CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/408,596, filed October 14, 2016, which is herein incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

This relates to the field of oncology, specifically to the use of CD300f inhibitors and/or the use of dendritic cells with modified genes encoding CD300f, for the treatment of solid tumors.

BACKGROUND

Cancer immunotherapy aims to enhance the ability of the patients' own immune response to destroy tumors. The magnitude of immune response is determined by the balance between immune activating signals and negative inhibitory signals. Checkpoint receptors encompass a specific subset of negative regulators that normally deliver inhibitory signals that dampen stimulatory signals and limit immune activation. Blockade of immune checkpoints represents an effective strategy to enhance the immune response against cancer cells. Several checkpoint receptors, including cytotoxic T lymphocyte associated protein-4 (CTLA-4) and Programmed Death (PD)-l, have been identified on T cells and targeting these with blocking antibodies has been successful in treating different cancer types (e.g., melanoma, bladder, and gastric cancer). However, multiple cancers, such as pancreatic and prostate cancer, are resistant to T cell checkpoint blocking, underscoring the importance of identifying novel checkpoints on immune cells for successful cancer therapy.

In addition to uncontrolled cell proliferation and expansion, malignant tumors display a high rate of cell loss due to apoptosis. As apoptotic cells expose phosphatidylserine (PS) on their cell surface, the engagement of PS on the tumor cell surface by PS -recognizing receptors of phagocytic immune cells could be a factor for the anti-tumor response, as it would regulate engulfment of the dying tumor cells and subsequent tumor antigen cross-presentation. A need remains for treatments for malignant tumors, such as treatments that target cell checkpoints.

SUMMARY OF THE DISCLOSURE

The PS -recognizing receptor, CD300f, expressed on myeloid cells (i.e., dendritic cells and macrophages) and a small sub-population of B cells in mice, regulates phagocytosis of apoptotic cells by macrophages and dendritic cells, thereby controlling inflammatory immune responses (Tian et al., Nat Commun 5:3146, 2014; Tian et al., Cell Death Differ 23: 1086-96, 2016). The use of CD300f inhibitors for the treatment of tumors, such as a solid tumor, is disclosed herein. Methods are also disclosed for targeting CD300f in dendritic cells, and the use of adoptive transfer of these dendritic cells or T cells activated by these dendritic cells for the treatment of solid tumors.

In some embodiments, methods are disclosed for treating a subject with a solid tumor. The methods include administering to the subject a therapeutically effective amount of a CD300f inhibitor, thereby treating the solid tumor in the subject.

In additional embodiments, methods are disclosed for treating a solid tumor in a subject, wherein the methods include administering to the subject a therapeutically effective amount of dendritic cells comprising an inactivated gene encoding CD300f.

In further embodiments, methods are treating a solid tumor in a subject that include isolating dendritic cells from the subject and transforming the dendritic cells with one or more vectors comprising: a) a Embryonal Fyn- Associated Substrate (EFS) promoter operably linked to a nucleotide sequence encoding a Type Π Cas9 nuclease, b) a U6 promoter operably linked to one or more nucleotide sequences encoding one or more CRISPR-Cas system guide RNAs that hybridize with the CD300f gene in the dendritic cell, wherein components (a) and (b) are located on same or different vectors. Alternatively, a ribonucleoprotein (RNP) complex can be utilized, wherein the guide RNA is attached to the protein and delivered to the dendritic cells. The one or more guide RNAs target the CD300f gene in the dendritic cell and the Cas9 protein cleaves the CD300f gene such that the sequence of the CD300f gene is modified or inactivated in the dendritic cell, thereby forming modified dendritic cells. The subject is administered a therapeutically effective amount of the modified dendritic cells, thereby treating the solid tumor in the subject.

In yet other embodiments, methods are disclosed treating a solid tumor in a subject that include isolating dendritic cells from the subject, and transforming the dendritic cells with one or more viral vectors comprising: a) a Embryonal Fyn- Associated Substrate (EFS) promoter operably linked to a nucleotide sequence encoding a Type II Cas9 nuclease, b) a U6 promoter operably linked to one or more nucleotide sequences encoding one or more CRISPR-Cas system guide RNAs that hybridize with the CD300f gene in the dendritic cell, wherein components (a) and (b) are located on same or different viral vectors. Alternatively, a RNP complex can be utilized, wherein the guide RNA is attached to the protein and delivered to the dendritic cells. The one or more guide RNAs target the CD300f gene in the dendritic cell and the Cas9 protein cleaves the CD300f gene such that the sequence of the CD300f gene is modified or inactivated in the dendritic cell, thereby forming modified dendritic cells. The modified dendritic cells are contacted with CD8 ⁺ T cells in the presence of tumor-associated antigens expressed by the solid tumor to form activated T cells. A therapeutically effective amount of the activated T cells is administered to the subject to treat the solid tumor.

The foregoing and other features of the disclosure will become more apparent from the following detailed description of several embodiments which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES FIGS. 1A-1C. Schematic overview of methods used to examine CD300f deficiency on solid tumor development in mice. A. Generation of Cd300f-/- mice on a C57BL/6 genetic background. Exon 2-3 of Cd300f gene was flanked by loxP sites. A PGK-neo cassette flanked by Flp recombinase target sites was used for selection. Following homologous recombination of the vector in embryonic stem cells, clones bearing the Cd300ffl/fl locus were established after deletion of PGK-neo selection cassette by Flp recombination, and clones with the Cd300f-/- locus were generated after deletion of the LoxP sites flanking regions together with the PGK-neo cassette using Cre recombinase. Identified targeted embryonic stem cell clones were microinjected into the blastocysts of C57BL/6 mice. B. Use the mouse model of tumor graft to study the effect of CD300f deficiency on solid tumor development. Cd300f +/+ or Cd300f-/- mice were subcutaneously inoculated with 10 ⁶ solid tumor cells, for example EL4-TfOVA cells, on dayO. Some of the mice were systemically irradiated at 3.25 Gy on day 7 (IR) and some of the irradiated mice were transferred with 10 ⁶ tumor antigen specific CD8 ⁺ T cells, for example OT-I T cells, on day 9 (OT- I). Irradiation was to deplete some existing immune cells and make space to allow for expansion of anti-tumor effectors. Tumor growth was measured on the indicated days; mice were euthanized when the longitudinal tumor diameter reached 15 mm. C. Use the mouse model of

azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colon cancer to examine CD300f deficiency on solid tumor development. Cd300f +/+ or Cd300f-/- mice were injected with AOM intraperitoneally and then fed with DSS-containing water in three 7-day cycles, with intermittent 14-day intervals of regular drinking water. After 10 weeks, mice were euthanized, and colon tumor sizes were measured.

FIGS. 2A-2D. CD300f functions as a checkpoint for tumor immunity. A. Inhibition of grafted tumor growth in G£?0O -deficient mice. Cd300f+I+ or Cd300f-I- mice were

subcutaneously inoculated with 10 ⁶ EL4-TfOVA cells on day 0. Some of the mice were systemically irradiated at 3.25 Gy on day 7 (IR) and some of the irradiated mice were transferred with 10 ⁶ OT-I T cells on day 9 (OT-I). Irradiation was to deplete some existing immune cells and make space to allow for expansion of anti-tumor effectors. Tumor growth was measured on the indicated days; mice were euthanized when the longitudinal tumor diameter reached 15 mm. The graph on the left shows the progression of tumor growth in Cd300f+I+ and Cd300f -I- mice; the images on the right illustrate tumors dissected on day 18 from Cd300f+I+ and Cd300f-I- mice that were both irradiated and OT-I T cell-transferred. B. Inhibition of growth of AOM/DSS-induced colorectal cancer in C<i?0O -deficient mice. Cd300f+I+ or Cd300f-I- mice were injected with AOM intraperitoneally and then fed with DSS-containing water in three 7-day cycles, with intermittent 14-day intervals of regular drinking water. After 10 weeks, mice were euthanized, and colon tumor sizes were measured. The images on the left show tumors in the colons of Cd300f+I+ and Cd300f- I- mice; arrowheads indicate the position of tumors. The graph on the right shows quantification of tumor sizes in Cd300f+I+ and Cd300f-I- mice. C. Enhanced activation of CD8 ⁺ T cells in Cd300f- deficient mice. Cd300f+I+ or Cd300f-I- mice were systemically irradiated at 3.25 Gy on day 1 and transferred with OT-I T cells (10 ⁶ ) on day 3. Splenocytes were isolated on day 12, and stimulated with 10 μg/ml OT-1 peptide for 6 hours, and the percentage of OT-I cells positive for IFN-γ was determined by flow cytometry. D. Enhanced infiltration of CD8 ⁺ T cells in the EL4-TfOVA tumor tissues in Gi?0O -deficient mice. The images show a representative staining of CD8 ⁺ T cells (arrowheads) in paraffin-embedded tumor tissues isolated from Cd300f+I+ and Cd300f-I- mice irradiated at 3.25 Gy.

FIGS. 3A-3B. Inhibition of grafted tumor growth in CD300f-deficient mice. Cd300f+I+ or Cd300f-I- mice were subcutaneously inoculated with 10 ⁶ MC38 cells on day 0. Tumor growth was monitored on the indicated days; mice were euthanized when the longitudinal tumor diameter reached 15 mm. A. The graph shows the progression of tumor growth in Cd300f+/+ and Cd300f-/- mice. B. The images show the tumors dissected on day 16 from Cd300f+/+ and Cd300f-/- mice.

FIGS. 4A-4B. Human CD300f recognizes PS and regulates the phagocytosis of apoptotic cells. A. Human CD300f binds PS by surface plasmon resonance analysis. ImM PS-containing liposomes were captured on the LI sensor chip, followed by injection of Fc-fused control protein ΝΓΓΡν, mouse CD300f and human CD300f at 10μg/ml. The sensorgrams show the resonance units over the indicated times. B. Human CD300f expression on L929 cells promotes phagocytosis of apoptotic cells. L929 cells, transduced with empty virus (EV) or human CD300f, were mixed with pHrodo-labeled unirradiated or irradiated mouse thymocytes at a 1:3 ratio for the indicated times. Cells were suspended in the pH 8.8 buffer, and analyzed for the percentage of pHrodo+ cells, representing the cells that engulfed apoptotic cells.

FIGS. 5A-5B. Human CD300f is expressed on human myeloid cell populations including monocytes and immature dendritic cells (DCs). A. Human peripheral blood mononuclear cells (PBMC) were isolated, stained with antibodies against human CD300f, CD3 (T cells), CD19 (B cells), CD56 (NK cells) and CD16 and CD14 (monocytes) and analyzed by flow cytometry. The Rl, R2, R3 and R4 were gated on the dot plots of forward scattered light (FSC) vs. side scattered light (SSC). B. Human peripheral blood monocytes were isolated and induced to differentiate into immature DCs with the combination of granulocyte macrophage colony stimulating factor (GM- CSF) and interleukin (IL)-4. The CD300f expression was tested with EFLUOR™ 660-conjuaged anti-human CD300f antibody and analyzed by flow cytometry.

SEQUENCE LISTING

The nucleic and amino acid sequences listed in the accompanying sequence listing are shown using standard letter abbreviations for nucleotide bases, and three letter code for amino acids, as defined in 37 C.F.R. 1.822. Only one strand of each nucleic acid sequence is shown, but the complementary strand is understood as included by any reference to the displayed strand. The Sequence Listing is submitted as an ASCII text file [Sequence_Listing, October 11, 2017, 17.0KB], which is incorporated by reference herein. In the accompanying sequence listing:

SEQ ID NOs: 1-8 are the amino acid sequences of human framework regions.

SEQ ID NO: 9 is the amino acid sequence of a Cas9 from Streptococcus pyogenes.

SEQ ID NO: 10 is the nucleic acid sequence of an Embryonal Fyn- Associated Substrate (EFS) promoter.

SEQ ID NOs: 11-12 are nucleic acid sequences encoding a crRNA.

SEQ ID NO: 13 is the nucleic acid sequence of a U6 promoter.

SEQ ID NO: 14 is a nucleic acid sequence encoding a U6 gRNA.

SEQ ID NO: 15 is a nucleic acid sequence encoding a tracrRNA.

SEQ ID NOs: 16-19 are RNAi nucleic acid sequences.

SEQ ID NO: 20 is a nucleic acid sequence of a target in exon 3 of human CD300LF.

SEQ ID NOs: 21 is a nucleic acid sequence of a target in exon 4 of human CD300LF. DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

The use of CD300f inhibitors for the treatment of solid tumors is disclosed herein. Methods are also disclosed for targeting CD300f in dendritic cells, and the use of adoptive transfer of these dendritic cells or T cells activated by these dendritic cells, for the treatment of solid tumors. These methods can be used in combination with other agents for the treatment of solid tumors, such as, but not limited to, sarcomas and carcinomas.

Terms

Administration: The introduction of a composition (such as one containing a CD300f inhibitor) into a subject by a chosen route. Administration can be local or systemic. For example, if the chosen route is intravenous, the composition is administered by introducing the composition into a vein of the subject. Exemplary routes of administration include, but are not limited to, oral, injection (such as subcutaneous, intramuscular, intradermal, intraperitoneal, intravenous, and intratumoral), sublingual, rectal, transdermal (for example, topical), intranasal, vaginal, and inhalation routes.

Animal: Living multi-cellular vertebrate organisms, a category that includes, for example, mammals and birds. The term mammal includes both human and non-human mammals. Similarly, the term "subject" includes both human and veterinary subjects.

Antibody: A polypeptide comprising at least a light chain or heavy chain immunoglobulin variable region which specifically recognizes and binds an epitope (e.g., an antigen, such as a CD300f protein or fragment thereof). This includes intact immunoglobulins and the variants and portions of them well known in the art, such as Fab' fragments, F(ab)'2 fragments, single chain Fv proteins ("scFv"), and disulfide stabilized Fv proteins ("dsFv"). A scFv protein is a fusion protein in which a light chain variable region of an immunoglobulin and a heavy chain variable region of an immunoglobulin are bound by a linker, while in dsFvs, the chains have been mutated to introduce a disulfide bond to stabilize the association of the chains. The term also includes genetically engineered forms such as chimeric antibodies (e.g., humanized murine antibodies), heteroconjugate antibodies (e.g., bispecific antibodies). See also, Pierce Catalog and Handbook, 1994-1995 (Pierce Chemical Co., Rockford, IL); Kuby, J., Immunology, 3 ^rd Ed., W.H. Freeman & Co., New York, 1997.

Typically, an immunoglobulin has a heavy and light chain. Each heavy and light chain contains a constant region and a variable region, (the regions are also known as "domains"). In combination, the heavy and the light chain variable regions specifically bind the antigen. Light and heavy chain variable regions contain a "framework" region interrupted by three hypervariable regions, also called "complementarity-determining regions" or "CDRs". The extent of the framework region and CDRs has been defined (see, Kabat et al., Sequences of Proteins of

Immunological Interest, U.S. Department of Health and Human Services, 1991, which is hereby incorporated by reference). The Kabat database is now maintained online. The sequences of the framework regions of different light or heavy chains are relatively conserved within a species. The framework region of an antibody, that is the combined framework regions of the constituent light and heavy chains, serves to position and align the CDRs in three-dimensional space.

The CDRs are primarily responsible for binding to an epitope of an antigen. The CDRs of each chain are typically referred to as CDR1, CDR2, and CDR3, numbered sequentially starting from the N- terminus, and are also typically identified by the chain in which the particular CDR is located. Thus, a VH CDR3 is located in the variable domain of the heavy chain of the antibody in which it is found, whereas a VL CDRl is the CDR1 from the variable domain of the light chain of the antibody in which it is found.

References to "VH" or "VH" refer to the variable region of an immunoglobulin heavy chain, including that of an Fv, scFv, dsFv or Fab. References to "VL" or "VL" refer to the variable region of an immunoglobulin light chain, including that of an Fv, scFv, dsFv or Fab.

A "monoclonal antibody" is an antibody produced by a single clone of B-lymphocytes or by a cell into which the light and heavy chain genes of a single antibody have been transfected.

Monoclonal antibodies are produced by methods known to those of skill in the art, for instance by making hybrid antibody-forming cells from a fusion of myeloma cells with immune spleen cells. Monoclonal antibodies include humanized monoclonal antibodies.

A "humanized" immunoglobulin is an immunoglobulin including a human framework region and one or more CDRs from a non-human (such as a mouse, rat, or synthetic)

immunoglobulin. The non-human immunoglobulin providing the CDRs is termed a "donor," and the human immunoglobulin providing the framework is termed an "acceptor." In one embodiment, all the CDRs are from the donor immunoglobulin in a humanized immunoglobulin. Constant regions need not be present, but if they are, they must be substantially identical to human immunoglobulin constant regions, i.e., at least about 85-90%, such as about 95% or more identical. Hence, all parts of a humanized immunoglobulin, except possibly the CDRs, are substantially identical to corresponding parts of natural human immunoglobulin sequences. A "humanized antibody" is an antibody comprising a humanized light chain and a humanized heavy chain immunoglobulin. A humanized antibody binds to the same antigen as the donor antibody that provides the CDRs. The acceptor framework of a humanized immunoglobulin or antibody may have a limited number of substitutions by amino acids taken from the donor framework.

Humanized or other monoclonal antibodies can have additional conservative amino acid substitutions which have substantially no effect on antigen binding or other immunoglobulin functions. Humanized immunoglobulins can be constructed by means of genetic engineering (e.g., see U.S. Patent No. 5,585,089).

A "neutralizing antibody" is an antibody that interferes with any of the biological activities of its target polypeptide, such as a CD300f polypeptide.

Apoptotic cells: Non-dividing, non-viable cells that can be distinguished from necrotic cells (other dead cells). Apoptosis is a result of programmed cell death. According to characteristic morphological and biochemical features, apoptosis is characterized by shrinkage of the cell, dramatic reorganization of the cell nucleus, cell membrane and cell metabolism, active membrane blebbing, and ultimate fragmentation of the cell into membrane-enclosed vesicles (apoptotic bodies). The nuclear events of apoptosis begin with collapse of the chromatin against the nuclear periphery and into one or a few large clumps within the nucleus. Nuclear features include chromatin aggregation followed by DNA fragmentation (a specific marker of apoptotic process) after activation of endonucleases resulting in multiples subunits of DNA of an approximately 180 base pairs. The cellular events include cytoplasmic condensation and partition of the cytoplasm and nucleus into membrane bound-vesicles which contain ribosomes, intact mitochondria and nuclear material which are surrounded by an intact cellular membrane (a specific marker of apoptotic process when compared with necrosis, the other non-physiological cell death process).

CD300 molecule like family member f (CD300f): The human CD300 receptors are type I transmembrane proteins with single IgV-like extracellular domains that are mainly expressed by myeloid cells. Mouse CD300f (CLM-1) possesses both activating and inhibitory signaling potentials for regulation of apoptotic cell engulfment upon PS recognition. CD300f deficiency predisposes C57BL/6 mice to develop autoimmune disease. While CD300f functions to promote macrophage efferocytosis, its role in dendritic cells serves to inhibit apoptotic cell engulfment. Conventional dendritic cells (cDC, CDl lc ^hl B220 ^" ) and plasmacytoid dendritic cells (pDC, CDllc ^lo B220 ⁺ PDCA-l ⁺ ) have similar levels of CD300f expression.

The CD300f gene is also known as CD300f, CLM1, IGSF13, IREM1, NKIR and CD300LF.

CD300f sequences are publicly avaible. For example, GenBank® Accession Nos. NP_620587.2, P 001276011.1, P 001276012.1, P 001276013.1, P 001276014.1, P 001276015.1, and NP_001276016.1, provide exemplary human CD300f protein sequences, and GenBank® Accession Nos. NM_139018.4, NM_001289082.1, NM_001289083.1, NM_001289084.1, NM_001289085.1, NM_001289086.1, and NM_001289087.1 provide exemplary human CD300f nucleic acid sequences (all sequences herein incorporated by reference as of October 14, 2016).

cDNA (complementary DNA): A piece of DNA lacking internal, non-coding segments (introns) and regulatory sequences that determine transcription. cDNA is synthesized in the laboratory by reverse transcription from messenger RNA extracted from cells.

Chemotherapeutic agent: Any chemical agent with therapeutic usefulness in the treatment of diseases characterized by abnormal cell growth. For example, chemotherapeutic agents can be useful for the treatment of a solid tumor cancer, such as a sarcoma, carcinoma, lymphoma, colorectal or skin cancer. Particular examples of chemotherapeutic agents that can be used include microtubule binding agents, DNA intercalators or cross-linkers, DNA synthesis inhibitors, DNA and RNA transcription inhibitors, antibodies, enzymes, enzyme inhibitors, gene regulators, and angiogenesis inhibitors. In one embodiment, a chemotherapeutic agent is a radioactive compound. Other chemotherapeutic agents that can be used are provided in Slapak and Kufe, Principles of Cancer Therapy, Chapter 86 in Harrison's Principles of Internal Medicine, 14th edition; Perry et al., Chemotherapy, Ch. 17 in Abeloff, Clinical Oncology 2 ^nd ed., © 2000 Churchill Livingstone, Inc; Baltzer, L., Berkery, R. (eds): Oncology Pocket Guide to Chemotherapy, 2nd ed. St. Louis, Mosby- Year Book, 1995; Fischer, D.S., Knobf, M.F., Durivage, H.J. (eds): The Cancer Chemotherapy Handbook, 4th ed. St. Louis, Mosby-Year Book, 1993; Chabner and Longo, Cancer Chemotherapy and Biotherapy: Principles and Practice (4th ed.). Philadelphia: Lippincott Willians & Wilkins, 2005; Skeel, Handbook of Cancer Chemotherapy (6th ed.). Lippincott Williams & Wilkins, 2003. Combination chemotherapy is the administration of more than one agent to treat cancer.

Conservative variants: "Conservative" amino acid substitutions are those substitutions that do not substantially affect or decrease an activity of a polypeptide, for example a CD300f peptide's ability to mediate negative regulatory signals by recruiting SHP1 or SHIP. Specific, non-limiting examples of a conservative substitution include the following examples:

Original Residue Conservative Substitutions

Ala Ser

Arg Lys

Asn Gin, His

Asp Glu

Cys Ser Gin Asn

Glu Asp

His Asn; Gin

lie Leu, Val

Leu He; Val

Lys Arg; Gin;

Met Leu; lie

Phe Met; Leu;

Ser Thr

Thr Ser

Trp Tyr

Tyr Trp; Phe

Val lie; Leu

The term conservative variation also includes the use of a substituted amino acid in place of an unsubstituted parent amino acid, provided that the polypeptide binds with the same affinity as the unsubstituted (parental) polypeptide. Non-conservative substitutions are those that reduce the ability of the polypeptide.

Consists Essentially Of/Consists Of: With regard to a polypeptide, a polypeptide that consists essentially of a specified amino acid sequence if it does not include any additional amino acid residues. However, the polypeptide can include additional non-peptide components, such as labels (for example, fluorescent, radioactive, or solid particle labels), sugars or lipids. With regard to a polypeptide, a polypeptide that consists of a specified amino acid sequence does not include any additional amino acid residues, nor does it include additional non-peptide components, such as lipids, sugars or labels.

Clustered regularly interspaced short palindromic repeats (CRISPR) associated protein 9 (Cas9): An RNA-guided DNA endonuclease enzyme associated with the CRISPR (Clustered Regularly Interspersed Palindromic Repeats) adaptive immunity system in Streptococcus pyogenes, among other bacteria. Cas9 can cleave nearly any sequence complementary to the guide RNA. Includes Cas9 nucleic acid molecules and proteins. Cas9 sequences are publically available, for example from the GENBANK® sequence database (e.g., Accession Nos. NP_269215.1 and AKS40378.1 provide exemplary Cas9 protein sequences, while Accession No. NC_002737.2 provides an exemplary Cas9 nucleic acid sequence therein). One of ordinary skill in the art can identify additional Cas9 nucleic acid and protein sequences, including Cas9 variants. Degenerate variant: A polynucleotide encoding a peptide that includes a sequence that is degenerate as a result of the genetic code. There are 20 natural amino acids, most of which are specified by more than one codon. Therefore, all degenerate nucleotide sequences are included in this disclosure as long as the amino acid sequence of the polypeptide encoded by the nucleotide sequence is unchanged.

Dendritic Cell (DC): An antigen presenting cell that processes antigens and presents them to T cells. In vivo, dendritic cells are present in the skin, the nose, lungs, stomach, intestines, and in the blood. Once activated, they migrate to the lymph nodes where they interact with T cells and B cells to initiate and shape the adaptive immune response. At certain development stages they grow branched projections, called "dendrities." Dendritic cells include conventional dendritic cells

(cDCs), that are similar to monocytes, and plasmacytoid dendritic cells (pDCs). Monocyte-derived dendritic cells can be generated in vitro from peripheral blood mononuclear cells (PBMCs).

Treatment of these monocytes with interleukin 4 (IL-4) and granulocyte-macrophage colony stimulating factor (GM-CSF) leads to differentiation to immature dendritic cells (iDCs) in about a week. Subsequent treatment with tumor necrosis factor (TNF) or lipopolysaccharide (LPS) further differentiates the iDCs into mature dendritic cells (mDCs).

Donor polynucleotide: A polynucleotide that is capable of specifically inserting into a genomic locus.

Downstream: A relative position on a polynucleotide, wherein the "downstream" position is closer to the 3 ' end of the polynucleotide than the reference point. In the instance of a double- stranded polynucleotide, the orientation of 5' and 3' ends are based on the sense strand, as opposed to the antisense strand.

Expression Control Sequences: Nucleic acid sequences that regulate the expression of a heterologous nucleic acid sequence to which it is operatively linked. Expression control sequences are operatively linked to a nucleic acid sequence when the expression control sequences control and regulate the transcription and, as appropriate, translation of the nucleic acid sequence. Thus, expression control sequences can include appropriate promoters, enhancers, transcription terminators, a start codon (i.e., ATG) in front of a protein-encoding gene, splicing signal for introns, maintenance of the correct gene reading frame to permit proper translation of mRNA, and stop codons. The term "control sequences" includes, at a minimum, components whose presence can influence expression, and can also include additional components whose presence is advantageous, for example, leader sequences and fusion partner sequences. Expression control sequences can include a promoter. A promoter is a minimal sequence sufficient to direct transcription. Also included are those promoter elements which are sufficient to render promoter-dependent gene expression controllable for cell-type specific, tissue- specific, or inducible by external signals or agents; such elements may be located in the 5' or 3' regions of the gene. Both constitutive and inducible promoters are included (see e.g., Bitter et al., 1987, Methods in Enzymology 153, 516-544). For example, when cloning in bacterial systems, inducible promoters such as pL of bacteriophage lambda, plac, ptrp, ptac (ptrp-lac hybrid promoter) and the like can be used. In one embodiment, when cloning in mammalian cell systems, promoters derived from the genome of mammalian cells (such as the metallothionein promoter) or from mammalian viruses (such as the retrovirus long terminal repeat; the adenovirus late promoter; the vaccinia virus 7.5K promoter) can be used. Promoters produced by recombinant DNA or synthetic techniques can also be used to provide for transcription of the nucleic acid sequences.

Heterologous: Originating from separate genetic sources or species. A polypeptide that is heterologous is derived from a different cell or tissue type, or a different species from the recipient, and is cloned into a cell that normally does not express that polypeptide. In one specific, non- limiting example, mouse (or human) CD300f cloned in a fibroblast cell line that does not express CD300f generates a heterologous CD300f protein. Generally, an antibody that specifically binds to a protein of interest, such as CD300f, will not specifically bind to a heterologous protein.

Host cells: Cells in which a vector can be propagated and its DNA expressed. The cell may be prokaryotic or eukaryotic. The cell can be mammalian, such as a human cell. The term also includes any progeny of the subject host cell. It is understood that all progeny may not be identical to the parental cell since there may be mutations that occur during replication. However, such progeny are included when the term "host cell" is used.

Immune response: A response of a cell of the immune system, such as a B cell, T cell, or monocyte, to a stimulus. In one embodiment, the response is specific for a particular antigen (an "antigen-specific response"). In one embodiment, an immune response is a T cell response, such as a CD4 response or a CD8 response. In another embodiment, the response is a B cell response, and results in the production of specific antibodies.

Inhibiting or treating a disease: Inhibiting a disease, such as a tumor, refers to inhibiting the full development of a disease. In several examples, inhibiting a disease refers to lessening symptoms of the particular tumor. "Treatment" refers to a therapeutic intervention that ameliorates a sign or symptom of a disease or pathological condition related to the disease, such as a tumor, such as reducing the size of a tumor, volume of a tumor, number of tumors, metastasis of a tumor, or combinations thereof.

Isolated: An "isolated" biological component (such as a nucleic acid or protein or organelle) has been substantially separated or purified away from other biological components in the cell of the organism in which the component naturally occurs, i.e., other chromosomal and extra-chromosomal DNA and RNA, proteins and organelles. Nucleic acids and proteins that have been "isolated" include nucleic acids and proteins purified by standard purification methods. The term also embraces nucleic acids and proteins prepared by recombinant expression in a host cell as well as chemically synthesized nucleic acids.

Label: A detectable compound or composition that is conjugated directly or indirectly to another molecule to facilitate detection of that molecule. Specific, non-limiting examples of labels include fluorescent tags, enzymatic linkages, and radioactive isotopes.

Lymphocytes: A type of white blood cell that is involved in the immune defenses of the body. There are two main types of lymphocytes: B cells and T cells.

Mammal: This term includes both human and non-human mammals. Similarly, the term "subject" includes both human and veterinary subjects.

Oligonucleotide: A linear polynucleotide sequence of up to about 100 nucleotide bases in length.

Open reading frame (ORF): A series of nucleotide triplets (codons) coding for amino acids without any internal termination codons. These sequences are usually translatable into a protein.

Operably linked: A first nucleic acid sequence is operably linked with a second nucleic acid sequence when the first nucleic acid sequence is placed in a functional relationship with the second nucleic acid sequence. For instance, a promoter is operably linked to a coding sequence if the promoter affects the transcription or expression of the coding sequence, such as a sequence that encodes a polypeptide. Generally, operably linked DNA sequences are contiguous and, where necessary to join two protein-coding regions, in the same reading frame.

Pharmaceutically acceptable carriers: The pharmaceutically acceptable carriers of use are conventional. Remington's Pharmaceutical Sciences, by E. W. Martin, Mack Publishing Co., Easton, PA, 15th Edition (1975), describes compositions and formulations suitable for

pharmaceutical delivery of the therapeutic agents (such as CD300f inhibitors, dendritic cells with an inactivated CD300f, or T cells activated by such dendritic cells) herein disclosed.

In general, the nature of the carrier will depend on the particular mode of administration being employed. For instance, parenteral formulations usually comprise injectable fluids that include pharmaceutically and physiologically acceptable fluids such as water, physiological saline, balanced salt solutions, aqueous dextrose, glycerol or the like as a vehicle. For solid compositions (such as powder, pill, tablet, or capsule forms), conventional non-toxic solid carriers can include, for example, pharmaceutical grades of mannitol, lactose, starch, or magnesium stearate. In addition to biologically neutral carriers, pharmaceutical compositions to be administered can contain minor amounts of non-toxic auxiliary substances, such as wetting or emulsifying agents, preservatives, and pH buffering agents and the like, for example sodium acetate or sorbitan monolaurate.

A "therapeutically effective amount" is a quantity of a composition or a cell to achieve a desired effect in a subject being treated. For instance, this can be the amount necessary to reduce growth of a tumor, number of tumors, and/or reduce or prevent metastasis. When administered to a subject, a dosage will generally be used that will achieve target tissue concentrations that has been shown to achieve an in vitro effect.

Polynucleotide: The term polynucleotide or nucleic acid sequence refers to a polymeric form of nucleotide at least 10 bases in length. A recombinant polynucleotide includes a polynucleotide that is not immediately contiguous with both of the coding sequences with which it is immediately contiguous (one on the 5' end and one on the 3' end) in the naturally occurring genome of the organism from which it is derived. The term therefore includes, for example, a recombinant DNA which is incorporated into a vector; into an autonomously replicating plasmid or virus; or into the genomic DNA of a prokaryote or eukaryote, or which exists as a separate molecule (e.g., a cDNA) independent of other sequences. The nucleotides can be ribonucleotides, deoxyribonucleotides, or modified forms of either nucleotide. The term includes single- and double- stranded forms of DNA.

Polypeptide: Any chain of amino acids, regardless of length or post-translational modification (e.g., glycosylation or phosphorylation). A polypeptide can be between 5 and 25 amino acids in length. In one embodiment, a polypeptide is from about 10 to about 20 amino acids in length. In yet another embodiment, a polypeptide is from about 11 to about 18 amino acids in length. With regard to polypeptides, the word "about" indicates integer amounts. Thus, in one example, a polypeptide "about" 11 amino acids in length is from 10 to 12 amino acids in length. Similarly, a polypeptide "about" 18 amino acids in length is from about 17 to about 19 amino acids in length. Thus, a polypeptide "about" a specified number of residues can be one amino acid shorter or one amino acid longer than the specified number. A fusion polypeptide includes the amino acid sequence of a first polypeptide and a second different polypeptide (for example, a heterologous polypeptide), and can be synthesized as a single amino acid sequence.

Probes and primers: A probe comprises an isolated nucleic acid attached to a detectable label or reporter molecule. Primers are short nucleic acids, such as DNA oligonucleotides, of about 15 nucleotides or more in length. Primers may be annealed to a complementary target DNA strand by nucleic acid hybridization to form a hybrid between the primer and the target DNA strand, and then extended along the target DNA strand by a DNA polymerase enzyme. Primer pairs can be used for amplification of a nucleic acid sequence, for example by polymerase chain reaction (PCR) or other nucleic-acid amplification methods. One of skill in the art will appreciate that the specificity of a particular probe or primer increases with its length. Thus, for example, a primer comprising 20 consecutive nucleotides will anneal to a target with a higher specificity than a corresponding primer of only 15 nucleotides. Thus, in order to obtain greater specificity, probes and primers can be selected that comprise about 20, 25, 30, 35, 40, 50 or more consecutive nucleotides.

Promoter: An array of nucleic acid control sequences which direct transcription of a nucleic acid. A promoter includes necessary nucleic acid sequences near the start site of transcription, such as, in the case of a polymerase II type promoter, a TATA element. A promoter also optionally includes distal enhancer or repressor elements which can be located as much as several thousand base pairs from the start site of transcription.

Purified: The polypeptides disclosed herein can be purified (and/or synthesized) by any means known in the art (see, e.g., Guide to Protein Purification, ed. Deutscher, Meth. Enzymol.

185, Academic Press, San Diego, 1990; and Scopes, Protein Purification: Principles and Practice, Springer Verlag, New York, 1982). Substantial purification denotes purification from other proteins or cellular components. A substantially purified protein is at least about 60%, 70%, 80%, 90%, 95%, 98% or 99% pure. Thus, in one specific, non-limiting example, a substantially purified protein is 90% free of other proteins or cellular components. Thus, the term purified does not require absolute purity; rather, it is intended as a relative term.

Similarly, a purified nucleic acid is one in which the nucleic acid is more enriched than the nucleic acid in its natural environment within a cell.

In some examples, a purified population of nucleic acids, proteins, or cells is greater than about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% pure, or free other nucleic acids, proteins, or cells, respectively.

Recombinant: A recombinant nucleic acid is one that has a sequence that is not naturally occurring or has a sequence that is made by an artificial combination of at least two otherwise separated segments of sequence. This artificial combination is can be accomplished by chemical synthesis or by the artificial manipulation of isolated segments of nucleic acids, e.g., by genetic engineering techniques. A recombinant polypeptide has an amino acid sequence that is not naturally occurring or that is made by two otherwise separated segments of an amino acid sequence.

Recombination: A process of exchange of genetic information between two

polynucleotides. "Homologous recombination (HR)" refers to the specialized form of an exchange that takes place, for example, during repair of double-strand breaks in cells. Nucleotide sequence homology is utilized in recombination, for example using a "donor" molecule to template repair of a "target" molecule (i.e., the one that experienced the double-strand break), and is variously known as "non-crossover gene conversion" or "short tract gene conversion," because it leads to the transfer of genetic information from the donor to the target.

Selectively hybridize: Hybridization under moderately or highly stringent conditions that excludes non-related nucleotide sequences.

In nucleic acid hybridization reactions, the conditions used to achieve a particular level of stringency will vary, depending on the nature of the nucleic acids being hybridized. For example, the length, degree of complementarity, nucleotide sequence composition (for example, GC v. AT content), and nucleic acid type (for example, RNA versus DNA) of the hybridizing regions of the nucleic acids can be considered in selecting hybridization conditions. An additional consideration is whether one of the nucleic acids is immobilized, for example, on a filter.

A specific example of progressively higher stringency conditions is as follows: 2 x

SSC/0.1% SDS at about room temperature (hybridization conditions); 0.2 x SSC/0.1% SDS at about room temperature (low stringency conditions); 0.2 x SSC/0.1% SDS at about 42°C (moderate stringency conditions); and 0.1 x SSC at about 68°C (high stringency conditions). One of skill in the art can determine variations on these conditions (e.g., Molecular Cloning: A Laboratory

Manual, 2nd ed., vol. 1-3, ed. Sambrook et al., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1989). Washing can be carried out using only one of these conditions, e.g., high stringency conditions, or each of the conditions can be used, e.g., for 10-15 minutes each, in the order listed above, repeating any or all of the steps listed. However, as mentioned above, optimal conditions will vary, depending on the particular hybridization reaction involved, and can be determined empirically.

Sequence identity: The similarity between amino acid sequences is expressed in terms of the similarity between the sequences, otherwise referred to as sequence identity. Sequence identity is frequently measured in terms of percentage identity (or similarity or homology); the higher the percentage, the more similar the two sequences are. Homologs or variants of a polypeptide will possess a relatively high degree of sequence identity when aligned using standard methods.

Methods of alignment of sequences for comparison are well known in the art. Various programs and alignment algorithms are described in: Smith and Waterman, Adv. Appl. Math. 2:482, 1981; Needleman and Wunsch, 1970, J Mol Biol 48, 443-453; Higgins and Sharp, 1988, Gene 73, 237-244; Higgins and Sharp, 1989, CABIOS 5, 151-153; Corpet et al., 1988, Nucleic Acids Research 16, 10881-10890; and Pearson and Lipman, 1988, Proc Natl Acad Sci USA 85, 2444-2448. Altschul et al., 1994, Nature Genet 6, 119-129, presents a detailed consideration of sequence alignment methods and homology calculations.

The NCBI Basic Local Alignment Search Tool (BLAST) (Altschul et al., 1990, J Mol Biol

215, 403-410) is available from several sources, including the National Center for Biotechnology Information (NCBI, Bethesda, MD) and on the internet, for use in connection with the sequence analysis programs blastp, blastn, blastx, tblastn and tblastx. A description of how to determine sequence identity using this program is available on the NCBI website on the internet.

Homologs and variants of a polypeptide are typically characterized by possession of at least

75%, for example at least 80%, sequence identity counted over the full length alignment with the amino acid sequence of a polypeptide using the NCBI Blast 2.0, gapped blastp set to default parameters. For comparisons of amino acid sequences of greater than about 30 amino acids, the Blast 2 sequences function is employed using the default BLOSUM62 matrix set to default parameters, (gap existence cost of 11, and a per residue gap cost of 1). When aligning short peptides (fewer than around 30 amino acids), the alignment should be performed using the Blast 2 sequences function, employing the PAM30 matrix set to default parameters (open gap 9, extension gap 1 penalties). Proteins with even greater similarity to the reference sequences will show increasing percentage identities when assessed by this method, such as at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% sequence identity. When less than the entire sequence is being compared for sequence identity, homologs and variants will typically possess at least 80% sequence identity over short windows of 10-20 amino acids, and can possess sequence identities of at least 85% or at least 90% or 95% depending on their similarity to the reference sequence. Methods for determining sequence identity over such short windows are available at the NCBI website on the internet. One of skill in the art will appreciate that these sequence identity ranges are provided for guidance only; it is entirely possible that strongly significant homologs could be obtained that fall outside of the ranges provided.

Subject: Human and non-human animals, including all vertebrates, such as mammals and non-mammals, such as non-human primates, mice, rabbits, sheep, dogs, cats, horses, cows, chickens, amphibians, and reptiles. In many embodiments of the described methods, the subject is a human, such as a human with a solid tumor.

Tumor: An abnormal growth of cells, which can be benign or malignant. Cancer is a malignant tumor, which is characterized by abnormal or uncontrolled cell growth. Other features often associated with malignancy include metastasis, interference with the normal functioning of neighboring cells, release of cytokines or other secretory products at abnormal levels and

suppression or aggravation of inflammatory or immunological response, invasion of surrounding or distant tissues or organs, such as lymph nodes, etc. "Metastatic disease" refers to cancer cells that have left the original tumor site and migrate to other parts of the body for example via the bloodstream or lymph system.

The amount of a tumor in an individual is the "tumor burden" which can be measured as the number, volume, or weight of the tumor. A tumor that does not metastasize is referred to as "benign." A tumor that invades the surrounding tissue and/or can metastasize is referred to as "malignant."

Examples of hematological tumors include leukemias, including acute leukemias (such as l lq23-positive acute leukemia, acute lymphocytic leukemia, acute myelocytic leukemia, acute myelogenous leukemia and myeloblastic, promyelocytic, myelomonocytic, monocytic and erythroleukemia), chronic leukemias (such as chronic myelocytic (granulocytic) leukemia, chronic myelogenous leukemia, and chronic lymphocytic leukemia), polycythemia vera, lymphoma,

Hodgkin's disease, non-Hodgkin's lymphoma (indolent and high grade forms), multiple myeloma, Waldenstrom's macroglobulinemia, heavy chain disease, myelodysplastic syndrome, hairy cell leukemia and myelodysplasia. In specific non-limiting examples, the lymphoid malignancy can be adult T cell leukemia, cutaneous T cell lymphoma, anaplastic large cell lymphoma, Hodgkin's lymphoma, or a diffuse large B cell lymphoma.

Examples of solid tumors, such as sarcomas and carcinomas, include fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, and other sarcomas, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, lymphoid malignancy, pancreatic cancer, breast cancer (including basal breast carcinoma, ductal carcinoma and lobular breast carcinoma), lung cancers, ovarian cancer, prostate cancer, hepatocellular carcinoma, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, medullary thyroid carcinoma, papillary thyroid carcinoma, pheochromocytomas sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, Wilms' tumor, cervical cancer, testicular tumor, seminoma, bladder carcinoma, and CNS tumors (such as a glioma, astrocytoma, medulloblastoma, craniopharyrgioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, meningioma, melanoma, neuroblastoma and retinoblastoma).

Lymphoma can be solid tumors is some presentations.

In some examples, a tumor is colorectal tumor, skin tumor or lymphoma.

Transgene: An exogenous gene.

Treating, Treatment, and Therapy: Any success or indicia of success in the attenuation or amelioration of an injury, pathology or condition, including any objective or subjective parameter such as abatement, remission, diminishing of symptoms or making the condition more tolerable to the patient, slowing in the rate of degeneration or decline, making the final point of degeneration less debilitating, improving a subject's physical state, such as decreasing tumor volume, tumor size, or a symptom of the tumor. The treatment may be assessed by objective or subjective parameters; including the results of a physical examination, neurological examination, or psychiatric evaluations.

Upstream: A relative position on a polynucleotide, wherein the "upstream" position is closer to the 5' end of the polynucleotide than the reference point. In the instance of a double- stranded polynucleotide, the orientation of 5' and 3' ends are based on the sense strand, as opposed to the antisense strand.

Vector: A nucleic acid molecule as introduced into a host cell, thereby producing a transformed host cell. A vector may include nucleic acid sequences that permit it to replicate in a host cell, such as an origin of replication. A vector may also include one or more selectable marker gene and other genetic elements known in the art. Vectors include plasmid vectors, including plasmids for expression in gram-negative and gram-positive bacterial cell. Exemplary vectors include those for expression in E. coli and Salmonella. Vectors also include viral vectors, such as, but are not limited to, retrovirus, orthopox, avipox, fowlpox, capripox, suipox, adenoviral, herpes virus, alpha virus, baculovirus, Sindbis virus, vaccinia virus and poliovirus vectors. Vectors also include vectors for expression in yeast cells or mammalian cells.

Virus: Microscopic infectious organism that reproduces inside living cells. A virus consists essentially of a core of a single nucleic acid surrounded by a protein coat and has the ability to replicate only inside a living cell. "Viral replication" is the production of additional virus by the occurrence of at least one viral life cycle. Viral vectors are known in the art, and include, for example, adenovirus, adeno-associated virus (AAV), lentivirus and herpes virus.

Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The singular terms "a," "an," and "the" include plural referents unless context clearly indicates otherwise. Similarly, the word "or" is intended to include "and" unless the context clearly indicates otherwise. It is further to be understood that all base sizes or amino acid sizes, and all molecular weight or molecular mass values, given for nucleic acids or polypeptides are

approximate, and are provided for description. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, suitable methods and materials are described below. The term "comprises" means "includes." All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including explanations of terms, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

CD300f Inhibitors

It is disclosed herein that CD300f inhibitors are of use for treating a solid tumor. In some embodiments, the solid tumor is a carcinoma or a sarcoma. In particular non-limiting examples, the solid tumor is a lymphoma, a colorectal cancer or a skin cancer.

The CD300f inhibitor can be, for example, a soluble protein, an antibody or aptamer that specifically binds CD300f, or an inhibitory nucleic acid molecule (RNAi), such as, but not limited to, a ribozyme, a siRNA or a shRNA. The CD300f antagonist can result in the induction of an immune response to the tumor.

A. Antibodies and Antigen Binding Fragments Thereof

The CD300f inhibitor can be an antibody, such as a monoclonal antibody. Antibodies that specifically bind CD300f are commercially available. Exemplary nucleic acid sequences encoding human CD300f are provided in GENBANK® Accession No. NM_139018.4 (August 26, 2016), and GENBANK Accession No. NM_001289082.1 (August 26, 2016), which are both incorporated by reference, and an exemplary amino acid sequence of human CD300f is provided in GENBANK® Accession No. AAH28199.1 (June 6, 2006), which is incorporated by reference herein. Other examples are provided herein. Antibodies that specifically bind CD300f are commercially available. For example, a mouse IgGi to human CD300f is available from BioLegend, Clone UP-D2; additional monoclonal antibodies that specifically bind CD300f are available from R&D systems, Catalog Number AF2774, Borbyt, Catalog Number orb 160320, and St. John's Laboratory, Catalog Numbers STJ92113 and STJ96840, eBioscience, Clone UP-D1, Catalog Number 50-3008-41/42.

Antibodies that specifically bind and substantially reduce or inhibit CD300f activity (such as a reduction of at least 20%, at least 40%, at least 50%, at least 75%, at least 80%, at least 90%, at least 95%, at least 98% or even 100%) are of use in the methods disclosed herein. Antibodies include monoclonal antibodies, human antibodies, humanized antibodies, deimmunized antibodies, and immunoglobulin (Ig) fusion proteins. Fully human and humanized antibodies that bind CD300f can also be produced using methods known to those of skill in the art.

Polyclonal anti-CD300f antibodies can be prepared, such as by immunizing a suitable subject (such as a veterinary subject) with a CD300f immunogen. The anti-CD300f antibody titer in the immunized subject can be monitored over time, such as with an enzyme linked

immunosorbent assay (ELISA) using immobilized CD300f polypeptide. In one example, the antibody molecules that specifically bind CD300f can be isolated from a mammal (such as from serum) and further purified, for example using protein A chromatography to isolate IgG antibodies.

Antibody-producing cells can be obtained from a subject and used to prepare monoclonal antibodies (see Kohler and Milstein Nature 256:495 49, 1995; Brown et al., J. Immunol. 127:539 46, 1981; Cole et al., Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc., pp. 77 96, 1985; Gefter, M. L. et al. (1977) Somatic Cell Genet. 3:231 36; Kenneth, R. H. in Monoclonal Antibodies: A New Dimension In Biological Analyses. Plenum Publishing Corp., New York, N.Y. (1980); Kozbor et al. Immunol. Today 4:72, 1983; Lerner, E. A. (1981) Yale J. Biol. Med. 54:387 402; Yeh et al., Proc. Natl. Acad. Sci. 76:2927 31, 1976). In one example, an immortal cell line (typically a myeloma) is fused to lymphocytes (typically splenocytes) from a mammal immunized with CD300f, and the culture supernatants of the resulting hybridoma cells are screened to identify a hybridoma producing a monoclonal antibody that specifically binds to the polypeptide of interest.

In one embodiment, to produce a hybridoma, an immortal cell line (such as a myeloma cell line) is derived from the same mammalian species as the lymphocytes. For example, murine hybridomas can be made by fusing lymphocytes from a mouse immunized with a CD300f peptide with an immortalized mouse cell line. In one example, a mouse myeloma cell line is utilized that is sensitive to culture medium containing hypoxanthine, aminopterin and thymidine ("HAT medium"). Any of a number of myeloma cell lines can be used as a fusion partner, including, for example, P3-NSl/l-Ag4-l, P3-x63-Ag8.653 or Sp2/0-Agl4 myeloma lines, which are available from the American Type Culture Collection (ATCC), Rockville, MD. HAT-sensitive mouse myeloma cells can be fused to mouse splenocytes using polyethylene glycol ("PEG"). Hybridoma cells resulting from the fusion are then selected using HAT medium, which kills unfused (and unproductively fused) myeloma cells. Hybridoma cells producing a monoclonal antibody of interest can be detected, for example, by screening the hybridoma culture supernatants for the production antibodies that bind a CD300f polypeptide, such as by using an immunological assay (such as an enzyme-linked immunosorbant assay (ELISA) or radioimmunoassay (RIA).

As an alternative to preparing monoclonal antibody-secreting hybridomas, a monoclonal antibody that specifically binds CD300f can be identified and isolated by screening a recombinant combinatorial immunoglobulin library (such as an antibody phage display library) with CD300f to isolate immunoglobulin library members that specifically bind the polypeptide. Library members can be selected that have particular activities, such as binding CD300f, or activation of T cells in an in vitro assay. Kits for generating and screening phage display libraries are commercially available (such as, but not limited to, Pharmacia and Stratagene). Examples of methods and reagents particularly amenable for use in generating and screening antibody display library can be found in, for example, U.S. Pat. No. 5,223,409; PCT Publication No. WO 90/02809; PCT Publication No. WO 91/17271 ; PCT Publication No. WO 92/18619; PCT Publication WO 92/20791 ; PCT

Publication No. WO 92/15679; PCT Publication No. WO 92/01047; PCT Publication WO

93/01288; PCT Publication No. WO 92/09690; Barbas et al., Proc. Natl. Acad. Sci. USA 88:7978 7982, 1991; Hoogenboom et al., Nucleic Acids Res. 19:4133 4137, 1991.

In one example the sequence of the specificity determining regions of each CDR is determined. Residues outside the SDR (specificity determining region, e.g., the non-ligand contacting sites) are substituted. For example, in any of the CDR sequences, at most one, two or three amino acids can be substituted. The production of chimeric antibodies, which include a framework region from one antibody and the CDRs from a different antibody, is known in the art. For example, humanized antibodies can be produced. The antibody or antibody fragment can be a humanized immunoglobulin having CDRs from a donor monoclonal antibody that binds CD300f, and immunoglobulin and heavy and light chain variable region frameworks from human acceptor immunoglobulin heavy and light chain frameworks.

Humanized monoclonal antibodies can be produced by transferring CDRs from heavy and light variable chains of the donor mouse immunoglobulin (that specifically binds CD300f) into a human variable domain, and then substituting human residues in the framework regions when required to retain affinity. The use of antibody components derived from humanized monoclonal antibodies obviates potential problems associated with the immunogenicity of the constant regions of the donor antibody. Techniques for producing humanized monoclonal antibodies are described, for example, by Jones et al., Nature 321 :522, 1986; Riechmann et al., Nature 332:323, 1988; Verhoeyen et al., Science 239: 1534, 1988; Carter et al., Proc. Natl. Acad. Sci. U.S.A. 89:4285, 1992; Sandhu, Crit. Rev. Biotech.12:437, 1992; and Singer et al., J. Immunol.150:2844, 1993. The antibody may be of any isotype, but in several embodiments the antibody is an IgG, including but not limited to, IgGi, IgG2, IgG3 and IgG ₄ .

In one embodiment, the sequence of the humanized immunoglobulin heavy chain variable region framework can be at least about 65% identical to the sequence of the donor immunoglobulin heavy chain variable region framework. Thus, the sequence of the humanized immunoglobulin heavy chain variable region framework can be at least about 75%, at least about 85%, at least about 99% or at least about 95%, identical to the sequence of the donor immunoglobulin heavy chain variable region framework. Human framework regions, and mutations that can be made in humanized antibody framework regions, are known in the art (see, for example, in U.S. Patent No. 5,585,089, incorporated herein by reference).

Exemplary human antibodies are LEN and 21/28 CL. The sequences of the heavy and light chain frameworks are known. Exemplary light chain frameworks of human MAb LEN have the following sequences:

FR1: DIVMTQS PDSLAVSLGERATINC (SEQ ID NO: 1)

FR2: WYQQKPGQPPLLIY (SEQ ID NO: 2)

FR3: G VPDRPFGS GS GTDFTLTIS S LQ AED V A V Y YC (SEQ ID NO: 3)

FR4: FGQGQTKLEIK (SEQ ID NO: 4)

Exemplary heavy chain frameworks of human MAb 21/28' CL have the following sequences:

FR1: Q VQLVQS G AE VKKPQ AS VKVSCKAS Q YTFT (SEQ ID NO: 5)

FR2: WVRQAPGQRLEWMG (SEQ ID NO: 6)

FR3: RVTITRDTSASTAYMELSSLRSEDTAVYYCAR (SEQ ID NO: 7)

FR4: WGQGTLVTVSS (SEQ ID NO: 8). Generally, an antibody, such as a human or humanized antibody specifically binds to CD300f with an affinity constant of at least 10 ⁷ M ^"1 , such as at least 10 ⁸ M ^"1 at least 5 X 10 ⁸ M ^"1 or at least 10 ⁹ M ^"1 . In several examples, the antibody specifically binds CD300f with an affinity constant of at least 10 ⁸ M ^"1 at least 5 X 10 ⁸ M ^"1 or at least 10 ⁹ M ^"1 .

Antibodies, such as murine monoclonal antibodies, chimeric antibodies, and humanized antibodies, include full length molecules as well as fragments thereof, such as Fab, F(ab')2, and Fv which include a heavy chain and light chain variable region and are capable of binding specific epitope determinants. These antibody fragments retain some ability to selectively bind with their antigen or receptor. These fragments include:

(1) Fab, the fragment which contains a monovalent antigen-binding fragment of an antibody molecule, can be produced by digestion of whole antibody with the enzyme papain to yield an intact light chain and a portion of one heavy chain;

(2) Fab', the fragment of an antibody molecule can be obtained by treating whole antibody with pepsin, followed by reduction, to yield an intact light chain and a portion of the heavy chain; two Fab' fragments are obtained per antibody molecule;

(3) (Fab')2, the fragment of the antibody that can be obtained by treating whole antibody with the enzyme pepsin without subsequent reduction; F(ab')2 is a dimer of two Fab' fragments held together by two disulfide bonds;

(4) Fv, a genetically engineered fragment containing the variable region of the light chain and the variable region of the heavy chain expressed as two chains; and

(5) Single chain antibody (such as scFv), defined as a genetically engineered molecule containing the variable region of the light chain, the variable region of the heavy chain, linked by a suitable polypeptide linker as a genetically fused single chain molecule.

Methods of making these fragments are known (see for example, Harlow and Lane,

Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, New York, 1988). In several examples, the variable region includes the variable region of the light chain and the variable region of the heavy chain expressed as individual polypeptides. Fv antibodies are typically about 25 kDa and contain a complete antigen-binding site with three CDRs per each heavy chain and each light chain. To produce these antibodies, the VH and the VL can be expressed from two individual nucleic acid constructs in a host cell. If the VH and the VL are expressed non-contiguously, the chains of the Fv antibody are typically held together by noncovalent interactions. However, these chains tend to dissociate upon dilution, so methods have been developed to crosslink the chains through glutaraldehyde, intermolecular disulfides, or a peptide linker. Thus, in one example, the Fv can be a disulfide stabilized Fv (dsFv), wherein the heavy chain variable region and the light chain variable region are chemically linked by disulfide bonds.

In an additional example, the Fv fragments comprise VH and VL chains connected by a peptide linker. These single-chain antigen binding proteins (scFv) are prepared by constructing a structural gene comprising DNA sequences encoding the VH and VL domains connected by an oligonucleotide. The structural gene is inserted into an expression vector, which is subsequently introduced into a host cell such as E. coli. The recombinant host cells synthesize a single polypeptide chain with a linker peptide bridging the two V domains. Methods for producing scFvs are known in the art (see Whitlow et al, Methods: a Companion to Methods in Enzymology, Vol. 2, page 97, 1991; Bird et al, Science 242:423, 1988; U.S. Patent No. 4,946,778; Pack et al,

Bio/Technology 11:1271, 1993; and Sandhu, supra).

Antibody fragments can be prepared by proteolytic hydrolysis of the antibody or by expression in E. coli of DNA encoding the fragment. Antibody fragments can be obtained by pepsin or papain digestion of whole antibodies by conventional methods. For example, antibody fragments can be produced by enzymatic cleavage of antibodies with pepsin to provide a 5S fragment denoted F(ab')2. This fragment can be further cleaved using a thiol reducing agent, and optionally a blocking group for the sulfhydryl groups resulting from cleavage of disulfide linkages, to produce 3.5S Fab' monovalent fragments. Alternatively, an enzymatic cleavage using pepsin produces two monovalent Fab' fragments and an Fc fragment directly (see U.S. Patent No.

4,036,945 and U.S. Patent No. 4,331,647, and references contained therein; Nisonhoff et al, Arch. Biochem. Biophys. 89:230, 1960; Porter, Biochem. J. 73:119, 1959; Edelman et al, Methods in Enzymology, Vol. 1, page 422, Academic Press, 1967; and Coligan et al. at sections 2.8.1-2.8.10 and 2.10.1-2.10.4).

Other methods of cleaving antibodies, such as separation of heavy chains to form monovalent light-heavy chain fragments, further cleavage of fragments, or other enzymatic, chemical, or genetic techniques may also be used, so long as the fragments bind to the antigen that is recognized by the intact antibody. Any of the antigen binding fragments described herein are of use.

Conservative variants of the antibodies can be produced. Such conservative variants employed in antibody fragments, such as dsFv fragments or in scFv fragments, will retain critical amino acid residues necessary for correct folding and stabilizing between the VH and the VL regions, and will retain the charge characteristics of the residues in order to preserve the low pi and low toxicity of the molecules. Amino acid substitutions (such as at most one, at most two, at most three, at most four, or at most five amino acid substitutions) can be made in the VH and the VL regions to increase yield. A table of conservative amino acid substitutions is provided above. One of skill in the art can readily review the amino acid sequence of an antibody of interest, locate one or more of the amino acids in the brief table above, identify a conservative substitution, and produce the conservative variant using well-known molecular techniques.

Effector molecules, such as therapeutic, diagnostic, or detection moieties can be linked to an antibody that specifically binds CD300f, using any number of means known to those of skill in the art. Both covalent and noncovalent attachment means may be used. The procedure for attaching an effector molecule to an antibody varies according to the chemical structure of the effector.

Polypeptides typically contain a variety of functional groups; such as carboxylic acid (COOH), free amine (-NH ₂ ) or sulfhydryl (-SH) groups, which are available for reaction with a suitable functional group on an antibody to result in the binding of the effector molecule. Alternatively, the antibody is derivatized to expose or attach additional reactive functional groups. The derivatization may involve attachment of any of a number of linker molecules such as those available from Pierce

Chemical Company, Rockford, IL. The linker can be any molecule used to join the antibody to the effector molecule. The linker is capable of forming covalent bonds to both the antibody and to the effector molecule. Suitable linkers include, but are not limited to, straight or branched-chain carbon linkers, heterocyclic carbon linkers, or peptide linkers. Where the antibody and the effector molecule are polypeptides, the linkers may be joined to the constituent amino acids through their side groups (such as through a disulfide linkage to cysteine) or to the alpha carbon amino and carboxyl groups of the terminal amino acids.

Nucleic acid sequences encoding the antibodies can be prepared by any suitable method including, for example, cloning of appropriate sequences or by direct chemical synthesis by methods such as the phosphotriester method of Narang et al., Meth. Enzymol. 68:90-99, 1979; the phosphodiester method of Brown et al., Meth. Enzymol. 68: 109-151, 1979; the

diethylphosphoramidite method of Beaucage et al., Tetra. Lett. 22: 1859-1862, 1981; the solid phase phosphoramidite triester method described by Beaucage & Caruthers, Tetra. Letts. 22(20): 1859- 1862, 1981, for example, using an automated synthesizer as described in, for example, Needham- VanDevanter et al., Nucl. Acids Res. 12:6159-6168, 1984; and, the solid support method of U.S. Patent No. 4,458,066. Chemical synthesis produces a single stranded oligonucleotide. This can be converted into double stranded DNA by hybridization with a complementary sequence, or by polymerization with a DNA polymerase using the single strand as a template. One of skill would recognize that while chemical synthesis of DNA is generally limited to sequences of about 100 bases, longer sequences may be obtained by the ligation of shorter sequences.

Exemplary nucleic acids encoding sequences encoding an antibody that specifically binds CD300f can be prepared by cloning techniques. Examples of appropriate cloning and sequencing techniques, and instructions sufficient to direct persons of skill through many cloning exercises are found in Sambrook et al., supra, Berger and Kimmel (eds.), supra, and Ausubel, supra. Product information from manufacturers of biological reagents and experimental equipment also provide useful information. Such manufacturers include the SIGMA Chemical Company (Saint Louis, MO), R&D Systems (Minneapolis, MN), Pharmacia Amersham (Piscataway, NJ), CLONTECH Laboratories, Inc. (Palo Alto, CA), Chem Genes Corp., Aldrich Chemical Company (Milwaukee, WI), Glen Research, Inc., GIBCO BRL Life Technologies, Inc. (Gaithersburg, MD), Fluka Chemica-Biochemika Analytika (Fluka Chemie AG, Buchs, Switzerland), Invitrogen (San Diego, CA), and Applied Biosystems (Foster City, CA), as well as other commercial sources.

Nucleic acids can also be prepared by amplification methods. Amplification methods include polymerase chain reaction (PCR), the ligase chain reaction (LCR), the transcription-based amplification system (TAS), the self-sustained sequence replication system (3SR). A wide variety of cloning methods, host cells, and in vitro amplification methodologies are known.

In one example, an antibody of use is prepared by inserting the cDNA, which encodes a variable region from an antibody that specifically binds CD300f, into a vector which comprises the cDNA encoding an effector molecule (EM). The insertion is made so that the variable region and the EM are read in frame so that one continuous polypeptide is produced. Thus, the encoded polypeptide contains a functional Fv region and a functional EM region. In one embodiment, cDNA encoding a detectable marker (such as an enzyme) is ligated to a scFv so that the marker is located at the carboxyl terminus of the scFv. In another example, a detectable marker is located at the amino terminus of the scFv. In a further example, cDNA encoding a detectable marker is ligated to a heavy chain variable region of an antibody that specifically binds CD300f, so that the marker is located at the carboxyl terminus of the heavy chain variable region. The heavy chain- variable region can subsequently be ligated to a light chain variable region of the antibody that specifically binds CD300f using disulfide bonds. In a yet another example, cDNA encoding a marker is ligated to a light chain variable region of an antibody that binds CD300f, so that the marker is located at the carboxyl terminus of the light chain variable region. The light chain- variable region can subsequently be ligated to a heavy chain variable region of the antibody that specifically binds CD300f using disulfide bonds. Once the nucleic acids encoding the antibody or functional fragment thereof are isolated and cloned, the protein can be expressed in a recombinantly engineered cell such as bacteria, plant, yeast, insect and mammalian cells. One or more DNA sequences encoding the antibody or functional fragment thereof can be expressed in vitro by DNA transfer into a suitable host cell. The cell may be prokaryotic or eukaryotic. The term also includes any progeny of the subject host cell. It is understood that all progeny may not be identical to the parental cell since there may be mutations that occur during replication. Methods of stable transfer, meaning that the foreign DNA is continuously maintained in the host, are known.

Polynucleotide sequences encoding the antibody or functional fragment thereof (such as an scFV) can be operatively linked to expression control sequences. An expression control sequence operatively linked to a coding sequence is ligated such that expression of the coding sequence is achieved under conditions compatible with the expression control sequences. The expression control sequences include, but are not limited to appropriate promoters, enhancers, transcription terminators, a start codon (i.e., ATG) in front of a protein-encoding gene, splicing signal for introns, maintenance of the correct reading frame of that gene to permit proper translation of mRNA, and stop codons.

The polynucleotide sequences encoding the antibody or functional fragment thereof can be inserted into an expression vector including, but not limited to a plasmid, virus or other vehicle that can be manipulated to allow insertion or incorporation of sequences and can be expressed in either prokaryotes or eukaryotes. Hosts can include microbial, yeast, insect and mammalian organisms. Methods of expressing DNA sequences having eukaryotic or viral sequences in prokaryotes are well known in the art. Biologically functional viral and plasmid DNA vectors capable of expression and replication in a host are known in the art.

Transformation of a host cell with recombinant DNA may be carried out by conventional techniques. Where the host is prokaryotic, such as E. coli, competent cells which are capable of DNA uptake can be prepared from cells harvested after exponential growth phase and subsequently treated by the CaC method. Alternatively, MgC can be used. Transformation can also be performed after forming a protoplast of the host cell if desired, or by electroporation.

When the host is a eukaryote, such methods of transfection of DNA as calcium phosphate coprecipitates, mechanical procedures such as microinjection, electroporation, insertion of a plasmid encased in liposomes, or virus vectors, may be used. Eukaryotic cells can also be cotransformed with polynucleotide sequences encoding the antibody of functional fragment thereof and a second foreign DNA molecule encoding a selectable phenotype, such as the herpes simplex thymidine kinase gene. Another method is to use a eukaryotic viral vector, such as simian virus 40 (SV40) or bovine papilloma virus, to transiently infect or transform eukaryotic cells and express the protein (see for example, Eukaryotic Viral Vectors, Cold Spring Harbor Laboratory, Gluzman ed., 1982). One of skill in the art can readily use expression systems such as plasmids and vectors of use in producing proteins in cells including higher eukaryotic cells such as the COS, CHO, HeLa and myeloma cell lines.

Isolation and purification of a recombinantly expressed polypeptide can be carried out by conventional means including preparative chromatography and immunological separations. Once expressed, the recombinant antibodies can be purified according to standard procedures of the art, including ammonium sulfate precipitation, affinity columns, column chromatography, and the like (see, generally, R. Scopes, Protein Purification, Springer- Verlag, N.Y., 1982). Substantially pure compositions of at least about 90 to 95% homogeneity are disclosed herein, and 98 to 99% or more homogeneity can be used for pharmaceutical purposes. Once purified, partially or to homogeneity as desired, if to be used therapeutically, the polypeptides should be substantially free of endotoxin.

Methods for expression of single chain antibodies and/or refolding to an appropriate active form, including single chain antibodies, from bacteria such as E. coli have been described and are applicable to the antibodies disclosed herein. See, Buchner et al., Anal. Biochem. 205:263-270, 1992; Pluckthun, Biotechnology 9:545, 1991; Huse et al, Science 246:1275, 1989 and Ward et al, Nature 341:544, 1989, all incorporated by reference herein.

Often, functional heterologous proteins from E. coli or other bacteria are isolated from inclusion bodies and require solubilization using strong denaturants, and subsequent refolding. During the solubilization step, a reducing agent must be present to separate disulfide bonds. An exemplary buffer with a reducing agent is: 0.1 M Tris pH 8, 6 M guanidine, 2 mM EDTA, 0.3 M DTE (dithioerythritol). Reoxidation of the disulfide bonds can occur in the presence of low molecular weight thiol reagents in reduced and oxidized form, as described in Saxena et al, Biochemistry 9: 5015-5021, 1970, incorporated by reference herein, and especially as described by Buchner et al, supra.

Renaturation is typically accomplished by dilution (for example, 100-fold) of the denatured and reduced protein into refolding buffer. An exemplary buffer is 0.1 M Tris, pH 8.0, 0.5 M L- arginine, 8 mM oxidized glutathione (GSSG), and 2 mM EDTA.

As a modification to the two chain antibody purification protocol, the heavy and light chain regions are separately solubilized and reduced and then combined in the refolding solution. An exemplary yield is obtained when these two proteins are mixed in a molar ratio such that a 5 fold molar excess of one protein over the other is not exceeded. It is desirable to add excess oxidized glutathione or other oxidizing low molecular weight compounds to the refolding solution after the redox-shuffling is completed.

In addition to recombinant methods, the antibodies and functional fragments thereof that are disclosed herein can also be constructed in whole or in part using standard peptide synthesis. Solid phase synthesis of the polypeptides of less than about 50 amino acids in length can be accomplished by attaching the C-terminal amino acid of the sequence to an insoluble support followed by sequential addition of the remaining amino acids in the sequence. Techniques for solid phase synthesis are described by Barany & Merrifield, The Peptides: Analysis, Synthesis, Biology. Vol. 2: Special Methods in Peptide Synthesis, Part A. pp. 3-284; Merrifield et al., J. Am. Chem. Soc. 85:2149-2156, 1963, and Stewart et al., Solid Phase Peptide Synthesis, 2nd ed. , Pierce Chem. Co., Rockford, 111., 1984. Proteins of greater length may be synthesized by condensation of the amino and carboxyl termini of shorter fragments. Methods of forming peptide bonds by activation of a carboxyl terminal end (such as by the use of the coupling reagent N, N'-dicycylohexylcarbodimide) are known.

B. Inhibitory Nucleic Acid Molecules

Inhibitory nucleic acids that decrease the expression and/or activity of CD300f can also be used in the methods disclosed herein. In some examples, such inhibitor nucleic acid molecules decrease CD300f expression or activity by at least 20%, at least 40%, at least 50%, at least 75%, at least 80%, at least 90%, at least 95%, at least 98% or even 100%. One embodiment is a RNA interference (RNAi), such as, but not limited to, small inhibitory RNA (siRNA) or short hairpin RNA, which can be used for interference or inhibition of expression of a target. RNAis that specifically target CD300f are commercially available, for example from Santa Cruz

Biotechnology, Inc., ThermoFisher Scientific, and Sigma Aldrich. Exemplary commercially available RNAi sequences are: 5 ' CGTATCAACGATGACAATAA3 ' (SEQ ID NO: 16), and 5 ' CAGTCTCTGGAGGGTGATCTCTGTT3 ' (SEQ ID NO: 17). Additional RNAi sequences of use are:

CD300f siRNA 1: CGTATCAACGATGACAATAATUU (SEQ ID NO: 18); and

CD300f siRNA 2: CAGTCTCTGGAGGGTGATCTCTGTTUU (SEQ ID NO: 19).

Generally, siRNAs are generated by the cleavage of relatively long double-stranded RNA molecules by Dicer or DCL enzymes (Zamore, Science, 296: 1265-1269, 2002; Bernstein et ah, Nature, 409:363-366, 2001). In animals and plants, siRNAs are assembled into RISC and guide the sequence specific ribonucleolytic activity of RISC, thereby resulting in the cleavage of mRNAs or other RNA target molecules in the cytoplasm. In the nucleus, siRNAs also guide heterochromatin- associated histone and DNA methylation, resulting in transcriptional silencing of individual genes or large chromatin domains.

The present disclosure provides RNA suitable for interference or inhibition of expression of CD300f, which RNA includes double stranded RNA of about 19 to about 40 nucleotides with the sequence that is substantially identical to a portion of an mRNA or transcript of a target gene, such as CD300f, for which interference or inhibition of expression is desired. For purposes of this disclosure, a sequence of the RNA "substantially identical" to a specific portion of the mRNA or transcript of the target gene for which interference or inhibition of expression is desired differs by no more than about 30%, and in some embodiments no more than about 10% or no more than 5% from the specific portion of the mRNA or transcript of the target gene. In particular embodiments, the sequence of the RNA is exactly identical to a specific portion of the mRNA or transcript of the target gene {e.g., CD300f).

Thus, siRNAs disclosed herein include double- stranded RNA of about 15 to about 40 nucleotides in length and a 3' or 5' overhang having a length of 0 to 5-nucleotides on each strand, wherein the sequence of the double stranded RNA is substantially identical to (see above) a portion of a mRNA or transcript of a nucleic acid encoding CD300f. In particular examples, the double stranded RNA contains about 19 to about 25 nucleotides, for instance 20, 21, or 22 nucleotides substantially identical to a nucleic acid encoding CD300f. In additional examples, the double stranded RNA contains about 19 to about 25 nucleotides 100% identical to a nucleic acid encoding CD300f. It should be not that in this context "about" refers to integer amounts only. In one example, "about" 20 nucleotides refers to a nucleotide of 19 to 21 nucleotides in length.

Regarding the overhang on the double-stranded RNA, the length of the overhang is independent between the two strands, in that the length of one overhang is not dependent on the length of the overhang on other strand. In specific examples, the length of the 3' or 5' overhang is 0-nucleotide on at least one strand, and in some cases it is 0-nucleotide on both strands (thus, a blunt dsRNA). In other examples, the length of the 3' or 5' overhang is 1 -nucleotide to 5- nucleotides on at least one strand. More particularly, in some examples the length of the 3 ' or 5 ' overhang is 2-nucleotides on at least one strand, or 2-nucleotides on both strands. In particular examples, the dsRNA molecule has 3' overhangs of 2-nucleotides on both strands. Thus, in one particular provided RNA embodiment, the double- stranded RNA contains 20, 21, or 22 nucleotides, and the length of the 3' overhang is 2-nucleotides on both strands. In embodiments of the RNAs provided herein, the double-stranded RNA contains about 40-60% adenine+uracil (AU) and about 60-40% guanine+cytosine (GC). More particularly, in specific examples the double- stranded RNA contains about 50% AU and about 50% GC.

Also described herein are RNAs that further include at least one modified ribonucleotide, for instance in the sense strand of the double- stranded RNA. In particular examples, the modified ribonucleotide is in the 3' overhang of at least one strand, or more particularly in the 3' overhang of the sense strand. It is contemplated that examples of modified ribonucleotides include

ribonucleotides that include a detectable label (for instance, a fluorophore, such as rhodamine or

FITC), a thiophosphate nucleotide analog, a deoxynucleotide (considered modified because the base molecule is ribonucleic acid), a 2'-fluorouracil, a 2'-aminouracil, a 2'-aminocytidine, a 4-thiouracil, a 5-bromouracil, a 5-iodouracil, a 5-(3-aminoallyl)-uracil, an inosine, or a 2'0-Me-nucleotide analog.

Antisense and ribozyme molecules for CD300f are also of use in the method disclosed herein. Antisense nucleic acids are DNA or RNA molecules that are complementary to at least a portion of a specific mRNA molecule (Weintraub, Scientific American 262:40, 1990). In the cell, the antisense nucleic acids hybridize to the corresponding mRNA, forming a double- stranded molecule. The antisense nucleic acids interfere with the translation of the mRNA, since the cell will not translate an mRNA that is double-stranded. Antisense oligomers of about 15 nucleotides are preferred, since they are easily synthesized and are less likely to cause problems than larger molecules when introduced into the target cell producing CD300f. The use of antisense methods to inhibit the in vitro translation of genes is known (see, for example, Marcus-Sakura, Anal. Biochem. 172:289, 1988).

An antisense oligonucleotide can be, for example, about 5, 10, 15, 20, 25, 30, 35, 40, 45 or

50 nucleotides in length. An antisense nucleic acid can be constructed using chemical synthesis and enzymatic ligation reactions. For example, an antisense nucleic acid molecule can be chemically synthesized using naturally occurring nucleotides or variously modified nucleotides designed to increase the biological stability of the molecules or to increase the physical stability of the duplex formed between the antisense and sense nucleic acids, such as phosphorothioate derivatives and acridine substituted nucleotides can be used. Examples of modified nucleotides which can be used to generate the antisense nucleic acid include 5-fluorouracil, 5-bromouracil, 5-chlorouracil, 5- iodouracil, hypoxanthine, xantine, 4-acetylcytosine, 5-(carboxyhydroxylmethyl) uracil, 5- carboxymethylaminomethyl-2-thiouridin- e, 5-carboxymethylaminomethyluracil, dihydrouracil, beta-D-galactosylqueosine, inosine, amongst others.

Use of an oligonucleotide to stall transcription is known as the triplex strategy where an oligonucleotide winds around double-helical DNA, forming a three-strand helix. Therefore, these triplex compounds can be designed to recognize a unique site on a chosen gene (Maher, et al. ,

Antisense Res. and Dev. 1(3):227, 1991 ; Helene, C, Anticancer Drug Design 6(6):569), 1991. This type of inhibitory oligonucleotide is also of use in the methods disclosed herein.

Ribozymes, which are RNA molecules possessing the ability to specifically cleave other single-stranded RNA in a manner analogous to DNA restriction endonucleases, are also of use. Through the modification of nucleotide sequences, which encode these RNAs, it is possible to engineer molecules that recognize specific nucleotide sequences in an RNA molecule and cleave it (Cech, /. Amer. Med. Assn. 260:3030, 1988). An advantage of this approach is that, because they are sequence-specific, only mRNAs with particular sequences are inactivated.

There are two basic types of ribozymes namely, tetrahymena-type (Hasselhoff, Nature 334:585, 1988) and "hammerhead"-type. Tetrahymena-type, ribozymes recognize sequences which are four bases in length, while "hammerhead"-type ribozymes recognize base sequences 11-18 bases in length. The longer the recognition sequence, the greater the likelihood that the sequence will occur exclusively in the target mRNA species. Consequently, hammerhead-type ribozymes are preferable to tetrahymena-type, ribozymes for inactivating a specific mRNA species and 18-base recognition sequences are preferable to shorter recognition sequences.

Various delivery systems are known and can be used to administer the siRNAs and other inhibitory nucleic acid molecules as therapeutics. Such systems include, for example,

encapsulation in liposomes, microparticles, microcapsules, nanoparticles, recombinant cells capable of expressing the therapeutic molecule(s) (see, e.g. , Wu et al. , J. Biol. Chem. 262, 4429, 1987), construction of a therapeutic nucleic acid as part of a retroviral or other vector, and the like.

D. Chemical Compounds and Small Molecules

CD300f inhibitors include molecules that are identified from large libraries of both natural product or synthetic (or semi-synthetic) extracts or chemical libraries. Screening methods that detect decreases in CD300f activity are useful for identifying compounds from a variety of sources for activity. The initial screens may be performed using a diverse library of compounds, a variety of other compounds and compound libraries. Thus, molecules that bind CD300f molecules that inhibit the expression of CD300f, and molecules that inhibit the activity of CD300f can be identified. These small molecules can be identified from combinatorial libraries, natural product libraries, or other small molecule libraries. In addition, CD300f antagonist can be identified as compounds from commercial sources, as well as commercially available analogs of identified inhibitors.

The precise source of test extracts or compounds is not critical to the identification of

CD300f small molecule antagonists. Accordingly, CD300f inhibitors can be identified from virtually any number of chemical extracts or compounds. Examples of such extracts or compounds that can be CD300f inhibitors include, but are not limited to, plant-, fungal-, prokaryotic- or animal- based extracts, fermentation broths, and synthetic compounds, as well as modification of existing compounds. Numerous methods are also available for generating random or directed synthesis (e.g., semi-synthesis or total synthesis) of any number of chemical compounds, including, but not limited to, saccharide-, lipid-, peptide-, and nucleic acid-based compounds. Synthetic compound libraries are commercially available from Brandon Associates (Merrimack, N.H.) and Aldrich Chemical (Milwaukee, Wis.). CD300f inhibitors can be identified from synthetic compound libraries that are commercially available from a number of companies including Maybridge Chemical Co. (Trevillet, Cornwall, UK), Comgenex (Princeton, N. J.), Brandon Associates (Merrimack, N.H.), and Microsource (New Milford, Conn.). CD300f inhibitors can be identified from a rare chemical library, such as the library that is available from Aldrich (Milwaukee, Wis.). CD300f inhibitors can be identified in libraries of natural compounds in the form of bacterial, fungal, plant, and animal extracts are commercially available from a number of sources, including Biotics (Sussex, UK), Xenova (Slough, UK), Harbor Branch Oceangraphics Institute (Ft. Pierce, Fla.), and PharmaMar, U.S.A. (Cambridge, Mass.). Natural and synthetically produced libraries and compounds are readily modified through conventional chemical, physical, and biochemical means.

Useful compounds may be found within numerous chemical classes, though typically they are organic compounds, including small organic compounds. Small organic compounds have a molecular weight of more than 50 yet less than about 2,500 daltons, such as less than about 750 or less than about 350 daltons can be utilized in the methods disclosed herein. Exemplary classes include heterocycles, peptides, saccharides, steroids, and the like. The compounds may be modified to enhance efficacy, stability, pharmaceutical compatibility, and the like. In several embodiments, compounds of use has a Kd for CD300f of less than InM, less than ΙΟηΜ, less than 1 μΜ, less than 10μΜ, or less than lmM. Methods of Treatment of a Subject with a Solid Tumor

and Pharmaceutical Compositions Including a CD 300f Inhibitor Methods are provided herein for treating a subject with a solid tumor. In some

embodiments the solid tumor is a carcinoma or a sarcoma. In other embodiments, the solid tumor is a lymphoma, skin cancer, or colorectal cancer. Without being bound by theory, administration of one or more CD300f inhibitors increases antigen presentation by dendritic cells, and results in the production of activated T cells, such as CD8+ cytotoxic cells, specific for the tumor.

In one specific, non-limiting example, a therapeutically effective amount of one or more CD300f inhibitors (such as 1, 2, or 3 of such inhibitors) is administered to a subject to treat a tumor, such as to decrease tumor volume or size (such as a decrease of at least 20%, at least 30%, at least 40%, at least 50%, at least 75%, at least 80%, at least 90%, at least 95%, at least 98%, or even 100% relative to absence of administration of the inhibitor). In another specific, non-limiting example, a therapeutically effective amount of the CD300f inhibitor is administered to a subject to treat a tumor, such as to decrease the number of tumors (such as a decrease of at least 20%, at least 30%, at least 40%, at least 50%, at least 75%, at least 80%, at least 90%, at least 95%, at least 98%, or even 100% relative to absence of administration of the inhibitor). In another specific, non- limiting example, a therapeutically effective amount of the CD300f inhibitor is administered to a subject to treat a tumor, such as to decrease metastasis, for example the volume or number of metastases (such as a decrease of at least 20%, at least 30%, at least 40%, at least 50%, at least 75%, at least 80%, at least 90%, at least 95%, at least 98%, or even 100% relative to absence of administration of the inhibitor). In other embodiments, a therapeutically effective amount of the CD300f inhibitor is administered to a subject to delay or prevent a symptom of the tumor. In one aspect of the disclosure, the formation of tumors, such as metastasis, are delayed, prevented or the number of metastases are decreased. In another aspect, the size of the primary tumor is decreased. In a further aspect, a symptom of the tumor is decreased. In yet another aspect, tumor volume is decreased.

Generally, the method involves selecting a subject with a solid tumor, and administering to the subject a therapeutically effective amount of one or more CD300f inhibitors. In some embodiments the subject has carcinoma or a sarcoma. In other embodiments, the subject has a lymphoma, skin cancer, or colorectal cancer. The tumor can be any tumor of interest, including, but not limited to, lymphoma, breast cancer, lung cancer and colon cancer. The tumor can be benign or malignant. Additional examples are breast, brain, cervical carcinomas, testicular carcinomas, head and neck, lung, mediastinum, gastrointestinal tract, genitourinary system, gynaecological system, breast, endocrine system, skin, childhood, unknown primary site or metastatic cancer, a sarcoma of the soft tissue and bone, a mesothelioma, a melanoma, a neoplasm of the central nervous system, a head and neck tumor, comprising tumors of the nasal cavity, paranasal sinuses, nasopharynx, oral cavity, oropharynx, larynx, hypopharynx, salivary glands and paragangliomas, a cancer of the lung, comprising non-small cell lung cancer, small cell lung cancer, a cancer of the mediastinum, a cancer of the gastrointestinal tract, comprising cancer of the oesophagus, stomach, pancreas, liver, biliary tree, small intestine, colon, rectum and anal region, a cancer of the genitourinary system, comprising cancer of the kidney, urethra, bladder, prostate, urethra, penis and testis, a gynaecologic cancer, comprising cancer of the cervix, vagina, vulva, uterine body, gestational trophoblastic diseases, ovarian, fallopian tube, peritoneal, a cancer of the breast, a cancer of the endocrine system, comprising a tumor of the thyroid, parathyroid, adrenal cortex, pancreatic endocrine tumors, carcinoid tumor and carcinoid syndrome, multiple endocrine neoplasias, a sarcoma of the soft tissue and bone, a mesothelioma, a cancer of the skin, a melanoma, comprising cutaneous melanomas and intraocular melanomas, a neoplasm of the central nervous system, a cancer of the childhood, comprising retinoblastoma, Wilm's tumor, neurofibromatoses, neuroblastoma, Ewing's sarcoma family of tumors, rhabdomyosarcoma, a solid lymphoma, cutaneous T-cell lymphomas, primary central nervous system lymphoma, a cancer of unknown primary origin, a peritoneal

carcinomastosis, a Kaposi's sarcoma, AIDS -associated lymphomas, AIDS -associated primary central nervous system lymphoma and AIDS -associated anogenital cancers. The presence of a tumor can be determined by methods known in the art, and typically include cytological and morphological evaluation.

Treatment of the conditions described herein are generally initiated after the development of a condition described herein, or after the initiation of a precursor condition (such as dysplasia or development of a benign tumor). Treatment can be initiated at the early stages of cancer, for instance, can be initiated before a subject manifests symptoms of a condition, such as during a stage I diagnosis or at the time dysplasia is diagnosed. However, treatment can be initiated during any stage of the disease, such as but not limited to stage I, stage II, stage III and stage IV cancers. In some examples, such as for breast cancer, treatment can be initiated before or during exposure to an agent that damages DNA, such as a result of an exposure to a carcinogen or UV light, oxidative stress, alkylation damage and deamination. Treatment prior to the development of the condition, such as treatment upon detecting dysplasia or an early (benign) precursor condition, is referred to herein as treatment of a subject that is "at risk" of developing the condition. In some embodiments, administration of a composition can be performed during or after the occurrence of the conditions described herein.

Generally, treatment involves increasing the immune response to the tumor. Treatment initiated after the development of a condition, such as malignant cancer, may result in decreasing the severity of the symptoms of one of the conditions, or completely removing the symptoms, or reducing metastasis, tumor volume or number of tumors. In a specific non-limiting example, there is an increased T cell response to the tumor, such as a CD8 ⁺ cytotoxic T cell response.

The compositions described herein may be formulated in a variety of ways for

administration to a subject to induce an immune response to a tumor, or to delay, prevent, reduce the risk of developing, or treat, any tumor of interest. Administration can be local, such as to the site of a tumor, or systemic. Examples of systemic methods for administering the composition into mammals include, but are not limited to, intravenous, intratumoral, intraperitoneal, subcutaneous, intradermal, inhalation, transdermal and intramuscular. Any of the CD300f inhibitors disclosed herein can be used in these methods. Thus, the method can include administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising a CD300f inhibitor.

While the CD300f inhibitor will typically be used to treat human subjects they may also be used to treat similar or identical diseases in other vertebrates, such as other primates, dogs, cats, horses, and cows. A suitable administration format may best be determined by a medical practitioner for each subject individually. Various pharmaceutically acceptable carriers and their formulation are described in standard formulation treatises, e.g., Remington 's Pharmaceutical Sciences by E. W. Martin. See also Wang, Y. J. and Hanson, M. A., Journal of Parenteral Science and Technology, Technical Report No. 10, Supp. 42: 2S, 1988. The dosage form of the pharmaceutical composition will be determined by the mode of administration chosen.

The amount of active compound(s) administered will be dependent on the subject being treated, the severity of the affliction, and the manner of administration, and is best left to the judgment of the prescribing clinician. Within these bounds, the formulation to be administered will contain a quantity of the active component(s) in amounts effective to achieve the desired effect in the subject being treated. Multiple treatments are envisioned, such as over defined intervals of time, such as daily, bi-weekly, weekly, bi-monthly or monthly, such that chronic administration is achieved. Administration may begin whenever the suppression or prevention of disease is desired, for example, at a certain age of a subject, or prior to an environmental exposure. Antibodies and antigen binding fragments thereof can be provided in lyophilized form and rehydrated with sterile water before administration, although they are also provided in sterile solutions of known concentration. The antibody solution is then added to an infusion bag containing 0.9% Sodium Chloride, USP, and typically administered at a dosage of from 0.5 to 15 mg/kg of body weight. Considerable experience is available in the art in the administration of antibody drugs, which have been marketed in the U.S. since the approval of Rituxan® in 1997. Antibody drugs can be administered by slow infusion, rather than in an IV push or bolus. In one example, a higher loading dose is administered, with subsequent, maintenance doses being administered at a lower level. For example, an initial loading dose of 4 mg/kg may be infused over a period of some 90 minutes, followed by weekly maintenance doses for 4-8 weeks of 2 mg/kg infused over a 30 minute period if the previous dose was well tolerated.

In one specific, non-limiting example, a pharmaceutical composition for intravenous administration would include about 0.1 μg to 10 mg of CD300f inhibitor, such as an antibody, per patient per day. Dosages from 0.1 up to about 100 mg per subject per day can be used, particularly if the agent is administered to a body cavity or into a lumen of an organ. Actual methods for preparing administrable compositions are described in more detail in such publications as

Remingtons Pharmaceutical Sciences, 19 ^th Ed., Mack Publishing Company, Easton, Pennsylvania, 1995.

In another embodiment, a pharmaceutical composition includes a nucleic acid encoding one or more of the antagonists, such as siRNA, shRNA or ribozyme, disclosed herein. A therapeutically effective amount of the polynucleotide can be administered to a subject, such as a subject with a solid tumor. In one specific, non-limiting example, a therapeutically effective amount of the polynucleotide is administered to a subject to treat a tumor, such as to decrease tumor volume. In another specific, non-limiting example, a therapeutically effective amount of the polynucleotide is administered to a subject to treat a tumor, such as to decrease metastasis. In other embodiments, a therapeutically effective amount of the polynucleotide is administered to a subject to delay or prevent a symptom of the tumor.

One approach to administration of nucleic acids is direct immunization with plasmid DNA, such as with a mammalian expression plasmid. As described above, the nucleotide sequence encoding a polypeptide can be placed under the control of a promoter to increase expression of the molecule.

Administration of nucleic acid constructs is taught, for example, in U.S. Patent No.

5,643,578; U.S. Patent No. 5,593,972 and U.S. Patent No. 5,817,637; and U.S. Patent No. 5,880,103. The methods include liposomal delivery of the nucleic acids (or of the synthetic peptides themselves).

In another approach to using nucleic acids for immunization, a polypeptide can also be expressed by attenuated viral hosts or vectors or bacterial vectors. Recombinant vaccinia virus, adeno-associated virus (AAV), herpes virus, retrovirus, or other viral vectors can be used to express the peptide or protein. For example, vaccinia vectors and methods of administration are described in U.S. Patent No. 4,722,848. BCG (Bacillus Calmette Guerin) provides another vector for expression of the peptides (see Stover, Nature 351 :456-460, 1991).

When a viral vector is utilized, it is desirable to provide the recipient with a dosage of each recombinant virus in the composition in the range of from about 10 ⁵ to about 10 ¹⁰ plaque forming units/mg mammal, although a lower or higher dose can be administered. The composition of recombinant viral vectors can be introduced into a subject with the solid tumor.

Examples of methods for administering the composition into mammals include, but are not limited to, intravenous, subcutaneous, intradermal or intramuscular administration of the nucleic acid, such as virus or other vector including the nucleic acid encoding the disclosed polypeptides. Generally, the quantity of recombinant viral vector, carrying the nucleic acid sequence of a polypeptide to be administered is based on the titer of virus particles. An exemplary range of the virus to be administered is 10 ⁵ to 10 ¹⁰ virus particles per mammal, such as a human.

For any CD300f inhibitor, single or multiple administrations of the compositions are administered depending on the dosage and frequency as required and tolerated by the subject. In any event, the composition should provide a sufficient quantity of at least one of the CD300f inhibitor disclosed herein to effectively treat the patient with the solid tumor. The dosage can be administered once but may be applied periodically until either a therapeutic result is achieved or until side effects warrant discontinuation of therapy. In one example, a dose of the CD300f inhibitor (such as an antibody) is infused for thirty minutes every other day. In this example, about one to about ten doses can be administered, such as three or six doses can be administered every other day. In a further example, a continuous infusion is administered for about five to about ten days.

The subject can be treated at regular intervals, such as monthly, until a desired therapeutic result is achieved. Generally, the dose is sufficient to treat or ameliorate symptoms or signs of disease without producing unacceptable toxicity to the patient.

Amounts effective for this use will depend upon the severity of the disease and the general state of the patient's health. A therapeutically effective amount of the CD300f inhibitor is that which provides either subjective relief of a symptom(s) or an objectively identifiable improvement as noted by the clinician or other qualified observer.

Controlled release parenteral formulations of the compositions can be made as implants, oily injections, or as particulate systems. For a broad overview of protein delivery systems see, Banga, A.J., Therapeutic Peptides and Proteins: Formulation, Processing, and Delivery Systems, Technomic Publishing Company, Inc., Lancaster, PA, (1995) incorporated herein by reference. Particulate systems include microspheres, microparticles, microcapsules, nanocapsules, nanospheres, and nanoparticles. Microcapsules contain the therapeutic protein, such as a cytotoxin or a drug, as a central core. In microspheres the therapeutic is dispersed throughout the particle. Particles, microspheres, and microcapsules smaller than about 1 μιη are generally referred to as nanoparticles, nanospheres, and nanocapsules, respectively. Capillaries have a diameter of approximately 5 μιη so that only nanoparticles are administered intravenously. Microparticles are typically around 100 μιη in diameter and are administered subcutaneously or intramuscularly. See, e.g., Kreuter, J., Colloidal Drug Delivery Systems, J. Kreuter, ed., Marcel Dekker, Inc., New York, NY, pp. 219-342, 1994; and Tice & Tabibi, Treatise on Controlled Drug Delivery, A. Kydonieus, ed., Marcel Dekker, Inc. New York, NY, pp. 315-339, 1992, both of which are incorporated herein by reference.

To extend the time during which the CD300f inhibitor is available, the therapeutic agent(s) can be provided as an implant, an oily injection, or as a particulate system. The particulate system can be a microparticle, a microcapsule, a microsphere, a nanocapsule, or similar particle.

Polymers can be used for ion-controlled release of the compositions disclosed herein.

Various degradable and nondegradable polymeric matrices for use in controlled drug delivery are known in the art (Langer, Accounts Chem. Res. 26:537-542, 1993). For example, the block copolymer, polaxamer 407, exists as a viscous yet mobile liquid at low temperatures but forms a semisolid gel at body temperature. It has shown to be an effective vehicle for formulation and sustained delivery of recombinant interleukin-2 and urease (Johnston et al., Pharm. Res. 9:425-434, 1992; and Pec et al., /. Parent. Sci. Tech. 44(2):58-65, 1990). Alternatively, hydroxyapatite has been used as a microcarrier for controlled release of proteins (Ijntema et al., Int. J. Pharm.112:215- 224, 1994). In yet another aspect, liposomes are used for controlled release as well as drug targeting of the lipid-capsulated drug (Betageri et al., Liposome Drug Delivery Systems, Technomic Publishing Co., Inc., Lancaster, PA, 1993). Numerous additional systems for controlled delivery of therapeutic proteins are known. See, e.g., U.S. Patent No. 5,055,303; U.S. Patent No. 5,188,837; U.S. Patent No. 4,235,871 ; U.S. Patent No. 4,501,728; U.S. Patent No. 4,837,028; U.S. Patent No. 4,957,735; U.S. Patent No. 5,019,369; U.S. Patent No. 5,055,303; U.S. Patent No. 5,514,670; U.S. Patent No. 5,413,797; U.S. Patent No. 5,268,164; U.S. Patent No. 5,004,697; U.S. Patent No. 4,902,505; U.S. Patent No. 5,506,206; U.S. Patent No. 5,271,961; U.S. Patent No. 5,254,342 and U.S. Patent No. 5,534,496, each of which is incorporated herein by reference.

The method can include administering additional therapeutic agents, such as, but not limited to, a chemotherapeutic agent, a biologic (such as a monoclonal antibody), a Programmed Death (PD)-l antagonist, or a cytotoxic T lymphocyte associated protein (CTLA)-4 antagonist, In an embodiment, the additional agent is an antibody or antibody fragment that binds to ΉΜ3. In an embodiment, the agent is an antibody or antibody fragment that binds to LAG3. Such agents can be administered before, after, or concurrently with the CD300f inhibitor.

Examples of chemotherapeutic agents are alkylating agents, antimetabolites, natural products, or hormones and their antagonists. Examples of alkylating agents include nitrogen mustards (such as mechlorethamine, cyclophosphamide, melphalan, uracil mustard or

chlorambucil), alkyl sulfonates (such as busulfan), nitrosoureas (such as carmustine, lomustine, semustine, streptozocin, or dacarbazine). Examples of antimetabolites include folic acid analogs (such as methotrexate), pyrimidine analogs (such as 5-FU or cytarabine), and purine analogs, such as mercaptopurine or thioguanine. Examples of natural products include vinca alkaloids (such as vinblastine, vincristine, or vindesine), epipodophyllotoxins (such as etoposide or teniposide), antibiotics (such as dactinomycin, daunorubicin, doxorubicin, bleomycin, plicamycin, or mitocycin C), and enzymes (such as L-asparaginase). Examples of miscellaneous agents include platinum coordination complexes (such as cis-diamine-dichloroplatinum Π also known as cisplatin), substituted ureas (such as hydroxyurea), methyl hydrazine derivatives (such as procarbazine), and adrenocrotical suppressants (such as mitotane and aminoglutethimide). Examples of hormones and antagonists include adrenocorticosteroids (such as prednisone), progestins (such as

hydroxyprogesterone caproate, medroxyprogesterone acetate, and magestrol acetate), estrogens (such as diethylstilbestrol and ethinyl estradiol), antiestrogens (such as tamoxifen), and androgens (such as testerone proprionate and fluoxymesterone). Examples of the most commonly used chemotherapy drugs include Adriamycin, Alkeran, Ara-C, BiCNU, Busulfan, CCNU,

Carboplatinum, Cisplatinum, Cytoxan, Daunorubicin, DTIC, 5-FU, Fludarabine, Hydrea,

Idarubicin, Ifosfamide, Methotrexate, Mithramycin, Mitomycin, Mitoxantrone, Nitrogen Mustard, Taxol (or other taxanes, such as docetaxel), Velban, Vincristine, VP- 16, while some more newer drugs include Gemcitabine (Gemzar), Herceptin, Irinotecan (Camptosar, CPT-11), Leustatin, Navelbine, Rituxan STI-571, Taxotere, Topotecan (Hycamtin), Xeloda (Capecitabine), Zevelin and calcitriol. Non-limiting examples of immunomodulators that can be used include AS- 101 (Wyeth- Ayerst Labs.), bropirimine (Upjohn), gamma interferon (Genentech), GM-CSF (granulocyte macrophage colony stimulating factor; Genetics Institute), IL-2 (Cetus or Hoffman-LaRoche), human immune globulin (Cutter Biological), IMREG (from Imreg of New Orleans, La.), SK&F 106528, and TNF (tumor necrosis factor; Genentech).

In one example, the additional therapeutic agent is a biologic agent (e.g. , mAb) or a small molecule, such as those shown in Table 1.

Table 1: Exemplary Tumor- specific antigens and therapeutics

Tumor-Specific Exemplary Tumors Exemplary Antibody/Small

Antigen Molecules

HER1 Adenocarcinoma (e.g., Cetuximab, panitumamab,

colorectal cancer, head and zalutumumab, nimotuzumab,

neck cancer) matuzumab. Small molecule

inhibitors gefitinib, erlotinib, and lapatinib can also be used.

HER2 breast cancer, ovarian cancer, Trastuzumab (Herceptin®),

stomach cancer, uterine pertuzumab

cancer

CD20 Non-Hodgkin lymphoma Tositumomab (Bexxar®); Rituximab

(Rituxan, Mabthera); or Ibritumomab tiuxetan (Zevalin, for example in combination with yttrium-90 or indium-I l l therapy)

CD25 T-cell lymphoma Daclizumab (Zenapax)

CD33 Acute myelogenous leukemia Gemtuzumab (Mylotarg, for example

in combination with calicheamicin therapy)

CD52 chronic lymphocytic leukemia Alemtuzumab (Campath)

CEA colorectal cancer, some CEA-scan (Fab fragment, approved

gastric cancers, biliary cancer by FDA), cololOl

Cancer antigen 125 ovarian cancer, mesothelioma, OC125 monoclonal antibody

(CA125) breast cancer

Alpha- fetoprotein hepatocellular carcinoma ab75705 (available from Abeam) and (AFP) other commercially available AFP

antibodies

Lewis Y colorectal cancer, biliary B3 (Humanized)

cancer

TAG72 adenocarcinomas including B72.3 (FDA-approved monoclonal

colorectal, pancreatic, gastric, antibody)

ovarian, endometrial,

mammary, and non-small cell

lung cancer

Vascular Colorectal cancer Bevacizumab (Avastin®)

endothelial growth

factor

The additional agent can be a PD-1 antagonist or a CTLA-4 antagonist. Irs embodiments, an inhibitory nucleic acid, e.g., an inhibitory nucleic acid, e.g., a dsRNA, e.g., a siRNA, shRNA, or ribozyme, can be used to inhibit expression of PD- 1 or CTLA-4. In other embodiments, the PD-1 antagonist or CTLA-4 antagonist is an antibody.

In some embodiments, the CTLA-4 antagonist is an antibody or antigen binding fragment thereof that specifically binds CTLA4 (e.g., ipilimumab (also referred to as MDX-010 and MDX- 101 , and marketed as YERVOY®; Bristol-Myers Squibb; Tremelimumab (IgG2 monoclonal antibody available from Pfizer, formerly known as ticilimumab, CP-675,206).).

In some embodiments, the CD300f inhibitor is administered with a PD-1 antagonist. PD-1 is an inhibitor}' member of the CD28 family of receptors that also includes CD28, CTLA-4, ICOS, and BTLA. PD-1 is expressed on activated B cells, T cells and myeloid cells (Agata et al. 1996 Int. Immunol 8:765-75). Two ligands for PD-1, PD-LI and PD-L2 have been shown to downregulate T cell activation upon binding to PD-1 (Freeman et al. 2000 J Exp Med 192: 1027-34; Latchman et al. 2001 Nat Immunol 2:261-8; Carter et al. 2002 Eur J Immunol 32:634-43). PD-LI is abundant in human cancers (Dong et al. 2003 J Mol Med 81 :281-7; Blank et al. 2005 Cancer Immunol.

Immunother 54:307-314; onishi et al. 2004 Clin Cancer Res 10:5094). Immune suppression can be reversed by inhibiting the local interaction of PD-1 with Programmed Death- Ligand (PD-L)l or PD-L2. In some examples, the PD-1 antagonist can be an antibody or antigen binding fragment thereof that binds to PD-1 , PD-LI , or PD-L2. Antibodies, antibody fragments, and other inhibitors of PD-1, PD-LI and PD-L2 are available in the art and may be used in the methods disclosed herein. For example, nivolumab (also referred to as BMS-936558 or MDX1106; Bristol-Myers Squibb) is a fully human IgG ₄ monoclonal antibody which specifically blocks PD-L Nivolumab (clone 5C4) and other human monoclonal antibodies that specifically bind to PD-1 are disclosed in U.S. Pat. No. 8,008,449 and PCX Publication No.WO2006/121168. Pidilizumab (CT-011; Cure Tech) is a humanized IgGlk monoclonal antibody that binds to PD-1. Pidilizumab and other humanized anti-PD-1 monoclonal antibodies are disclosed in PCT Publication No.

WO2009/1016H. Lambrolizumab (also referred to as MK03475; Merck) is a humanized IgG ₄ monoclonal antibody that binds to PD-1. Lambrolizumab and other humanized anti-PD-1 antibodies are disclosed in U.S. Pat. No. 8,354,509 and PCT Publication No. WO2009/ 114335. MDPL3280A (Genentech/Roche) is a human Fc optimized IgGi monoclonal antibody that binds to PD-L1. MDPL3280A and other human monoclonal antibodies to PD-L1 are disclosed in U.S. Patent No. 7,943,743 and U.S. Publication No. 2012/0039906. Other anti-PD-Ll binding agents include YW243.55.S70 (heavy and light chain variable regions are shown in SEQ ID NOs: 20 and 21 in PCT Publication No. WO2010/077634) and MDX-1 105 (also referred to as BMS-936559, and, e.g., anti-PD-Ll binding agents disclosed in PCT Publication No. WO2007/005874). AMP- 224 (B7-DCIg; Amplimmune; e.g., disclosed in PCT Publication No. WO2010/027827 and PCT Publication No. WO2011/066342), is a PD-L2 Fc fusion soluble receptor that blocks the interaction between PD-1 and B7-H1. Other anti-PD-1 antibodies include AMP 514 (Amplimmune), among others, e.g., anti-PD-1 antibodies disclosed in U.S. Patent No. 8,609,089, U.S. Publication No. 2010/028330, and/or U.S. Publication No. 2012/0114649. Any of these PD- 1 antagonists are of use in the methods disclosed herein.

Disruption of the CD300f Gene

Methods and compositions are disclosed herein for altering the CD300f gene, such as in monocytes, monocyte-derived cells (such as monocyte-derived dendritic cells), CD34 ⁺

hematopoietic progenitor cells, including dendritic precursor cells). The methods and compositions described herein introduce one or more breaks near the site of the CD300f gene to decrease the production of functional CD300f protein, such as in a dendritic cell. As noted in the section above, the CD300f gene is also known as CD300LF, CLM1, IGSF13, IREM1, and NKIR.

Exemplary nucleic acid sequences encoding human CD300f are provided in GENBANK®

Accession No. NM_139018.4 (August 26, 2016), and GENBANK Accession No.

NM_001289082.1 (August 26, 2016), which are both incorporated by reference, and an exemplary amino acid sequence of human CD300f is provided in GENBANK® Accession No. AAH28199.1 (June 6, 2006), which is incorporated by reference herein. Other examples are provided herein.

A typical set of CRISPR system is composed of two components, a CRISPR-associated nuclease 9 (Cas9) and one or more guide RNAs (gRNAs), each of which contains a CRISPR RNA (crRNA) and a trans-activating CRISPR RNA (tracrRNA). Simple gene disruptions can be generated by cleavage of the target site, followed by alteration of nucleic acids, such as a deletion, and repair by the non-homologous-end-joining pathway (NHEJ). Target recognition by crRNAs occurs through complementary base pairing with target DNA, which directs cleavage of foreign sequences by means of Cas proteins. In some embodiments, DNA recognition by guide RNA and consequent cleavage by the endonuclease requires complementary base-pairing with a protospacer adjacent motif (PAM) (e.g. 5'-NGG-3') and with a protospacer region in the target. (Jinek et. al., Science. 337:816-821, 2012). The PAM motif recognized by a Cas9 varies for different Cas9 proteins. Any Cas9 protein can be used in the systems and methods disclosed herein.

One Cas9 of use is from Streptococcus pyogenes as depicted in below (SEQ ID NO: 9) MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAE ATRLKR TARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDEV AYHEKY PTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTY NQLFEE NPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSNFDL AEDAKL QLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNTEITKAPLSASMIKR YDEHHQ DLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEELL VKLNRE DLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLA RGNSRF AWMTRKSEETITPWNFEEWDKGASAQSFIERMTNFDKNLPNEKVLPKHSLLYEYFTVYNE LTKVK YVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTVKQLKEDYFKKIECFDSVEISGVEDRFN ASLGTY HDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRR RYTGWG RLSRKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSL HEHIAN LAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEE GIKELG SQILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSI DNKVLT RSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIK RQLVET RQITKHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHA HDAYLN AWGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEIT LANGE IRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIAR KKDWDPKKYGGFDSPTVAYSVLWAKVEKGKSKKLKSVKELLGITIMERSSFEKNPIDFLE AKGYK EVKKDLI IKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASHYEKLKGSPEDNEQ KQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIREQAENI IHLFTLTNLGA PAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQLGGD In other embodiments, the Streptococcus pyogenes Cas9 peptide can include one or more of the mutations described in the literature, including but not limited to the functional mutations described in: Fonfara et al., Nucleic Acids Res. 2014 Feb;42(4):2577-90; Nishimasu et al. Cell. 2014 Feb 27;156(5):935-49; Jinek M et al. Science. 2012 Aug 17;337(6096):816-21 ; and Jinek et al. Science. 2014 Mar 14;343(6176). Thus in some embodiments the systems and methods disclosed herein can be used with the wild type Cas9 protein having double- stranded nuclease activity, Cas9 mutants that act as single stranded nickases, or other mutants with modified nuclease activity.

The Cas9 includes a catalytically active nuclease domain. In some embodiments, the Cas9 nuclease includes an HNH-like endonuclease and a RuvC-like endonuclease. Thus in some embodiments, to generate a double-stranded DNA break, the HNH-like endonuclease cleaves the DNA strand complementary to the gRNA, and the RuvC-like domain cleaves the non- complementary DNA strand. A Cas9 endonuclease can be guided to specific genomic targets using specific gRNA (see below).

In other embodiments of the the systems and methods disclosed herein, a promoter, such as the Embryonal Fyn- Associated Substrate (EFS) promoter is operably linked to the nucleic acid encoding Cas9. This promoter provides for cell specific expression of Cas9. The sequence of this promoter is shown below (SEQ ID NO: 10):

TGGCTCCGGTGCCCGTCAGTGGGCAGAGCGCACATCGCCCACAGTCCCCGAGA AGTTGGGGGGAGGGGTCGGCAATTGATCCGGTGCCTAGAGAAGGTGGCGCGGGGTAA ACTGGGAAAGTGATGTCGTGTACTGGCTCCGCCTTTTTCCCGAGGGTGGGGGAGAACC GTATATAAGTGCAGTAGTCGCCGTGAACGTTCTTTTTCGCAACGGGTTTGCCGCCAGAA CACAGG

The promoter can include 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 substitutions in SEQ ID NO: 10, provided the promoter allows for expression in dendritic cells. The promoter can be at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical SEQ ID NO: 10, provided the promoter allows for expression in dendritic cells.

Other promoters of use, include, but are not limited to, a cytomegalovirus (CMV) promoter, a synthetic promoter such as CAG promoter, a simian virus (SV)40 promoter, a 35S promoter, and an alcohol dehydrogenase (ADH)l promoter. One of skill in the art can readily identify promoters of use.

Optionally, a nucleic acid molecule encoding a marker also can be operably linked to the EFS promoter. Markers include, but are not limited to, enzymes and fluorescent proteins. In one specific non-limiting example, the marker is tdTomato fluorescent protein. In other embodiments, a nucleic acid molecule encoding a marker is not operably linked the EFS.

As noted above, the Cas9 RNA guide system includes a mature crRNA that is base-paired to trans-activating crRNA (tracrRNA), forming a two-RNA structure that directs Cas9 to the locus of a desired double- stranded (ds) break in target DNA, namely the CD300f gene. In some

embodiments base-paired tracrRNA: crRNA combination is engineered as a single RNA chimera to produce a guide sequence (e.g., gRNA) which preserves the ability to direct sequence-specific Cas9 dsDNA cleavage (see Jinek et al., Science. 337:816-821, 2012). In some embodiments, the Cas9- guide sequence complex results in cleavage of one or both strands at a target sequence within the CD300f gene, such as in exons 1 or 3 of the CD300f gene. Thus, the Cas9 endonuclease (Jinek et al., Science. 337:816-821, 2012; Mali et. al., Nat Methods. 2013 Oct; 10(10): 1028-1034) and the gRNA molecules are used sequence- specific target recognition, cleavage, and genome editing of the CD300f gene. In one embodiment, the cleavage site is at a specific nucleotide, such as, but not limited to the 16, 17, or 18 ^th nucleotide of a 20 nucleotide target. In one non-limiting example, the cleavage site is at the 17 ^th nucleotide of a 20-nt target sequence. The cleavage can be a double stranded cleavage.

In some embodiments, the gRNA molecule is selected so that the target genomic targets bear a protospacer adjacent motif (PAM). In some embodiments, DNA recognition by guide RNA and consequent cleavage by the endonuclease requires the presence of a protospacer adjacent motif (PAM) (e.g., 5'-NGG-3') in immediately after the target. The PAM is present in the targeted nucleic acid sequence but not in the crRNA that is produced to target it. In some embodiments, the proto-spacer adjacent motif (PAM) corresponds to 2 to 5 nucleotides starting immediately or in the vicinity of the proto-spacer at the leader distal end. The PAM motif also can be NNAGAA, NAG, NGGNG, AWG, CC, CC, CCN, TCN, or TTC.

In some embodiments, cleavage occurs at a site about 3 base-pairs upstream from the PAM.

In some embodiments, the Cas9 nuclease cleaves a double stranded nucleic acid sequence.

In some embodiments, the guide sequence is selected to reduce the degree of secondary structure within the sequence. Secondary structure may be determined by any suitable

polynucleotide folding algorithm. Some programs are based on calculating the minimal Gibbs free energy. An example of one such algorithm is mFold (Zuker and Stiegler, Nucleic Acids Res. 9 (1981), 133-148). Another example folding algorithm is the online webserver RNAfold, which uses the centroid structure prediction algorithm (see e.g., Gruber et al., 2008, Cell 106(1): 23-24; and Can and Church, 2009, Nature Biotechnology 27(12): 1151-62). Guide sequences can be designed using the MIT CRISPR design tool found at crispr.mit.edu, Harvard and University of Bergen CHOPCHOP web tool found at chopchop.cbu.uib.no, or the E-CRISP tool found at www.e- crisp.org/E-CRISP. Additional tools for designing tracrRNA and guide sequences are described in Naito et al., Bioinformatics. 2014 Nov 20, and Ma et al. BioMed Research International,

Volume 2013 (2013), Article ID 270805. The crRNA can be 18-48 nucleotides in length. The crRNA can be 18, 19, 20, 21, 22, 23, 24 or 25 nucleotides in length. In one example, the crRNA is 20 nucleotides in length. In additional embodiments, the tracrRNA is pre-optimized, and is 83 nucleotides in length, see SEQ ID NO: 7.

In some embodiments, the human CD300f gene is targeted, such as exon 3 or exon 4, and the crRNA is encoded by a nucleic acid sequence set forth as one of SEQ ID NO: 11 or 12. In specific non-limiting examples, the crRNA is encoded by one of the DNA sequences below. The PAM, which is recognized by Cas9 is shown next to the target DNA sequence below.

Sequence (5'-3') PAM (5'-3')*

GAAAACTGGAAATGACCTTG (SEQ ID NO : 11 ) GGG

GTGGTGGCCGGTCAGAGTTG (SEQ ID NO: 12) GGG

In some embodiments, the DNA encoding the crRNA includes or consists of, one of the nucleic acid sequence sent forth as one of SEQ ID NO: 11 or 12, which target Exon 3 and Exon 4, respectively. The PAM, which is recognized by Cas9, is shown next to the target DNA sequence. The DNA encoding the crRNA can alternatively target another exon, such as, but not limited to, Exon 1 or Exon 2.

The system disclosed herein introduces double stranded DNA breaks at the CD300f gene, such that the CD300f target is cleaved by Cas9. This results in functional CD300f protein not being produced.

The system disclosed herein can include a promoter, such as, but not limited to, a U6 or HI promoter operably linked to one or more nucleotide sequences encoding one or more CRISPR-Cas RNAs.

The U6 promoter can include the following nucleic acid sequence:

GAGGGCCTATTTCCCATGATTCCTTCATATTTGCATATACGATACAAGGCTGTTAGA GA GATAATTGGAATTAATTTGACTGTAAACACAAAGATATTAGTACAAAATACGTGACGT AGAAAGTAATAATTTCTTGGGTAGTTTGCAGTTTTAAAATTATGTTTTAAAATGGACTA TCATATGCTTACCGTAACTTGAAAGTATTTCGATTTCTTGGCTTTATATATCTTGTGGAA AGGACGAAACACC (SEQ ID NO: 13, see also GENBANK® Accession No. X07425.1, incorporated herein by reference).

Disclosed below is a U6 gRNA sequence, wherein the tracrRNA is underlined. The tracer sequence includes seven thymidines for terminating RNA transcription. The small "g," "ga," and the second "g" border the Saplrev and Sapl sites where the nucleic acid encoding the gRNA is inserted.

GGCGCGCCGGATCCGAGGGCCTATTTCCCATGATTCCTTCATATTTGCATATACGAT AC AAGGCTGTTAGAGAGATAATTGGAATTAATTTGACTGTAAACACAAAGATATTAGTAC

AAAATACGTGACGTAGAAAGTAATAATTTCTTGGGTAGTTTGCAGTTTTAAAATTAT GT

TTTAAAATGGACTATCATATGCTTACCGTAACTTGAAAGTATTTCGATTTCTTGGCT TTA

TATATCTTGTGGAAAGGACGAAACACCgGAAGAGCgaGCTCTTCgGnnAGAGCTAGA

AATAGCAAGTTA^

GTGC riTTlTGGTACCGGCGCGCC (SEQ ID NO: 14)

In one example, the tracrRNA is encoded by the nucleic acid sequence set forth as:

GTTTTAGAGCTAGAAATAGCAAGTTAAAATAAGGCTAGTCCGTTATCAACTTGAAAAA

GTGGCACCGAGTCGGTGCTTTTTTT (SEP ID NO: 15). In some embodiments, more than one DNA break can be introduced by using more than one gRNA. For example, two gRNAs can be utilized, such that two breaks are achieved. When two or more gRNAs are used to position two or more cleavage events, in a target nucleic acid, it is contemplated that in an embodiment the two or more cleavage events may be made by the same or different Cas9 proteins. For example, when two gRNAs are used to position two double strand breaks, a single Cas9 nuclease may be used to create both double strand breaks. Thus, both of the gRNAs corresponding to the DNA sequences set forth as SEQ ID NOs: 11 and 12 can be used.

In some embodiments, the disclosed methods include the use of one or more vectors comprising: a) a EFS promoter operably linked to a nucleotide sequence encoding a Type II Cas9 nuclease, b) a U6 promoter operably linked to one or more nucleotide sequences encoding one or more CRISPR-Cas guide RNAs that hybridize with the CD300f gene in a target cell, such as a human cell. Components (a) and (b) can be located on same or different vectors, whereby the one or more guide RNAs target the CD300f gene in the target cell and the Cas9 protein cleaves the CD300f gene. In specific non-limiting examples, the one or more vectors are viral vectors such as lentiviral vectors. In other non-limiting examples, the viral vectors are adenovirus vectors, adeno- associated virus vectors, or retroviral vectors.

Lentiviral vectors are retroviral vectors that are able to transduce or infect non- dividing cells and typically produce high viral titers. Retroviral vectors are comprised of cis- acting long terminal repeats with packaging capacity for up to 6-10 kb of foreign sequence. The minimum cis- acting LTRs are sufficient for replication and packaging of the vectors, which are then used to integrate the desired nucleic acid into the target cell to provide permanent expression. One non- limiting example of a lentiviral vector is the lentiCRISPRv2 vector (Adgene Plasmid #52961, see the addgene website, addgene.org/52961/).

Retroviral vectors of use include murine leukemia virus (MuLV) vectors, gibbon ape leukemia virus (GaLV) vectprs, Simian Immunodeficiency virus (SIV) vectors, human immuno deficiency virus (HIV) vectors, and combinations thereof (see, e.g., Buchscher et ah, (1992) J. Virol. 66:2731-2739; Johanti et al, (1992) J. Virol. 66: 1635-1640; Sommnerfeit et al., (1990) Virol. 176:58-59; Wilson et al, (1998) J. Virol. 63:2374-2378; Miller et al, (1991) J. Virol.

65:2220-2224; PCT/US94/05700). The use of lentiviral vectors for the delivery of Cas9 and sgRNAs is disclosed in U.S. Published Patent Application No. US20150191744, which is incorporated herein by reference.

Methods are disclosed herein for altering expression of CD300f in a subject. The method included introducing into a dendritic cell, such as a human dendritic cell comprising a gene encoding CD300f an engineered, non-naturally occurring Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR associated (Cas) system comprising one or more viral vectors, such as lentiviral vectors. The one or more viral vectors include a) an EFS (or other retina- specific promoter) operably linked to a nucleotide sequence encoding a Cas9 protein, and b) a U6 promoter operably linked to at least one nucleotide sequence encoding a CRISPR-Cas guide RNA that hybridizes with the CD300f gene, wherein components (a) and (b) are located on same or different vectors of the system, whereby the guide RNA targets the CD300f gene and the Cas9 protein cleaves the CD300f gene.

In some embodiments, the Cas9 protein is expressed in a recombinant cell, such as E. coli, and purified. The resulting purified Cas9 protein, along with an appropriate guide molecule specific for the target, is then introduced into a cell or organism where one or genomic sequences can be targeted. In some examples, the Cas9 protein and guide nucleic acid molecule (i.e., gRNA) are introduced as separate components into the target cell. In other examples, the purified Cas9 protein is complexed with the guide nucleic acid, and this ribonucleoprotein (RNP) complex is introduced into target cells (e.g., using transfection or injection). In some examples, the Cas9 protein and guide molecule are injected into the cell of interest. Once the Cas9 protein and guide nucleic acid molecule are in the cell, one or more genomic sequences can be targeted. Modification of Dendritic Cells and Their Use

Methods are disclosed herein that utilize dendritic cells deficient for expression of CD300f. These dendritic cells can be used to induce an immune response to a solid tumor. The dendritic cells deficient for expression of CD300f can be in combination with a CD300f inhibitor (or other chemotherapeutic or anti-neoplastic agent), using any of the methods disclosed above, for the treatment of a tumor in a subject, such as a solid tumor. However, the dendritic cells deficient for expression of CD300f can also be used without the administration of a CD300f inhibitor. In some embodiments, the dendritic cells are used to treat a leukemia or a lymphoma. In other

embodiments, the dendritic cells are used to treat a lymphoma.

In some embodiments, a therapeutically effective amount of the dendritic cells deficient for expression of CD300f are administered to a subject with the solid tumor. In another embodiment, the dendritic cells deficient for expression of CD300f are used to induce activated T cells, such as activated cytotoxic CD8 ⁺ T cells, specific for the tumor. A therapeutically effective amount of the activated T cells can be administered to subject with the tumor. In particular embodiments, the T cells and/or dendritic cells are autologous. In some non-limiting examples, the subject can be administered an additional therapeutic agent, such as, but not limited to, a CD300f inhibitor, a chemotherapeutic agent, an anti-neoplastic agent, a PD- 1 antagonist or a CTLA-4 antagonist, as discussed above.

The production of dendritic cells is disclosed, for example, in U.S. Application No.

20150335679, incorporated herein by reference. As disclosed in this publication, dendritic cells can be generated in vivo or ex vivo from immature precursors (e.g., monocytes, CD34 ⁺ hematopoietic precursor cells). For example, for ex vivo dendritic cell generation, a cell population enriched for dendritic cell precursor cells (e.g., peripheral blood mononuclear cells (PBMCs)) is obtained from a subject, such as with a solid tumor, and then the dendritic cell precursor cells are differentiated ex vivo into mature dendritic cells. Typically, to generate immature dendritic cells, monocytic precursors are first enriched or purified from other cell types. For example, peripheral blood mononuclear cells (PBMCs) are extracted from whole blood (e.g., over Ficoll density gradient centrifugation). Then the PBMCs will be used to generate monocytic dendritic cell precursors. In certain embodiments, monocytic dendritic cell precursors are isolated by adherence to a monocyte-binding substrate. For example, a population of leukocytes (e.g., isolated by

leukapheresis) can be contacted with a monocytic dendritic cell precursor adhering substrate. When the population of leukocytes is contacted with the substrate, the monocytic dendritic cell precursors in the leukocyte population preferentially adhere to the substrate. In one embodiment, monocytes are isolated through adherence of the monocytic precursors to a plastic (polystyrene) surface, as the monocytes have a greater tendency to stick to plastic than other cells found in, for example, peripheral blood, such as lymphocytes

Additional methods for isolating cell populations enriched for dendritic cell precursors and immature dendritic cells from various sources, including blood and bone marrow, are known in the art. For example, dendritic cell precursors and immature dendritic cells can be isolated by phlebotomy, by apheresis or leukapheresis, by collecting heparinized blood, by preparation of buffy coats, rosetting, centrifugation, density gradient centrifugation (e.g., using Ficoll, Percoll (colloidal silica particles of 15-30 mm diameter coated with polyvinylpyrrolidone (PVP)), sucrose, and the like), differential lysis of cells, filtration, and the like. In one embodiment, dendritic cell precursors can be selected using CD 14 selection of G-CSF mobilized peripheral blood. See U.S. Patent No. 8,728,806, incorporated herein by reference.

Before the subject's blood or bone marrow is obtained to isolate dendritic cell precursors, the subject may be administered granulocyte macrophage colony stimulating factor (GM-CSF) to increase bone marrow production of monocytes and dendritic cell precursors. In certain embodiments, GM-CSF is administered at a dose ranging from about 10 μg/day to about 500 μg/day, from about 20 μg/day to about 300 μg/day, from about 50 μg/day to about 250 μg/day, from about 100 μg/day to about 300 μg/day, from about 200 μg/day to about 300 μg/day, about 200 μg/day, or about 250 μg/day. In certain embodiments, GM-CSF may be administered for about 1 day, about 2 days, about 3 days, about 4 day, about 5 days, about 6 days, about 1 week, about 1.5 weeks, about 2 weeks, or longer. The effect of GM-CSF may be potentiated by another immunostimulant (such as plerixafor). In some embodiments, monocytes, monocyte-derived cells including dendritic cells, or monocyte precursors are treated with the CRISPR/Cas9 system disclosed herein to reduce expression of CD300f.

Variations on this method include different methods of purifying monocytes, including, for example, tangential flow filtration (TFF), or by binding antibodies attached to beads to surface molecules on the monocytes. The beads with the bound cells are then concentrated in a column, or on a magnetic surface, such that contaminating cells can be washed away, after which the monocytes are eluted off the beads. In yet another method to obtain dendritic cell precursors, cells expressing the stem cell marker CD34, either from blood (see U.S. Patent No. 5,994,126, incorporated herein by reference) or from the bone marrow are purified. These cells are cultured with GM-CSF to differentiate into immature dendritic cells.

Isolated dendritic cell precursors can be cultured ex vivo for differentiation, maturation and/or expansion. In certain embodiments, monocytic dendritic cells precursors are differentiated to form immature dendritic cells. The dendritic cell precursors, such as CD34 ⁺ dendritic cell precursors, or immature dendritic cells are then treated using the CRISPR/Cas9 system disclosed above to reduce or eliminate expression of CD300f. These cells are then matured to mature dendritic cells.

Dendritic cell precursors and/or immature dendritic cells can be cultured and differentiated in suitable culture conditions. The tissue culture media can be supplemented with, e.g., plasma, serum, amino acids, vitamins, cytokines (e.g., granulocyte-macrophage colony- stimulating factor (GM-CSF), interleukins such as interleukin 4 (IL-4), interleukin 13 (IL-13), interleukin 15 (IL-15), or combinations thereof), purified proteins (such as serum albumin), divalent cations (e.g., calcium and/or magnesium ions), growth factors, and the like, to promote differentiation of the cells (Sallusto et al., J. Exp. Med., 179:1109-18, 1994, incorporated herein by reference). Such culture conditions can optionally exclude any animal-derived products. In one embodiment, a dendritic cell culture medium contains about 200 units/ml to about 1500 units/ml (e.g., about 1000 units/ml, about 500 units/ml, etc.) of GM-CSF and about 200 units/ml to about 1500 units/ml (e.g., about 800 units/ml, about 500 units/ml, etc.) IL-4.

Immature dendritic cell have a high capacity for taking up and processing antigen, but have a limited ability to initiate immune responses. The ability to initiate an immune response is acquired by maturation of the immature dendritic cell. This maturation is also referred to as activating, or activation of, the dendritic cell. The maturation process may be initiated and/or induced through contact with maturation-inducing cytokines, tumor- associated antigens or tumor- associated peptide antigens and/or nucleic acids encoding tumor- associated antigens or tumor- associated peptide antigens, and the like.

In some embodiments, mature dendritic cells can be selected by expression of one or more markers. The markers include, but are not limited to, CD86, CD80, CD83, CD58, CDla, HLA-DR, CD40, CDllc, IL-2-beta, TLR-4 and combinations thereof. The dendritic cells can also be identified as lacking or expressing low levels of markers such as CD14. In one embodiment, mature dendritic cells are identified as being CD80+, CD83+, CD86+, and CD14-. Greater MHC expression leads to an increase in antigen density on the dendritic cell surface, while up-regulation of costimulatory molecules CD80 and CD86 strengthens the T cell activation signal through the counterparts of the costimulatory molecules, such as CD28 on the T cells. Any of these cells types can be treated with the CRISPR/Cas9 system disclosed herein such that expression of CD300f is decreased or eliminated.

Cell surface markers can be detected in suitable assays, such as flow cytometry, immunohistochemistry, and the like. The cells can also be monitored for cytokine production (e.g., by ELISA, FACS, or other immune assay). Dendritic cell precursors, immature dendritic cells, and mature dendritic cells, either primed or unprimed with antigens, and/or treated using the

CRISPR/Cas9 system disclosed herein, can be cryopreserved for use at a later date.

Tumor cells, such as apoptotic or killed cells, may be used to deliver antigen to either immature or mature dendritic cells, either freshly isolated or obtained from in vitro culture, wherein expression of CD300f is decreased in the dendritic cells. In one embodiment, tumor cells comprising an antigen (e.g., tumor antigen) are co-cultured with immature dendritic cells for a time sufficient to allow the antigen to be internalized by the immature dendritic cells. These immature dendritic cells are then caused to mature by the addition of a maturation factor to the culture medium. The matured dendritic cells expressing processed antigen on their surface are then exposed to T cells for potent cytotoxic T cell induction to the tumor. Alternatively, one or more specific tumor antigens can be used. Exemplary tumor antigens that can be used include but are not limited to those shown in Table 1 above.

In one embodiment, peripheral blood mononuclear cells (PBMCs) can be isolated from blood by sedimentation techniques. Human CD8 ⁺ T cell are purified with a commercial kit from Miltenyi Biotec. Dendritic cells are prepared, treated using the CRISPR/Cas9 system disclosed herein, and are cultured for 7 days to 10 days in the presence of GM-CSF and IL-4. On about day 7 through 10, apoptotic tumor cells can be co-cultured with the dendritic cells and the dendritic cells caused to mature over the next four days with the addition of monocyte conditioned medium, a signal for maturation. Alternatively, a combination of cytokines may be used to induce maturation of the immature dendritic cells. Examples of cytokines which may be used alone or in combination with each other include, but are not limited to, TNF-a, IL-Ιβ, IL-6, and IFN-β. In some embodiments, a therapeutically effective amount of these dendritic cells are administered to a subject with the solid tumor. In other embodiments, the dendritic cells are contacted with CD8 ⁺ T cells, and a therapeutically effective amount of the CD8 ⁺ T cells are administered to the subject with the solid tumor.

In further embodiments, dendritic cells (or immature dendritic cells) are treated with the CRISPR/Cas9 system disclosed herein to reduce expression of CD300f. These dendritic cells are then loaded with one or more peptide antigens (e.g., a tumor- associated peptide antigen, such as those listed in Table 1). In certain aspects, 1, 2, 3, 4, 5, 6, 7, 8, 9, or more tumor-associated peptide antigens are used. Generally, these peptide antigens are expressed by the solid tumor. A cell or membrane bound composition (e.g., a liposome) "loaded" (or "pulsed") with a peptide can be used. For example, antigen presenting cells (APCs, e.g., dendritic cells) can be incubated with one or more tumor- associated peptide antigens under conditions that are needed to load the major histocompatibility complex (MHC) of the dendritic cells. Suitable conditions for antigen loading are provided that permit a dendritic cell to contact, process and/or present one or more antigens on its MHC, whether intracellularly or on the cell surface. The incubation time may range from about 10 minutes to about 3 days or longer, from about 30 minutes to about 36 hours, from about 1 hour to about 28 hours, from about 2 hours to about 24 hours, from about 4 hours to about 24 hours, from about 4 hours to about 16 hours, from about 16 hours to about 24 hours, from about 20 hours to about 28 hours, from about 2 hours to about 4 hours, from about 1 hour to about 12 hours, from about 2 hours to about 8 hours, from about 3 hours to about 5 hours, for less than about a week, illustratively, for about 1 minute to about 48 hours, about 2 minutes to about 36 hours, about 3 minutes to about 24 hours, about 4 minutes to about 12 hours, about 6 minutes to about 8 hours, about 8 minutes to about 6 hours, about 10 minutes to about 5 hours, about 15 minutes to about 4 hours, about 20 minutes to about 3 hours, about 30 minutes to about 2 hours, about 40 minutes to about 1 hour, about 16 hours, about 20 hours, about 24 hours, about 28 hours, about 1 hour, about 2 hours, or about 4 hours. The incubation temperature may range from about 4 °C to about 37 °C, from about 25 °C to about 37 °C, about 4 °C, about 25 °C, or about 37 °C. The concentration of the peptide for loading can range from about 1 μg/ml to about 1 mg/ml, from about 5 μg/ml to about 800 μg /ml, from about 10 μg /ml to about 600 μg /ml, from about 15 μg /ml to about 400 ^g/ml, from about 10 μg/ml to about 200 μg/ml, from about 10 μg/ml to about 100 μg/ml, from about 50 μg/ml to about 100 μg/ml, from about 20 μg/ml to about 100 μg/ml, etc.

A number of methods for delivery of antigens to the endogenous processing pathway of antigen-presenting cells may be optionally used. Such methods include, but are not limited to, methods involving pH-sensitive liposomes, coupling of antigens to potent adjuvants, apoptotic cell delivery, pulsing cells onto dendritic cells, delivering recombinant chimeric virus-like particles (VLPs) comprising antigen to the MHC class I processing pathway of a dendritic cell line.

Dendritic cells also can be contacted with nucleic acids encoding one or tumor-associated antigens under a condition sufficient for the at least one tumor-associated peptide antigen to be presented by the dendritic cell. For example, dendritic cells can be transfected with expression vectors or infected with viral vectors for introducing nucleic acids encoding tumor-associated antigens into the dendritic cells. Expression can be optionally effected by targeting the expression construct to specific cells, such as with a viral vector or a receptor ligand, or by using a tissue- specific promoter, or combinations thereof. Non-limiting viral vectors include adeno-associated viruses, lentiviruses, retroviruses, herpes viruses, adenoviruses, vaccinia viruses, baculoviruses, Fowl pox, AV-pox, modified vaccinia Ankara (MVA) and other recombinant viruses.

The time and amount of antigens, or nucleic acids encoding the antigens, necessary for the antigen presenting cells to process and present the antigens can be determined, for example, by assaying T cell cytotoxic activity in vitro or using antigen-presenting cells as targets of CTLs. The antigen-presenting cells, such as dendritic cells that are treated with the CRISPR/Cas9 system disclosed herein such that expression of CD300f is decreased, are loaded with the antigen, and then can be used to stimulate CTL proliferation in vivo or ex vivo.

The ability of the loaded dendritic cells to stimulate a cytotoxic T lymphocyte (CTL) response can be measured by assaying the ability of the effector cells to lyse target cells. For example, the non-radioactive LDH cytotoxicity assay or the europium release assay can be used. Volgmann et al., J. Immunol. Methods 119:45-51, 1989. As noted above, ex vivo or in vitro maturation of dendritic cells can be induced by various maturation factors, including, but not limited to, tumor necrosis factor alpha (TNF-a), interferon alpha (IFN-a), poly (I:C), interferon gamma (IFN-γ), Interleukin 1 beta (IL-Ιβ), Interleukin 6 (IL-6), prostaglandin E2 (PGE2), poly- dldC, vasointestinal peptide (VIP), bacterial lipopolysaccharide (LPS), mycobacteria or components of mycobacteria (such as cell wall constituents), or combinations thereof. Additional maturation factors include, for example, an imidazoquinoline compound, e.g., R848 (see PCT Publication No. WO 00/47719, incorporated herein by reference), a synthetic double stranded polyribonucleotide, agonists of a Toll-like receptor (TLR), such as TLR3, TLR4, TLR7 and/or TLR9, a sequence of nucleic acids containing unmethylated CpG motifs known to induce the maturation of dendritic cells, and the like. Further, a combination of any of the above agents can be used in inducing the maturation of immature dendritic cells or dendritic precursor cells.

In certain other embodiments, mature dendritic cells or T cells can be expanded in vitro from freshly isolated or frozen cell stocks to generate sufficient numbers of cells for effective adoptive immunotherapy.

Methods are provided for administration of mature dendritic cells to a subject in need of immunostimulation. In certain embodiments, such methods are performed by obtaining dendritic cell precursors or immature dendritic cells, differentiating and maturing those cells, using the CDRISPR/Cas9 system disclosed herein to produce dendritic cells with reduced expression of CD300f, and then culturing the cells in the presence of a tumor-associated antigen or a tumor- associated peptide antigen, a nucleic acid composition, and/or apoptotic tumor cells, to form a mature dendritic cell population. A therapeutically effective amount of any of these dendritic cells can be administered to a subject with a solid tumor.

In certain embodiments, the present methods induces an immune response to a tumor in a subject. Such methods can include one or more steps of (a) obtaining monocytes (which may act as dendritic cell precursors) from a patient; (b) culturing the monocytes (e.g., with specific cytokines) to induce differentiation into immature dendritic cells; (c) contacting the immature dendritic cells with apoptotic tumor cells to induce engulfment and presentation of tumor-associated antigens; (d) differentiating the immature dendritic cells into mature dendritic cells with maturation factors such as cytokines or TLR ligands ;and (e) administering the mature dendritic cells to the patient. The monocytes, monocyte-derived cells or CD34 ⁺ progenitor-derived cells including immature dendritic cells can be treated with the CDRISPR/Cas9 system disclosed herein to produce cells with reduced expression of CD300f. Dendritic cells can be administered to the subject once, twice, three times, four times, five times, six times, seven times, eight times, nine times, ten times, eleven times, twelve times, thirteen times, fourteen times, fifteen times, or more, within a treatment regime to a subject/patient. Dendritic cells can be administered to a subject every 2 days, every 3 days, every 4 days, every 5 days, every 6 days, every 7 days, every 8 days, every 9 days, every 10 days, every 11 days, every 12 days, every 13 days, every 14 days, every 16 days, every 18 days, every 20 days, every 1 month, every 2 months, every 3 months, every 6 months, or at different frequencies. In some embodiments, the cells are administered intranodally or intradermally.

The dendritic cells can be administered at a dose ranging from about 1 X 10 ³ dendritic cells to about 1 X 10 ¹² dendritic cells, from about 1 X10 ⁴ dendritic cells to about 1 X 10 ¹⁰ dendritic cells, from about 1 X 10 ⁵ dendritic cells to about 1 X 10 ⁹ dendritic cells, from about 1 X 10 ⁶ dendritic cells to about 11 X 10 ⁸ dendritic cells, from about 1 X 10 ⁶ dendritic cells to about 1 X 10 ⁷ dendritic cells, from about 1 X 10 ⁷ dendritic cells to about 1 X 10 ⁸ dendritic cells, or from about 1 X 10 ⁸ dendritic cells to about 1 X 10 ⁹ dendritic cells. In other embodiments, the mature dendritic cells can be contacted with, and thus, activate, lymphocytes. The activated, polarized lymphocytes, optionally followed by clonal expansion in cell culture, can be administered to a subject with a solid tumor. In these embodiments, the dendritic cells that engulfed apoptotic tumor cells, or dendritic cells loaded with antigen, are contacted with lymphocytes under conditions sufficient to produce tumor-associated antigen- specific lymphocyte capable of eliciting an immune response against a tumor cell, such as cytotoxic CD8 ⁺ lymphocytes.

In one embodiment, CD8 ⁺ T lymphocytes are contacted with the dendritic cells described above for a period of time, such as for at least about 10 days, for priming and expanding the tumor antigen specific CD8 ⁺ T lymphocytes. The ability to induce lymphocytes to exhibit an immune response can be determined by any method including, but not limited to, determining T lymphocyte cytotoxic activity in vitro using for example tumor-associated antigen- specific antigen-presenting cells as targets of tumor- associated antigen- specific cytotoxic T lymphocytes (CTL); assaying tumor-associated antigen- specific T lymphocyte proliferation and ELISA methods.

CD8 ⁺ T lymphocytes can be obtained, for example, from peripheral blood and used as purified preparations, which can be obtained by standard techniques including, but not limited to, methods involving immunomagnetic or flow cytometry techniques using antibodies.

In another embodiment, resulting CTL are reinfused autologously to the subject. In one aspect, the method includes administering to a subject antigen-presenting cells, T lymphocytes, or both, where the antigen-presenting cells have engulfed apoptotic tumor cells and presented tumor- associated antigens, or wherein the antigen-presenting cells have been loaded with at least one tumor-associated peptide antigen, or where the antigen-presenting cells comprise nucleic acids encoding at least one tumor-associated antigen, under a condition sufficient for at least one tumor- associated peptide antigen to be presented by the antigen-presenting cells. The T lymphocytes have been contacted with antigen-presenting cells presenting at least one tumor-associated antigen.

Generally, the dendritic cells and the T cells are autologous. In specific, non-limiting examples, the APCs and the responder T cells are from the same individual. However, the APCs and the responder T cells can be syngeneic. The APC can be used to present any antigen to a population of autologous T cells.

One of skill in the art will appreciate that antigenic peptides that bind to MHC class I and II molecules can be generated ex vivo (for example instead of being processed from a full-length protein in a cell), and allowed to interact with (such as bind) MHC I and II molecules on a cell surface. Generally, APCs present antigen in the context of both MHC class I and Π. The amount of antigen used to prime T cells can be readily determined using methods known in the art. Generally, if the antigen is used in a purified form, about 1-10 μg/ ml of peptide is used.

In a specific example, lymphocytes are primed in vitro by incubating them with soluble antigen or viral lysate for 5-7 days under conditions that permit priming of T cells. Viable T cells are recovered, for example by Ficoll-Hypaque centrifugation, thereby generating primed T cells. If desired, the viable primed T cells can be primed again one or more times, for example by incubation with the antigen for another 5-7 days under the same conditions as those used for the first priming, and viable T cells recovered.

To increase the number of antigen- specific CD8 ⁺ T cells, proliferation of the cells can be stimulated, for example by incubation in the presence of a cytokine, such as interleukin (IL)-2, IL-7, IL-12 and IL-15. The amount of cytokine added is sufficient to stimulate production and proliferation of T cells, and can be determined using routine methods. In some examples, the amount of IL-2, IL-7, IL-12, or IL-15 added is about 0.1-100 IU/mL, such as at least 1 IU/mL, at least 10 IU/mL, or at least 20 IU/mL.

In one example, during stimulation of proliferation of activated CD8 ⁺ T cells, the cells can be counted to determine the cell number. When the desired number of cells is achieved, purity is determined. Purity can be determined, for example, using markers present on the surface of activated T cells concomitant with the assessment of cytokine production upon antigen recognition, such as interferon (IFN)y, tumor necrosis factor (TNF)oc, or interleukin (IL)-2. Generally, activated CD8 ⁺ T cells are positive for the CD3 marker, along with the CD8 marker, and IFN-γ (which is specific for activated T cells). For example, fluorescence activated cell sorting (FACS) can be used to identify (and sort if desired) populations of cells that are positive for CD3, CD8, and IFN-γ by using differently colored anti-CD3, anti-CD8 and anti-IFN-γ. Briefly, stimulated T activated cells are permeabilized and incubated in the presence of anti-CD3, anti-CD8 and anti-IFN-γ (each having a different fluorophore attached), for a time sufficient for the antibody to bind to the cells. After removing unbound antibody, cells are analyzed by FACS using routine methods. Antigen- specific T cells are those that are INF-γ positive.

In another example, the method further includes determining the cytotoxicity of the antigen- specific T cells. Methods for determining cytotoxicity are known in the art, for example a ⁵¹ Cr- release assay (for example see Walker et al. Nature 328:345-8, 1987; Qin et al. Acta Pharmacol. Sin. 23(6):534-8, 2002; all herein incorporated by reference). The present disclosure also provides therapeutic compositions that include the enriched (such as purified) activated T cells. In particular examples, the resulting enriched population of activated T cells (specific for the antigen of interest) are placed in a therapeutic dose form for administration to a subject with a solid tumor.

Expanded and selected activated CD8 ⁺ T cells can be tested for mycoplasma, sterility, endotoxin and quality controlled for function and purity prior cryopreservation or prior to infusion into the recipient.

A therapeutically effective amount of activated CD8 ⁺ T cells is administered to the subject. Specific, non- limiting examples of a therapeutically effective amount of purified activated T cells include purified activated T cells administered at a dose of about 1 X 10 ⁵ cells per kilogram of subject to about 1 X 10 ⁹ cells per kilogram of subject, such as from about 1 X 10 ⁶ cells per kilogram to about 1 X 10 ⁸ cells per kilogram, such as from about 5 X 10 ⁶ cells per kilogram to about 75 X 10 ⁶ cells per kilogram, such as at about 25 X 10 ⁶ cells per kilogram, or at about 50 X 10 ⁶ cells per kilogram.

Purified activated T cells can be administered in single or multiple doses as determined by a clinician. For example, the cells can be administered at intervals of approximately two weeks depending on the response desired and the response obtained. In some examples, once the desired response is obtained, no further activated T cells are administered. However, if the recipient displays one or more symptoms associated with the presence or growth of a tumor, a therapeutically effective amount of activated T cells can be administered at that time. The administration can be local or systemic.

The purified activated T cells disclosed herein can be administered with a pharmaceutically acceptable carrier, such as saline. Other therapeutic agents can be administered before, during, or after administration of the activated T cells, depending on the desired effect. Exemplary therapeutic agents include, but are not limited to, anti-microbial agents, immune stimulants such as interferon- alpha, chemotherapeutic agents, biologic agents (such as those listed in Table 1) or peptide vaccines of the same antigen used to stimulate T cells in vitro. In a particular example, compositions containing purified activated T cells also include one or more therapeutic agents.

EXAMPLES

Using mouse cancer models, it was determined that blocking CD300f function in dendritic cells (DCs) markedly enhanced their ability to phagocytose and process apoptotic tumor cells, and cross-present tumor cell antigens to cytotoxic CD8 ⁺ T cells (CTL), leading to substantial inhibition of tumor growth. The results show that inhibiting CD300f function on DCs is an anti-cancer therapy. Anti-CD300f blocking antibodies can release a checkpoint on human DC in order to enhance tumor cell antigen presentation by DC and induce the expansion and activation of tumor- specific autologous CTL.

Example 1

It was demonstrated that CD300f uniquely functions as a checkpoint receptor to inhibit DC- mediated apoptotic cell phagocytosis and antigen cross-presentation for T cell priming. An overview of the method is provided in FIG. 1. Mouse with the deficiency of Cd300f gene supplies a very useful tool to examine CD300f function. To generate the knock out mice, exon 2-3 of Cd300f gene was flanked by loxP sites. A PGK-neo cassette flanked by Flp recombinase target sites was used for selection. Following homologous recombination of the vector in embryonic stem cells, clones bearing the Cd300fil/fl locus were established after deletion of PGK-neo selection cassette by Flp recombination, and clones with the Cd300f-I- locus were generated after deletion of the LoxP sites flanking regions together with the PGK-neo cassette using Cre recombinase. Identified targeted embryonic stem cell clones were microinjected into the blastocysts of C57BL/6 mice. With the Cd300f-I- mice, two tumor models were developed to examine CD300f deficiency on solid tumor development. For tumor graft mouse model, mice were subcutaneously inoculated with 10 ⁶ solid tumor cells on day 0. Some of the mice were systemically irradiated at 3.25 Gy on day 7 (IR) and some of the irradiated mice were transferred with 10 ⁶ tumor antigen specific CD8 ⁺ T cells on day 9 (OT-I). Irradiation was to deplete some existing immune cells and make space to allow for expansion of anti-tumor effectors. Tumor growth was measured on the indicated days; mice were euthanized when the longitudinal tumor diameter reached 15 mm. For the mouse model of

AOM/DSS-induced colon cancer, mice were injected with AOM intraperitoneally and then fed with DSS-containing water in three 7-day cycles, with intermittent 14-day intervals of regular drinking water. After 10 weeks, mice were euthanized, and colon tumor sizes were measured. The results showed that G£?0O -deficient mice have a significantly inhibited growth of solid tumors (e.g., EL4-TfOVA lymphoma grafts, AOM/DSS-induced colorectal cancer; FIGS. 2A, 2B), indicating that CD300f negatively regulates anti-tumor responses against different cancer types. It was also demonstrated that the release of the CD300f checkpoint inhibition leads to inhibition of grafted adenocarcinoma cells (MC38) in a mouse model. Cd300f+I+ or Cd300f -I- mice were subcutaneously inoculated with 10 ⁶ MC38 cells on day 0. Tumor growth was monitored on the indicated days; mice were euthanized when the longitudinal tumor diameter reached 15 mm.

Cd300f-deficient mice had significantly inhibited growth of the grafted adenocarcinoma cells, see FIGS. 3A-3B. Furthermore, the data indicated that the improved tumor clearance in Cd300f- deficient mice is due to enhanced activation of CD8 ⁺ T cells (FIG. 2C), indicating that the blockade of CD300f function in DC enhances their cross-presentation of tumor antigens.

In line with this hypothesis, DC from CD300f-deficient mice show increased efferocytosis and enhanced stimulation of CD8 ⁺ T cells, and the enhanced anti-tumor response correlates with a significant CD8 ⁺ T cell infiltration of the tumor tissues (FIG. 2D). These results demonstrate that releasing a checkpoint on DC has remarkable efficacy, as CTL kill different tumors even when their own checkpoint receptors (e.g., PD-1, CTLA-4, LAG-3) are not blocked.

A database search (Human Protein Atlas, Expression Atlas) indicates that CD300f expression is found on immune cells and immune-associated tissues, but not on non-immune tissues (e.g., heart, muscle, liver, kidneys). It was demonstrated that human CD300f is present on human myeloid cell populations (e.g., monocytes and DCs, see FIGS. 5A-5B). Furthermore, it was found that in human blood CD300f is not expressed on lymphoid cells (T, B, NK or NKT cells), but is highly expressed on myeloid cells (monocytes, neutrophils, DC). Thus, targeting CD300f to release a checkpoint on human is a unique and potent therapeutic method for cancer management, as DC function upstream of T cells.

Releasing a DC checkpoint can be used in patients where blocking T cell checkpoints is ineffective. Moreover, a combined therapy, blocking checkpoints on both DC and T cells may elicit strong anti-tumor responses. Example 2

Commercially available anti-mouse CD300f antibodies (e.g., from R&D systems, Novus, BioLegend, Invitrogen) can block PS recognition and enhance apoptotic cell phagocytosis by mouse DC in vitro. Once a blocking antibody is selected, mouse models and assays are used to demonstrate that antibody-mediated blocking of CD300f functions to inhibit tumor progression (e.g., lymphoma grafts, colorectal cancer).

A humanized monoclonal antibody is produced that specifically recognizes human CD300f, with no cross-reactivity with other CD300 family members. Such an antibody has blocking potential, i.e., interfere with CD300f ability to recognize its ligand, phosphatidylserine, and thus neutralize CD300f signaling potential (function). Selected clones of the antibodies are tested using standard ELISA, flow cytometry and apoptotic cell phagocytosis assays, in order to determine the best clone capable of blocking PS recognition by CD300f and inhibiting CD300f function. Once selected, anti-CD300f blocking antibody (or antibodies) are used in vitro. Monocytes were isolated from patient blood samples (using a negative selection kit), and then differentiated into DC in vitro, using standard methods (i.e., culture with GM-CSF and IL-4; Dauer M. et al., J Immunol 2003). CD300f -blocked DC were incubated with apoptotic tumor cells (generated from patient's tumor samples), allowing them to engulf and process apoptotic tumor cells. Human CD300f, like mouse CD300f, recognized phosphatidylserine and regulated the phagocytosis of apoptosis (see FIGS. 4A-4B).

Next, these DC are incubated with autologous CTL (isolated from patient's blood samples using a negative selection kit), in order to cross-present apoptotic tumor cell-derived antigens and prime CTL. Enhanced CTL activation over control treated CTL is verified by monitoring cytokine production (e.g., TNF-oc, IFN-γ). The activated CTL will be tested for their ability to kill patient tumor cells that were the source of the DC-presented antigens, by standard cytotoxicity assays (e.g., chromium release assay). With the selected antibodies from the in vitro analysis, it is tested whether they can cross-react with mouse CD300f and block its function. If so, established mouse models are used to test its therapeutic effect, if not, humanized mice (e.g., NSG mice) can be used as the testing vehicle. In addition, a combinatorial therapeutic approach, combining the blockade of checkpoints on DC (CD300f) and CTL, (PD-1, CTLA-4, and/or LAG-3, can be used.

The engineered humanized antibodies are used in patients to activate DC and stimulate antigen cross-presentation, and thus mediate a potent anti-tumor response. The biological readout of physiological efficacy and measureable biomarkers for the therapy is the monitoring of IFN-γ (and/or other cytokines, e.g., IL-2) production by the activated CTL, and the presence of activated CTL themselves in the patients, as already tested in the mouse models.

An advantage of this approach over the existing methods is the independence from the requirement for a definitive tumor antigen, as DC are fed intact patient tumor cells, and can cross- present a multitude of tumor antigens. Thus, the method can be used to treat a broad range of cancer types, and be quickly adapted to treat a particular patient's cancer.

Example 3

The CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats )/Cas9 Type II system is used to facilitate a site-specific genome editing to disrupt CD300F (CD300LF) gene. The target sequences in the genomic DNA are designed using E-CRISP Designer (v. 4.2; e-crisp.org/E- CRISP/designcrispr_html), or CHOPCHOP web tool for genome editing

(http://chopchop.cbu.uib.no/). Initially, 5 different sequences targeting CD300LF gene are generated. Their nucleotide sequences are aligned against those present in the human genomic and transcript database, to verify the specificity of CD300LF targeting. The oligomers are synthesized, annealed and cloned into lentiCRISPRv2 (AddGene.org), a one vector system co-expressing a mammalian codon-optimized Cas9 nuclease along with a single guide RNA, according to the protocol found at the Zhang Lab GeCKO website (genome-engineering_org/gecko/). The lentiviral expression constructs, verified by DNA sequencing, are transfected into 293T cells with the psPAX2 and pMD2.G helper plasmids (AddGene.org) using PolyJet transfection reagent

(Signagen). The 293T cell culture medium containing lentivirus particles are used to infect 2xl0 ⁶ human monocytes, monocyte-derived cells (e.g., DCs, macrophages), in the presence of 10 μg/ml protamine sulphate (Sigma). CD300f expression on the cell surface is monitored routinely at protein levels by flow cytometry, to verify the lack of CD300f expression by the transduced cells. All CRISPR constructs are evaluated for their ability to disrupt CD300LF and generate human CD300f-deficient cells. The constructs targeting the

5 ' -GAAAACTGGAAATGACCTTGGGG-3 ' (SEQ ID NO: 20), and/or 5'-

GTGGTGGCCGGTCAGAGTTGGGG-3 ' (SEQ ID NO: 21) sequence of CD300LF (exon 3 and 4, respectively) were determined to be the most optimal to mediate gene disruption, and are chosen for generation of CD300f-deficeint human cells.

Example 4

Monocytes are isolated from patient' s blood samples using a negative selection kit (Miltenyi Monocyte Isolation Kit II), and then differentiated into DC in vitro, using standard methods (for example, culture with GM-CSF and IL-4, see Dauer M. et al., J Immunol 2003). Those monocyte- derived DC are treated with the anti-CD300f antibody to block CD300f, thereby enhancing DC activity and promoting antigen cross-presentation. In parallel, tumor cells isolated from cancer patients (e.g., biopsy samples) are exposed to UV irradiation to induce apoptosis and generate apoptotic tumor cells. CD300f -blocked DC is incubated with the apoptotic tumor cells (generated from a patient's tumor sample), allowing them to engulf and process the apoptotic tumor cells. Those DC are then matured with 10 ng/ml LPS plus 100 IU/ml IFN-γ and incubated with autologous cytotoxic T lymphocytes (CTLs) (isolated from patient's blood samples using a negative selection kit, such as the Miltenyi CD8 ⁺ T Cell Isolation Kit) using the protocol described in Nature Protocols 9, 950-966 (2014), incorporated herein by reference, in order to cross-present apoptotic tumor cell-derived antigens and prime CTL. The activation of CTL by DC in co-cultures is verified by monitoring the ability of CTL to produce different cytokines (e.g., TNF-a, IFN-γ), using ELISA and flow cytometry. The activated CTL are subsequently tested for their ability to kill patient tumor cells that were the source of the DC-presented antigens, by standard cytotoxicity assays (e.g., DELFIA or chromium release assay). In some cases, combining the blockade of checkpoints on DC and CTL, using anti-CD300f in combination with anti-PD-1, anti-CTLA-4, and/or anti-LAG-3 antibodies is also tested.

Additionally, knock-out of CD300f in human monocyte-derived DC cells using CRISPR is performed. The CD300f deficiency on DCs results in enhanced engulfment of apoptotic tumor cells and cross-presentation of tumor-specific antigens, leading to elevated priming and cytotoxicity of CTL against a variety of tumor cell lines. The CD300f-deficient DCs are used to prime and expand the tumor antigen-specific CTL in vitro or are administered directly alone or with CTL to the patient to depress tumor growth.

In view of the many possible embodiments to which the principles the disclosure may be applied, it should be recognized that illustrated embodiments are only examples of the disclosure and should not be considered a limitation on the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.