FROM CANCER

FIELD OF THE INVENTION:

The present invention relates to methods for predicting the survival time of patients suffering from cancer.

BACKGROUND OF THE INVENTION:

Sphingolipids (SLs) act as bioactive molecules in various signaling pathways, modulating cell growth, differentiation, migration and death as well as cancer progression ^{1 4} . Our group has recently documented some alterations of SL metabolism in cancer, including melanoma ^5"8 . Ceramide, an anti-oncometabolite can be generated by sphingomyelin (SM) hydrolysis, as a consequence of sphingomyelinase (SMase) activation ⁹ ' ¹⁰ . Several SMases have been described so far including neutral, alkaline and acid SMases ¹¹ . The growth of B16F1 melanoma cell line is potentiated in acid SMase-deficient mice, indicating that acid SMase-dependent SM-ceramide pathway plays some critical role in melanoma microenvironment ¹² , most likely by modulating tumor angiogenesis rather than the anti- melanoma immune response ¹³ . Furthemore, acid SMase expression in human and mouse melanoma cells enhances the activation of the extracellular signal-regulated kinase (ERK), which phosphorylates the Microphthalmia-Associated Transcription Factor (MITF), leading to its proteasomal degradation ¹⁴ . Consequently, acid SMase limits the expression of key proteins involved in melanoma progression, such as Cdk2, Bcl-2 and cMet, which are regulated by MITF ¹⁴ . More recently, melanoma acid SMase was shown to enhance the anti- melanoma immune response in mice, yet the molecular mechanisms remain to be established ¹⁵ .

Among the neutral SMases, neutral SMase 2 (nSMase2), which is encoded by SMPD3 ¹⁶ , is activated by diverse stimuli, including pro-inflammatory cytokines, such as IL-Ι β ¹⁷ and TNFa ^18~20 . Daunorubicin increased the transcription of SMPD3 in MCF-7 breast cancer cells, enhancing cell death ²¹ . In addition, doxorubicin-induced MCF-7 cell growth arrest has been recently shown to involve an ATR/Chkl/p53 -dependent SMPD3 transcription upregulation ²² . Overexpression of nSMase2 inhibits the growth of cancer cell lines, including MCF-7 ²³ and F4328 mouse osteosarcoma ²⁴ cell lines. Inactivating SMPD3 mutations have been found in human acute myeloid and lymphoid leukemias ²⁴ . SMPD3 expression is also downregulated in cancer via epigenetic mechanisms ²⁵ . In addition, nSMase2 is involved in exosome budding into multivesicular endosome ²⁶ . NSMase2 expression in breast cancer cell lines enhances the secretion of exosomes, which contain miR-210 ²¹ , as well as miR-lOb ²⁸ and miR-21 ²⁹ . NSMase2 is also likely involved in cellular export of miRNAs to HDLs ³⁰ . To the best of our knowledge, the role of nSMase2 in cancer and in particular melanoma is currently unknown.

Melanoma is a highly immunogenic cancer, the progression of which is likely associated with immune escape mechanisms. Monoclonal antibodies inhibiting immune checkpoints such as CTLA-4 (ipilimumab) and PD-1 (nivolumab, pembrolizumab) have demonstrated significant efficacy in the treatment of metastatic melanoma, promoting high response rate and long-lasting tumor control. Despite promising results, about 40% of patients do not display therapeutic response and a significant proportion of responders experience tumor relapse in the 2 years following treatment induction ³¹ . The putative consequences of SL metabolism changes in melanoma on the resistance to immune checkpoint inhibitors have not yet been investigated. Moreover, despite findings pointing the implication of the nSMase2-dependent SM-ceramide pathway in inflammation, the biological function of nSMase2 in adaptive immune response towards cancer cells remains unknown.

SUMMARY OF THE INVENTION:

The present invention relates to methods for predicting the survival time of patients suffering from cancer. In particular, the present invention is defined by the claims.

DETAILED DESCRIPTION OF THE INVENTION:

Neutral sphingomyelinase 2 (nSMase2), encoded by SMPD3, catalyzes sphingomyelin breakdown to ceramide. Herein, the inventors show that SMPD3 is frequently downregulated in human metastatic melanoma, likely contributing to immune escape mechanisms and shortened overall survival. In good agreement, ectopic expression of nSMase2 in mouse melanoma reduced tumor growth in syngeneic wild-type (i.e., immunocompetent) but not in CD8-deficient mice. Analysis of tumor content showed that nSMase2 overexpression elicited accumulation of both ceramide and CD8+ tumor-infiltrating lymphocytes (TIL) in wild-type mice. Overexpression of wild-type but not a catalytic inactive mutant of nSMase2 in mouse melanoma synergized with immune checkpoint inhibitors (i.e., anti-CTLA-4 and anti-PD-1).

Accordingly, the first object of the present invention relates to a method for predicting the survival of a patient suffering from cancer comprising i) determining the expression level of SMPD3 in tumor sample obtained from the patient, ii) comparing the expression level determined at step i) with a predetermined reference value and iii) and concluding that the patient will have short survival time when the level determined at step i) is lower than the predetermined reference value or concluding that the patient will have long survival time when the expression level determined at step i) is higher than the predetermined reference value.

As used herein, the term "cancer" has its general meaning in the art and includes, but is not limited to, solid tumors and blood-borne tumors. The term cancer includes diseases of the skin, tissues, organs, bone, cartilage, blood and vessels. The term "cancer" further encompasses both primary and metastatic cancers. Examples of cancers that may be treated by methods and compositions of the invention include, but are not limited to, cancer cells from the bladder, blood, bone, bone marrow, brain, breast, colon, esophagus, gastrointestinal tract, gum, head, kidney, liver, lung, nasopharynx, neck, ovary, prostate, skin, stomach, testis, tongue, or uterus. In addition, the cancer may specifically be of the following histological type, though it is not limited to these: neoplasm, malignant; carcinoma; carcinoma, undifferentiated; giant and spindle cell carcinoma; small cell carcinoma; papillary carcinoma; squamous cell carcinoma; lymphoepithelial carcinoma; basal cell carcinoma; pilomatrix carcinoma; transitional cell carcinoma; papillary transitional cell carcinoma; adenocarcinoma; gastrinoma, malignant; cholangiocarcinoma; hepatocellular carcinoma; combined hepatocellular carcinoma and cholangiocarcinoma; trabecular adenocarcinoma; adenoid cystic carcinoma; adenocarcinoma in adenomatous polyp; adenocarcinoma, familial polyposis coli; solid carcinoma; carcinoid tumor, malignant; branchiolo-alveolar adenocarcinoma; papillary adenocarcinoma; chromophobe carcinoma; acidophil carcinoma; oxyphilic adenocarcinoma; basophil carcinoma; clear cell adenocarcinoma; granular cell carcinoma; follicular adenocarcinoma; papillary and follicular adenocarcinoma; nonencapsulating sclerosing carcinoma; adrenal cortical carcinoma; endometroid carcinoma; skin appendage carcinoma; apocrine adenocarcinoma; sebaceous adenocarcinoma; ceruminous; adenocarcinoma; mucoepidermoid carcinoma; cystadenocarcinoma; papillary cystadenocarcinoma; papillary serous cystadenocarcinoma; mucinous cystadenocarcinoma; mucinous adenocarcinoma; signet ring cell carcinoma; infiltrating duct carcinoma; medullary carcinoma; lobular carcinoma; inflammatory carcinoma; Paget's disease, mammary; acinar cell carcinoma; adenosquamous carcinoma; adenocarcinoma w/squamous metaplasia; thymoma, malignant; ovarian stromal tumor, malignant; thecoma, malignant; granulosa cell tumor, malignant; and roblastoma, malignant; Sertoli cell carcinoma; Leydig cell tumor, malignant; lipid cell tumor, malignant; paraganglioma, malignant; extra-mammary paraganglioma, malignant; pheochromocytoma; glomangiosarcoma; malignant melanoma; amelanotic melanoma; superficial spreading melanoma; malignant melanoma in giant pigmented nevus; epithelioid cell melanoma; blue nevus, malignant; sarcoma; fibrosarcoma; fibrous histiocytoma, malignant; myxosarcoma; liposarcoma; leiomyosarcoma; rhabdomyosarcoma; embryonal rhabdomyosarcoma; alveolar rhabdomyosarcoma; stromal sarcoma; mixed tumor, malignant; mullerian mixed tumor; nephroblastoma; hepatoblastoma; carcinosarcoma; mesenchymoma, malignant; brenner tumor, malignant; phyllodes tumor, malignant; synovial sarcoma; mesothelioma, malignant; dysgerminoma; embryonal carcinoma; teratoma, malignant; struma ovarii, malignant; choriocarcinoma; mesonephroma, malignant; hemangiosarcoma; hemangioendothelioma, malignant; kaposi's sarcoma; hemangiopericytoma, malignant; lymphangiosarcoma; osteosarcoma; juxtacortical osteosarcoma; chondrosarcoma; chondroblastoma, malignant; mesenchymal chondrosarcoma; giant cell tumor of bone; Ewing's sarcoma; odontogenic tumor, malignant; ameloblastic odontosarcoma; ameloblastoma, malignant; ameloblastic fibrosarcoma; pinealoma, malignant; chordoma; glioma, malignant; ependymoma; astrocytoma; protoplasmic astrocytoma; fibrillary astrocytoma; astroblastoma; glioblastoma; oligodendroglioma; oligodendroblastoma; primitive neuroectodermal; cerebellar sarcoma; ganglioneuroblastoma; neuroblastoma; retinoblastoma; olfactory neurogenic tumor; meningioma, malignant; neurofibrosarcoma; neurilemmoma, malignant; granular cell tumor, malignant; malignant lymphoma; Hodgkin's disease; Hodgkin's lymphoma; paragranuloma; malignant lymphoma, small lymphocytic; malignant lymphoma, large cell, diffuse; malignant lymphoma, follicular; mycosis fungoides; other specified non-Hodgkin's lymphomas; malignant histiocytosis; multiple myeloma; mast cell sarcoma; immunoproliferative small intestinal disease; leukemia; lymphoid leukemia; plasma cell leukemia; erythroleukemia; lymphosarcoma cell leukemia; myeloid leukemia; basophilic leukemia; eosinophilic leukemia; monocytic leukemia; mast cell leukemia; megakaryoblastic leukemia; myeloid sarcoma; and hairy cell leukemia.

In some embodiments, the subject suffers from melanoma. As used herein,

"melanoma" refers to a condition characterized by the growth of a tumor arising from the melanocytic system of the skin and other organs. Most melanocytes occur in the skin, but are also found in the meninges, digestive tract, lymph nodes and eyes. When melanoma occurs in the skin, it is referred to as cutaneous melanoma. Melanoma can also occur in the eyes and is called ocular or intraocular melanoma. Melanoma occurs rarely in the meninges, the digestive tract, lymph nodes or other areas where melanocytes are found. 40-60 % of melanomas carry an activating mutation in the gene encoding the serine-threonine protein kinase B-RAF (BRAF). Among the BRAF mutations observed in melanoma, over 90 % are at codon 600, and among these, over 90 % are a single nucleotide mutation resulting in substitution of glutamic acid for valine (BRAFV600E).

The method is particularly suitable for predicting the duration of the overall survival (OS), progression-free survival (PFS) and/or the disease-free survival (DFS) of the cancer patient. Those of skill in the art will recognize that OS survival time is generally based on and expressed as the percentage of people who survive a certain type of cancer for a specific amount of time. Cancer statistics often use an overall five-year survival rate. In general, OS rates do not specify whether cancer survivors are still undergoing treatment at five years or if they've become cancer-free (achieved remission). DSF gives more specific information and is the number of people with a particular cancer who achieve remission. Also, progression-free survival (PFS) rates (the number of people who still have cancer, but their disease does not progress) includes people who may have had some success with treatment, but the cancer has not disappeared completely. As used herein, the expression "short survival time" indicates that the patient will have a survival time that will be lower than the median (or mean) observed in the general population of patients suffering from said cancer. When the patient will have a short survival time, it is meant that the patient will have a "poor prognosis". Inversely, the expression "long survival time" indicates that the patient will have a survival time that will be higher than the median (or mean) observed in the general population of patients suffering from said cancer. When the patient will have a long survival time, it is meant that the patient will have a "good prognosis".

As used herein, the term "tumor tissue sample" has its general meaning in the art and encompasses pieces or slices of tissue that have been removed including following a surgical tumor resection. The tumor tissue sample can be subjected to a variety of well-known post- collection preparative and storage techniques (e.g., fixation, storage, freezing, etc.) prior to determining the cell densities. Typically the tumor tissue sample is fixed in formalin and embedded in a rigid fixative, such as paraffin (wax) or epoxy, which is placed in a mould and later hardened to produce a block which is readily cut. Thin slices of material can be then prepared using a microtome, placed on a glass slide and submitted e.g. to immunohistochemistry (using an IHC automate such as BenchMark® XT, for obtaining stained slides). The tumour tissue sample can be used in microarrays, called as tissue microarrays (TMAs). TMA consists of paraffin blocks in which up to 1000 separate tissue cores are assembled in array fashion to allow multiplex histological analysis. This technology allows rapid visualization of molecular targets in tissue specimens at a time, either at the DNA, RNA or protein level. TMA technology is described in WO2004000992, US8068988, Olli et al 2001 Human Molecular Genetics, Tzankov et al 2005, Elsevier; Kononen et al 1198; Nature Medicine.

As used herein, the term "5 PDJ" has its general meaning in the art and refers to the gene encoding neutral shingomyelinase (SMase) 2. NCBI gene ID for SMPD3 is Gene ID: 55512. An exemplary human nucleic acid sequence is represented by the NCBI reference sequence NM_018667.3. An exemplary human amino acid sequence for SMase2 is represented by the NCBI reference sequence NP_061137.1.

In some embodiments, the expression level of SMPD3 in the tumor tissue sample is determined by immunohistochemistry. For example, the determination is performed by contacting the tumor tissue sample with a binding partner (e.g. an antibody) specific SMase2.

Immunohistochemistry typically includes the following steps i) fixing the tumor tissue sample with formalin, ii) embedding said tumor tissue sample in paraffin, iii) cutting said tumor tissue sample into sections for staining, iv) incubating said sections with the binding partner specific for SMase2, v) rinsing said sections, vi) incubating said section with a secondary antibody typically biotinylated and vii) revealing the antigen-antibody complex typically with avidin-biotin-peroxidase complex. Accordingly, the tumor tissue sample is firstly incubated with the binding partners having for SMase2. After washing, the labeled antibodies that are bound to SMase2 are revealed by the appropriate technique, depending of the kind of label is borne by the labeled antibody, e.g. radioactive, fluorescent or enzyme label. Multiple labelling can be performed simultaneously. Alternatively, the method of the present invention may use a secondary antibody coupled to an amplification system (to intensify staining signal) and enzymatic molecules. Such coupled secondary antibodies are commercially available, e.g. from Dako, En Vision system. Counterstaining may be used, e.g. Hematoxylin & Eosin, DAPI, Hoechst. Other staining methods may be accomplished using any suitable method or system as would be apparent to one of skill in the art, including automated, semi-automated or manual systems.

For example, one or more labels can be attached to the antibody, thereby permitting detection of the target protein. Exemplary labels include radioactive isotopes, fluorophores, ligands, chemiluminescent agents, enzymes, and combinations thereof. Non-limiting examples of labels that can be conjugated to primary and/or secondary affinity ligands include fluorescent dyes or metals (e.g. fluorescein, rhodamine, phycoerythrin, fluorescamine), chromophoric dyes (e.g. rhodopsin), chemiluminescent compounds (e.g. luminal, imidazole) and bioluminescent proteins (e.g. luciferin, luciferase), haptens (e.g. biotin). A variety of other useful fluorescers and chromophores are described in Stryer L (1968) Science 162:526- 533 and Brand L and Gohlke J R (1972) Annu. Rev. Biochem. 41 :843-868. Affinity ligands can also be labeled with enzymes (e.g. horseradish peroxidase, alkaline phosphatase, beta- lactamase), radioisotopes (e.g. ³ H, ¹⁴ C, ³² P, ³⁵ S or ¹²⁵ I) and particles (e.g. gold). The different types of labels can be conjugated to an affinity ligand using various chemistries, e.g. the amine reaction or the thiol reaction. However, other reactive groups than amines and thiols can be used, e.g. aldehydes, carboxylic acids and glutamine. Various enzymatic staining methods are known in the art for detecting a protein of interest. For example, enzymatic interactions can be visualized using different enzymes such as peroxidase, alkaline phosphatase, or different chromogens such as DAB, AEC or Fast Red. In some embodiments, the label is a quantum dot. For example, Quantum dots (Qdots) are becoming increasingly useful in a growing list of applications including immunohistochemistry, flow cytometry, and plate-based assays, and may therefore be used in conjunction with this invention. Qdot nanocrystals have unique optical properties including an extremely bright signal for sensitivity and quantitation; high photostability for imaging and analysis. A single excitation source is needed, and a growing range of conjugates makes them useful in a wide range of cell-based applications. Qdot Bioconjugates are characterized by quantum yields comparable to the brightest traditional dyes available. Additionally, these quantum dot-based fluorophores absorb 10-1000 times more light than traditional dyes. The emission from the underlying Qdot quantum dots is narrow and symmetric which means overlap with other colors is minimized, resulting in minimal bleed through into adjacent detection channels and attenuated crosstalk, in spite of the fact that many more colors can be used simultaneously. In other examples, the antibody can be conjugated to peptides or proteins that can be detected via a labeled binding partner or antibody. In an indirect IHC assay, a secondary antibody or second binding partner is necessary to detect the binding of the first binding partner, as it is not labeled.

In some embodiments, the resulting stained specimens are each imaged using a system for viewing the detectable signal and acquiring an image, such as a digital image of the staining. Methods for image acquisition are well known to one of skill in the art. For example, once the sample has been stained, any optical or non-optical imaging device can be used to detect the stain or biomarker label, such as, for example, upright or inverted optical microscopes, scanning confocal microscopes, cameras, scanning or tunneling electron microscopes, canning probe microscopes and imaging infrared detectors. In some examples, the image can be captured digitally. The obtained images can then be used for quantitatively or semi-quantitatively determining the amount of SMase2 in the sample, or the absolute number of cells positive for the maker of interest, or the surface of cells positive for the maker of interest. Various automated sample processing, scanning and analysis systems suitable for use with IHC are available in the art. Such systems can include automated staining and microscopic scanning, computerized image analysis, serial section comparison (to control for variation in the orientation and size of a sample), digital report generation, and archiving and tracking of samples (such as slides on which tissue sections are placed). Cellular imaging systems are commercially available that combine conventional light microscopes with digital image processing systems to perform quantitative analysis on cells and tissues, including immunostained samples. See, e.g., the CAS-200 system (Becton, Dickinson & Co.). In particular, detection can be made manually or by image processing techniques involving computer processors and software. Using such software, for example, the images can be configured, calibrated, standardized and/or validated based on factors including, for example, stain quality or stain intensity, using procedures known to one of skill in the art (see e.g., published U.S. Patent Publication No. US20100136549). The image can be quantitatively or semi-quantitatively analyzed and scored based on staining intensity of the sample. Quantitative or semi-quantitative histochemistry refers to method of scanning and scoring samples that have undergone histochemistry, to identify and quantify the presence of the specified biomarker (i.e. SMase2). Quantitative or semi-quantitative methods can employ imaging software to detect staining densities or amount of staining or methods of detecting staining by the human eye, where a trained operator ranks results numerically. For example, images can be quantitatively analyzed using a pixel count algorithms and tissue recognition pattern (e.g. Aperio Spectrum Software, Automated QUantitatative Analysis platform (AQUA® platform), or Tribvn with Ilastic and Calopix software), and other standard methods that measure or quantitate or semi-quantitate the degree of staining; see e.g., U.S. Pat. No. 8,023,714; U.S. Pat. No. 7,257,268; U.S. Pat. No. 7,219,016; U.S. Pat. No. 7,646,905; published U.S. Patent Publication No. US20100136549 and 20110111435; Camp et al. (2002) Nature Medicine, 8: 1323-1327; Bacus et al. (1997) Analyt Quant Cytol Histol, 19:316-328). A ratio of strong positive stain (such as brown stain) to the sum of total stained area can be calculated and scored. The amount of the detected biomarker (i.e. the SMAse2) is quantified and given as a percentage of positive pixels and/or a score. For example, the amount can be quantified as a percentage of positive pixels. In some examples, the amount is quantified as the percentage of area stained, e.g., the percentage of positive pixels. For example, a sample can have at least or about at least or about 0, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%), 80%), 85%), 90%), 95% or more positive pixels as compared to the total staining area. For example, the amount can be quantified as an absolute number of cells positive for the maker of interest. In some embodiments, a score is given to the sample that is a numerical representation of the intensity or amount of the histochemical staining of the sample, and represents the amount of target biomarker (e.g., the SMase2) present in the sample. Optical density or percentage area values can be given a scaled score, for example on an integer scale.

In some embodiments, it is advantageous for the technique to preserve the localization of the biomarker and be capable of distinguishing the presence of biomarkers in cancerous and non-cancerous cells. Such methods include layered immunohistochemistry (L-IHC), layered expression scanning (LES) or multiplex tissue immunoblotting (MTI) taught, for example, in U.S. Pat. Nos. 6,602,661, 6,969,615, 7,214,477 and 7,838,222; U.S. Publ. No. 2011/0306514 (incorporated herein by reference); and in Chung & Hewitt, Meth Mol Biol, Prot Blotting Detect, Kurlen & Scofield, eds. 536: 139-148, 2009, each reference teaches making up to 8, up to 9, up to 10, up to 11 or more images of a tissue section on layered and blotted membranes, papers, filters and the like, can be used. Coated membranes useful for conducting the L-IHC /MTI process are available from 20/20 GeneSystems, Inc. (Rockville, MD). In some embodiments, the L-IHC method can be performed on any of a variety of tissue samples, whether fresh or preserved. The samples included core needle biopsies that were routinely fixed in 10% normal buffered formalin and processed in the pathology department. Standard five μιη thick tissue sections were cut from the tissue blocks onto charged slides that were used for L-IHC. Thus, L-IHC enables testing of multiple markers in a tissue section by obtaining copies of molecules transferred from the tissue section to plural bioaffmity- coated membranes to essentially produce copies of tissue "images." In the case of a paraffin section, the tissue section is deparaffmized as known in the art, for example, exposing the section to xylene or a xylene substitute such as NEO-CLEAR®, and graded ethanol solutions. The section can be treated with a proteinase, such as, papain, trypsin, proteinase K and the like. Then, a stack of a membrane substrate comprising, for example, plural sheets of a 10 μιη thick coated polymer backbone with 0.4 μιη diameter pores to channel tissue molecules, such as, proteins, through the stack, then is placed on the tissue section. The movement of fluid and tissue molecules is configured to be essentially perpendicular to the membrane surface. The sandwich of the section, membranes, spacer papers, absorbent papers, weight and so on can be exposed to heat to facilitate movement of molecules from the tissue into the membrane stack. A portion of the proteins of the tissue are captured on each of the bioaffmity-coated membranes of the stack (available from 20/20 GeneSystems, Inc., Rockville, MD). Thus, each membrane comprises a copy of the tissue and can be probed for a different biomarker using standard immunoblotting techniques, which enables open-ended expansion of a marker profile as performed on a single tissue section. As the amount of protein can be lower on membranes more distal in the stack from the tissue, which can arise, for example, on different amounts of molecules in the tissue sample, different mobility of molecules released from the tissue sample, different binding affinity of the molecules to the membranes, length of transfer and so on, normalization of values, running controls, assessing transferred levels of tissue molecules and the like can be included in the procedure to correct for changes that occur within, between and among membranes and to enable a direct comparison of information within, between and among membranes. Hence, total protein can be determined per membrane using, for example, any means for quantifying protein, such as, biotinylating available molecules, such as, proteins, using a standard reagent and method, and then revealing the bound biotin by exposing the membrane to a labeled avidin or streptavidin; a protein stain, such as, Blot fastStain, Ponceau Red, brilliant blue stains and so on, as known in the art.

In some embodiments, multiplex tissue imaging can be performed when using fluorescence (e.g. fluorophore or Quantum dots) where the signal can be measured with a multispectral imagine system. Multispectral imaging is a technique in which spectroscopic information at each pixel of an image is gathered and the resulting data analyzed with spectral image -processing software. For example, the system can take a series of images at different wavelengths that are electronically and continuously selectable and then utilized with an analysis program designed for handling such data. The system can thus be able to obtain quantitative information from multiple dyes simultaneously, even when the spectra of the dyes are highly overlapping or when they are co-localized, or occurring at the same point in the sample, provided that the spectral curves are different. Many biological materials auto fluoresce, or emit lower- energy light when excited by higher-energy light. This signal can result in lower contrast images and data. High-sensitivity cameras without multispectral imaging capability only increase the autofluorescence signal along with the fluorescence signal. Multispectral imaging can unmix, or separate out, autofluorescence from tissue and, thereby, increase the achievable signal-to-noise ratio. Briefly the quantification can be performed by following steps: i) providing a tumor tissue microarray (TMA) obtained from the patient, ii) TMA samples are then stained with anti-antibodies having specificity of the SMAse2(s) of interest, iii) the TMA slide is further stained with an epithelial cell marker to assist in automated segmentation of tumour and stroma, iv) the TMA slide is then scanned using a multispectral imaging system, v) the scanned images are processed using an automated image analysis software (e.g.Perkin Elmer Technology) which allows the detection, quantification and segmentation of specific tissues through powerful pattern recognition algorithms. The machine-learning algorithm was typically previously trained to segment tumor from stroma and identify cells labelled. Thus, in some embodiments, the method of the present invention comprises the steps consisting in i) providing one or more immunostained slices of tissue section obtained by an automated slide-staining system by using a binding partner capable of selectively interacting with SMase2, ii) proceeding to digitalisation of the slides of step i).by high resolution scan capture, iii) detecting the slice of tissue section on the digital picture iv) providing a size reference grid with uniformly distributed units having a same surface, said grid being adapted to the size of the tissue section to be analyzed, and v) detecting, quantifying and measuring intensity or the absolute number of stained cells in each unit.

In some embodiments, the expression level of SMPD3 is determined by determining the quantity of mRNA encoding for SMase2. Methods for determining the quantity of mRNA are well known in the art. For example the nucleic acid contained in the samples (e.g., cell or tissue prepared from the subject) is first extracted according to standard methods, for example using lytic enzymes or chemical solutions or extracted by nucleic-acid-binding resins following the manufacturer's instructions. The extracted mRNA is then detected by hybridization (e. g., Northern blot analysis, in situ hybridization) and/or amplification (e.g., RT-PCR). Other methods of Amplification include ligase chain reaction (LCR), transcription- mediated amplification (TMA), strand displacement amplification (SDA) and nucleic acid sequence based amplification (NASBA).

Nucleic acids having at least 10 nucleotides and exhibiting sequence complementarity or homology to the mRNA of interest herein find utility as hybridization probes or amplification primers. It is understood that such nucleic acids need not be identical, but are typically at least about 80% identical to the homologous region of comparable size, more preferably 85% identical and even more preferably 90-95% identical. In some embodiments, it will be advantageous to use nucleic acids in combination with appropriate means, such as a detectable label, for detecting hybridization.

Typically, the nucleic acid probes include one or more labels, for example to permit detection of a target nucleic acid molecule using the disclosed probes. In various applications, such as in situ hybridization procedures, a nucleic acid probe includes a label (e.g., a detectable label). A "detectable label" is a molecule or material that can be used to produce a detectable signal that indicates the presence or concentration of the probe (particularly the bound or hybridized probe) in a sample. Thus, a labeled nucleic acid molecule provides an indicator of the presence or concentration of a target nucleic acid sequence (e.g., genomic target nucleic acid sequence) (to which the labeled uniquely specific nucleic acid molecule is bound or hybridized) in a sample. A label associated with one or more nucleic acid molecules (such as a probe generated by the disclosed methods) can be detected either directly or indirectly. A label can be detected by any known or yet to be discovered mechanism including absorption, emission and/ or scattering of a photon (including radio frequency, microwave frequency, infrared frequency, visible frequency and ultra-violet frequency photons). Detectable labels include colored, fluorescent, phosphorescent and luminescent molecules and materials, catalysts (such as enzymes) that convert one substance into another substance to provide a detectable difference (such as by converting a colorless substance into a colored substance or vice versa, or by producing a precipitate or increasing sample turbidity), haptens that can be detected by antibody binding interactions, and paramagnetic and magnetic molecules or materials.

Particular examples of detectable labels include fluorescent molecules (or fluorochromes). Numerous fluorochromes are known to those of skill in the art, and can be selected, for example from Life Technologies (formerly Invitrogen), e.g., see, The Handbook— A Guide to Fluorescent Probes and Labeling Technologies). Examples of particular fluorophores that can be attached (for example, chemically conjugated) to a nucleic acid molecule (such as a uniquely specific binding region) are provided in U.S. Pat. No. 5,866, 366 to Nazarenko et al., such as 4-acetamido-4'-isothiocyanatostilbene-2,2' disulfonic acid, acridine and derivatives such as acridine and acridine isothiocyanate, 5-(2'-aminoethyl) aminonaphthalene-1 -sulfonic acid (EDANS), 4-amino -N- [3 vinylsulfonyl)phenyl]naphthalimide-3,5 disulfonate (Lucifer Yellow VS), N-(4-anilino-l- naphthyl)maleimide, antllranilamide, Brilliant Yellow, coumarin and derivatives such as coumarin, 7-amino-4-methylcoumarin (AMC, Coumarin 120), 7-amino-4- trifluoromethylcouluarin (Coumarin 151); cyanosine; 4',6-diarninidino-2-phenylindole (DAPI); 5',5"dibromopyrogallol-sulfonephthalein (Bromopyrogallol Red); 7 -diethylamino -3 (4'-isothiocyanatophenyl)-4-methylcoumarin; diethylenetriamine pentaacetate; 4,4'- diisothiocyanatodihydro-stilbene-2,2'-disulfonic acid; 4,4'-diisothiocyanatostilbene-2,2'- disulforlic acid; 5-[dimethylamino] naphthalene- 1-sulfonyl chloride (DNS, dansyl chloride); 4-(4'-dimethylaminophenylazo)benzoic acid (DABCYL); 4-dimethylaminophenylazophenyl- 4'-isothiocyanate (DABITC); eosin and derivatives such as eosin and eosin isothiocyanate; erythrosin and derivatives such as erythrosin B and erythrosin isothiocyanate; ethidium; fluorescein and derivatives such as 5-carboxyf uorescein (FAM), 5-(4,6diclllorotriazin-2- yDarninof uorescein (DTAF), 2'7'dimethoxy-4'5'-dichloro-6-carboxyfluorescein (JOE), fluorescein, fluorescein isothiocyanate (FITC), and QFITC Q(RITC); 2',7'-difluorofluorescein (OREGON GREEN®); fluorescamine; IR144; IR1446; Malachite Green isothiocyanate; 4- methylumbelliferone; ortho cresolphthalein; nitrotyrosine; pararosaniline; Phenol Red; B- phycoerythrin; o-phthaldialdehyde; pyrene and derivatives such as pyrene, pyrene butyrate and succinimidyl 1 -pyrene butyrate; Reactive Red 4 (Cibacron Brilliant Red 3B-A); rhodamine and derivatives such as 6-carboxy-X-rhodamine (ROX), 6-carboxyrhodamine (R6G), lissamine rhodamine B sulfonyl chloride, rhodamine (Rhod), rhodamine B, rhodamine 123, rhodamine X isothiocyanate, rhodamine green, sulforhodamine B, sulforhodamine 101 and sulfonyl chloride derivative of sulforhodamine 101 (Texas Red); Ν,Ν,Ν',Ν'-tetramethyl- 6-carboxyrhodamine (TAMRA); tetramethyl rhodamine; tetramethyl rhodamine isothiocyanate (TRITC); riboflavin; rosolic acid and terbium chelate derivatives. Other suitable fluorophores include thiol-reactive europium chelates which emit at approximately 617 mn (Heyduk and Heyduk, Analyt. Biochem. 248:216-27, 1997; J. Biol. Chem. 274:3315- 22, 1999), as well as GFP, LissamineTM, diethylaminocoumarin, fluorescein chlorotriazinyl, naphthofluorescein, 4,7-dichlororhodamine and xanthene (as described in U.S. Pat. No. 5,800,996 to Lee et al.) and derivatives thereof. Other fluorophores known to those skilled in the art can also be used, for example those available from Life Technologies (Invitrogen; Molecular Probes (Eugene, Oreg.)) and including the ALEXA FLUOR® series of dyes (for example, as described in U.S. Pat. Nos. 5,696,157, 6, 130, 101 and 6,716,979), the BODIPY series of dyes (dipyrrometheneboron difluoride dyes, for example as described in U.S. Pat. Nos. 4,774,339, 5,187,288, 5,248,782, 5,274,113, 5,338,854, 5,451,663 and 5,433,896), Cascade Blue (an amine reactive derivative of the sulfonated pyrene described in U.S. Pat. No. 5,132,432) and Marina Blue (U.S. Pat. No. 5,830,912).

In addition to the fluorochromes described above, a fluorescent label can be a fluorescent nanoparticle, such as a semiconductor nanocrystal, e.g., a QUANTUM DOTTM (obtained, for example, from Life Technologies (QuantumDot Corp, Invitrogen Nanocrystal Technologies, Eugene, Oreg.); see also, U.S. Pat. Nos. 6,815,064; 6,682,596; and 6,649, 138). Semiconductor nanocrystals are microscopic particles having size-dependent optical and/or electrical properties. When semiconductor nanocrystals are illuminated with a primary energy source, a secondary emission of energy occurs of a frequency that corresponds to the handgap of the semiconductor material used in the semiconductor nanocrystal. This emission can he detected as colored light of a specific wavelength or fluorescence. Semiconductor nanocrystals with different spectral characteristics are described in e.g., U.S. Pat. No. 6,602,671. Semiconductor nanocrystals that can he coupled to a variety of biological molecules (including dNTPs and/or nucleic acids) or substrates by techniques described in, for example, Bruchez et al., Science 281 :20132016, 1998; Chan et al., Science 281 :2016- 2018, 1998; and U.S. Pat. No. 6,274,323. Formation of semiconductor nanocrystals of various compositions are disclosed in, e.g., U.S. Pat. Nos. 6,927, 069; 6,914,256; 6,855,202; 6,709,929; 6,689,338; 6,500,622; 6,306,736; 6,225,198; 6,207,392; 6,114,038; 6,048,616; 5,990,479; 5,690,807; 5,571,018; 5,505,928; 5,262,357 and in U.S. Patent Publication No. 2003/0165951 as well as PCT Publication No. 99/26299 (puhlished May 27, 1999). Separate populations of semiconductor nanocrystals can he produced that are identifiable based on their different spectral characteristics. For example, semiconductor nanocrystals can he produced that emit light of different colors hased on their composition, size or size and composition. For example, quantum dots that emit light at different wavelengths based on size (565 mn, 655 mn, 705 mn, or 800 mn emission wavelengths), which are suitable as fluorescent labels in the probes disclosed herein are available from Life Technologies (Carlshad, Calif). Additional labels include, for example, radioisotopes (such as 3 H), metal chelates such as DOTA and DPTA chelates of radioactive or paramagnetic metal ions like Gd3+, and liposomes. Detectable labels that can he used with nucleic acid molecules also include enzymes, for example horseradish peroxidase, alkaline phosphatase, acid phosphatase, glucose oxidase, beta-galactosidase, beta-glucuronidase, or beta-lactamase. Alternatively, an enzyme can he used in a metallographic detection scheme. For example, silver in situ hyhridization (SISH) procedures involve metallographic detection schemes for identification and localization of a hybridized genomic target nucleic acid sequence. Metallographic detection methods include using an enzyme, such as alkaline phosphatase, in combination with a water-soluble metal ion and a redox-inactive substrate of the enzyme. The substrate is converted to a redox-active agent by the enzyme, and the redoxactive agent reduces the metal ion, causing it to form a detectable precipitate. (See, for example, U.S. Patent Application Publication No. 2005/0100976, PCT Publication No. 2005/ 003777 and U.S. Patent Application Publication No. 2004/ 0265922). Metallographic detection methods also include using an oxido-reductase enzyme (such as horseradish peroxidase) along with a water soluble metal ion, an oxidizing agent and a reducing agent, again to form a detectable precipitate. (See, for example, U.S. Pat. No. 6,670,113). Probes made using the disclosed methods can be used for nucleic acid detection, such as ISH procedures (for example, fluorescence in situ hybridization (FISH), chromogenic in situ hybridization (CISH) and silver in situ hybridization (SISH)) or comparative genomic hybridization (CGH).

In situ hybridization (ISH) involves contacting a sample containing target nucleic acid sequence (e.g., genomic target nucleic acid sequence) in the context of a metaphase or interphase chromosome preparation (such as a cell or tissue sample mounted on a slide) with a labeled probe specifically hybridizable or specific for the target nucleic acid sequence (e.g., genomic target nucleic acid sequence). The slides are optionally pretreated, e.g., to remove paraffin or other materials that can interfere with uniform hybridization. The sample and the probe are both treated, for example by heating to denature the double stranded nucleic acids. The probe (formulated in a suitable hybridization buffer) and the sample are combined, under conditions and for sufficient time to permit hybridization to occur (typically to reach equilibrium). The chromosome preparation is washed to remove excess probe, and detection of specific labeling of the chromosome target is performed using standard techniques.

For example, a biotinylated probe can be detected using fluorescein-labeled avidin or avidin-alkaline phosphatase. For fiuorochrome detection, the fiuorochrome can be detected directly, or the samples can be incubated, for example, with fluorescein isothiocyanate (FITC)-conjugated avidin. Amplification of the FITC signal can be effected, if necessary, by incubation with biotin-conjugated goat antiavidin antibodies, washing and a second incubation with FITC-conjugated avidin. For detection by enzyme activity, samples can be incubated, for example, with streptavidin, washed, incubated with biotin-conjugated alkaline phosphatase, washed again and pre-equilibrated (e.g., in alkaline phosphatase (AP) buffer). For a general description of in situ hybridization procedures, see, e.g., U.S. Pat. No. 4,888,278.

Numerous procedures for FISH, CISH, and SISH are known in the art. For example, procedures for performing FISH are described in U.S. Pat. Nos. 5,447,841; 5,472,842; and 5,427,932; and for example, in Pirlkel et al, Proc. Natl. Acad. Sci. 83:2934-2938, 1986; Pinkel et al, Proc. Natl. Acad. Sci. 85:9138-9142, 1988; and Lichter et al, Proc. Natl. Acad. Sci. 85:9664-9668, 1988. CISH is described in, e.g., Tanner et al, Am. .1. Pathol. 157: 1467- 1472, 2000 and U.S. Pat. No. 6,942,970. Additional detection methods are provided in U.S. Pat. No. 6,280,929.

Numerous reagents and detection schemes can be employed in conjunction with FISH, CISH, and SISH procedures to improve sensitivity, resolution, or other desirable properties. As discussed above probes labeled with fluorophores (including fiuorescent dyes and QUANTUM DOTS®) can be directly optically detected when performing FISH. Alternatively, the probe can be labeled with a nonfluorescent molecule, such as a hapten (such as the following non-limiting examples: biotin, digoxigenin, DNP, and various oxazoles, pyrrazoles, thiazoles, nitroaryls, benzofurazans, triterpenes, ureas, thioureas, rotenones, coumarin, courmarin-based compounds, Podophyllotoxin, Podophyllotoxin-based compounds, and combinations thereof), ligand or other indirectly detectable moiety. Probes labeled with such non-fluorescent molecules (and the target nucleic acid sequences to which they bind) can then be detected by contacting the sample (e.g., the cell or tissue sample to which the probe is bound) with a labeled detection reagent, such as an antibody (or receptor, or other specific binding partner) specific for the chosen hapten or ligand. The detection reagent can be labeled with a fluorophore (e.g., QUANTUM DOT®) or with another indirectly detectable moiety, or can be contacted with one or more additional specific binding agents (e.g., secondary or specific antibodies), which can be labeled with a fluorophore.

In other examples, the probe, or specific binding agent (such as an antibody, e.g., a primary antibody, receptor or other binding agent) is labeled with an enzyme that is capable of converting a fiuorogenic or chromogenic composition into a detectable fluorescent, colored or otherwise detectable signal (e.g., as in deposition of detectable metal particles in SISH). As indicated above, the enzyme can be attached directly or indirectly via a linker to the relevant probe or detection reagent. Examples of suitable reagents (e.g., binding reagents) and chemistries (e.g., linker and attachment chemistries) are described in U.S. Patent Application Publication Nos. 2006/0246524; 2006/0246523, and 2007/ 01 17153.

It will he appreciated by those of skill in the art that by appropriately selecting labelled probe-specific binding agent pairs, multiplex detection schemes can he produced to facilitate detection of multiple target nucleic acid sequences (e.g., genomic target nucleic acid sequences) in a single assay (e.g., on a single cell or tissue sample or on more than one cell or tissue sample). For example, a first probe that corresponds to a first target sequence can he labelled with a first hapten, such as biotin, while a second probe that corresponds to a second target sequence can be labelled with a second hapten, such as DNP. Following exposure of the sample to the probes, the bound probes can he detected by contacting the sample with a first specific binding agent (in this case avidin labelled with a first fluorophore, for example, a first spectrally distinct QUANTUM DOT®, e.g., that emits at 585 mn) and a second specific binding agent (in this case an anti-DNP antibody, or antibody fragment, labelled with a second fluorophore (for example, a second spectrally distinct QUANTUM DOT®, e.g., that emits at 705 mn). Additional probes/binding agent pairs can he added to the multiplex detection scheme using other spectrally distinct fluorophores. Numerous variations of direct, and indirect (one step, two step or more) can he envisioned, all of which are suitable in the context of the disclosed probes and assays.

Probes typically comprise single-stranded nucleic acids of between 10 to 1000 nucleotides in length, for instance of between 10 and 800, more preferably of between 15 and 700, typically of between 20 and 500. Primers typically are shorter single-stranded nucleic acids, of between 10 to 25 nucleotides in length, designed to perfectly or almost perfectly match a nucleic acid of interest, to be amplified. The probes and primers are "specific" to the nucleic acids they hybridize to, i.e. they preferably hybridize under high stringency hybridization conditions (corresponding to the highest melting temperature Tm, e.g., 50 % formamide, 5x or 6x SCC. SCC is a 0.15 M NaCl, 0.015 M Na-citrate).

The nucleic acid primers or probes used in the above amplification and detection method may be assembled as a kit. Such a kit includes consensus primers and molecular probes. A preferred kit also includes the components necessary to determine if amplification has occurred. The kit may also include, for example, PCR buffers and enzymes; positive control sequences, reaction control primers; and instructions for amplifying and detecting the specific sequences.

In some embodiments, the methods of the invention comprise the steps of providing total R As extracted from cumulus cells and subjecting the RNAs to amplification and hybridization to specific probes, more particularly by means of a quantitative or semiquantitative RT-PCR.

In some embodiments, the level is determined by DNA chip analysis. Such DNA chip or nucleic acid microarray consists of different nucleic acid probes that are chemically attached to a substrate, which can be a microchip, a glass slide or a microsphere-sized bead. A microchip may be constituted of polymers, plastics, resins, polysaccharides, silica or silica- based materials, carbon, metals, inorganic glasses, or nitrocellulose. Probes comprise nucleic acids such as cDNAs or oligonucleotides that may be about 10 to about 60 base pairs. To determine the level, a sample from a test subject, optionally first subjected to a reverse transcription, is labelled and contacted with the microarray in hybridization conditions, leading to the formation of complexes between target nucleic acids that are complementary to probe sequences attached to the microarray surface. The labelled hybridized complexes are then detected and can be quantified or semi-quantified. Labelling may be achieved by various methods, e.g. by using radioactive or fluorescent labelling. Many variants of the microarray hybridization technology are available to the man skilled in the art (see e.g. the review by Hoheisel, Nature Reviews, Genetics, 2006, 7:200-210).

In some embodiments, the nCounter® Analysis system is used to detect intrinsic gene expression. The basis of the nCounter® Analysis system is the unique code assigned to each nucleic acid target to be assayed (International Patent Application Publication No. WO 08/124847, U.S. Patent No. 8,415,102 and Geiss et al. Nature Biotechnology. 2008. 26(3): 317-325; the contents of which are each incorporated herein by reference in their entireties). The code is composed of an ordered series of colored fluorescent spots which create a unique barcode for each target to be assayed. A pair of probes is designed for each DNA or RNA target, a biotinylated capture probe and a reporter probe carrying the fluorescent barcode. This system is also referred to, herein, as the nanoreporter code system. Specific reporter and capture probes are synthesized for each target. The reporter probe can comprise at a least a first label attachment region to which are attached one or more label monomers that emit light constituting a first signal; at least a second label attachment region, which is non-over-lapping with the first label attachment region, to which are attached one or more label monomers that emit light constituting a second signal; and a first target- specific sequence. Preferably, each sequence specific reporter probe comprises a target specific sequence capable of hybridizing to no more than one gene and optionally comprises at least three, or at least four label attachment regions, said attachment regions comprising one or more label monomers that emit light, constituting at least a third signal, or at least a fourth signal, respectively. The capture probe can comprise a second target-specific sequence; and a first affinity tag. In some embodiments, the capture probe can also comprise one or more label attachment regions. Preferably, the first target- specific sequence of the reporter probe and the second target- specific sequence of the capture probe hybridize to different regions of the same gene to be detected. Reporter and capture probes are all pooled into a single hybridization mixture, the "probe library". The relative abundance of each target is measured in a single multiplexed hybridization reaction. The method comprises contacting the tumor tissue sample with a probe library, such that the presence of the target in the sample creates a probe pair - target complex. The complex is then purified. More specifically, the sample is combined with the probe library, and hybridization occurs in solution. After hybridization, the tripartite hybridized complexes (probe pairs and target) are purified in a two-step procedure using magnetic beads linked to oligonucleotides complementary to universal sequences present on the capture and reporter probes. This dual purification process allows the hybridization reaction to be driven to completion with a large excess of target-specific probes, as they are ultimately removed, and, thus, do not interfere with binding and imaging of the sample. All post hybridization steps are handled robotically on a custom liquid-handling robot (Prep Station, NanoString Technologies). Purified reactions are typically deposited by the Prep Station into individual flow cells of a sample cartridge, bound to a streptavidin-coated surface via the capture probe,electrophoresed to elongate the reporter probes, and immobilized. After processing, the sample cartridge is transferred to a fully automated imaging and data collection device (Digital Analyzer, NanoString Technologies). The level of a target is measured by imaging each sample and counting the number of times the code for that target is detected. For each sample, typically 600 fields-of-view (FOV) are imaged (1376 X 1024 pixels) representing approximately 10 mm2 of the binding surface. Typical imaging density is 100- 1200 counted reporters per field of view depending on the degree of multiplexing, the amount of sample input, and overall target abundance. Data is output in simple spreadsheet format listing the number of counts per target, per sample. This system can be used along with nanoreporters. Additional disclosure regarding nanoreporters can be found in International Publication No. WO 07/076129 and WO07/076132, and US Patent Publication No. 2010/0015607 and 2010/0261026, the contents of which are incorporated herein in their entireties. Further, the term nucleic acid probes and nanoreporters can include the rationally designed (e.g. synthetic sequences) described in International Publication No. WO 2010/019826 and US Patent Publication No.2010/0047924, incorporated herein by reference in its entirety.

Expression level of a gene may be expressed as absolute level or normalized level. Typically, levels are normalized by correcting the absolute level of a gene by comparing its expression to the expression of a gene that is not a relevant for determining the cancer stage of the subject, e.g., a housekeeping gene that is constitutively expressed. Suitable genes for normalization include housekeeping genes such as the actin gene ACTB, ribosomal 18S gene, GUSB, PGK1 and TFRC. This normalization allows the comparison of the level in one sample, e.g., a subject sample, to another sample, or between samples from different sources.

In some embodiments, the predetermined reference value is a threshold value or a cutoff value. Typically, a "threshold value" or "cut-off value" can be determined experimentally, empirically, or theoretically. A threshold value can also be arbitrarily selected based upon the existing experimental and/or clinical conditions, as would be recognized by a person of ordinary skilled in the art. For example, retrospective measurement of expression level of the gene in properly banked historical subject samples may be used in establishing the predetermined reference value. The threshold value has to be determined in order to obtain the optimal sensitivity and specificity according to the function of the test and the benefit/risk balance (clinical consequences of false positive and false negative). Typically, the optimal sensitivity and specificity (and so the threshold value) can be determined using a Receiver Operating Characteristic (ROC) curve based on experimental data. For example, after determining the expression level of the gene in a group of reference, one can use algorithmic analysis for the statistic treatment of the measured expression levels of the gene(s) in samples to be tested, and thus obtain a classification standard having significance for sample classification. The full name of ROC curve is receiver operator characteristic curve, which is also known as receiver operation characteristic curve. It is mainly used for clinical biochemical diagnostic tests. ROC curve is a comprehensive indicator that reflects the continuous variables of true positive rate (sensitivity) and false positive rate (1 -specificity). It reveals the relationship between sensitivity and specificity with the image composition method. A series of different cut-off values (thresholds or critical values, boundary values between normal and abnormal results of diagnostic test) are set as continuous variables to calculate a series of sensitivity and specificity values. Then sensitivity is used as the vertical coordinate and specificity is used as the horizontal coordinate to draw a curve. The higher the area under the curve (AUC), the higher the accuracy of diagnosis. On the ROC curve, the point closest to the far upper left of the coordinate diagram is a critical point having both high sensitivity and high specificity values. The AUC value of the ROC curve is between 1.0 and 0.5. When AUC>0.5, the diagnostic result gets better and better as AUC approaches 1. When AUC is between 0.5 and 0.7, the accuracy is low. When AUC is between 0.7 and 0.9, the accuracy is moderate. When AUC is higher than 0.9, the accuracy is quite high. This algorithmic method is preferably done with a computer. Existing software or systems in the art may be used for the drawing of the ROC curve, such as: MedCalc 9.2.0.1 medical statistical software, SPSS 9.0, ROCPOWER.SAS, DESIGNROC.FOR, MULTIREADER POWER.SAS, CREATE-ROC.SAS, GB STAT VIO.O (Dynamic Microsystems, Inc. Silver Spring, Md., USA), etc.

In some embodiments, the predetermined reference value is determined by carrying out a method comprising the steps of a) providing a collection of samples; b) providing, for each ample provided at step a), information relating to the actual clinical outcome for the corresponding subject (i.e. the duration of the survival); c) providing a serial of arbitrary quantification values; d) determining the expression level of the gene for each sample contained in the collection provided at step a); e) classifying said samples in two groups for one specific arbitrary quantification value provided at step c), respectively: (i) a first group comprising samples that exhibit a quantification value for level that is lower than the said arbitrary quantification value contained in the said serial of quantification values; (ii) a second group comprising samples that exhibit a quantification value for said level that is higher than the said arbitrary quantification value contained in the said serial of quantification values; whereby two groups of samples are obtained for the said specific quantification value, wherein the samples of each group are separately enumerated; f) calculating the statistical significance between (i) the quantification value obtained at step e) and (ii) the actual clinical outcome of the subjects from which samples contained in the first and second groups defined at step f) derive; g) reiterating steps f) and g) until every arbitrary quantification value provided at step d) is tested; h) setting the said predetermined reference value as consisting of the arbitrary quantification value for which the highest statistical significance (most significant) has been calculated at step g).

For example the expression level of the gene has been assessed for 100 samples of 100 subjects. The 100 samples are ranked according to the expression level of the gene. Sample 1 has the highest level and sample 100 has the lowest level. A first grouping provides two subsets: on one side sample Nr 1 and on the other side the 99 other samples. The next grouping provides on one side samples 1 and 2 and on the other side the 98 remaining samples etc., until the last grouping: on one side samples 1 to 99 and on the other side sample Nr 100. According to the information relating to the actual clinical outcome for the corresponding subject, Kaplan Meier curves are prepared for each of the 99 groups of two subsets. Also for each of the 99 groups, the p value between both subsets was calculated. The predetermined reference value is then selected such as the discrimination based on the criterion of the minimum p value is the strongest. In other terms, the expression level of the gene corresponding to the boundary between both subsets for which the p value is minimum is considered as the predetermined reference value.

It should be noted that the predetermined reference value is not necessarily the median value of expression levels of the gene. Thus in some embodiments, the predetermined reference value thus allows discrimination between a poor and a good prognosis for a subject. Practically, high statistical significance values (e.g. low P values) are generally obtained for a range of successive arbitrary quantification values, and not only for a single arbitrary quantification value. Thus, in one alternative embodiment of the invention, instead of using a definite predetermined reference value, a range of values is provided. Therefore, a minimal statistical significance value (minimal threshold of significance, e.g. maximal threshold P value) is arbitrarily set and a range of a plurality of arbitrary quantification values for which the statistical significance value calculated at step g) is higher (more significant, e.g. lower P value) are retained, so that a range of quantification values is provided. This range of quantification values includes a "cut-off value as described above. For example, according to this specific embodiment of a "cut-off value, the outcome can be determined by comparing the expression level of the gene with the range of values which are identified. In some embodiments, a cut-off value thus consists of a range of quantification values, e.g. centered on the quantification value for which the highest statistical significance value is found (e.g. generally the minimum p value which is found). For example, on a hypothetical scale of 1 to 10, if the ideal cut-off value (the value with the highest statistical significance) is 5, a suitable (exemplary) range may be from 4-6. For example, a subject may be assessed by comparing values obtained by measuring the expression level of the gene, where values higher than 5 reveal a poor prognosis and values less than 5 reveal a good prognosis. In some embodiments, a subject may be assessed by comparing values obtained by measuring the expression level of the gene and comparing the values on a scale, where values above the range of 4-6 indicate a poor prognosis and values below the range of 4-6 indicate a good prognosis, with values falling within the range of 4-6 indicating an intermediate occurrence (or prognosis).

The method of the present invention is also suitable for determining whether a patient is eligible or not to a treatment with an immune checkpoint inhibitor.

Accordingly, the second object of the present invention relates to a method of treating cancer in patient in need thereof comprising i) determining the expression level of SMPD3 in a tumor sample obtained from the patient ii) comparing the expression level determined at step i) with a predetermined reference value and iii) administering to the patient a therapeutically effective amount of an immune checkpoint inhibitor.

The present invention relates also to a method of treating cancer in a patient in need thereof comprising i) determining the survival time of said patient using the method of the invention ii) administering to the patient a therapeutically effective amount of an immune checkpoint inhibitor when it is concluded that that the patient will have short survival time.

As used herein, the term "treatment" or "treat" refer to both prophylactic or preventive treatment as well as curative or disease modifying treatment, including treatment of subjects at risk of contracting the disease or suspected to have contracted the disease as well as subjects who are ill or have been diagnosed as suffering from a disease or medical condition, and includes suppression of clinical relapse. The treatment may be administered to a subject having a medical disorder or who ultimately may acquire the disorder, in order to prevent, cure, delay the onset of, reduce the severity of, or ameliorate one or more symptoms of a disorder or recurring disorder, or in order to prolong the survival of a subject beyond that expected in the absence of such treatment. By "therapeutic regimen" is meant the pattern of treatment of an illness, e.g., the pattern of dosing used during therapy. A therapeutic regimen may include an induction regimen and a maintenance regimen. The phrase "induction regimen" or "induction period" refers to a therapeutic regimen (or the portion of a therapeutic regimen) that is used for the initial treatment of a disease. The general goal of an induction regimen is to provide a high level of drug to a subject during the initial period of a treatment regimen. An induction regimen may employ (in part or in whole) a "loading regimen", which may include administering a greater dose of the drug than a physician would employ during a maintenance regimen, administering a drug more frequently than a physician would administer the drug during a maintenance regimen, or both. The phrase "maintenance regimen" or "maintenance period" refers to a therapeutic regimen (or the portion of a therapeutic regimen) that is used for the maintenance of a subject during treatment of an illness, e.g., to keep the subject in remission for long periods of time (months or years). A maintenance regimen may employ continuous therapy (e.g., administering a drug at a regular intervals, e.g., weekly, monthly, yearly, etc.) or intermittent therapy (e.g., interrupted treatment, intermittent treatment, treatment at relapse, or treatment upon achievement of a particular predetermined criteria [e.g., disease manifestation, etc.]).

As used herein the term "immune checkpoint protein" has its general meaning in the art and refers to a molecule that is expressed by T cells in that either turn up a signal (stimulatory checkpoint molecules) or turn down a signal (inhibitory checkpoint molecules). Immune checkpoint molecules are recognized in the art to constitute immune checkpoint pathways similar to the CTLA-4 and PD-1 dependent pathways (see e.g. Pardoll, 2012. Nature Rev Cancer 12:252-264; Mellman et al. , 2011. Nature 480:480- 489). Examples of inhibitory checkpoint molecules include A2AR, B7-H3, B7-H4, BTLA, CTLA-4, CD277, IDO, KIR, PD-1, LAG-3, TIM-3 and VISTA. The Adenosine A2A receptor (A2AR) is regarded as an important checkpoint in cancer therapy because the tumor microenvironment has relatively high levels of adenosine, which lead to a negative immune feedback loop through the activation of A2AR. B7-H3, also called CD276, was originally understood to be a co-stimulatory molecule but is now regarded as co-inhibitory. B7-H4, also called VTCN1, is expressed by tumor cells and tumor-associated macrophages and plays a role in tumor escape. B and T Lymphocyte Attenuator (BTLA), also called CD272, is a ligand of HVEM (Herpesvirus Entry Mediator) . Cell surface expression of BTLA is gradually downregulated during differentiation of human CD8+ T cells from the naive to effector cell phenotype, however tumor-specific human CD8+ T cells express high levels of BTLA. CTLA-4, Cytotoxic T -Lymphocyte- Associated protein 4 and also called CD 152 is overexpressed on Treg cells serves to control T cell proliferation. IDO, Indoleamine 2,3-dioxygenase, is a tryptophan catabolic enzyme, a related immune-inhibitory enzymes. Another important molecule is TDO, tryptophan 2,3-dioxygenase. IDO is known to suppress T and NK cells, generate and activate Tregs and myeloid-derived suppressor cells, and promote tumor angiogenesis. KIR, Killer-cell Immunoglobulin- like Receptor, is a receptor for MHC Class I molecules on Natural Killer cells. LAG3, Lymphocyte Activation Gene-3, works to suppress an immune response by action to Tregs as well as direct effects on CD8+ T cells. PD-1, Programmed Death 1 (PD-1) receptor, has two ligands, PD-L1 and PD-L2. This checkpoint is the target of Merck & Co.'s melanoma drug Keytruda, which gained FDA approval in September 2014. An advantage of targeting PD-1 is that it can restore immune function in the tumor microenvironment. TIM-3, short for T-cell Immunoglobulin domain and Mucin domain 3, expresses on activated human CD4+ T cells and regulates Thl and Thl7 cytokines. TIM-3 acts as a negative regulator of Thl /Tel function by triggering cell death upon interaction with its ligand, galectin-9. VISTA. Short for V-domain Ig suppressor of T cell activation, VISTA is primarily expressed on hematopoietic cells so that consistent expression of VISTA on leukocytes within tumors may allow VISTA blockade to be effective across a broad range of solid tumors.

As used herein, the term "immune checkpoint inhibitor" has its general meaning in the art and refers to any compound inhibiting the function of an immune inhibitory checkpoint protein. Inhibition includes reduction of function and full blockade. Preferred immune checkpoint inhibitors are antibodies that specifically recognize immune checkpoint proteins. A number of immune checkpoint inhibitors are known and in analogy of these known immune checkpoint protein inhibitors, alternative immune checkpoint inhibitors may be developed in the (near) future. The immune checkpoint inhibitors include peptides, antibodies, nucleic acid molecules and small molecules. In particular, the immune checkpoint inhibitor of the present invention is administered for enhancing the proliferation, migration, persistence and/or cytoxic activity of CD8+ T cells in the subject and in particular the tumor- infiltrating of CD8+ T cells of the subject. As used herein "CD8+ T cells" has its general meaning in the art and refers to a subset of T cells, which express CD8 on their surface. They are MHC class I-restricted, and function as cytotoxic T cells. "CD8+ T cells" are also called called cytotoxic T lymphocytes (CTL), T-killer cells, cytolytic T cells, or killer T cells. CD8 antigens are members of the immunoglobulin supergene family and are associative recognition elements in major histocompatibility complex class I-restricted interactions. The ability of the immune checkpoint inhibitor to enhance T CD8 cell killing activity may be determined by any assay well known in the art. Typically said assay is an in vitro assay wherein CD8+ T cells are brought into contact with target cells (e.g. target cells that are recognized and/or lysed by CD8+ T cells). For example, the immune checkpoint inhibitor of the present invention can be selected for the ability to increase specific lysis by CD8+ T cells by more than about 20%, preferably with at least about 30%, at least about 40%, at least about 50%, or more of the specific lysis obtained at the same effector: target cell ratio with CD8+ T cells or CD8 T cell lines that are contacted by the immune checkpoint inhibitor of the present invention. Examples of protocols for classical cytotoxicity assays are conventional.

In some embodiments, the immune checkpoint inhibitor is an antibody selected from the group consisting of anti-CTLA4 antibodies, anti-PD-1 antibodies, anti-PD-Ll antibodies, anti-PD-L2 antibodies anti-TIM-3 antibodies, anti-LAG3 antibodies, anti-B7H3 antibodies, anti-B7H4 antibodies, anti-BTLA antibodies, and anti-B7H6 antibodies.

In some embodiments, the antibody is a humanized antibody. In some embodiments, the antibody is a fully human antibody.In some embodiments, the antibody comprises human heavy chain constant regions sequences but will not deplete CD8+ T cells to which they are bound and preferably do not comprise an Fc portion that induces antibody dependent cellular cytotoxicity (ADCC). In some embodiments, the antibody of the present invention does not comprise an Fc domain capable of substantially binding to a FcgRIIIA (CD 16) polypeptide. In some embodiments, the antibody of the present invention lacks an Fc domain (e.g. lacks a CH2 and/or CH3 domain) or comprises an Fc domain of IgG2 or IgG4 isotype. In some embodiments, the antibody of the present invention is not linked to a toxic moiety.

Examples of anti-CTLA-4 antibodies are described in US Patent Nos: 5,811,097; 5,811,097; 5,855,887; 6,051,227; 6,207,157; 6,682,736; 6,984,720; and 7,605,238. One anti- CTLA-4 antibody is tremelimumab, (ticilimumab, CP-675,206). In some embodiments, the anti-CTLA-4 antibody is ipilimumab (also known as 10D1, MDX-D010) a fully human monoclonal IgG antibody that binds to CTLA-4.

Examples of PD-1 and PD-L1 antibodies are described in US Patent Nos. 7,488,802; 7,943,743; 8,008,449; 8,168,757; 8,217,149, and PCT Published Patent Application Nos: WO03042402, WO2008156712, WO2010089411, WO2010036959, WO2011066342, WO2011159877, WO2011082400, and WO2011161699. In some embodiments, the PD-1 blockers include anti-PD-Ll antibodies. In certain other embodiments the PD-1 blockers include anti-PD-1 antibodies and similar binding proteins such as nivolumab (MDX 1106, BMS 936558, ONO 4538), a fully human IgG4 antibody that binds to and blocks the activation of PD-1 by its ligands PD-L1 and PD-L2; lambrolizumab (MK-3475 or SCH 900475), a humanized monoclonal IgG4 antibody against PD-1 ; CT-011 a humanized antibody that binds PD-1 ; AMP -224 is a fusion protein of B7-DC; an antibody Fc portion; BMS-936559 (MDX- 1105-01) for PD-L1 (B7-H1) blockade.

Other immune-checkpoint inhibitors include lymphocyte activation gene-3 (LAG-3) inhibitors, such as IMP321, a soluble Ig fusion protein (Brignone et al, 2007, J. Immunol. 179:4202-4211). Other immune-checkpoint inhibitors include B7 inhibitors, such as B7-H3 and B7-H4 inhibitors. In particular, the anti-B7-H3 antibody MGA271 (Loo et al, 2012, Clin. Cancer Res. July 15 (18) 3834). Also included are TIM3 (T-cell immunoglobulin domain and mucin domain 3) inhibitors (Fourcade et al., 2010, J. Exp. Med. 207:2175-86 and Sakuishi et al, 2010, J. Exp. Med. 207:2187-94). As used herein, the term "TIM-3" has its general meaning in the art and refers to T cell immunoglobulin and mucin domain-containing molecule 3. The natural ligand of TIM-3 is galectin 9 (Gal9). Accordingly, the term "TIM-3 inhibitor" as used herein refers to a compound, substance or composition that can inhibit the function of TIM-3. For example, the inhibitor can inhibit the expression or activity of TIM-3, modulate or block the TIM-3 signaling pathway and/or block the binding of TIM-3 to galectin-9. Antibodies having specificity for TIM-3 are well known in the art and typically those described in WO2011155607, WO2013006490 and WO2010117057.

In some embodiments, the immune checkpoint inhibitor is an IDO inhibitor. Examples of IDO inhibitors are described in WO 2014150677. Examples of IDO inhibitors include without limitation 1-methyl-tryptophan (IMT), β- (3-benzofuranyl)-alanine, β-(3- benzo(b)thienyl)-alanine), 6-nitro-tryptophan, 6- fluoro-tryptophan, 4-methyl-tryptophan, 5 - methyl tryptophan, 6-methyl-tryptophan, 5-methoxy-tryptophan, 5 -hydroxy-tryptophan, indole 3-carbinol, 3,3'- diindolylmethane, epigallocatechin gallate, 5-Br-4-Cl-indoxyl 1,3- diacetate, 9- vinylcarbazole, acemetacin, 5-bromo-tryptophan, 5-bromoindoxyl diacetate, 3- Amino-naphtoic acid, pyrrolidine dithiocarbamate, 4-phenylimidazole a brassinin derivative, a thiohydantoin derivative, a β-carboline derivative or a brassilexin derivative. Preferably the IDO inhibitor is selected from 1-methyl-tryptophan, β-(3- benzofuranyl)-alanine, 6-nitro-L- tryptophan, 3-Amino-naphtoic acid and β-[3- benzo(b)thienyl] -alanine or a derivative or prodrug thereof.

By a "therapeutically effective amount" is meant a sufficient amount of the immune checkpoint inhibitor for treating or reducing the symptoms at reasonable benefit/risk ratio applicable to any medical treatment. It will be understood that the total daily usage of the compounds and compositions of the present invention will be decided by the attending physician within the scope of sound medical judgment. The specific therapeutically effective dose level for any particular subject will depend upon a variety of factors including the disorder being treated and the severity of the disorder; activity of the specific compound employed; the specific composition employed, the age, body weight, general health, sex and diet of the subject; the time of administration, route of administration, and rate of excretion of the specific compound employed; the duration of the treatment; drugs used in combination with the active ingredients; and like factors well known in the medical arts. For example, it is well within the skill of the art to start doses of the compound at levels lower than those required to achieve the desired therapeutic effect and to gradually increase the dosage until the desired effect is achieved. However, the daily dosage of the products may be varied over a wide range from 0.01 to 1,000 mg per adult per day. Typically, the compositions contain 0.01, 0.05, 0.1, 0.5, 1.0, 2.5, 5.0, 10.0, 15.0, 25.0, 50.0, 100, 250 and 500 mg of the active ingredient for the symptomatic adjustment of the dosage to the subject to be treated. A medicament typically contains from about 0.01 mg to about 500 mg of the active ingredient, typically from 1 mg to about 100 mg of the active ingredient. An effective amount of the drug is ordinarily supplied at a dosage level from 0.0002 mg/kg to about 20 mg/kg of body weight per day, especially from about 0.001 mg/kg to 7 mg/kg of body weight per day.

Typically the immune checkpoint inhibitor is combined with pharmaceutically acceptable excipients, and optionally sustained-release matrices, such as biodegradable polymers, to form pharmaceutical compositions. The term "Pharmaceutically" or "pharmaceutically acceptable" refers to molecular entities and compositions that do not produce an adverse, allergic or other untoward reaction when administered to a mammal, especially a human, as appropriate. A pharmaceutically acceptable carrier or excipient refers to a non-toxic solid, semi-solid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type. The carrier can also be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol, and the like), suitable mixtures thereof, and vegetables oils. The proper fluidity can be maintained, for example, by the use of a coating, such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. The prevention of the action of microorganisms can be brought about by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the use in the compositions of agents delaying absorption, for example, aluminium monostearate and gelatin. In the pharmaceutical compositions of the present invention, the active ingredients of the invention can be administered in a unit administration form, as a mixture with conventional pharmaceutical supports. Suitable unit administration forms comprise oral-route forms such as tablets, gel capsules, powders, granules and oral suspensions or solutions, sublingual and buccal administration forms, aerosols, implants, subcutaneous, transdermal, topical, intraperitoneal, intramuscular, intravenous, subdermal, transdermal, intrathecal and intranasal administration forms and rectal administration forms.

The invention will be further illustrated by the following figures and examples. However, these examples and figures should not be interpreted in any way as limiting the scope of the present invention.

FIGURES:

Figure 1: Melanoma nSMase2 enhances CD8 T cell-dependent immune response.

A, Analysis of overall survival in metastatic melanoma patients from the TCGA melanoma cohort, exhibiting high (80th percentile) and low (20th percentile) SMPD3 expression in melanoma samples. B, Heatmap for a selected list of genes in samples with highest (SMPD3 ^hig ) and lowest (SMPD3 ^low ) SMPD3 expression. Genes were clustered using a Euclidean distant matrix and average linkage clustering. C, Correlation analyses of SMPD3 expression with the indicated genes. D-G, WT (D, F and G) and CD8 KO (E) mice were intradermally injected with B16K1 cells expressing high (nSMase2 ^hlgh ) (white bars) or low (nSMase2 ^low ) (black bars) levels of nSMase2. WT mice were sacrificed and tumor-infiltrating leukocytes were analysed by using flow cytometry (F). Ceramide levels were determined in tumors (G). Alternatively, tumor volume was determined at the indicated days in WT (D) or CD8 KO (E) mice. Data are means ± sem of minimum 6 determinations per group (*: p<0.05; ***: p<0.001).

Figure 2: Melanoma nSMase2 enhances the response to immunotherapies. A,

Upper panel, heatmap for a selected list of genes in human metastatic melanoma samples exhibiting highest {SMPD3 ^hi s ^h ) and lowest (SMPD3 ^low ) SMPD3 expression. Genes were clustered using a Euclidean distant matrix and average linkage clustering. Lower panel, correlation analysis of SMPD3 and PDCD1 expression. B-D, WT mice were intradermally injected with B16K1 expressing high (nSMase2 ^high ) or low (nSMase2 ^low ) levels of nSMase2 and 12 days later, tumors were collected, dissociated and the content of PD-1+CD8+ or PD- 1+CD4+ TILs was analysed by using flow cytometry (B). Alternatively, mice received intraperitoneal injection of anti-PD-1 (aPD-1, 200 μg) or vehicle (PBS) at days 6, 10 and 13 (n=10 tumors per group). Individual tumor curves are depicted. Inserts, numbers indicate the number of total regression out of total tumors (C). Overall survival was determined for each group (D) (*: p<0.05; **: p<0.01; ***: pO.001).

EXAMPLE:

Methods

SMPD3 expression and mutations in human melanoma: SMPD3 expression was analysed by using the TCGA melanoma cohort ³² . TCGA genomic and clinical data were downloading from UCSC cancer genome browser project (https://genomecancer.ucsc.edu). Analysis population consisted on 342 patients with distant metastasis for whom RNAseq and clinical data overlap. Gene expression was measured experimentally using the Illumina HiSeq 2000 RNA Sequencing platform and log2(x+l) transformed. The strength of relationship between genes was assessed using Spearman's rank correlation coefficient. Date of origin for computation of overall survival was date to specimen procurement. Survival rates were estimated using Kaplan-Meier method and comparison between groups (low expression vs high expression) was performed using log-rank test. SMPD3 mutation analysis in human melanoma was assessed on cBioportal (http://www.cbioportal.org/) ³³ ' ³⁴ and polyphen2 (http ://genetics .bwh.harvard.edu/pph2/) .

Cells: B16K1 is a genetically modified cell line obtained from B16F10 cells, which stably express the MHC-I molecule H-2Kb ^35~37 . Cells were cultured in DMEM medium containing 10% heat-inactivated fetal calf serum (FCS). For dendritic cell (DC) preparation, bone morrow derived cells were cultured in complete RPMI supplemented with 10% fetal bovine serum, penicillin, streptomycin, 50 μΜ β-mercaptoethanol and 20 ng/mL granulocyte macrophage colony-stimulating factor (GM-CSF) at 37°C with 5% CO2. Medium was changed every second-third day. After at least 7 days of culture, DC differentiation was analyzed by FACS. In some experiments, DCs were cultured during 24h with 10 μg/mL exosomes. In some experiments, DCs were transfected by using RNAi lipofectamin (Thermo Fisher Scientific) with or without a specific target site blocker (Exiqon), which is an antisense oligonucleotide that binds to the miR-155 target site on SOCS-1 mRNA. Three days after trans fection, DCs were cultured during 24h with or without 10 μg/mL exosomes.

Mice: Wild-type (WT) C57BL/6 mice were from Janvier laboratories. CD8-deficient C57BL/6 mice were a gift from Prof. J. van Meerwijk (INSERM U1043, Toulouse, France). Mice were housed in temperature-controlled rooms in the specific pathogen-free animal facility (Anexplo platform, Toulouse, France), kept on a 12-h light/dark cycle, and had unrestricted access to food and water. All animal studies were conducted according to national and international policies and were approved by the local committee for animal experimentation.

In vivo tumorigenesis: 3xl0 ⁵ B16K1 cells expressing WT V5-tagged nSMase2 at high or low levels were intra-dermally injected in WT and CD8 ^{~ ~} mice. Tumor volume was calculated using a caliper at the indicated days.

Immunotherapy protocol: 3xl0 ⁵ B16K1 cells were intra-dermally and bilaterally injected in WT mice (n=5 mice per condition). Mice received intraperitoneal injection of anti- PD-1 antibodies (BioXcell) (aPD-1, 10 mg/Kg) or anti-CTLA-4 antibodies (BioXcell) (aCTLA-4, 10 mg/Kg for the first injection and then 5 mg/Kg) or vehicle (PBS) at days 6, 10 and 13. Tumor volume was calculated using a 30caliper at the indicated days.

Analysis of lymphocyte content in tumors: One million B16K1 cells expressing or not WT V5-tagged nSMase2 at high or low levels were intra-dermally injected in WT mice. At day 12, mice were sacrificed and tumors were collected, weighted and digested with the Tumor Dissociation Kit, mouse (Miltenyi). Cells were stained with antibodies and live-dead reagents (Invitrogen) before flow cytometry analysis. Antibodies used in this study were anti- mouse CD45 (BD Biosciences, BUV395), anti-mouse Thyl (Biolegend, APC-Cy7), anti- mouse CD8 (BD Biosciences, BV605), anti-mouse CD4 (Biolegend, BUV496) and anti-PD-1 (eBioscience, FITC).

RNA isolation and qRT-PCR. For RNA isolation from tumors at 12 days post B16K1 cell injection, tumors were collected and dissociated by using the homogenizer (Precellys) at 6,500 rpm during 2 cycles of 30 s in vials containing ceramic balls and RNA was purified by using the RNeasy Midi Kit (Qiagen).

Sphingolipid analysis from tumors: Tumors were collected and disrupted by using

FastPREP technology (MP Biomedicals). Lipids were extracted from 5 mg of tumor samples. Sphingolipids were measured by mass spectrometry on a Thermo Finnigan TSQ 7000 triple quadrupole mass spectrometer operating in a multiple reaction monitoring positive ionization mode as described previously ³⁸ . Results from mass spectrometry analysis were normalized to total protein concentration as determined by using Bradford assay. (To be checked by Chris and Yusuf)

Statistical analyses: Results are expressed as means of at least three independent determinations per experiment. Mean values were compared using Student's t-test with Prism software (Graph-Pad). Differences were considered to be statistically significant when P<0.05 (*p<0.05; **p<0.01; ***p<0.001; n.s.: not significant).

Results

NSMase2 expression enhances CD8+ Tumor-Infiltrating Lymphocytes in melanoma.

Analysis from the Oncomine and TCGA databases indicated that mRNA encoding nSMase2 is expressed at low levels in human metastatic melanoma as compared to primary tumors, suggesting that nSMase2 downregulation is likely associated with melanoma progression. The clinical outcome in metastatic melanoma patients exhibiting high (80th percentile) and low (20th percentile) SMPD3 expression was next analysed. Low SMPD3 expression was statistically associated with shortened overall survival (Fig. 1A), further arguing that SMPD3 downregulation is associated with a bad prognosis in melanoma.

We next analysed the gene signatures in patients from the TCGA melanoma cohort exhibiting high and low SMPD3 expression in melanoma samples. Of great interest was the finding that high SMPD3 expression was mostly associated with the "Immune system process" and "Lymphocyte activation" according to Gene ontology classification. We next identified the genes that were differentially expressed in human melanoma exhibiting either high or low SMPD3 expression in melanoma samples from patients affected with metastatic melanoma (Fig. IB). High SMPD3 expression was associated with high expression of CD3G, CD3D and CD3E, which reflect tumor-infiltrating T lymphocytes (TIL). Among T cell genes, we found that CD8A, CD8B and CD4 were enriched in melanoma samples expressing SMPD3 at high levels. Moreover, various Thl -related genes such as IFNG, TNF, CXCL9, CXCL10 and CCL5 as well as cell-mediated cytotoxicity genes were highly expressed in melanoma samples exhibiting high SMPD3 expression (Fig. IB). Accordingly, SMPD3 expression was significantly correlated with the expression of diverse genes, which likely reflect CD8 T cell infiltration (Fig. 1C). This observation was not restricted to metastatic melanoma since similar correlations were found in triple negative breast cancers (Table 1). Of note, the expression level of genes encoding the other known sphingomyelinase isoforms was not associated with a gene signature of CD8+ TIL in metastatic melanoma patients, except SMPD2 the expression of which poorly, yet significantly, correlated with that of CD8B. As a matter of fact, SMPD4 was anti-correlated with T cell-related genes. Thus, SMPD3 expression is associated with a signature of CD8+ T cell tumor infiltration in human melanoma samples, and this cannot be extended to the other sphingomyelinase isoforms. We hypothesized that SMPD3 downregulation contributes to melanoma immune escape and nSMase2 expression level is critical for the CD8+ T cell-dependent immune response towards melanoma. To evaluate this tenet, we selected B16K1 (MHC-I ^hlgh ) mouse melanoma cell line, which express endogenous nSMase2 at low levels, due to HDAC- dependent epigenetic mechanism. We first generated B16K1 melanoma cell lines overexpressing or not nSMase2. Overexpressed enzyme was mainly located at the plasma membrane and led to robust increase in intracellular neutral sphingomyelinase activity and ceramide level without affecting two- and three-dimensional cell growth in vitro. We next analysed the immune response in mice grafted with B16K1 melanoma cells expressing nSMase2 at low or high levels. Twelve days after B16K1 cell injection, the tumor content of leukocytes (CD45+) and T lymphocytes (Thyl+) was significantly enhanced in tumors that expressed nSMase2 at high levels (Fig. IF). Among the T cells, the proportion of CD8+ TILs was 3-fold higher in tumors expressing nSMase2 at high levels (Fig. IF).

Interestingly, nSMase2 overexpression as evaluated by western blot triggered an intra- tumor increase (i) in the nSMase activity, C16 and C24-ceramides (Fig. 1G) and sphingosine and (ii) a reduction of B16K1 tumor growth in WT mice (Fig. ID). Of note, no significant changes were noticed for tumor sphingomyelin and SIP content in nSMase2 overexpressing tumors. A similar trend was observed in B16F10 melanoma cells in which nSMase2 overexpression significantly reduced tumorigenesis in WT mice without affecting their proliferation rate in vitro. Importantly, nSMase2 overexpression failed to impair B16K1 melanoma growth in CD8-deficient mice (Fig. IE).

Collectively, our data indicate that (i) SMPD3 expression is associated with CD8+ T cell gene signature in human metastatic melanoma samples, which may translate into improved overall survival, (ii) nSMase2 overexpression in mouse melanoma enhances CD8+ T cell-dependent immunity, which impairs tumor growth.

The nSMase2 enzyme activity is required for enhancing T cell-dependent anti- melanoma immune response.

Analysis of the SMPD3 nucleotide sequence from 5 independent studies indicated mutations in the coding sequence, ranging from 2.5% to 20% mutation frequency depending on the study. The highest mutation frequency was observed in desmoplastic melanoma, whereas the lowest being in uveal melanoma. Most of the mutations were missense mutations and half of them affected residues in the catalytic domain. Moreover, twelve mutations are predicted to be probably damaging (HumDiv score>0.85) according to PolyPhen-2 analysis. We next evaluated whether a single missense mutation (D428A) into the catalytic domain, which abolished enzyme activity ³⁹ , had a putative impact on nSMase2 biological activity in CD8+ T cell-dependent immune response and melanoma growth in mice. B16K1 cells were transduced with a retroviral vector encoding either WT or catalytically-inactive nSMase2. This approach induced a mild expression of both WT and catalytically-inactive nSMase2, leading to significant increase of nSMase activity in WT nSMase2 expressing cells without affecting cell proliferation capacity in vitro nor subcellular localisation. The in vivo tumor growth of WT nSMase2 expressing cells was reduced (by more than 50%) as compared to mock-transduced B16K1 cells or catalytically-inactive nSMase2 expressing cells in syngeneic mice.

The immune response was next analyzed at day 12 post-melanoma B16K1 cell injection. T cells (Thyl+) as well as dendritic cells (DC) (CD1 lc+) were increased in draining lymph nodes and tumors upon WT nSMase2 expression. Of note, whereas the content of Tregs was increased in lymph nodes, the Treg tumor infiltration was slightly, yet not significantly, enhanced by WT nSMase2 expression. WT nSMase2 overexpression significantly increased CD45+ leukocytes, CD4+ and CD8+ T cells, and DC content in both lymph nodes and tumors and reduced the tumor weight. We next evaluated the tumor content of CD8+ T cells specific for tyrosinase-related protein 2 (TRP2), a differentiation antigen of melanocytic cells. By using MHC-I dextramer technology, we show that TRP2-specific CD8+ T cell content was higher in tumors expressing WT nSMase2. Of note, the levels of mR A encoding CXCL9 and IFNy, two major Thl -related cytokines, were significantly increased upon WT nSMase2 expression in melanoma tumors but not in B16K1 cell culture.

Altogether, our data indicate that nSMase2 catalytic activity is required for enhancing T cell-dependent immune response towards melanoma cells.

nSMase2 expression in melanoma synergises with immune checkpoint inhibitors.

In human melanoma samples, high SMPD3 levels were associated with an increased expression of immunosuppressive genes, such as PDCD1, which encodes the immune checkpoint PD-1 (Fig. 2A). Similar findings were observed in triple negative breast cancers (Table 2). In good agreement with this finding, we observed in mouse melanoma an increased proportion of CD8+ TILs and, albeit to a lesser extent, CD4+ TILs expressing PD-1 in B16K1 tumors expressing WT nSMase2 (Fig. 2B). We next evaluated the therapeutic activity of anti- PD-1 towards melanoma cells expressing nSMase2 at low and high levels. Whereas anti-PD-1 significantly delayed nSMase2 ^low melanoma growth (Fig. 2C), all tumors relapsed presumably due to immune escape mechanisms and, consequently, all mice died within 40 days post- B16K1 injection (Fig. 2D). Moreover, nSMase2 overexpression delayed melanoma growth and slightly, yet significantly, increased the overall survival (Figs. 2C and 2D). Of a major interest, the therapeutic efficacy of anti-PD-1 was dramatically enhanced by nSMase2 overexpression (Fig. 2C). In the group of mice injected with B16K1 nSMase2 ^hlgh and anti-PD- 1, all mice survived (Fig. 2D) and none of them developed melanoma upon a second B16K1 cell injection, indicating that they were fully vaccinated against melanoma cells. Our observation was unlikely restricted to anti-PD-1 since WT nSMase2 expression greatly enhanced the therapeutic effect of anti-CTLA-4 blocking antibodies against melanoma.

Altogether, our data indicate that expression of WT nSMase2 in B16K1 melanoma synergizes with immune checkpoint blockade therapies in mice.

Discussion:

The present study provides the first evidence that (i) SMPD3 is expressed at low levels in most human metastatic melanoma samples and (ii) low SMPD3 expression is associated with shortened overall survival in patients. Noteworthy, high SMPD3 expression was associated with "Immune system process" and "Lymphocyte activation". Accordingly, melanoma samples expressing SMPD3 at high levels exhibited gene signature of TIL, including genes encoding cytotoxic CD8 T cell markers such as CD8A/B, GZMA/B and GNLY. As a matter of fact, the expression of genes (SMPD1, SMPD2, SMPD4) encoding the other sphingomyelinase isoforms did not correlate with TCR signaling pathway. Thus, the distinctive biological properties of nSMase2 in melanoma do not extend to the other sphingomyelinases, presumably due to different subcellular localisation and/or biochemical properties as well as different role in cell signaling ² . One should note, however, that enforced expression of acid SMase, encoded by Smpdl in B16F1 melanoma, is associated with an augmentation of CD8+ TIL ¹⁵ . The lack of correlation between SMPD1 expression and immune -related gene signature in human metastatic melanoma samples indicates that acid SMase is unlikely a critical modulator of CD8+ T cell-dependent immune response in melanoma patients.

In good agreement with data from human melanoma, nSMase2 heightens the CD8+ T cell dependent immune response, thereby slowing down melanoma growth in mice. Strikingly, nSMase2 overexpression in mouse melanoma cell lines enhanced CD8+ TIL content and impaired melanoma growth in WT animals (i.e., immuno-competent) but not in mice lacking CD8+ T cells (i.e., CD8-deficient mice), demonstrating that nSMase2 anti- tumorigenic properties are fully dependent on its ability to stimulate adaptive immunity. Collectively, our data reveal that SMPD3 downregulation or mutation likely contributes to melanoma immune escape, facilitating melanoma progression.

The mechanisms by which nSMase2 facilitates the CD8 T cell-dependent immune response most likely rely on the alteration of intratumor SL content since expression of a catalytically inactive nSMase2 mutant had no effect on B16K1 tumor growth. Accordingly, intra-tumor ceramide and sphingosine content was significantly increased in nSMase2- overexpressing melanoma tumors. Taking into account that sphingosine facilitates the secretion of RANTES/CCL5 ^44,45 , which is a potent chemoattractant towards CD8+ T cells, the possibility that the nSMase 2-induced sphingosine increase is involved in CD8+ T cell infiltration cannot be ruled out. In addition, sphingosine is the substrate of sphingosine kinases, which produce SIP, a critical mediator of lymphocyte traffic ⁴⁶ . One should note however that the levels of intratumor SIP remained unchanged upon nSMase2 overexpression. Hence, it is unlikely that SIP directly mediates the nSMase2 -triggered increase of CD8+ TIL content. Another interesting hypothesis is that ceramide, which exhibits some analogy with Lipid A, the biologically active core of lipopolysaccharide ⁴⁷ , may mimic pathogen-associated molecular patterns, facilitating DC maturation and ultimately priming of adaptive immune response.

SMPD3 expression in patients was also associated with the expression of genes encoding immune checkpoints such as PD-1, presumably leading to melanoma immune escape. Accordingly, we observed an increased proportion of CD4+PD-1+ and CD8+PD-1+ TILs in mouse melanoma tumors, which overexpressed nSMase2. Consequently, whereas nSMase2 overexpression in mouse melanoma significantly delayed melanoma growth, all mice died within 40 days post-melanoma cell injection, which strongly suggests melanoma immune escape. In addition, whereas immune checkpoint inhibitors had limited therapeutic effects towards B16K1 melanoma, both anti-PD-1 and anti-CTLA4 greatly suppressed tumor growth of WT nSMase2 expressing melanoma. These observations demonstrate that melanoma nSMase2 enhances the therapeutic response to emerging immunotherapies.

It is tempting to speculate that targeting SL metabolism in melanoma tumors may constitute an original therapeutic strategy to overcome resistance of melanoma, and possibly other cancer types, to emerging immunotherapies. In addition, SMPD3 expression in melanoma samples may serve as a novel biomarker to predict survival and response to immunotherapy.

TABLES: Table 1: correlation between SMPD3 and various genes of immunoactivation in human TNBC (*p<0.05; **p<0.01; ***p<0.001):

Table 2: correlation between SMPD3 and various genes of immune escape in human TNBC (*p<0.05; **p<0.01; ***p<0.001):

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