling

[0202] Base calling refers to the raw output of a sequencing device, e.g., the determined sequence of nucleotides in an oligonucleotide molecule. Mutation calling refers to the process of selecting a nucleotide value, e.g., A, G, T, or C, for a given nucleotide position being sequenced. Typically, the sequence reads (or base calling) for a position will provide more than one value, e.g., some reads will indicate a T and some will indicate a G. Mutation calling is the process of assigning a correct nucleotide value, e.g., one of those values, to the sequence. Although it is referred to as “mutation” calling, it can be applied to assign a nucleotide value to any nucleotide position, e.g., positions corresponding to mutant alleles, wild-type alleles, alleles that have not been characterized as either mutant or wild-type, or to positions not characterized by variability.

[0203] In some instances, the disclosed methods may comprise the use of customized or tuned mutation calling algorithms or parameters thereof to optimize performance when applied to sequencing data, particularly in methods that rely on massively parallel sequencing (MPS) of a large number of diverse genetic events at a large number of diverse genomic loci (e.g., gene loci, micro satellite regions, etc.) in samples, e.g., samples from a subject having cancer. Optimization of mutation calling is described in the art, e.g., as set out in International Patent Application Publication No. WO 2012/092426. [0204] Methods for mutation calling can include one or more of the following: making independent calls based on the information at each position in the reference sequence (e.g., examining the sequence reads; examining the base calls and quality scores; calculating the probability of observed bases and quality scores given a potential genotype; and assigning genotypes (e.g., using Bayes’ rule)); removing false positives (e.g., using depth thresholds to reject SNPs with read depth much lower or higher than expected; local realignment to remove false positives due to small indels); and performing linkage disequilibrium (LD)/imputation- based analysis to refine the calls.

[0205] Equations used to calculate the genotype likelihood associated with a specific genotype and position are described in, e.g., Li, H. and Durbin, R. Bioinformatics, 2010; 26(5): 589-95. The prior expectation for a particular mutation in a certain cancer type can be used when evaluating samples from that cancer type. Such likelihood can be derived from public databases of cancer mutations, e.g., Catalogue of Somatic Mutation in Cancer (COSMIC), HGMD (Human Gene Mutation Database), The SNP Consortium, Breast Cancer Mutation Data Base (BIC), and Breast Cancer Gene Database (BCGD).

[0206] Examples of LD/imputation based analysis are described in, e.g., Browning, B.L. and Yu, Z. Am. J. Hum. Genet. 2009, 85(6):847-61. Examples of low-coverage SNP calling methods are described in, e.g., Li, Y., et al., Annu. Rev. Genomics Hum. Genet. 2009, 10:387-406.

[0207] After alignment, detection of substitutions can be performed using a mutation calling method (e.g., a Bayesian mutation calling method) which is applied to each base in each of the subject intervals, e.g., exons of a gene or other locus to be evaluated, where presence of alternate alleles is observed. This method will compare the probability of observing the read data in the presence of a mutation with the probability of observing the read data in the presence of basecalling error alone. Mutations can be called if this comparison is sufficiently strongly supportive of the presence of a mutation.

[0208] An advantage of a Bayesian mutation detection approach is that the comparison of the probability of the presence of a mutation with the probability of base-calling error alone can be weighted by a prior expectation of the presence of a mutation at the site. If some reads of an alternate allele are observed at a frequently mutated site for the given cancer type, then presence of a mutation may be confidently called even if the amount of evidence of mutation does not meet the usual thresholds. This flexibility can then be used to increase detection sensitivity for even rarer mutations/lower purity samples, or to make the test more robust to decreases in read coverage. The likelihood of a random base-pair in the genome being mutated in cancer is ~le-6. The likelihood of specific mutations occurring at many sites in, for example, a typical multigenic cancer genome panel can be orders of magnitude higher. These likelihoods can be derived from public databases of cancer mutations (e.g., COSMIC).

[0209] Indel calling is a process of finding bases in the sequencing data that differ from the reference sequence by insertion or deletion, typically including an associated confidence score or statistical evidence metric. Methods of indel calling can include the steps of identifying candidate indels, calculating genotype likelihood through local re-alignment, and performing LD-based genotype inference and calling. Typically, a Bayesian approach is used to obtain potential indel candidates, and then these candidates are tested together with the reference sequence in a Bayesian framework.

[0210] Algorithms to generate candidate indels are described in, e.g., McKenna, A., et al., Genome Res. 2010; 20(9): 1297-303; Ye, K., et al., Bioinformatics, 2009; 25(21):2865-71; Lunter, G., and Goodson, M., Genome Res. 2011; 21(6):936-9; and Li, H., et al. (2009), Bioinformatics 25(16):2078-9.

[0211] Methods for generating indel calls and individual-level genotype likelihoods include, e.g., the Dindel algorithm (Albers, C.A., et al., Genome Res. 2011;21(6):961-73). For example, the Bayesian EM algorithm can be used to analyze the reads, make initial indel calls, and generate genotype likelihoods for each candidate indel, followed by imputation of genotypes using, e.g., QCALL (Le S.Q. and Durbin R. Genome Res. 2011;21(6):952-60). Parameters, such as prior expectations of observing the indel can be adjusted {e.g., increased or decreased), based on the size or location of the indels.

[0212] Methods have been developed that address limited deviations from allele frequencies of 50% or 100% for the analysis of cancer DNA. (see, e.g., SNVMix -Bioinformatics. 2010 March 15; 26(6): 730-736.) Methods disclosed herein, however, allow consideration of the possibility of the presence of a mutant allele at frequencies (or allele fractions) ranging from 1% to 100% (i.e., allele fractions ranging from 0.01 to 1.0), and especially at levels lower than 50%. This approach is particularly important for the detection of mutations in, for example, low-purity FFPE samples of natural (multi-clonal) tumor DNA.

[0213] In some instances, the mutation calling method used to analyze sequence reads is not individually customized or fine-tuned for detection of different mutations at different genomic loci. In some instances, different mutation calling methods are used that are individually customized or fine-tuned for at least a subset of the different mutations detected at different genomic loci. In some instances, different mutation calling methods are used that are individually customized or fine-tuned for each different mutant detected at each different genomic loci. The customization or tuning can be based on one or more of the factors described herein, e.g., the type of cancer in a sample, the gene or locus in which the subject interval to be sequenced is located, or the variant to be sequenced. This selection or use of mutation calling methods individually customized or fine-tuned for a number of subject intervals to be sequenced allows for optimization of speed, sensitivity and specificity of mutation calling.

[0214] In some instances, a nucleotide value is assigned for a nucleotide position in each of X unique subject intervals using a unique mutation calling method, and X is at least 2, at least 3, at least 4, at least 5, at least 10, at least 15, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 200, at least 300, at least 400, at least 500, at least 1000, at least 1500, at least 2000, at least 2500, at least 3000, at least 3500, at least 4000, at least 4500, at least 5000, or greater. The calling methods can differ, and thereby be unique, e.g., by relying on different Bayesian prior values.

[0215] In some instances, assigning said nucleotide value is a function of a value which is or represents the prior (e.g., literature) expectation of observing a read showing a variant, e.g., a mutation, at said nucleotide position in a tumor of type.

[0216] In some instances, the method comprises assigning a nucleotide value (e.g., calling a mutation) for at least 10, 20, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1,000 nucleotide positions, wherein each assignment is a function of a unique value (as opposed to the value for the other assignments) which is or represents the prior (e.g., literature) expectation of observing a read showing a variant, e.g., a mutation, at said nucleotide position in a tumor of type.

[0217] In some instances, assigning said nucleotide value is a function of a set of values which represent the probabilities of observing a read showing said variant at said nucleotide position if the variant is present in the sample at a specified frequency (e.g., 1%, 5%, 10%, etc.) and/or if the variant is absent (e.g., observed in the reads due to base-calling error alone).

[0218] In some instances, the mutation calling methods described herein can include the following: (a) acquiring, for a nucleotide position in each of said X subject intervals: (i) a first value which is or represents the prior (e.g., literature) expectation of observing a read showing a variant, e.g., a mutation, at said nucleotide position in a tumor of type X; and (ii) a second set of values which represent the probabilities of observing a read showing said variant at said nucleotide position if the variant is present in the sample at a frequency (e.g., 1%, 5%, 10%, etc.) and/or if the variant is absent (e.g., observed in the reads due to base-calling error alone); and (b) responsive to said values, assigning a nucleotide value (e.g., calling a mutation) from said reads for each of said nucleotide positions by weighing, e.g., by a Bayesian method described herein, the comparison among the values in the second set using the first value (e.g., computing the posterior probability of the presence of a mutation), thereby analyzing said sample.

[0219] Additional description of mutation calling methods is provided in, e.g., International Patent Application Publication No. WO 2020/236941, the entire content of which is incorporated herein by reference.

Systems

[0220] Also disclosed herein are systems designed to implement any of the disclosed methods for determining tumor DNA fraction (e.g., ctDNA fraction) in a sample from a subject. The systems may comprise, e.g., one or more processors, and a memory unit communicatively coupled to the one or more processors and configured to store instructions that, when executed by the one or more processors, cause the system to: receive sequence read data for a plurality of sequence reads derived from a sample from a subject; determine a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generate an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fit a model to the empirical distribution of tumor DNA fraction values; and determine a tumor DNA fraction for the sample based on the model.

[0221] In some instances, the disclosed systems may further comprise a sequencer, e.g., a next generation sequencer (also referred to as a massively parallel sequencer). Examples of next generation (or massively parallel) sequencing platforms include, but are not limited to, Roche/454’s Genome Sequencer (GS) FLX system, Illumina/Solexa’s Genome Analyzer (GA), Illumina’s HiSeq® 2500, HiSeq® 3000, HiSeq® 4000 and NovaSeq® 6000 sequencing systems, Life/APG’s Support Oligonucleotide Ligation Detection (SOLiD) system, Polonator’s G.007 system, Helicos BioSciences’ HeliScope Gene Sequencing system, ThermoFisher Scientific’s Ion Torrent Genexus system, or Pacific Biosciences’ PacBio® RS system.

[0222] In some instances, the disclosed systems may be used for determining tumor DNA fraction in any of a variety of samples as described herein (e.g., a tissue sample, biopsy sample, hematological sample, or liquid biopsy sample derived from the subject).

[0223] In some instances, a plurality of gene loci for which sequencing data is processed to determine tumor DNA fraction (e.g., ctDNA fraction) may comprise between 10 and 20 loci, between 10 and 40 loci, between 10 and 60 loci, between 10 and 80 loci, between 10 and 100 loci, between 10 and 150 loci, between 10 and 200 loci, between 10 and 250 loci, between 10 and 300 loci, between 10 and 350 loci, between 10 and 400 loci, between 10 and 450 loci, between 10 and 500 loci, between 20 and 40 loci, between 20 and 60 loci, between 20 and 80 loci, between 20 and 100 loci, between 20 and 150 loci, between 20 and 200 loci, between 20 and 250 loci, between 20 and 300 loci, between 20 and 350 loci, between 20 and 400 loci, between 20 and 500 loci, between 40 and 60 loci, between 40 and 80 loci, between 40 and 100 loci, between 40 and 150 loci, between 40 and 200 loci, between 40 and 250 loci, between 40 and 300 loci, between 40 and 350 loci, between 40 and 400 loci, between 40 and 500 loci, between 60 and 80 loci, between 60 and 100 loci, between 60 and 150 loci, between 60 and 200 loci, between 60 and 250 loci, between 60 and 300 loci, between 60 and 350 loci, between 60 and 400 loci, between 60 and 500 loci, between 80 and 100 loci, between 80 and 150 loci, between 80 and 200 loci, between 80 and 250 loci, between 80 and 300 loci, between 80 and 350 loci, between 80 and 400 loci, between 80 and 500 loci, between 100 and 150 loci, between 100 and 200 loci, between 100 and 250 loci, between 100 and 300 loci, between 100 and 350 loci, between 100 and 400 loci, between 100 and 500 loci, between 150 and 200 loci, between 150 and 250 loci, between 150 and 300 loci, between 150 and 350 loci, between 150 and 400 loci, between 150 and 500 loci, between 200 and 250 loci, between 200 and 300 loci, between 200 and 350 loci, between 200 and 400 loci, between 200 and 500 loci, between 250 and 300 loci, between 250 and 350 loci, between 250 and 400 loci, between 250 and 500 loci, between 300 and 350 loci, between 300 and 400 loci, between 300 and 500 loci, between 350 and 400 loci, between 350 and 500 loci, or between 400 and 500 loci.

[0224] In some instance, the nucleic acid sequence data is acquired using a next generation sequencing technique (also referred to as a massively parallel sequencing technique) having a read-length of less than 400 bases, less than 300 bases, less than 200 bases, less than 150 bases, less than 100 bases, less than 90 bases, less than 80 bases, less than 70 bases, less than 60 bases, less than 50 bases, less than 40 bases, or less than 30 bases.

[0225] In some instances, the determination of tumor DNA fraction (e.g., ctDNA fraction) is used to select, initiate, adjust, or terminate a treatment for cancer in the subject (e.g., a patient) from which the sample was derived, as described elsewhere herein.

[0226] In some instances, the disclosed systems may further comprise sample processing and library preparation workstations, microplate-handling robotics, fluid dispensing systems, temperature control modules, environmental control chambers, additional data storage modules, data communication modules (e.g., Bluetooth®, WiFi, intranet, or internet communication hardware and associated software), display modules, one or more local and/or cloud-based software packages (e.g., instrument / system control software packages, sequencing data analysis software packages), etc., or any combination thereof. In some instances, the systems may comprise, or be part of, a computer system or computer network as described elsewhere herein.

Computer systems and networks

[0227] FIG. 2 illustrates an example of a computing device or system in accordance with one embodiment. Device 200 can be a host computer connected to a network. Device 200 can be a client computer or a server. As shown in FIG. 2, device 200 can be any suitable type of microprocessor-based device, such as a personal computer, workstation, server or handheld computing device (portable electronic device) such as a phone or tablet. The device can include, for example, one or more processor(s) 210, input devices 220, output devices 230, memory or storage devices 240, communication devices 260, and nucleic acid sequencers 270. Software 250 residing in memory or storage device 240 may comprise, e.g., an operating system as well as software for executing the methods described herein. Input device 220 and output device 230 can generally correspond to those described herein, and can either be connectable or integrated with the computer.

[0228] Input device 220 can be any suitable device that provides input, such as a touch screen, keyboard or keypad, mouse, or voice-recognition device. Output device 230 can be any suitable device that provides output, such as a touch screen, haptics device, or speaker.

[0229] Storage 240 can be any suitable device that provides storage (e.g., an electrical, magnetic or optical memory including a RAM (volatile and non-volatile), cache, hard drive, or removable storage disk). Communication device 260 can include any suitable device capable of transmitting and receiving signals over a network, such as a network interface chip or device. The components of the computer can be connected in any suitable manner, such as via a wired media (e.g., a physical system bus 280, Ethernet connection, or any other wire transfer technology) or wirelessly (e.g., Bluetooth®, Wi-Fi®, or any other wireless technology).

[0230] Software module 250, which can be stored as executable instructions in storage 240 and executed by processor(s) 210, can include, for example, an operating system and/or the processes that embody the functionality of the methods of the present disclosure (e.g., as embodied in the devices as described herein).

[0231] Software module 250 can also be stored and/or transported within any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as those described herein, that can fetch instructions associated with the software from the instruction execution system, apparatus, or device and execute the instructions. In the context of this disclosure, a computer-readable storage medium can be any medium, such as storage 240, that can contain or store processes for use by or in connection with an instruction execution system, apparatus, or device. Examples of computer- readable storage media may include memory units like hard drives, flash drives and distribute modules that operate as a single functional unit. Also, various processes described herein may be embodied as modules configured to operate in accordance with the embodiments and techniques described above. Further, while processes may be shown and/or described separately, those skilled in the art will appreciate that the above processes may be routines or modules within other processes.

[0232] Software module 250 can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as those described above, that can fetch instructions associated with the software from the instruction execution system, apparatus, or device and execute the instructions. In the context of this disclosure, a transport medium can be any medium that can communicate, propagate or transport programming for use by or in connection with an instruction execution system, apparatus, or device. The transport readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium.

[0233] Device 200 may be connected to a network (e.g., network 304, as shown in FIG. 3 and/or described below), which can be any suitable type of interconnected communication system. The network can implement any suitable communications protocol and can be secured by any suitable security protocol. The network can comprise network links of any suitable arrangement that can implement the transmission and reception of network signals, such as wireless network connections, T1 or T3 lines, cable networks, DSL, or telephone lines.

[0234] Device 200 can be implemented using any operating system, e.g., an operating system suitable for operating on the network. Software module 250 can be written in any suitable programming language, such as C, C++, Java or Python. In various embodiments, application software embodying the functionality of the present disclosure can be deployed in different configurations, such as in a client/server arrangement or through a Web browser as a Web-based application or Web service, for example. In some embodiments, the operating system is executed by one or more processors, e.g., processor(s) 210. [0235] Device 200 can further include a sequencer 270, which can be any suitable nucleic acid sequencing instrument.

[0236] FIG. 3 illustrates an example of a computing system in accordance with one embodiment. In system 300, device 200 (e.g., as described above and illustrated in FIG. 2) is connected to network 304, which is also connected to device 306. In some embodiments, device 306 is a sequencer. Exemplary sequencers can include, without limitation, Roche/454’s Genome Sequencer (GS) FLX System, Illumina/Solexa’s Genome Analyzer (GA), Illumina’s HiSeq® 2500, HiSeq® 3000, HiSeq® 4000 and NovaSeq® 6000 Sequencing Systems, Life/APG’s Support Oligonucleotide Ligation Detection (SOLiD) system, Polonator’s G.007 system, Helicos BioSciences’ HeliScope Gene Sequencing system, or Pacific Biosciences’ PacBio® RS system.

[0237] Devices 200 and 306 may communicate, e.g., using suitable communication interfaces via network 304, such as a Local Area Network (LAN), Virtual Private Network (VPN), or the Internet. In some embodiments, network 304 can be, for example, the Internet, an intranet, a virtual private network, a cloud network, a wired network, or a wireless network. Devices 200 and 306 may communicate, in part or in whole, via wireless or hardwired communications, such as Ethernet, IEEE 802.1 lb wireless, or the like. Additionally, devices 200 and 306 may communicate, e.g., using suitable communication interfaces, via a second network, such as a mobile/cellular network. Communication between devices 200 and 306 may further include or communicate with various servers such as a mail server, mobile server, media server, telephone server, and the like. In some embodiments, Devices 200 and 306 can communicate directly (instead of, or in addition to, communicating via network 304), e.g., via wireless or hardwired communications, such as Ethernet, IEEE 802.11b wireless, or the like. In some embodiments, devices 200 and 306 communicate via communications 308, which can be a direct connection or can occur via a network (e.g., network 304).

[0238] One or all of devices 200 and 306 generally include logic (e.g., http web server logic) or are programmed to format data, accessed from local or remote databases or other sources of data and content, for providing and/or receiving information via network 304 according to various examples described herein. EXAMPLES

Example 1 - Simulation of VAF vs. ctDNA Fraction & Comparison to Actual Patient Data

[0239] As described above, the methods disclosed herein may comprise the following concepts:

[0240] I. The fraction of a cfDNA sample that consists of ctDNA can be expressed using the following formula, which was derived based on the physical properties of cfDNA samples: where p is the tumor purity (as used herein the terms “tumor purity” and “cellular purity are equivalent) and is tumor average ploidy (z.e., the average ploidy across a genome in a tumor cell).

[0241] II. The variant allele frequency (VAF) of a variant (e.g., a somatic variant, or a somatic short variant) can be expressed using the following formula, which was derived based on physical properties of somatic variants:

Somatic VAF = - — — - (6) pC+2(l-p) ^{V 7} where p is tumor purity, C is the copy number at the genomic location of the variant, and V is the variant allele number.

[0242] III. Equations (5) and (6) can be solved to derive relationships between ctDNA fraction and variant allele frequency as a function of each other, the copy number state of the genomic location containing a given variant, and the tumor average ploidy, as shown below: ctDNA_fr action = f(SomaticVAF, C, V, if) (7)

Somatic VAF = f(ctDNA_fraction, C, V, F) (8)

[0243] IV. Equations (7) and (8) show that for any given sample with known C and V for somatic variants, as well as a tumor average ploidy, ip, for the sample, ctDNA fraction can be derived from somatic variant allele frequency (somatic VAF). Alternatively, somatic VAF can be derived from ctDNA fraction. Equations (7) and (8) can be solved to derive an explicit relationship between ctDNA fraction and somatic VAF given by:

[0244] This conclusion is verified by the following analysis. A set of approximately 2200 samples with known tumor average ploidy, y/, as well as known C and V for the top somatic variant in each sample (e.g., the somatic variant with the highest allele frequency), were randomly selected from a genomics database. A random number generator was used to simulate ctDNA fraction in the range of 0.04 to 0.96. Each of the simulated ctDNA fraction values was plugged into equation (4), together with a set of values for C, V, and i// randomly selected from one of the approximately 2200 samples to calculate the expected somatic VAF for the given values of ctDNA fraction, C, V, and i//. The results of the simulated somatic VAF versus ctDNA fraction data are plotted in FIG. 4 (where the traces for variants having different copy number values of 1, 2, 3, or 4 are overlaid) and in FIG. 5 (which shows the simulated data for variants having a copy number of 1 in the upper left panel, simulated data for variants having a copy number of 2 in the upper right panel, simulated data for variants having a copy number of 3 in the lower left panel, and simulated data for variants having a copy number of 4 in the lower right panel). The solid line in FIGS. 4-7 indicates the case where VAF is equal to ctDNA fraction. The dashed line in FIGS. 4-7 indicates the case where VAF is equal to one half of ctDNA fraction. As can be seen, in a majority of cases the VAF of the top variant (the variant with the highest VAF) is equal to either the tumor DNA fraction or half of the tumor fraction. This explains the two peaks that are apparent in the probability density plot shown in FIG. 8, and the “bifurcation” observed in FIGS. 4-7. Those variants that follow the VAF = ctDNA fraction relationship are typically variants that have a mutant copy allele number that is close to the tumor average ploidy. Those variants that follow the VAF = * (ctDNA fraction) relationship are typically variants that have a mutant allele number that is equal to about half of the tumor average ploidy (e.g., where the tumor average ploidy is 2, but only one allele carries the mutation).

[0245] The simulated results were found to be in close agreement with what was observed for actual patient data, as shown in FIG. 6 and FIG. 7. FIG. 6 provides a plot of measured somatic VAF for the patient samples versus ctDNA fraction determined during copy number modeling, where, again, the traces for variants having different copy number values of 1, 2, 3, or 4 are overlaid. FIG. 7 shows the same patient data plotted for variants having a copy number of 1 in the upper left panel, patient data for variants having a copy number of 2 in the upper right panel, patient data for variants having a copy number of 3 in the lower left panel, and patient data for variants having a copy number of 4 in the lower right panel).

[0246] The agreement between simulated and actual results demonstrate that ctDNA fraction, somatic allele frequency, C, as measured by a sequencing-based assay, indeed follow the principles described by the equations above, and indicate that on can accurately infer ctDNA fraction based on measured somatic variant allele frequency by leveraging data for the known values of C, V, and i// for a large number of patient samples included in existing genomic databases.

[0247] FIG. 8 provides a non-limiting example of an output probability density plot as a function of possible ctDNA fraction values in a sample for a given value of observed maximum somatic VAF. A reference table comprising sets of (C, V, ip) was constructed for somatic variants exhibiting a maximum VAF in a plurality of tissue samples for which good copy number alteration (CNA) modeling data was available. To estimate tumor DNA fraction of a liquid sample (z.e., cfDNA fraction), somatic variants exhibiting maximum VAF were identified for the sample, and equation (9) was used to calculate ctDNA fraction values based on the tissue reference table of (C, V, p), thereby forming an empirical distribution of all possible ctDNA fraction values. The empirical distribution was fit to a non-parametric probability density model and used to output the most probable ctDNA fraction value as well as upper and lower bounds for ctDNA fraction (indicated by the vertical dashed lines in FIG. 8.

Example 2 - Exemplary Process Workflow

[0248] One non-limiting example of a process workflow for implementing the disclosed methods may comprise the following steps:

[0249] 1. Select a set of representative patient samples for which reliable CNA modeling data is available from a variant database. Non-limiting examples of selection criteria may include, but are not limited to, disease ontology, tissue type, clinical data, and other considerations. [0250] 2. Construct a reference table of sets of (C, V, y/) for somatic variants with the highest allele frequency in the selected set of samples. An exemplary, incomplete table is shown in Table 1 (for illustration purposes only).

[0251] 3. To estimate ctDNA fraction of a liquid biopsy sample, identify all somatic variants in the sample and find the highest allele frequency among these somatic variants. This is the somatic VAF value to be used for inferring ctDNA fraction.

[0252] 4. Use equation (9) above to calculate all possible ctDNA fraction values based on the reference table of (C, V, f ) values, thereby forming an empirical distribution of possible ctDNA fractions.

[0253] 5. Fit a model, e.g., a non-parametric probability density model, to the distribution. Identify the most probable ctDNA fraction based on the non-parametric probability density model, along with upper and lower bounds for the ctDNA fraction based on a desired confidence interval.

Table 1. A representative, incomplete table of reference sets of C, V, and y (for illustration purposes only). EXEMPLARY IMPLEMENTATIONS

[0254] Exemplary implementations of the methods and systems described herein include:

1. A method comprising: providing a plurality of nucleic acid molecules obtained from a sample from a subject; ligating one or more adapters onto one or more nucleic acid molecules from the plurality of nucleic acid molecules; amplifying the one or more ligated nucleic acid molecules from the plurality of nucleic acid molecules; capturing amplified nucleic acid molecules from the amplified nucleic acid molecules; sequencing, by a sequencer, the captured nucleic acid molecules to obtain a plurality of sequence reads that represent the captured nucleic acid molecules; receiving, at one or more processors, sequence read data for the plurality of sequence reads; determining, using the one or more processors, a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generating, using the one or more processors, an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fitting, using the one or more processors, a model to the empirical distribution of tumor DNA fraction values; and determining a tumor DNA fraction for the sample based on the model.

2. The method of clause 1, further comprising determining a confidence interval for the tumor DNA fraction based on the model.

3. The method of clause 1 or clause 2, wherein the one or more variants comprise one or more somatic short variants. 4. The method of clause 3, wherein the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

5. The method of any one of clauses 1 to 4, wherein generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

6. The method of any one of clauses 1 to 4, wherein generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

7. The method of clause 5 or clause 6, wherein tumor DNA fraction values are calculated or precalculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

8. The method of any one of clauses 5 to 7, wherein the plurality of historical subject samples comprise solid biopsy samples, liquid biopsy samples, or any combination thereof.

9. The method of any one of clauses 5 to 8, wherein the plurality of historical subject samples comprises cancer samples. 10. The method of clause 9, wherein the plurality of historical subject samples comprises samples for a single type of cancer.

11. The method of clause 9, wherein the plurality of historical subject samples comprises samples for multiple types of cancer.

12. The method of any one of clauses 5 to 11, wherein the plurality of historical subject samples comprise acute lymphoblastic leukemia (Philadelphia chromosome positive) samples, acute lymphoblastic leukemia (precursor B-cell) samples, acute myeloid leukemia (FLT3+) samples, acute myeloid leukemia (with an IDH2 mutation) samples, anaplastic large cell lymphoma samples, basal cell carcinoma samples, B-cell chronic lymphocytic leukemia samples, bladder cancer samples, breast cancer (HER2 overexpressed/amplified) samples, breast cancer (HER2+) samples, breast cancer (HR+, HER2-) samples, cervical cancer samples, cholangiocarcinoma samples, chronic lymphocytic leukemia samples, chronic lymphocytic leukemia (with 17p deletion) samples, chronic myelogenous leukemia samples, chronic myelogenous leukemia (Philadelphia chromosome positive) samples, classical Hodgkin lymphoma samples, colorectal cancer samples, colorectal cancer (dMMR and MSI-H) samples, colorectal cancer (KRAS wild type) samples, cryopyrin-associated periodic syndrome samples, cutaneous T-cell lymphoma samples, dermatofibrosarcoma protuberans samples, diffuse large B-cell lymphoma samples, fallopian tube cancer samples, follicular B-cell non-Hodgkin lymphoma samples, follicular lymphoma samples, gastric cancer samples, gastric cancer (HER2+) samples, gastroesophageal junction (GEJ) adenocarcinoma samples, gastrointestinal stromal tumor samples, gastrointestinal stromal tumor (KIT+) samples, giant cell tumor of the bone samples, glioblastoma samples, granulomatosis with polyangiitis samples, head and neck squamous cell carcinoma samples, hepatocellular carcinoma samples, Hodgkin lymphoma samples, juvenile idiopathic arthritis samples, lupus erythematosus samples, mantle cell lymphoma samples, medullary thyroid cancer samples, melanoma samples, melanoma samples with a BRAF V600 mutation, melanoma samples with a BRAF V600E or V600K mutation, Merkel cell carcinoma samples, multicentric Castleman's disease samples, multiple hematologic malignancy samples including Philadelphia chromosome-positive ALL and CML, multiple myeloma samples, myelofibrosis samples, nonHodgkin’s lymphoma samples, nonresectable subependymal giant cell astrocytoma samples associated with tuberous sclerosis, non-small cell lung cancer samples, non-small cell lung cancer (ALK+) samples, non-small cell lung cancer (PD-L1+) samples, non-small cell lung cancer (with ALK fusion or ROS1 gene alteration) samples, non-small cell lung cancer (with BRAF V600E mutation) samples, non-small cell lung cancer samples (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutation), non-small cell lung cancer samples (with an EGFR T790M mutation), ovarian cancer samples, ovarian cancer samples (with a BRCA mutation), pancreatic cancer samples, pancreatic cancer samples, gastrointestinal cancer samples, lung origin neuroendocrine tumor samples, pediatric neuroblastoma samples, peripheral T-cell lymphoma samples, peritoneal cancer samples, prostate cancer samples, renal cell carcinoma samples, rheumatoid arthritis samples, small lymphocytic lymphoma samples, soft tissue sarcoma samples, solid tumor (MSI-H/dMMR) samples, squamous cell cancer samples of the head and neck, squamous non-small cell lung cancer samples, thyroid cancer samples, thyroid carcinoma samples, urothelial cancer samples, urothelial carcinoma samples, Waldenstrom's macroglobulinemia samples, or any combination thereof.

13. The method of any one of clauses 1 to 12, wherein the model is a non-parametric probability density model.

14. The method of any one of clauses 1 to 13, wherein the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction.

15. The method of any one of clauses 1 to 14, wherein the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

16. The method of any one of clauses 1 to 15, wherein the sample comprises DNA extracted from a blood sample, a plasma sample, a cerebrospinal fluid sample, a pleural effusion fluid sample, a sputum sample, a stool sample, a urine sample, or a saliva sample.

17. The method of any one of clauses 1 to 16, wherein the subject is suspected of having or is determined to have cancer.

18. The method of clause 17, wherein the cancer is acute lymphoblastic leukemia (Philadelphia chromosome positive), acute lymphoblastic leukemia (precursor B-cell), acute myeloid leukemia (FLT3+), acute myeloid leukemia (with an IDH2 mutation), anaplastic large cell lymphoma, basal cell carcinoma, B-cell chronic lymphocytic leukemia, bladder cancer, breast cancer (HER2 overexpressed/amplified), breast cancer (HER2+), breast cancer (HR+, HER2-), cervical cancer, cholangiocarcinoma, chronic lymphocytic leukemia, chronic lymphocytic leukemia (with 17p deletion), chronic myelogenous leukemia, chronic myelogenous leukemia (Philadelphia chromosome positive), classical Hodgkin lymphoma, colorectal cancer, colorectal cancer (dMMR/MSI-H), colorectal cancer (KRAS wild type), cryopyrin-associated periodic syndrome, a cutaneous T-cell lymphoma, dermatofibrosarcoma protuberans, a diffuse large B-cell lymphoma, fallopian tube cancer, a follicular B-cell non-Hodgkin lymphoma, a follicular lymphoma, gastric cancer, gastric cancer (HER2+), gastroesophageal junction (GEJ) adenocarcinoma, a gastrointestinal stromal tumor, a gastrointestinal stromal tumor (KIT+), a giant cell tumor of the bone, a glioblastoma, granulomatosis with polyangiitis, a head and neck squamous cell carcinoma, a hepatocellular carcinoma, Hodgkin lymphoma, juvenile idiopathic arthritis, lupus erythematosus, a mantle cell lymphoma, medullary thyroid cancer, melanoma, a melanoma with a BRAF V600 mutation, a melanoma with a BRAF V600E or V600K mutation, Merkel cell carcinoma, multicentric Castleman's disease, multiple hematologic malignancies including Philadelphia chromosome-positive ALL and CML, multiple myeloma, myelofibrosis, a non-Hodgkin’ s lymphoma, a nonresectable subependymal giant cell astrocytoma associated with tuberous sclerosis, a non-small cell lung cancer, a non-small cell lung cancer (ALK+), a non-small cell lung cancer (PD-L1+), a non-small cell lung cancer (with ALK fusion or ROS1 gene alteration), a non-small cell lung cancer (with BRAF V600E mutation), a non-small cell lung cancer (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutations), a non- small cell lung cancer (with an EGFR T790M mutation), ovarian cancer, ovarian cancer (with a BRCA mutation), pancreatic cancer, a pancreatic, gastrointestinal, or lung origin neuroendocrine tumor, a pediatric neuroblastoma, a peripheral T-cell lymphoma, peritoneal cancer, prostate cancer, a renal cell carcinoma, rheumatoid arthritis, a small lymphocytic lymphoma, a soft tissue sarcoma, a solid tumor (MSLH/dMMR), a squamous cell cancer of the head and neck, a squamous non-small cell lung cancer, thyroid cancer, a thyroid carcinoma, urothelial cancer, a urothelial carcinoma, or Waldenstrom's macroglobulinemia.

19. The method of clause 18, further comprising treating the subject with an anti-cancer therapy. 20. The method of clause 19, wherein the anti-cancer therapy comprises a targeted anti-cancer therapy.

21. The method of clause 20, wherein the targeted anti-cancer therapy comprises abemaciclib (Verzenio), abiraterone acetate (Zytiga), acalabrutinib (Calquence), ado-trastuzumab emtansine (Kadcyla), afatinib dimaleate (Gilotrif), aldesleukin (Proleukin), alectinib (Alecensa), alemtuzumab (Campath), alitretinoin (Panretin), alpelisib (Piqray), amivantamab-vmjw (Rybrevant), anastrozole (Arimidex), apalutamide (Erleada), asciminib hydrochloride (Scemblix), atezolizumab (Tecentriq), avapritinib (Ayvakit), avelumab (Bavencio), axicabtagene ciloleucel (Yescarta), axitinib (Inlyta), belantamab mafodotin-blmf (Blenrep), belimumab (Benlysta), belinostat (Beleodaq), belzutifan (Welireg), bevacizumab (Avastin), bexarotene (Targretin), binimetinib (Mektovi), blinatumomab (Blincyto), bortezomib (Velcade), bosutinib (Bosulif), brentuximab vedotin (Adcetris), brexucabtagene autoleucel (Tecartus), brigatinib (Alunbrig), cabazitaxel (Jevtana), cabozantinib (Cabometyx), cabozantinib (Cabometyx, Cometriq), canakinumab (Haris), capmatinib hydrochloride (Tabrecta), carfilzomib (Kyprolis), cemiplimab-rwlc (Libtayo), ceritinib (LDK378/Zykadia), cetuximab (Erbitux), cobimetinib (Cotellic), copanlisib hydrochloride (Aliqopa), crizotinib (Xalkori), dabrafenib (Tafinlar), dacomitinib (Vizimpro), daratumumab (Darzalex), daratumumab and hyaluronidase-fihj (Darzalex Faspro), darolutamide (Nubeqa), dasatinib (Sprycel), denileukin diftitox (Ontak), denosumab (Xgeva), dinutuximab (Unituxin), dostarlimab-gxly (Jemperli), durvalumab (Imfinzi), duvelisib (Copiktra), elotuzumab (Empliciti), enasidenib mesylate (Idhifa), encorafenib (Braftovi), enfortumab vedotin-ejfv (Padcev), entrectinib (Rozlytrek), enzalutamide (Xtandi), erdafitinib (Balversa), erlotinib (Tarceva), everolimus (Afinitor), exemestane (Aromasin), fam-trastuzumab deruxtecan-nxki (Enhertu), fedratinib hydrochloride (Inrebic), fulvestrant (Faslodex), gefitinib (Iressa), gemtuzumab ozogamicin (Mylotarg), gilteritinib (Xospata), glasdegib maleate (Daurismo), hyaluronidase-zzxf (Phesgo), ibrutinib (Imbruvica), ibritumomab tiuxetan (Zevalin), idecabtagene vicleucel (Abecma), idelalisib (Zydelig), imatinib mesylate (Gleevec), infigratinib phosphate (Truseltiq), inotuzumab ozogamicin (Besponsa), iobenguane 1131 (Azedra), ipilimumab (Yervoy), isatuximab-irfc (Sarclisa), ivosidenib (Tibsovo), ixazomib citrate (Ninlaro), lanreotide acetate (Somatuline Depot), lapatinib (Tykerb), larotrectinib sulfate (Vitrakvi), lenvatinib mesylate (Lenvima), letrozole (Femara), lisocabtagene maraleucel (Breyanzi), loncastuximab tesirine-lpyl (Zynlonta), lorlatinib (Lorbrena), lutetium Lu 177-dotatate (Lutathera), margetuximab-cmkb (Margenza), midostaurin (Rydapt), mobocertinib succinate (Exkivity), mogamulizumab-kpkc (Poteligeo), moxetumomab pasudotox-tdfk (Lumoxiti), naxitamab-gqgk (Danyelza), necitumumab (Portrazza), neratinib maleate (Nerlynx), nilotinib (Tasigna), niraparib tosylate monohydrate (Zejula), nivolumab (Opdivo), obinutuzumab (Gazyva), ofatumumab (Arzerra), olaparib (Lynparza), olaratumab (Lartruvo), osimertinib (Tagrisso), palbociclib (Ibrance), panitumumab (Vectibix), panobinostat (Farydak), pazopanib (Votrient), pembrolizumab (Keytruda), pemigatinib (Pemazyre), pertuzumab (Perjeta), pexidartinib hydrochloride (Turalio), polatuzumab vedotin-piiq (Polivy), ponatinib hydrochloride (Iclusig), pralatrexate (Folotyn), pralsetinib (Gavreto), radium 223 dichloride (Xofigo), ramucirumab (Cyramza), regorafenib (Stivarga), ribociclib (Kisqali), ripretinib (Qinlock), rituximab (Rituxan), rituximab and hyaluronidase human (Rituxan Hycela), romidepsin (Istodax), rucaparib camsylate (Rubraca), ruxolitinib phosphate (Jakafi), sacituzumab govitecan-hziy (Trodelvy), seliciclib, selinexor (Xpovio), selpercatinib (Retevmo), selumetinib sulfate (Koselugo), siltuximab (Sylvant), sipuleucel-T (Provenge), sirolimus protein-bound particles (Fyarro), sonidegib (Odomzo), sorafenib (Nexavar), sotorasib (Lumakras), sunitinib (Sutent), tafasitamab-cxix (Monjuvi), tagraxofusp-erzs (Elzonris), talazoparib tosylate (Talzenna), tamoxifen (Nolvadex), tazemetostat hydrobromide (Tazverik), tebentafusp-tebn (Kimmtrak), temsirolimus (Torisel), tepotinib hydrochloride (Tepmetko), tisagenlecleucel (Kymriah), tisotumab vedotin-tftv (Tivdak), tocilizumab (Actemra), tofacitinib (Xeljanz), tositumomab (Bexxar), trametinib (Mekinist), trastuzumab (Herceptin), tretinoin (Vesanoid), tivozanib hydrochloride (Fotivda), toremifene (Fareston), tucatinib (Tukysa), umbralisib tosylate (Ukoniq), vandetanib (Caprelsa), vemurafenib (Zelboraf), venetoclax (Venclexta), vismodegib (Erivedge), vorinostat (Zolinza), zanubrutinib (Brukinsa), ziv-aflibercept (Zaltrap), or any combination thereof.

22. The method of any one of clauses 1 to 21, further comprising obtaining the sample from the subject.

23. The method of any one of clauses 1 to 22, wherein the sample comprises a tissue biopsy sample, a liquid biopsy sample, or a normal control. 24. The method of clause 23, wherein the sample is a liquid biopsy sample and comprises blood, plasma, cerebrospinal fluid, sputum, stool, urine, or saliva.

25. The method of clause 23, wherein the sample is a liquid biopsy sample and comprises circulating tumor cells (CTCs).

26. The method of clause 23, wherein the sample is a liquid biopsy sample and comprises cell- free DNA (cfDNA), circulating tumor DNA (ctDNA), or any combination thereof.

27. The method of any one of clauses 1 to 26, wherein the plurality of nucleic acid molecules comprises a mixture of tumor nucleic acid molecules and non-tumor nucleic acid molecules.

28. The method of clause 27, wherein the tumor nucleic acid molecules are derived from a tumor portion of a heterogeneous tissue biopsy sample, and the non-tumor nucleic acid molecules are derived from a normal portion of the heterogeneous tissue biopsy sample.

29. The method of clause 27, wherein the sample comprises a liquid biopsy sample, and wherein the tumor nucleic acid molecules are derived from a circulating tumor DNA (ctDNA) fraction of the liquid biopsy sample, and the non-tumor nucleic acid molecules are derived from a non- tumor, cell-free DNA (cfDNA) fraction of the liquid biopsy sample.

30. The method of any one of clauses 1 to 29, wherein the one or more adapters comprise amplification primers, flow cell adaptor sequences, substrate adapter sequences, or sample index sequences.

31. The method of any one of clauses 1 to 30, wherein the captured nucleic acid molecules are captured from the amplified nucleic acid molecules by hybridization to one or more bait molecules.

32. The method of clause 31, wherein the one or more bait molecules comprise one or more nucleic acid molecules, each comprising a region that is complementary to a region of a captured nucleic acid molecule. 33. The method of any one of clauses 1 to 32, wherein amplifying nucleic acid molecules comprises performing a polymerase chain reaction (PCR) amplification technique, a non-PCR amplification technique, or an isothermal amplification technique.

34. The method of any one of clauses 1 to 33, wherein the sequencing comprises use of a massively parallel sequencing (MPS) technique, whole genome sequencing (WGS), whole exome sequencing, targeted sequencing, direct sequencing, or Sanger sequencing technique.

35. The method of clause 34, wherein the sequencing comprises massively parallel sequencing, and the massively parallel sequencing technique comprises next generation sequencing (NGS).

36. The method of any one of clauses 1 to 35, wherein the sequencer comprises a next generation sequencer.

37. The method of any one of clauses 1 to 36, wherein one or more of the plurality of sequencing reads overlap one or more gene loci within one or more subgenomic intervals in the sample.

38. The method of clause 37, wherein the one or more gene loci comprises between 10 and 20 loci, between 10 and 40 loci, between 10 and 60 loci, between 10 and 80 loci, between 10 and 100 loci, between 10 and 150 loci, between 10 and 200 loci, between 10 and 250 loci, between 10 and 300 loci, between 10 and 350 loci, between 10 and 400 loci, between 10 and 450 loci, between 10 and 500 loci, between 20 and 40 loci, between 20 and 60 loci, between 20 and 80 loci, between 20 and 100 loci, between 20 and 150 loci, between 20 and 200 loci, between 20 and 250 loci, between 20 and 300 loci, between 20 and 350 loci, between 20 and 400 loci, between 20 and 500 loci, between 40 and 60 loci, between 40 and 80 loci, between 40 and 100 loci, between 40 and 150 loci, between 40 and 200 loci, between 40 and 250 loci, between 40 and 300 loci, between 40 and 350 loci, between 40 and 400 loci, between 40 and 500 loci, between 60 and 80 loci, between 60 and 100 loci, between 60 and 150 loci, between 60 and 200 loci, between 60 and 250 loci, between 60 and 300 loci, between 60 and 350 loci, between 60 and 400 loci, between 60 and 500 loci, between 80 and 100 loci, between 80 and 150 loci, between 80 and 200 loci, between 80 and 250 loci, between 80 and 300 loci, between 80 and 350 loci, between 80 and 400 loci, between 80 and 500 loci, between 100 and 150 loci, between 100 and 200 loci, between 100 and 250 loci, between 100 and 300 loci, between 100 and 350 loci, between 100 and 400 loci, between 100 and 500 loci, between 150 and 200 loci, between 150 and 250 loci, between 150 and 300 loci, between 150 and 350 loci, between 150 and 400 loci, between 150 and 500 loci, between 200 and 250 loci, between 200 and 300 loci, between 200 and 350 loci, between 200 and 400 loci, between 200 and 500 loci, between 250 and 300 loci, between 250 and 350 loci, between 250 and 400 loci, between 250 and 500 loci, between 300 and 350 loci, between 300 and 400 loci, between 300 and 500 loci, between 350 and 400 loci, between 350 and 500 loci, or between 400 and 500 loci.

39. The method of clause 37 or clause 38, wherein the one or more gene loci comprise ABL1, ACVR1B, AKT1, AKT2, AKT3, ALK, ALOX12B, AMER1, APC, AR, ARAF, ARFRP1, ARID1A, ASXL1, ATM, ATR, ATRX, AURKA, AURKB, AXIN1, AXL, BAP1, BARD1, BCL2, BCL2L1, BCL2L2, BCL6, BCOR, BCORL1, BCR, BRAF, BRCA1, BRCA2, BRD4, BRIP1, BTG1, BTG2, BTK, CALR, CARD11, CASP8, CBFB, CBL, CCND1, CCND2, CCND3, CCNE1, CD22, CD274, CD70, CD74, CD79A, CD79B, CDC73, CDH1, CDK12, CDK4, CDK6, CDK8, CDKN1A, CDKN1B, CDKN2A, CDKN2B, CDKN2C, CEBPA, CHEK1, CHEK2, CIC, CREBBP, CRKL, CSF1R, CSF3R, CTCF, CTNNA1, CTNNB1, CUL3, CUL4A, CXCR4, CYP17A1, DAXX, DDR1, DDR2, DIS3, DNMT3A, DOT1L, EED, EGFR, EMSY (Cllorf30), EP300, EPHA3, EPHB1, EPHB4, ERBB2, ERBB3, ERBB4, ERCC4, ERG, ERRFI1, ESRI, ETV4, ETV5, ETV6, EWSR1, EZH2, EZR, FAM46C, FANCA, FANCC, FANCG, FANCL, FAS, FBXW7, FGF10, FGF12, FGF14, FGF19, FGF23, FGF3, FGF4, FGF6, FGFR1, FGFR2, FGFR3, FGFR4, FH, FLCN, FLT1, FLT3, FOXL2, FUBP1, GABRA6, GATA3, GATA4, GATA6, GID4 (C17orf39), GNA11, GNA13, GNAQ, GNAS, GRM3, GSK3B, H3F3A, HDAC1, HGF, HNF1A, HRAS, HSD3B1, ID3, IDH1, IDH2, IGF1R, IKBKE, IKZF1, INPP4B, IRF2, IRF4, IRS2, JAK1, JAK2, JAK3, JUN, KDM5A, KDM5C, KDM6A, KDR, KEAP1, KEL, KIT, KLHL6, KMT2A (MLL), KMT2D (MLL2), KRAS, LTK, LYN, MAF, MAP2K1, MAP2K2, MAP2K4, MAP3K1, MAP3K13, MAPK1, MCL1, MDM2, MDM4, MED12, MEF2B, MEN1, MERTK, MET, MITF, MKNK1, MLH1, MPL, MRE11A, MSH2, MSH3, MSH6, MST1R, MTAP, MTOR, MUTYH, MYB, MYC, MYCL, MYCN, MYD88, NBN, NF1, NF2, NFE2L2, NFKBIA, NKX2-1, NOTCH1, NOTCH2, NOTCH3, NPM1, NRAS, NT5C2, NTRK1, NTRK2, NTRK3, NUTM1, P2RY8, PALB2, PARK2, PARP1, PARP2, PARP3, PAX5, PBRM1, PDCD1, PDCD1LG2, PDGFRA, PDGFRB, PDK1, PIK3C2B, PIK3C2G, PIK3CA, PIK3CB, PIK3R1, PIM1, PMS2, POLDI, POLE, PPARG, PPP2R1A, PPP2R2A, PRDM1, PRKAR1A, PRKCI, PTCHI, PTEN, PTPN11, PTPRO, QKI, RAC1, RAD21, RAD51, RAD51B, RAD51C, RAD51D, RAD52, RAD54L, RAFI, RARA, RBI, RBM10, REL, RET, RICTOR, RNF43, ROS1, RPTOR, RSPO2, SDC4, SDHA, SDHB, SDHC, SDHD, SETD2, SF3B 1, SGK1, SLC34A2, SMAD2, SMAD4, SMARCA4, SMARCB 1, SMO, SNCAIP, SOCS1, SOX2, SOX9, SPEN, SPOP, SRC, STAG2, STAT3, STK11, SUFU, SYK, TBX3, TEK, TERC, TERT, TET2, TGFBR2, TIPARP, TMPRSS2, TNFAIP3, TNFRSF14, TP53, TSC1, TSC2, TYRO3, U2AF1, VEGFA, VHL, WHSCI, WHSC1L1, WT1, XPO1, XRCC2, ZNF217, ZNF703, or any combination thereof.

40. The method of clause 37 or clause 38, wherein the one or more gene loci comprise ABL, ALK, ALL, B4GALNT1, BAFF, BCL2, BRAF, BRCA, BTK, CD19, CD20, CD3, CD30, CD319, CD38, CD52, CDK4, CDK6, CML, CRACC, CS1, CTLA-4, dMMR, EGFR, ERBB 1, ERBB2, FGFR1-3, FLT3, GD2, HDAC, HER1, HER2, HR, IDH2, IL-ip, IL-6, IL-6R, JAK1, JAK2, JAK3, KIT, KRAS, MEK, MET, MSLH, mTOR, PARP, PD-1, PDGFR, PDGFRa, PDGFRP, PD-L1, PI3K5, PIGF, PTCH, RAF, RANKL, RET, ROS1, SLAMF7, VEGF, VEGFA, VEGFB, or any combination thereof.

41. The method of any one of clauses 1 to 40, further comprising generating, by the one or more processors, a report indicating the determined tumor DNA fraction of the sample.

42. The method of clause 41, further comprising transmitting the report to a healthcare provider.

43. The method of clause 42, wherein the report is transmitted via a computer network or a peer- to-peer connection.

44. A method for determining a tumor DNA fraction for a cell-free DNA sample from a subject, the method comprising: receiving, at one or more processors, sequence read data for a plurality of sequence reads derived from the cell-free DNA (cfDNA) sample from the subject; determining, using the one or more processors, a variant allele frequency (VAF) for one or more variants detected in the cfDNA sample based on the sequence read data; generating, using the one or more processors, an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fitting, using the one or more processors, a model to the empirical distribution of tumor DNA fraction values; and determining a tumor DNA fraction for the cfDNA sample based on the model.

45. The method of clause 44, further comprising determining a confidence interval for the tumor DNA fraction based on the model.

46. The method of clause 44 or clause 45, wherein the one or more variants comprise one or more short variants.

47. The method of clause 46, wherein the one or more short variants comprise one or more somatic short variants.

48. The method of clause 47, wherein the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

49. The method of any one of clauses 44 to 48, wherein generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

50. The method of any one of clauses 44 to 48, wherein generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants. 51. The method of clause 49 or clause 50, wherein tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the cfDNA sample from the subject.

52. The method of clause 49 or clause 50, wherein tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the cfDNA sample from the subject.

53. The method of clause 49 or clause 50, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the cfDNA sample from the subject.

54. The method of clause 49 or clause 50, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the cfDNA sample from the subject that comprise known driver mutations.

55. The method of clause 49 or clause 50, wherein the tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

56. The method of any one of clauses 49 to 55, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples.

57. The method of any one of clauses 49 to 56, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants. 58. The method of any one of clauses 49 to 57, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations comprising: a first equation that equates tumor DNA fraction to a product of tumor purity and tumor average ploidy, divided by a sum of the product of tumor purity and tumor average ploidy and a product of two times a quantity of one minus tumor purity; and a second equation that equates somatic VAF to a product of tumor purity and a variant allele number for each of the one or more variants, divided by a sum of a product of tumor purity and copy number at a genomic location of the one or more variants and a product of two times a quantity of one minus tumor purity; to eliminate tumor purity and derive a relationship that equates tumor DNA fraction to tumor average ploidy divided by a quantity equal to tumor average ploidy minus the copy number at a genomic location of the one or more variants plus a ratio of variant allele number for the one or more variants to somatic VAF for each of the one or more variants.

59. The method of any one of clauses 49 to 58, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations: pif tumor DNA fraction = — - - — - - -

~ ^J pif + 2(l - p) pV

Somatic VAF = — — — — - r C + 2(l - ) to eliminate p and obtain a relationship between tumor DNA fraction and somatic VAF described by: where p is a tumor purity, yr is an tumor average ploidy, C is the copy number at a genomic location of the one or more variants, and V is a variant allele number for each of the one or more variants.

60. The method of any one of clauses 49 to 59, wherein the plurality of historical subject samples comprises solid biopsy samples, liquid biopsy samples, or any combination thereof.

61. The method of any one of clauses 49 to 60, wherein the plurality of historical subject samples comprises cancer samples.

62. The method of clause 61, wherein the plurality of historical subject samples comprises samples for a single type of cancer.

63. The method of clause 62, wherein the plurality of historical subject samples comprises samples for multiple types of cancer.

64. The method of any one of clauses 49 to 63, wherein the plurality of historical subject samples comprise bladder cancer samples, breast cancer samples, colorectal cancer samples, endometrial cancer samples, kidney cancer samples, leukemia samples, liver cancer samples, lung cancer samples, melanoma samples, non-Hodgkin lymphoma samples, pancreatic cancer samples, prostate cancer samples, thyroid cancer samples, or any combination thereof.

65. The method of any one of clauses 49 to 64, wherein the plurality of historical subject samples comprise acute lymphoblastic leukemia (Philadelphia chromosome positive) samples, acute lymphoblastic leukemia (precursor B-cell) samples, acute myeloid leukemia (FLT3+) samples, acute myeloid leukemia (with an IDH2 mutation) samples, anaplastic large cell lymphoma samples, basal cell carcinoma samples, B-cell chronic lymphocytic leukemia samples, bladder cancer samples, breast cancer (HER2 overexpressed/amplified) samples, breast cancer (HER2+) samples, breast cancer (HR+, HER2-) samples, cervical cancer samples, cholangiocarcinoma samples, chronic lymphocytic leukemia samples, chronic lymphocytic leukemia (with 17p deletion) samples, chronic myelogenous leukemia samples, chronic myelogenous leukemia (Philadelphia chromosome positive) samples, classical Hodgkin lymphoma samples, colorectal cancer samples, colorectal cancer (dMMR and MSI-H) samples, colorectal cancer (KRAS wild type) samples, cryopyrin-associated periodic syndrome samples, cutaneous T-cell lymphoma samples, dermatofibrosarcoma protuberans samples, diffuse large B-cell lymphoma samples, fallopian tube cancer samples, follicular B-cell non-Hodgkin lymphoma samples, follicular lymphoma samples, gastric cancer samples, gastric cancer (HER2+) samples, gastroesophageal junction (GEJ) adenocarcinoma samples, gastrointestinal stromal tumor samples, gastrointestinal stromal tumor (KIT+) samples, giant cell tumor of the bone samples, glioblastoma samples, granulomatosis with polyangiitis samples, head and neck squamous cell carcinoma samples, hepatocellular carcinoma samples, Hodgkin lymphoma samples, juvenile idiopathic arthritis samples, lupus erythematosus samples, mantle cell lymphoma samples, medullary thyroid cancer samples, melanoma samples, melanoma samples with a BRAF V600 mutation, melanoma samples with a BRAF V600E or V600K mutation, Merkel cell carcinoma samples, multicentric Castleman's disease samples, multiple hematologic malignancy samples including Philadelphia chromosome-positive ALL and CML, multiple myeloma samples, myelofibrosis samples, nonHodgkin’s lymphoma samples, nonresectable subependymal giant cell astrocytoma samples associated with tuberous sclerosis, non-small cell lung cancer samples, non-small cell lung cancer (ALK+) samples, non-small cell lung cancer (PD-L1+) samples, non-small cell lung cancer (with ALK fusion or ROS1 gene alteration) samples, non-small cell lung cancer (with BRAF V600E mutation) samples, non-small cell lung cancer samples (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutation), non-small cell lung cancer samples (with an EGFR T790M mutation), ovarian cancer samples, ovarian cancer samples (with a BRCA mutation), pancreatic cancer samples, pancreatic cancer samples, gastrointestinal cancer samples, lung origin neuroendocrine tumor samples, pediatric neuroblastoma samples, peripheral T-cell lymphoma samples, peritoneal cancer samples, prostate cancer samples, renal cell carcinoma samples, rheumatoid arthritis samples, small lymphocytic lymphoma samples, soft tissue sarcoma samples, solid tumor (MSLH/dMMR) samples, squamous cell cancer samples of the head and neck, squamous non-small cell lung cancer samples, thyroid cancer samples, thyroid carcinoma samples, urothelial cancer samples, urothelial carcinoma samples, Waldenstrom's macroglobulinemia samples, or any combination thereof.

66. The method of any one of clauses 44 to 65, wherein the model is a non-parametric probability density model. 67. The method of any one of clauses 44 to 66, wherein the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction.

68. The method of any one of clauses 44 to 67, wherein the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

69. The method of any one of clauses 44 to 68, wherein the cfDNA sample comprises DNA extracted from a blood sample, a plasma sample, a cerebrospinal fluid sample, a pleural effusion fluid sample, a sputum sample, a stool sample, a urine sample, or a saliva sample.

70. A method for determining a tumor DNA fraction for a sample from a subject, the method comprising: receiving, at one or more processors, sequence read data for a plurality of sequence reads derived from the sample from the subject; determining, using the one or more processors, a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generating, using the one or more processors, an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fitting, using the one or more processors, a model to the empirical distribution of tumor DNA fraction values; and determining a tumor DNA fraction for the sample based on the model.

71. The method of clause 70, further comprising determining a confidence interval for the tumor DNA fraction based on the model.

72. The method of clause 70 or clause 71, wherein the one or more variants comprise one or more short variants.

73. The method of clause 72, wherein the one or more short variants comprise one or more somatic short variants. 74. The method of clause 73, wherein the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

75. The method of any one of clauses 70 to 74, wherein generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

76. The method of any one of clauses 70 to 75, wherein generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

77. The method of clause 75 or clause 76, wherein tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the sample from the subject.

78. The method of clause 75 or clause 76, wherein tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject.

79. The method of clause 75 or clause 76, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject.

80. The method of clause 75 or clause 76, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations.

81. The method of clause 75 or clause 76, wherein the tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject. 82. The method of any one of clauses 75 to 81, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

83. The method of any one of clauses 75 to 82, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations comprising: a first equation that equates tumor DNA fraction to a product of tumor purity and tumor average ploidy, divided by a sum of the product of tumor purity and tumor average ploidy and a product of two times a quantity of one minus tumor purity; and a second equation that equates somatic VAF to a product of tumor purity and a variant allele number for each of the one or more variants, divided by a sum of a product of tumor purity and copy number at a genomic location of the one or more variants and a product of two times a quantity of one minus tumor purity; to eliminate tumor purity and derive a relationship that equates tumor DNA fraction to tumor average ploidy divided by a quantity equal to tumor average ploidy minus the copy number at a genomic location of the one or more variants plus a ratio of variant allele number for the one or more variants to somatic VAF for each of the one or more variants.

84. The method of any one of clauses 75 to 83, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations: pif tumor DNA fraction = — - - — - - -

~ ^J pif + 2(l - p) pV Somatic VAF = — — — — - C + 2(l - ) to eliminate p and obtain a relationship between tumor DNA fraction and somatic VAF described by: where p is a tumor purity, y is an tumor average ploidy, C is the copy number at a genomic location of the one or more variants, and V is a variant allele number for each of the one or more variants.

85. The method of any one of clauses 75 to 84, wherein the plurality of historical subject samples comprise solid biopsy samples, liquid biopsy samples, or any combination thereof.

86. The method of any one of clauses 75 to 85, wherein the plurality of historical subject samples comprises cancer samples.

87. The method of clause 86, wherein the plurality of historical subject samples comprises samples for a single type of cancer.

88. The method of clause 86, wherein the plurality of historical subject samples comprises samples for multiple types of cancer.

89. The method of any one of clauses 75 to 88, wherein the plurality of historical subject samples comprise bladder cancer samples, breast cancer samples, colorectal cancer samples, endometrial cancer samples, kidney cancer samples, leukemia samples, liver cancer samples, lung cancer samples, melanoma samples, non-Hodgkin lymphoma samples, pancreatic cancer samples, prostate cancer samples, thyroid cancer samples, or any combination thereof. 90. The method of any one of clauses 75 to 89, wherein the plurality of historical subject samples comprise acute lymphoblastic leukemia (Philadelphia chromosome positive) samples, acute lymphoblastic leukemia (precursor B-cell) samples, acute myeloid leukemia (FLT3+) samples, acute myeloid leukemia (with an IDH2 mutation) samples, anaplastic large cell lymphoma samples, basal cell carcinoma samples, B-cell chronic lymphocytic leukemia samples, bladder cancer samples, breast cancer (HER2 overexpressed/amplified) samples, breast cancer (HER2+) samples, breast cancer (HR+, HER2-) samples, cervical cancer samples, cholangiocarcinoma samples, chronic lymphocytic leukemia samples, chronic lymphocytic leukemia (with 17p deletion) samples, chronic myelogenous leukemia samples, chronic myelogenous leukemia (Philadelphia chromosome positive) samples, classical Hodgkin lymphoma samples, colorectal cancer samples, colorectal cancer (dMMR and MSI-H) samples, colorectal cancer (KRAS wild type) samples, cryopyrin-associated periodic syndrome samples, cutaneous T-cell lymphoma samples, dermatofibrosarcoma protuberans samples, diffuse large B-cell lymphoma samples, fallopian tube cancer samples, follicular B-cell non-Hodgkin lymphoma samples, follicular lymphoma samples, gastric cancer samples, gastric cancer (HER2+) samples, gastroesophageal junction (GEJ) adenocarcinoma samples, gastrointestinal stromal tumor samples, gastrointestinal stromal tumor (KIT+) samples, giant cell tumor of the bone samples, glioblastoma samples, granulomatosis with polyangiitis samples, head and neck squamous cell carcinoma samples, hepatocellular carcinoma samples, Hodgkin lymphoma samples, juvenile idiopathic arthritis samples, lupus erythematosus samples, mantle cell lymphoma samples, medullary thyroid cancer samples, melanoma samples, melanoma samples with a BRAF V600 mutation, melanoma samples with a BRAF V600E or V600K mutation, Merkel cell carcinoma samples, multicentric Castleman's disease samples, multiple hematologic malignancy samples including Philadelphia chromosome-positive ALL and CML, multiple myeloma samples, myelofibrosis samples, nonHodgkin’s lymphoma samples, nonresectable subependymal giant cell astrocytoma samples associated with tuberous sclerosis, non-small cell lung cancer samples, non-small cell lung cancer (ALK+) samples, non-small cell lung cancer (PD-L1+) samples, non-small cell lung cancer (with ALK fusion or ROS1 gene alteration) samples, non-small cell lung cancer (with BRAF V600E mutation) samples, non-small cell lung cancer samples (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutation), non-small cell lung cancer samples (with an EGFR T790M mutation), ovarian cancer samples, ovarian cancer samples (with a BRCA mutation), pancreatic cancer samples, pancreatic cancer samples, gastrointestinal cancer samples, lung origin neuroendocrine tumor samples, pediatric neuroblastoma samples, peripheral T-cell lymphoma samples, peritoneal cancer samples, prostate cancer samples, renal cell carcinoma samples, rheumatoid arthritis samples, small lymphocytic lymphoma samples, soft tissue sarcoma samples, solid tumor (MSI-H/dMMR) samples, squamous cell cancer samples of the head and neck, squamous non-small cell lung cancer samples, thyroid cancer samples, thyroid carcinoma samples, urothelial cancer samples, urothelial carcinoma samples, Waldenstrom's macroglobulinemia samples, or any combination thereof.

91. The method of any one of clauses 70 to 90, wherein the model is a non-parametric probability density model.

92. The method of any one of clauses 70 to 91, wherein the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction.

93. The method of any one of clauses 70 to 92, wherein the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

94. The method of any one of clauses 70 to 93, wherein the sample comprises DNA extracted from a blood sample, a plasma sample, a cerebrospinal fluid sample, a pleural effusion fluid sample, a sputum sample, a stool sample, a urine sample, or a saliva sample.

95. The method of any one of clauses 44 to 94, wherein the determination of tumor DNA fraction is used to diagnose or confirm a diagnosis of disease in the subject.

96. The method of clause 95, wherein the disease is cancer.

97. The method of clause 96, wherein the cancer is acute lymphoblastic leukemia (Philadelphia chromosome positive), acute lymphoblastic leukemia (precursor B-cell), acute myeloid leukemia (FLT3+), acute myeloid leukemia (with an IDH2 mutation), anaplastic large cell lymphoma, basal cell carcinoma, B-cell chronic lymphocytic leukemia, bladder cancer, breast cancer (HER2 overexpressed/amplified), breast cancer (HER2+), breast cancer (HR+, HER2-), cervical cancer, cholangiocarcinoma, chronic lymphocytic leukemia, chronic lymphocytic leukemia (with 17p deletion), chronic myelogenous leukemia, chronic myelogenous leukemia (Philadelphia chromosome positive), classical Hodgkin lymphoma, colorectal cancer, colorectal cancer (dMMR/MSI-H), colorectal cancer (KRAS wild type), cryopyrin-associated periodic syndrome, a cutaneous T-cell lymphoma, dermatofibrosarcoma protuberans, a diffuse large B-cell lymphoma, fallopian tube cancer, a follicular B-cell non-Hodgkin lymphoma, a follicular lymphoma, gastric cancer, gastric cancer (HER2+), gastroesophageal junction (GEJ) adenocarcinoma, a gastrointestinal stromal tumor, a gastrointestinal stromal tumor (KIT+), a giant cell tumor of the bone, a glioblastoma, granulomatosis with polyangiitis, a head and neck squamous cell carcinoma, a hepatocellular carcinoma, Hodgkin lymphoma, juvenile idiopathic arthritis, lupus erythematosus, a mantle cell lymphoma, medullary thyroid cancer, melanoma, a melanoma with a BRAF V600 mutation, a melanoma with a BRAF V600E or V600K mutation, Merkel cell carcinoma, multicentric Castleman's disease, multiple hematologic malignancies including Philadelphia chromosome-positive ALL and CML, multiple myeloma, myelofibrosis, a non-Hodgkin’ s lymphoma, a nonresectable subependymal giant cell astrocytoma associated with tuberous sclerosis, a non-small cell lung cancer, a non-small cell lung cancer (ALK+), a non-small cell lung cancer (PD-L1+), a non-small cell lung cancer (with ALK fusion or ROS1 gene alteration), a non-small cell lung cancer (with BRAF V600E mutation), a non-small cell lung cancer (with an EGFR exon 19 deletion or exon 21 substitution (L858R) mutations), a non- small cell lung cancer (with an EGFR T790M mutation), ovarian cancer, ovarian cancer (with a BRCA mutation), pancreatic cancer, a pancreatic, gastrointestinal, or lung origin neuroendocrine tumor, a pediatric neuroblastoma, a peripheral T-cell lymphoma, peritoneal cancer, prostate cancer, a renal cell carcinoma, rheumatoid arthritis, a small lymphocytic lymphoma, a soft tissue sarcoma, a solid tumor (MSLH/dMMR), a squamous cell cancer of the head and neck, a squamous non-small cell lung cancer, thyroid cancer, a thyroid carcinoma, urothelial cancer, a urothelial carcinoma, or Waldenstrom's macroglobulinemia.

98. The method of any one of clauses 44 to 97, further comprising selecting an anti-cancer therapy to administer to the subject based on the determination of tumor DNA fraction.

99. The method of any one of clauses 44 to 98, further comprising determining an effective amount of an anti-cancer therapy to administer to the subject based on the determination of tumor DNA fraction. 100. The method of clause 98 or clause 99, further comprising administering the anti-cancer therapy to the subject based on the determination of tumor DNA fraction.

101. The method of any one of clauses 98 to 100, wherein the anti-cancer therapy comprises chemotherapy, radiation therapy, immunotherapy, a targeted therapy, or surgery.

102. A method for diagnosing a disease, the method comprising: diagnosing that a subject has the disease based on a determination of tumor DNA fraction for a sample from the subject, wherein tumor DNA fraction is determined according to the method of any one of clauses 44 to 94.

103. A method of selecting an anti-cancer therapy, the method comprising: responsive to determining tumor DNA fraction for a sample from a subject, selecting an anti-cancer therapy for the subject, wherein tumor DNA fraction is determined according to the method of any one of clauses 44 to 94.

104. A method of treating a cancer in a subject, comprising: responsive to determining tumor DNA fraction for a sample from the subject, administering an effective amount of an anti-cancer therapy to the subject, wherein tumor DNA fraction is determined according to the method of any one of clauses 44 to 94.

105. A method for determining a prognosis for a subject having cancer comprising: determining tumor DNA fraction for a sample from the subject, and determining a prognosis for the subject based on the tumor DNA fraction, wherein tumor DNA fraction is determined according to the method of any one of clauses 44 to 94.

106. A method for assessing molecular residual disease (MRD), the method comprising: determining tumor DNA fraction for a sample from the subject, and assessing molecular residual disease (MRD) for the subject based on the tumor DNA fraction, wherein tumor DNA fraction is determined according to the method of any one of clauses 44 to 94.

107. A method for monitoring cancer progression or recurrence in a subject, the method comprising: determining a first tumor DNA fraction in a first sample obtained from the subject at a first time point according to the method of any one of clauses 44 to 94; determining a second tumor DNA fraction in a second sample obtained from the subject at a second time point; and comparing the first tumor DNA fraction to the second tumor DNA fraction, thereby monitoring the cancer progression or recurrence.

108. The method of clause 107, wherein the second tumor DNA fraction for the second sample is determined according to the method of any one of clauses 44 to 94.

109. The method of clause 107 or clause 108, further comprising selecting an anti-cancer therapy for the subject in response to the cancer progression.

110. The method of clause 107 or clause 108, further comprising administering an anti-cancer therapy to the subject in response to the cancer progression.

111. The method of clause 107 or clause 108, further comprising adjusting an anti-cancer therapy for the subject in response to the cancer progression.

112. The method of any one of clauses 109 to 111, further comprising adjusting a dosage of the anti-cancer therapy or selecting a different anti-cancer therapy in response to the cancer progression.

113. The method of clause 112, further comprising administering the adjusted anti-cancer therapy to the subject.

114. The method of any one of clauses 107 to 113, wherein the first time point is before the subject has been administered an anti-cancer therapy, and wherein the second time point is after the subject has been administered the anti-cancer therapy.

115. The method of any one of clauses 107 to 114, wherein the subject has a cancer, is at risk of having a cancer, is being routine tested for cancer, or is suspected of having a cancer.

116. The method of any one of clauses 107 to 115, wherein the cancer is a solid tumor.

117. The method of any one of clauses 107 to 116, wherein the cancer is a hematological cancer. 118. The method of any one of clauses 107 to 117, wherein the anti-cancer therapy comprises chemotherapy, radiation therapy, immunotherapy, a targeted therapy, or surgery.

119. The method of any one of clauses 44 to 94, further comprising determining, identifying, or applying the value of tumor DNA fraction for the sample as a diagnostic value associated with the sample.

120. The method of any one of clauses 44 to 94, further comprising generating a genomic profile for the subject based on the determination of tumor DNA fraction.

121. The method of clause 120, wherein the genomic profile for the subject further comprises results from a comprehensive genomic profiling (CGP) test, a gene expression profiling test, a cancer hotspot panel test, a DNA methylation test, a DNA fragmentation test, an RNA fragmentation test, or any combination thereof.

122. The method of clause 120 or clause 121, wherein the genomic profile for the subject further comprises results from a nucleic acid sequencing-based test.

123. The method of any one of clauses 120 to 122, further comprising selecting an anti-cancer therapy, administering an anti-cancer therapy, or applying an anti-cancer therapy to the subject based on the generated genomic profile.

124. The method of any one of clauses 44 to 94, wherein the determination of tumor DNA fraction for the sample is used in making suggested treatment decisions for the subject.

125. The method of any one of clauses 44 to 94, wherein the determination of tumor DNA fraction for the sample is used in applying or administering a treatment to the subject.

126. A system comprising: one or more processors; and a memory communicatively coupled to the one or more processors and configured to store instructions that, when executed by the one or more processors, cause the system to:

I l l receive sequence read data for a plurality of sequence reads derived from a sample from a subject; determine a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generate an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fit a model to the empirical distribution of tumor DNA fraction values; and determine a tumor DNA fraction for the sample based on the model.

127. The system of clause 126, further comprising instructions for determining a confidence interval for the tumor DNA fraction based on the model.

128. The system of clause 126 or clause 127, wherein the one or more variants comprise one or more short variants.

129. The system of clause 128, wherein the one or more short variants comprise one or more somatic short variants.

130. The system of clause 129, wherein the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP).

131. The system of any one of clauses 126 to 130, wherein generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

132. The system of any one of clauses 126 to 130, wherein generating the empirical distribution of tumor DNA fraction values comprises pre-calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

133. The system of clause 131 or clause 132, wherein tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the sample from the subject.

134. The system of clause 131 or clause 132, wherein tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject.

135. The system of clause 131 or clause 132, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject.

136. The system of clause 131 or clause 132, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations.

137. The system of clause 131 or clause 132, wherein the tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

138. The system of any one of clauses 131 to 137, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

139. The system of any one of clauses 126 to 138, wherein the model is a non-parametric probability density model. 140. The system of any one of clauses 126 to 139, wherein the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction.

141. The system of any one of clauses 126 to 140, wherein the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

142. A non-transitory computer-readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by one or more processors of a system, cause the system to: receive sequence read data for a plurality of sequence reads derived from a sample from a subject; determine a variant allele frequency (VAF) for one or more variants detected in the sample based on the sequence read data; generate an empirical distribution of tumor DNA fraction values as a function of the determined VAF for the one or more variants; fit a model to the empirical distribution of tumor DNA fraction values; and determine a tumor DNA fraction for the sample based on the model.

143. The non-transitory computer-readable storage medium of clause 142, further comprising instructions for determining a confidence interval for the tumor DNA fraction based on the model.

144. The non-transitory computer-readable storage medium of clause 142 or clause 143, wherein the one or more variants comprise one or more short variants.

145. The non-transitory computer-readable storage medium of clause 144, wherein the one or more short variants comprise one or more somatic short variants.

146. The non-transitory computer-readable storage medium of clause 145, wherein the one or more somatic short variants are known not to be associated with clonal hematopoiesis of indeterminate potential (CHIP). 147. The non-transitory computer-readable storage medium of any one of clauses 142 to 146, wherein generating the empirical distribution of tumor DNA fraction values comprises calculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

148. The non-transitory computer-readable storage medium of any one of clauses 142 to 147, wherein generating the empirical distribution of tumor DNA fraction values comprises precalculating a tumor DNA fraction value based on a known copy number for the one or more variants and a corresponding known tumor average ploidy for a plurality of historical subject samples having a range of VAF values for the one or more variants, and selecting a subset of the pre-calculated tumor DNA fraction values that corresponds to samples having a known VAF for the one or more variants that is substantially the same as the determined VAF for the one or more variants.

149. The non-transitory computer-readable storage medium of clause 147 or clause 148, wherein tumor DNA fraction values are calculated or selected for a variant that exhibits the highest VAF in the sample from the subject.

150. The non-transitory computer-readable storage medium of clause 147 or clause 148, wherein tumor DNA fraction values are calculated or selected for a rank-ordered set of two or more variants that exhibit the highest rank-ordered VAFs in the sample from the subject.

151. The non-transitory computer-readable storage medium of clause 147 or clause 148, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject.

152. The non-transitory computer-readable storage medium of clause 147 or clause 148, wherein the tumor DNA fraction values are calculated or selected for a predetermined set of two or more variants detected in the sample from the subject that comprise known driver mutations. 153. The non-transitory computer-readable storage medium of clause 147 or clause 148, wherein the tumor DNA fraction values are calculated or selected for all variants detected in the cfDNA sample from the subject.

154. The non-transitory computer-readable storage medium of any one of clauses 147 to 153, wherein tumor DNA fraction values are calculated or pre-calculated based on the known VAF for the one or more variants, the known copy number for the one or more variants, and the corresponding known tumor average ploidy for the plurality of historical subject samples by solving a set of equations that describe: (i) a relationship between tumor DNA fraction, tumor purity, and tumor average ploidy, and (ii) a relationship between somatic VAF, tumor purity, copy number at the genomic location(s) of the one or more variants, and variant allele number for each of the one or more variants, to eliminate tumor purity and derive a relationship for tumor DNA fraction as a function of somatic VAF, tumor average ploidy, copy number at a genomic location of the one or more variants, and variant allele number for the one or more variants.

155. The non-transitory computer-readable storage medium of any one of clauses 142 to 154, wherein the model is a non-parametric probability density model.

156. The non-transitory computer-readable storage medium of any one of clauses 142 to 155, wherein the determined tumor DNA fraction for the sample is a most probable tumor DNA fraction.

157. The non-transitory computer-readable storage medium of any one of clauses 142 to 156, wherein the determined tumor DNA fraction for the cfDNA sample is the mean, median, or mode of a dominant peak in the empirical distribution of tumor DNA fraction values.

[0255] It should be understood from the foregoing that, while particular implementations of the disclosed methods and systems have been illustrated and described, various modifications can be made thereto and are contemplated herein. It is also not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the preferable embodiments herein are not meant to be construed in a limiting sense. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. Various modifications in form and detail of the embodiments of the invention will be apparent to a person skilled in the art. It is therefore contemplated that the invention shall also cover any such modifications, variations and equivalents.