CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of application No 12/673528, which is the national stage of PCT Application No PCT/CA2008/001441 filed August 8, 2008, which claims priority to US provisional application No 60/935505 filed August 16, 2007. The entire content of these applications is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a method for diagnosis and prognosis of cancer and for monitoring the progression of cancer and/or the therapeutic efficacy of an anti-cancer treatment in a sample of a subject by detecting oncogenic proteins and/or molecular mediators of their transforming activity in microvesicles. BACKGROUND OF THE INVENTION

The transformation of a normal cell into a malignant cell results, among other things, in the uncontrolled proliferation of the progeny cells, which exhibit immature, undifferentiated morphology, exaggerated survival and proangiogenic properties and expression, overexpression or constitutive activation of oncogenes not normally expressed in this form by normal, mature cells.

Oncogenic mutations and resultant intrinsic perturbations in cellular signaling are viewed as causal events in cancer development. For example, aggressive growth of human brain tumors (gliomas) is often associated with over- expression and amplification of the epidermal growth factor receptor (EGFR) and its ligand-independent, truncated mutant known as EGFRvlll (Cavenee, 2002, Carcinogenesis, 23: 683-686). The persistent activation of this oncogenic receptor triggers abnormal activation of transforming signalling pathways, regulatory mechanisms and ultimately in expression of genes involved in cell proliferation, survival and angiogenesis.

Many genetic mutations are known which result in the activation of oncogenes and thereby increase the chance that a normal cell will develop into a tumor cell. In addition, inactivation of tumor suppressor genes, which function normally to counteract oncogenes by repairing DNA damage, or by inducing apoptosis of damaged cells, and keeping cellular activities under control, can also lead to cancer. There is much evidence to support the notion that activation of oncogenes or inactivation of tumor suppressors can lead to cancer (Hanahan & Weinberg, 2000, Cell, 100: 57-70). Mutations of proto-oncogenes in somatic cells are increasingly recognized as significant in the initiation of human cancers. Some examples of oncogenes formed by such mutations include: neu, fes, fos, myc, myb, fms, Ha-ras, and Ki-ras. Much needs to be learned in order to understand how oncogenes and their expression products function to transform normal cells into cancer cells.

Growth factors and their receptors are involved in the regulation of cell proliferation and they also appear to play a key role in oncogenesis. For example, the following three proto-oncogenes are related to a growth factor or a growth factor receptor: 1) c-sis, which is homologous to the transforming gene of the simian sarcoma virus and is the B chain of platelet-derived growth factor (PDGF); 2) c-fms, which is homologous to the transforming gene of the feline sarcoma virus and is closely related to the macrophage colony-stimulating factor receptor (CSF-1 R); and 3) c-erbB, which encodes the epidermal growth factor receptor (EGFR) and is homologous to the transforming gene of the avian erythroblastosis virus (v-erbB). The two receptor-related proto- oncogenes, c-fms and c-erbB, are members of the tyrosine-specific protein kinase family to which many proto-oncogenes belong.

In addition, aggressive growth of human brain tumors (gliomas) is often associated with over-expression and amplification of EGFR and its ligand- independent, truncated mutant known as EGFRvlll. The persistent activation of this oncogenic receptor triggers abnormal expression of genes involved in cell proliferation, survival and angiogenesis.

Several groups have investigated the expression of EGFR in a variety of tumors using quantitative as well as semi-quantitative immunohistochemical methods. The types of tumors investigated include gynecological, bladder, head and neck, lung, colorectal, pancreatic and breast carcinomas. Such studies almost exclusively rely upon radioligand binding methodology or immunorecognition for quantifying EGFR in tissue samples.

The most extensive correlations of EGFR expression with clinical data have been carried out in studies with breast cancer patients dating back several decades (e.g. Nicholson et a/., 1988, Int. J. Cancer, 42: 36-41). In several studies with up to 246 patients, it was demonstrated that EGFR is a highly significant marker of poor prognosis for breast cancer. It is considered to be one of the most important variables in predicting relapse-free and overall survival in lymph node-negative patients, and to be the second most important variable, after nodal status, in lymph node-positive patients. In general, EGFR positive tumors are larger and occur in a higher proportion of patients with lymph node involvement. The prognostic significance of EGFR/ErbB1/HER-1 is enhanced by a simultaneous detection of its related and interacting oncogenic receptor tyrosine kinase known as ErbB2/HER-2/neu, a target of herceptin (Citri & Yarden, 2006, Nature Rev. Mol. Cell. Biol., 7: 505-516).

Mutated oncogenes are therefore markers of malignant or premalignant conditions. It is also known that other, non-oncogenic portions of the genome may be altered in the neoplastic state. There is widespread recognition of the importance of tests for early detection of cancer. In some cases, abnormal or malignant cells exfoliated from the surface of an organ can be identified by cytologic examination of brushings and fluids. For example, a PAP smear (Papanicolaou test) may detect abnormal (e.g., pre-cancerous or cancerous) cells of the cervix. Alternatively, genetic abnormalities in cancer cells or pre- cancer cells may be detected using molecular techniques. For example, techniques such as DNA sequence or methylation analysis may be used to detect specific mutations and/or structural as well as epigenetic alterations in DNA.

Nucleic acid based assays can detect both oncogenic and non-oncogenic DNA, whether mutated or non-mutated, provided that cancer cells or their related cellular debris are directly available for analysis (e.g. in surgical or biopsy material, lavage, stool, or circulating cancer cells). In particular, nucleic acid amplification methods (for example, by polymerase chain reaction) allow the detection of small numbers of mutant molecules among a background of normal ones. While alternate means of detecting small numbers of tumor cells (such as flow cytometry) have generally been limited to hematological malignancies, nucleic acid amplification assays have proven both sensitive and specific in identifying malignant cells and for predicting prognosis following chemotherapy (Fey ef a/., 1991 , Eur. J. Cancer 27: 89-94).

Various nucleic acid amplification strategies for detecting small numbers of mutant molecules in solid tumor tissue have been developed, particularly for the ras oncogene (Chen and Viola, 1991 , Anal. Biochem. 195: 51-56). For example, one sensitive and specific method identifies mutant ras oncogene DNA on the basis of failure to cleave a restriction site at the crucial 12th codon (Kahn et a/., 1991 , Oncogene, 6: 1079-1083). Similar protocols can be applied to detect any mutated region of DNA in a neoplasm, allowing detection of other oncogene-containing DNA or tumor-associated DNA.

Many studies use nucleic acid amplification assays to analyze the peripheral blood of patients with cancer in order to detect intracellular DNA extracted from circulating cancer cells, including one study which detected the intracellular ras oncogene from circulating pancreatic cancer cells (Tada et at., 1993, Cancer Res. 53: 2472-4). The assay is performed on the cellular fraction of the blood, i.e. the cell pellet or cells within whole blood, and the serum or plasma fraction is ignored or discarded prior to analysis. Since such an approach requires the presence of metastatic circulating cancer cells (for non-hematologic tumors), it is of limited clinical use in patients with early cancers, and it is not useful in the detection of non-invasive neoplasms or pre-malignant states. It has not been generally recognized that nucleic acid amplification assays can detect tumor-associated extracellular mutated DNA, including oncogene DNA, in the plasma or serum fraction of blood. Furthermore, it has not been recognized that this can be accomplished in a clinically useful manner, i.e. rapidly within one day, or within less than 8 hours.

Detection of a mutant oncogene by nucleic acid amplification assay, in peripheral blood plasma or serum, has been the subject of reports in the prior art. However, this method requires time-consuming and technically demanding approaches to DNA extraction and are thus of limited clinical utility. Tests for proteins expressed by certain cancers may be performed. For example, screening for prostate-specific antigen (PSA) may be used to identify patients at risk for, or having prostate cancer. Still, PSA screening may suffer from variability of assay methods and a lack of specificity. For example, although malignant prostate cells make higher amounts of PSA, PSA is not specific to cancer cells but is made by both normal and cancerous prostate cells. PSA levels may vary depending upon the age of the patient, the physiology of the prostate, the grade of the cancer, and the sensitivity of PSA levels to pharmacologic agents. Also, the molecular basis for many cancers is as yet unknown, and therefore, molecular tests are not yet comprehensive enough to detect most cancers.

Thus, detection of many cancers still relies on detection of an abnormal mass in the organ of interest. In many cases, a tumor is often detected only after a malignancy is advanced and may have metastasized to other organs. For example, breast cancer is typically detected by obtaining a biopsy from a lump detected by a mammogram or by physical examination of the breast. Also, although measurement of prostate-specific antigen (PSA) has significantly improved the detection of prostate cancer, confirmation of prostate cancer typically requires detection of an abnormal morphology or texture of the prostate. Thus, there is a need for methods and devices for earlier detection of cancer. Such new methods could, for example, replace or complement the existing ones, reducing the margins of uncertainty and expanding the basis for medical decision making.

As indicated above, several methods have been used to detect EGFR levels in tumor tissues. There are, however, many cases in which tissue is not readily available or in which it is not desirable or not possible to withdraw biopsy tissue from tumors. Therefore, there is a need in the medical art for rapid, accurate and reliable diagnostic tests that are also convenient and non-traumatic to patients.

Thus, it would be highly desirable to be provided with a method that permits medically useful, rapid, and sensitive detection of mutated oncogenes, in conjunction with molecular transducers, modulators and effectors of their activity, associated with cancer.

SUMMARY OF THE INVENTION

The present invention relates to a method for diagnosing or determining prognosis, or therapeutic prediction of a cancer in a subject, comprising the steps of collecting a sample from the subject, isolating microvesicles from the sample and detecting the presence of an oncogenic protein, a tumor-related protein and/or an MV-associated protein in the microvesicles, wherein the presence of the oncogenic protein, the tumor-related protein and/or the MV- associated protein in the sample is indicative that the subject may have cancer.

There is also provided in accordance with the present invention a method of detecting the presence of an oncogenic protein, a tumor-related protein, and/or an MV-associated protein in a subject, comprising collecting a sample from the subject, isolating microvesicles from the sample, and detecting the presence of the oncogenic protein, the tumor-related protein, and/or the MV-associated protein in the microvesicles.

Furthermore, the method disclosed herein can further comprise the step of measuring the phosphorylation, or other post-translational modification state of the oncogenic protein, the tumor-related protein (e.g., an oncogenic signal- transducing, or oncogenic effect-mediating protein), and/or the MV-associated protein.

In accordance with the present invention, there is also disclosed a kit for detecting a cancer in a sample from a subject comprising at least one antibody against an oncogenic protein, a tumor-related protein and/or an MV-associated protein, and instructions for using said at least one antibody to detect the oncogenic protein, the tumor-related protein, and/or the MV-associated protein in microvesicles in the sample.

In accordance with the present invention, there is also provided a use of at least one antibody for diagnosing or determining prognosis of a cancer in a sample of a subject, wherein said at least one antibody binds to an oncogenic protein, a tumor-related protein, and/or an MV-associated protein present in microvesicles.

In a particular embodiment, the at least one antibody is a phosphospecific antibody.

There is also disclosed herein a use of an agent blocking exchange of microvesicles for treating cancer. In a particular embodiment, the agent is annexin V or a derivative thereof or an agent blocking P-selectin or its ligand PSGL, or other similar agents blocking receptors for molecules involved in the uptake of cancer-related MVs by target cells.

In accordance with the present invention, there is also provjded a method for monitoring progression of a cancer in a subject, comprising the steps of collecting a first sample from a subject having cancer at a first timepoint, isolating microvesicles from the first sample, and measuring an oncogenic protein, a tumor-related protein, and/or an MV-associated protein in the microvesicles obtained from the first sample; and collecting a second sample from the subject having cancer at a second timepoint, the second timepoint occurring after the first timepoint, isolating microvesicles from the second sample, and measuring the oncogenic protein, the tumor-related protein, and/or the MV-associated protein in the microvesicles obtained from the second sample, wherein a change in the amount of the oncogenic protein, the tumor- related protein, and/or the MV-associated protein in the microvesicles obtained from the second sample compared to the amount of the oncogenic protein, the tumor-related protein, and/or the MV-associated protein in the microvesicles obtained from the first sample is indicative of progression of the cancer.

It is also encompassed that the first timepoint may occur before the subject has received the anti-cancer treatment, and the second timepoint may occur after the subject has received the anti-cancer treatment. In another embodiment, both timepoints may occur after the subject has received the anti-cancer treatment. In an embodiment, the anti-cancer treatment is surgical resection or removal of the tumour.

In another embodiment, a reduction or no change in the amount of the oncogenic protein, the tumor-related protein and/or the MV-associated protein in the microvesicles obtained from the second sample compared to the amount of the oncogenic protein, the tumor-related protein, and/or the MV-associated protein in the microvesicles obtained from the first sample indicates therapeutic efficacy of the anti-cancer treatment.

In accordance with the present invention, there is also provided a method for monitoring therapeutic efficacy of an anti-cancer treatment, comprising the steps of collecting a first sample from a subject having cancer at a first timepoint, isolating microvesicles from the first sample, and measuring an oncogenic protein, a tumor-related protein, and/or an MV-associated protein in the microvesicles obtained from the first sample; and co!lecting a second sample from the subject having cancer at a second timepoint, the second timepoint occurring after the first timepoint, isolating microvesicles from the second sample, and measuring the oncogenic protein, the tumor-related protein and/or the MV-associated protein in the microvesicles obtained from the second sample; wherein a reduction or no change in the amount of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the second sample compared to the amount of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the first sample indicates therapeutic efficacy of the anti-cancer treatment. In other embodiments, a change in the composition of the MVs is indicative of therapeutic efficacy.

In one embodiment, the first timepoint occurs before the subject has received the anti-cancer treatment, and the second timepoint occurs after the subject has received the anti-cancer treatment. Alternatively, the first and second timepoints may both occur after the subject has received the anti-cancer treatment. In yet another embodiment, the first and second timepoints may both occur in the absence of anti-cancer treatment, or before the subject receives anti-cancer treatment, and the amount of the oncogenic, tumor-related and/or MV-associated protein in microvesicles obtained from the second sample compared to that in the first sample would provide an indication of the progression or aggressiveness of the cancer.

In another embodiment, at least two oncogenic, tumor-related and/or MV- associated proteins are detected in the microvesicles. More specifically, the oncogenic or MV-associated proteins can be EGFR and HER-2, or HER-2 and HER-3, or HER-2 and EGFR2, or EGFRvlll and HER-2. In another embodiment, the MV-associated proteins may be EGFR, FGFR3, EphB2, ROR1 , EphA2, and EphA4, alone or in combination. In another embodiment, the microvesicles are isolated by ultracentrifugation, immunoprecipitation, affinity chromatography, gel filtration, affinity purification, microfiltration, or combinations thereof, or other similar methods of which many are known in the art.

Furthermore, the presence of the oncogenic, tumor-related or MV-associated protein in the microvesicles can be detected or measured by immunoblot, immunoprecipitation, ELISA, RIA, flow cytometry, electron microscopy, antibody array platforms, antibody-based multiplexing platforms or mass spectrometry.

The methods as described herein can further comprise the step of measuring the phosphorylation state of the oncogenic, tumor-related or MV-associated protein in the microvesicles obtained from the first and second sample. In another embodiment, a reduction or no change in phosphorylation of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the second sample compared to the amount of phosphorylation of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the first sample indicates therapeutic efficacy of the anti-cancer treatment.

Alternatively, an increase in phosphorylation of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the second sample compared to the amount of phosphorylation of the oncogenic, tumor- related and/or MV-associated protein in the microvesicles obtained from the first sample indicates that the cancer has progressed or continued to proliferate.

Furthermore, a reduction in phosphorylation of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the second sample compared to the amount of phosphorylation of the oncogenic, tumor- related and/or MV-associated protein in the microvesicles obtained from the first sample indicates that the cancer has regressed or ceased the phase of active growth (stabilized).

Further, no change in phosphorylation of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the second sample compared to the amount of phosphorylation of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the first sample indicates that the cancer has not progressed.

In other embodiments, a change in the protein composition or the proteome of the MVs is used for detection, diagnosis, prognosis, monitoring, etc. of a tumour.

In accordance with the present invention, there is also provided an isolated microvesicle comprising an oncogenic, tumor-related or MV-associated protein.

In a particular embodiment, the anti-cancer treatment is surgery, radiology, chemotherapy, or a targeted cancer treatment. More specifically, the targeted cancer treatment is selected from the group consisting of small molecules, monoclonal antibodies, cancer vaccines, antisense, siRNA, aptamers, gene therapy and combinations thereof.

In another embodiment, the encompassed cancer is selected from the group consisting of breast cancer, glioma, large intestinal cancer, lung cancer, small cell lung cancer, stomach cancer, liver cancer, blood cancer, bone cancer, pancreatic cancer, skin cancer, head or neck cancer, cutaneous or intraocular melanoma, uterine sarcoma, ovarian cancer, rectal or colorectal cancer, anal cancer, colon cancer, gastrointestinal stromal tumors (GIST), fallopian tube carcinoma, endometrial carcinoma, cervical cancer, vulval cancer, squamous cell carcinoma, vaginal carcinoma, Hodgkin's disease, non-Hodgkin's lymphoma, esophageal cancer, small intestine cancer, endocrine cancer, thyroid cancer, parathyroid cancer, adrenal cancer, soft tissue tumor, urethral cancer, penile cancer, prostate cancer, chronic or acute leukemia, lymphocytic lymphoma, bladder cancer, kidney cancer, ureter cancer, renal cell carcinoma, renal pelvic carcinoma, CNS tumor, astrocytoma, glioblastoma multiforme, oligodendroglioma, primary CNS lymphoma, bone marrow tumor, brain stem nerve gliomas, pituitary adenoma, uveal melanoma, testicular cancer, oral cancer, pharyngeal cancer, pediatric neoplasms, leukemia, neuroblastoma, retinoblastoma, pediatric glioma, medulloblastoma, Wilms tumor, osteosarcoma, teratoma, rhabdomyoblastoma and sarcoma.

In yet another embodiment, the oncogenic or MV-associated protein is selected from the group consisting of EGFRvlll, EGFR, HER-2, HER-3, HER-4, MET, cKit, PDGFR, Wnt, beta-catenin, K-ras, H-ras, N-ras, Raf, N-myc, c-myc, IGFR, PI3K, Akt, BRCA1 , BRCA2, PTEN, and receptors of cells associated with cancer (cancer-related receptors) such as VEGFR-2, VEGFR-1 , Tie-2, TEM-1 and CD276.

In an embodiment, more than one oncogenic, tumor-related and/or MV- associated protein, or a combination of oncogenic, tumor-related and/or MV- associated proteins, are detected in the microvesicles and/or used in the methods of the invention. In another embodiment, the phosphorylation state of the oncogenic, tumor-related and/or MV-associated protein or proteins in the microvesicles is determined and/or used in the methods of the invention. In yet another embodiment, the combination of oncogenic, tumor-related and/or MV- associated proteins detected in the microvesicles is diagnostic of the cancer type. Determining the combination of oncogenic or tumor-related proteins present in the microvesicles may be used for diagnosis and/or prognosis.

In an embodiment, the MV-associated protein is attached to the membrane, e.g. an integral membrane protein or membrane-bound. In an alternative embodiment, the MV-associated protein is a soluble protein present in the lumen of the microvesicle. In addition, the sample is a bodily fluid, or more specifically, a body fluid selected from the group consisting of blood, urine, lymph, cerebrospinal fluid, ascites, saliva, lavage, semen, glandular secretions, exudate, contents of cysts and feces.

In an aspect, there are provided herein methods for monitoring progression of a cancer or therapeutic efficacy of an anti-cancer treatment in a subject, comprising collecting a first blood sample from a subject having cancer at a first timepoint, isolating microvesicles from the first blood sample, and measuring the phosphorylation state of an oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the first blood sample; collecting a second blood sample from the subject having cancer at a second timepoint, the second timepoint occurring after the first timepoint, isolating microvesicles from the second blood sample, and measuring the phosphorylation state of the oncogenic, tumor-related and/or MV-associated protein in the microvesicles obtained from the second blood sample; wherein a change in the phosphorylation state of the oncogenic, tumor-related and/or MV-associated protein, or in the amount of the oncogenic, tumor-related and/or MV-associated protein which is phosphorylated or unphosphorylated, in the microvesicles obtained from the second blood sample compared to the microvesicles obtained from the first blood sample is indicative of progression or regression of the cancer, or indicates therapeutic efficacy or ineffectiveness of the anti-cancer treatment when the first timepoint occurs before the subject has received an anti-cancer treatment, and the second timepoint occurs after the subject has received the anti-cancer treatment; and wherein regression of the cancer or therapeutic efficacy of the anti-cancer treatment is indicated by an increase in the non-active form of the oncogenic, tumor-related and/or MV-associated protein, and progression of the cancer or ineffectiveness of the anti-cancer treatment is indicated by an increase in the activated form of the oncogenic, tumor-related and/or MV-associated protein, as determined by the phosphorylation state or the amount of phosphorylated protein detected in the MVs. In one aspect, the oncogenic or MV-associated protein may be a receptor tyrosine kinase, or another protein related to malignancy, such as an oncogene, a tumour suppressor, or a mediator of cellular signaling, or one of the MV-associated phosphoproteins described herein. A combination of oncogenic, tumor-related and/or MV-associated proteins may also be used in the methods provided herein. There are further provided methods for monitoring the activation of an oncogenic receptor tyrosine kinase in a tumour, comprising collecting a blood sample from a subject having the tumour, isolating microvesicles from the blood sample, and measuring the phosphorylation state of the oncogenic receptor tyrosine kinase in the microvesicles, wherein the phosphorylation state of the oncogenic receptor tyrosine kinase indicates activation or non-activation of the receptor tyrosine kinase.

In a particular embodiment, the type of cancer is breast cancer, glioma, brain cancer, lung cancer, pancreatic cancer, skin cancer, prostate cancer and colorectal cancer. It should be understood that the methods and kits provided herein are not limited to oncogenic proteins, but encompass the MV-associated proteins (e.g., tumor-related proteins) identified herein, in addition to other cancer-related proteins or known proteins related to malignancy such as oncogenes, tumour suppressors, or mediators of cellular signaling, and any other proteins detected in microvesicles which may be found to be tumour-related. As used herein, the term "MV-associated protein" refers to any cancer-associated protein which is detected in a microvesicle derived from a tumour and is useful for the detection, diagnosis, prognosis, monitoring, etc. of the tumour, in accordance with the methods provided herein. Non-limiting examples of MV-associated proteins include oncogenic proteins, tumour suppressor proteins, mediators of cellular signaling, receptor tyrosine kinases, biomarkers and proteins listed in Tables 1- 4 herein.

It should also be understood that in some cases, it may be the absence or reduction of a protein which is usually present in normal tissue which is diagnostic or prognostic for cancer. For example, the absence or reduction in levels of a tumour suppressor protein in Vs may be useful for the detection, diagnosis, prognosis, monitoring, etc. of a tumour.

In some embodiments, measurement of other post-translation modifications in MV-associated proteins, such as cleavage of isoforms, glycosylation patterns, and so on, may be used for detection, diagnosis, prognosis, monitoring, etc. of a tumour.

In further embodiments, there are provided methods for detecting cancer in a subject, wherein a sample of a bodily fluid, e.g., blood, is collected from the subject, microvesicles are isolated from the sample, and the microvesicles are assayed to determine the presence of an oncogenic protein or a tumor-related protein in the microvesicles, wherein the presence of an oncogenic protein or tumor-related protein in the microvesicles indicates that the subject has cancer. In some embodiments, the oncogenic or tumor-related protein is not detected in a biopsy specimen (e.g., a tissue sample) obtained from the subject.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration, an embodiment or embodiments thereof, and in which:

Fig. 1 illustrates the production of EGFRvlll-containing microvesicles by human glioma cells wherein in (A) the generation of multiple microvesicular structures on the surfaces of U373vlll glioma cells harboring EGFRvlll oncogene (white arrowheads; SEM image), but not by their indolent parental U373 counterparts, is shown; in (B) the increase in abundance of the microvesicular fraction of the conditioned media, as a function of EGFRvlll expression in U373 glioma (measured by total protein content) is shown; in (C) the inclusion of oncogenic EGFRs in lipid raft-derived microvesicles released by EGFR-expressing cancer cells is shown; in (D) the dependence of tumorigenic properties of U373vlll cells on functional EGFRvlll is shown; in (E) the predominant expression of EGFRvlll but not EGFR in U373vlll tumors is shown; in (F) the release of EGFRvlll containing and flotilin- -positive microvesicles to the circulating blood of SCID mice harbouring U373vlll tumors (top panels) is shown;

Fig. 2 illustrates the microvesicular transfer of the oncogenic EGFRvlll between glioma cells, wherein in (A) it is shown that U373 cells incubated with microvesicles released by their EGFRvlll-transformed counterparts (U373vlll) acquired the expression of the EGFRvlll antigen on their surface (FACS); in (B) the detection of EGFRvlll on the surface of U373 cells incubated with U373vlll- derived microvesicles is shown; in (C) the generation of the U373/EGFRvlll- GFP cell line by expression of the GFP-tagged EGFRvlll in U373 cells is observed; and in (D) the direct GFP-fluorescence of U373 cells incubated with EGFRvlll-GFP containing microvesicles is observed;

Fig. 3 illustrates the activation of growth promoting signaling pathways in cells that have acquired oncogenic EGFRvlll through microvesicle-mediated intercellular transfer, wherein in (A) it is shown the EGFRvlll-dependent increase in Erk1/2 phosphorylation in U373 cells that have incorporated microvesicles shed by U373vlll cells; in (B) Inhibition of Erk1/2 phosphorylation in U373 cells by blocking their uptake of EGFRvlll-containing microvesicles with annexin V is observed; and in (C) the increase in phosphorylation of Akt in U373 cells that have incorporated EGFRvlll-containing microvesicles is observed; Fig. 4 illustrates the induction of cellular transformation by the uptake of EGFRvlll-containing microvesicles, wherein in (A) EGFRvlll-dependent increase in VEGF secretion by U373 cells that have incorporated U373vlll microvesicles is shown; in (B) it is shown that the stimulation of VEGF promoter activity in U373 cells by incorporation of EGFRvlll containing microvesicles can be blocked by pretreatment with annexin V; in (C) the increase in expression of BclxL (prosurvival), and reduced expression of p27 (cell cycle inhibitor) in U373 cells exposed to EGFRvlll containing microvesicles is shown, and in (D-E) it is observed the increase in soft agar colony forming capacity of U373 cells after pretreated with EGFRvlll containing microvesicles;

Fig. 5 illustrates a western blot analysis of blood-borne microvesicles wherein the detection of circulating EGFRvlll from blood samples of 6 patients (lanes 1 to 6) with glioblastoma multiforme is demonstrated for patient 2 (circled bands) and potentially for patient 3;

Fig. 6 illustrates microvesicle-like structures in vivo, wherein in (A) Transmission Electron Micrograph of microvesicular structures present in the intercellular space between two cancer cells (black arrow) within the mixed tumor xenograft in the SCID mouse are shown (bar - 1 m); and in (B) immunogold staining for EGFRvlll reveals the presence of this receptor (white arrow) in association with the microvesicles-like structures found within mixed U373vlll/U373-GFP tumors (bar - 100 nm); and Fig. 7 illustrates emission of the FLAG/EGFRvlll-positive material from U373vlll cells in mixed tumors in vivo wherein photographic representation are shown of confocal microscopy of mixed tumors composed of U373-GFP (green) and U373vlll-FLAG glioma cells (red) and stained for GFP (green, panel A) and FLAG (red, panel B), respectively; merged channels (C and D) reveal the presence of the FLAG/EGFRvlll-positive microvesicle-like structures (arrows) which are associated not only with overtly FLAG/ EGFRvlll-positive cells (U373vlll-FLAG, right side of panels C and D), but also with GFP-positive (U373-GFP) cells (bars - 5 pm).

Fig. 8 illustrates detection of microvesicle (MV)-associated EGFRIII oncogene in a cohort of glioblastoma multiforme (GBM) patients, wherein (+) indicates detection of the oncoprotein in microvesicles (MVs) in a blood sample or detection of the oncogene in a tumor sample using PCR and (-) indicates the oncoprotein/oncogene was not detected, in a cohort (coh.) of 24 patients from the Toronto Tumor Bank (TO);

Fig. 9 illustrates detection of the EGFR signal (wild type EGFR (wt EGFR) or EGFRvlll mutant) in MVs collected from blood of SCID mice harbouring xenotransplants of human cancer cell lines, wherein the SCC-derived A431 cells express wild type EGFR, glioma-derived U373vlll express mainly the EGFRvlll mutant, and Cc are control mouse plasma samples, and wherein the EGFR signal is detected using EGFR ELISA;

Fig. 10 illustrates detection of multiple cancer-related molecular targets in the cargo of microvesicles released by human tumour cells into culture media, wherein in (A), the indicated cell lines were tested for the indicated proteins using Western analysis, wherein (+) indicates robust reactivity, (+/-) indicates faint reactivity, and (-) indicates no detectable reactivity; and in (B), examples of the Western blot analysis are shown, wherein the proteins detected are shown on the right and the cell lines are shown above;

Fig. 11 illustrates the in vitro detection of multiple phospho-receptor tyrosine kinases (RTKs) in MVs released into culture medium by several types of human cancer cells using a Phospho-Protein Antibody Array containing probes for 42 Phospho-RTKs, wherein in (A), examples of RTKs for which relative phosphorylation can be simultaneously detected in a single sample using the array are listed; in (B), major phospho-RTKs detected in MVs from the indicated cell lines are shown; and in (C), examples of the assay output are shown, wherein the cell lines are indicated on the right;

Fig. 12 illustrates an example of an RTK assay looking at the phosphoprotein profile of MVs circulating in blood of mice harbouring a human A431 tumour xenograft, wherein: EGFR/HER-1 is epidermal growth factor receptor; ErbB2/HER-2 is epidermal growth factor receptor 2; ErbB3/HER-3 is epidermal growth factor receptor 3; ErbB4/HER-4 is epidermal growth factor receptor 4; FGFR1 is fibroblast growth factor receptor 1 ; FGFR2a is fibroblast growth factor receptor a; InsulinR is insulin receptor; IGF-1 R is insulin-like growth factor 1 receptor; Axl is Gas6 receptor; Dtk/TYR03 is Gas6 receptor interacting with PI3K; Mer/MERTK is retinitis pigmentosa protein; HGFR/MET is hepatocyte growth factor receptor; and MSPR/MST1 R/RON is macrophage stimulating protein receptor; PDGFRa is platelet-derived growth factor receptor alpha; PDGFRb is platelet-derived growth factor receptor beta; SCFR/cKit/CD1 7 is stem cell factor receptor; Flt-3/CD135 is fms-like tyrosine kinase receptor 3; M- CSFR/CSF1 R/CD- 15 is macrophage colony stimulating factor receptor; c-Ret is receptor for GDNF family of ligands; ROR1 is RAR-related orphan receptor 1 (nuclear, binding melatonin); ROR2 is RAR-related orphan receptor 1 (nuclear); Tie-1 is Orphan receptor involved in angiogenesis; Tie-2 is Angiopoietin receptor; TrkA/NTRK1 is nerve growth factor (NGF) receptor A; TrkB/NTRK2 is brain derived neurotrophic (BDNF) factor receptor; TrkC/NTRK3 is neurotrophin 3 (NT-3) receptor; VEGFR1/FIM is VEGF/PIGF receptor; VEGFR2/KDR/Flk-1 is VEGF signalling receptor; VEGFR3/Flt-4 is VEGF-C/D receptor (lymphangiogenesis); MuSK is muscle specific kinase/agrin receptor (neuromuscular signalling); EphA1 is ephrin type A receptor ; EphA2 is ephrin type A receptor 2; EphA3 is ephrin type A receptor 3; EphA4/TYRO1/SEK is ephrin type A receptor 4; EphA6 is ephrin type A receptor 6; EphA7 is ephrin type A receptor 7; EphB1 is ephrin type B receptor 1 ; EphB2/DRT/Tyro5 is ephrin type B receptor 2; EphB4/MYK1/TYRO11 is ephrin type B receptor 4; and EphB6 is ephrin type B receptor 6; and

Fig. 13 illustrates a reduction in phosphorylated human EGFR in MVs circulating in blood of mice bearing EGFR-driven subcutaneous tumours and treated with the EGFR inhibitor CI-1022, wherein in (A), the responsiveness of A431 and U373vlll tumours to exposure to daily dosing of CI-1033 is shown; tumour volume (mm ³ ) is shown on the y-axis and days post inoculation is shown on the x-axis; and in (B), there is shown a Western blot of MVs from mice bearing A431 subcutaneous tumours treated for 7 days with 20 mg/kg of CI-1033 intraperitoneally (top), and from mice bearing U373vlll tumours treated for 7 days with 20 mg.kg of CI-1033 intraperitoneally (bottom), wherein anti- phospho-EGFR antibody was used for the Western analysis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with the present invention, there is provided a method of detecting the presence of an oncogenic protein in a subject, comprising collecting a sample from the subject, isolating microvesicles (MVs) from the sample, and detecting the presence of the oncogenic protein in the microvesicles. There is also provided herein a method for diagnosing cancer in a sample of a subject by detecting oncogenic proteins in microvesicles.

In an embodiment, cancer is detected by analyzing microvesicles in a sample, such as a bodily fluid, such as blood, urine, cerebrospinal fluid, lymph, ascites, saliva, lavage, semen, and glandular secretions, as well as feces, exudate, contents of cysts and other sources.

In another embodiment, a method for prognosis of cancer, by detecting oncogenic proteins in microvesicles, is provided.

In yet another embodiment, a method for monitoring progression of cancer and/or response to treatment is provided. Cancer refers herein to a cluster of cancer cells showing over proliferation by non-coordination of the growth and proliferation of cells due to the loss of the differentiation ability of cells.

The term "cancer" includes but is not limited to, breast cancer, large intestinal cancer, lung cancer, small cell lung cancer, stomach cancer, liver cancer, blood cancer, bone cancer, pancreatic cancer, skin cancer, head or neck cancer, cutaneous or intraocular melanoma, uterine sarcoma, ovarian cancer, rectal or colorectal cancer, anal cancer, colon cancer (generally considered the same entity as colorectal and large intestinal cancer), fallopian tube carcinoma, endometrial carcinoma, cervical cancer, vulval cancer, squamous cell carcinoma, vaginal carcinoma, Hodgkin's disease, non-Hodgkin's lymphoma, esophageal cancer, small intestine cancer, endocrine cancer, thyroid cancer, parathyroid cancer, adrenal cancer, soft tissue tumor, urethral cancer, penile cancer, prostate cancer, chronic or acute leukemia, lymphocytic lymphoma, bladder cancer, kidney cancer, ureter cancer, renal cell carcinoma, renal pelvic carcinoma, CNS tumor, glioma, astrocytoma, glioblastoma multiforme, primary CNS lymphoma, bone marrow tumor, brain stem nerve gliomas, pituitary adenoma, uveal melanoma (also known as intraocular melanoma), testicular cancer, oral cancer, pharyngeal cancer or a combination thereof. In an embodiment, the cancer is a brain tumor, e.g. glioma. In another embodiment, the cancer expresses certain oncoproteins, e.g. HER-2, HER-3 etc. The term "cancer" also includes pediatric cancers, including pediatric neoplasms, including leukemia, neuroblastoma, retinoblastoma, glioma, rhabdomyoblastoma, sarcoma and other malignancies.

Non-limiting examples of oncogenic proteins which can be detected using the methods of the invention are as follows: (i) membrane-associated oncoproteins derived from cancer cells such as EGFRvlll in glioma, EGFR in squamous cell carcinoma, glioma, lung cancer, or bladder cancer, breast cancer mutant (e.g. Iressa sensitive, mutant or non-expressed tumor suppressor proteins BRCA1 and/or BRCA2), EGFR in lung cancer, HER-2 in breast and ovarian carcinoma, MET in various metastatic and invasive cancers, Kit in gastro-intestinal stromal tumors, PDGFR in glioma, Wnt in various tumors, various phosphatases; (ii) combinatorial clusters of transforming receptors such as EGFR/HER-2 in breast cancer, HER-2/HER-3 in various tumors; (iii) membrane-associated cytoplasmic molecules with transforming properties such as K-ras in colorectal, pancreatic and lung cancer, PTEN (lack of or inactivated) in glioma and prostate cancer; (iv) signaling complexes that could be present (and active) in lipid rafts and microvesicles such as PI3K/Akt, Raf/MEK/MAPK; and (v) tumor related endothelial receptor related to tumor angiogenesis and antiangiogenesis such as VEGFR-2, VEGFR-1 , Tie-2 and TEMs (e.g. TEM-1 , CD276). These proteins may be detected alone or in combination. Other non-limiting examples of oncogenic proteins include EGFRvlll, EGFR, HER-2, HER-3, HER-4, MET, cKit, PDGFR, Wnt, beta-catenin, K-ras, H-ras, N- ras, Raf, N-myc, c-myc, IGFR, IGFR, PI3K, and Akt; tumor suppressor proteins such as BRCA1 , BRCA2 and PTEN; cancer-related host receptors and microvesicle-associated molecules, e.g. those involved in angiogenesis such as VEGFR-2, VEGFR-1 , Tie-2, TEM-1 and CD276. It is contemplated that all oncogenic proteins, tumor suppressor proteins, host-cell related receptors and microvesicle-associated molecules may be used, alone or in combination, in the methods, compositions and kits of the present invention. It is further contemplated that any oncogenic protein, and any combination of oncogenic proteins, which is determined to be mechanistically, diagnostically, prognostically or therapeutically important for cancer, may be used in the methods, compositions and kits of the present invention.

It is well-known in the art that "oncogenic proteins" are proteins which are products of mutant genes and which cause or contribute to the transformation of normal cells into cancerous tumor cells or of low grade cancer to higher grade cancer (for review, see Vogelstein and Kinzler, Nat. Medicine, 10(8): 789- 799, 2004; Croce, CM., N. Engl. J. Med. 358(5): 502-511 , 2008).

There are three main types of genes responsible for tumorigenesis: oncogenes, tumor-suppressor genes and stability genes. Oncogenes are generally mutated such that the protein encoded by the gene (the oncogenic protein) becomes constitutively active, overexpressed, misexpressed (e.g., at the wrong time or place) or active under conditions in which the wild-type protein is not.

In contrast, tumor-suppressor genes are generally mutated to reduce their gene activity, which results in uncontrolled cell proliferation and tumorigenesis. Stability genes are generally also inactivated by mutation. These genes are termed "stability genes" because in their wild-type form they serve to minimize genetic mutations. They are involved, for example, in DNA repair, mitotic recombination and chromosomal segregation. Inactivation of these genes leads to an increased rate of mutation overall, which increases the chance of a tumorigenic mutation occurring in an oncogene or a tumor suppressor gene. It is clear therefore that, in addition to oncogenic proteins, changes in tumor suppressor and stability genes are also associated with, and may be indicative of, cancer.

It is also known that tumor suppressors can serve to induce apoptosis in cells that harbor mutations.

It is also well-established that cancer-gene mutations often function in pathways or networks. For example, oncogenic proteins can act to regulate downstream effector proteins, which may in turn regulate other proteins, leading to a cascade of signaling events which ultimately results in cancerous transformation. Thus it should be understood that in addition to changes in the oncogenic proteins themselves, changes in such downstream effector or mediator proteins are also associated with, and may be indicative of, cancer.

It should be understood therefore that, in addition to the oncogenic proteins which cause cellular transformation, changes in other proteins are also associated with tumorigenesis and may be detected in tumor-derived microvesicles. Such other proteins are referred to herein as "tumor-related proteins". Non-limiting examples of tumor-related proteins include: tumor suppressor proteins; stability proteins; and proteins downstream of oncogenic proteins (i.e., downstream effector proteins) such as tumor-related cellular receptors, mediators of cellular signalling, transcription factors, nuclear receptors, biomarkers associated with cancer and tumorigenesis, and proteins associated with tumor angiogenesis, migration or invasion. For example, the term "tumor-related proteins" includes tumor related endothelial receptors related to tumor angiogenesis and antiangiogenesis such as VEGFR-2, VEGFR-1 , Tie-2 and TEMs (e.g., TEM-1 , CD276). Changes in expression or activity of "tumor-related proteins" which are associated with tumorigenesis may be determined in tumor-derived microvesicles (for example, downregulation of a tumor suppressor protein may be seen in a tumor-derived microvesicle, or increased expression or activation of a tumor related endothelial receptor such as VEGR-2 or VEGFR-1 may be seen). It is contemplated that, in addition to oncogenic proteins, any tumor-related protein which is determined to be mechanistically, diagnostically, prognostically or therapeutically important for cancer, may be used in the methods, compositions and kits of the present invention.

In one embodiment, the term "MV-associated protein" includes both oncogenic proteins and tumor-related proteins, as defined above, which are detected in microvesicles derived from a tumour and useful for the detection, diagnosis, prognosis, monitoring, etc., of the tumour, in accordance with the methods provided herein.

The invention described herein is based, at least in part, on the novel and unexpected observation that EGFRvlll oncoprotein can be emitted and shared between glioma cells via intercellular transfer of the activated receptor that occurs as cargo of membrane-derived microvesicles released from cells producing the mutant protein. Indeed, EGFRvlll stimulates the formation of lipid-raft related microvesicles, to which it becomes incorporated. Microvesicles containing EGFRvlll oncoprotein are released to conditioned media or blood of tumor bearing mice and can merge with the plasma membranes of tumor cells lacking this receptor. Such transfer of EGFRvlll triggers the activation of downstream signaling pathways (MAPK and Akt), progression-related changes in gene expression (VEGF, BclxL, p27) and manifestation of exacerbated cellular transformation, notably altered morphology and increased soft agar colony formation efficiency. These observations point to the role of membrane microvesicles in horizontal propagation of transforming proteins between different subsets of cancer cells and suggest that the transforming impact of membrane-associated oncoproteins may extend beyond the cells harboring the corresponding mutant genes.

Activated cells of various types are known to produce and shed into their surroundings membrane microvesicles, also known as microparticles, ectosomes, or argosomes; in the case where such vesicles originate from the lysosomal pathway, they are often referred to as exosomes. The biological role of these structures is poorly understood, but may include secretory processes, immunomodulation, coagulation and intercellular communication (Janowska- Wieczorek et al., 2005, Int. J Cancer, 20: 752-760).

Microvesicles may vary in the mechanism of their generation, size and composition, but often (especially ectosomes) contain material associated with membrane lipid rafts, including functional transmembrane proteins. For instance, procoagulant tissue factor (TF) can be released in this fashion from inflammatory cells and, importantly, becomes subsequently incorporated into membranes of platelets, endothelium and other cells where it exerts its biological effects. As used herein, the term "microvesicles" includes microvesicles, microparticles, ectosomes, argosomes, exosomes, tumor vesicles and all other vesicular bodies released from cells.

Cancer cells lacking the p53 tumor suppressor gene may in some instances mimic this process by releasing altered amounts of TF-containing (Yu et al., 2005, Blood, 105: 1734-1741 ), or secretory (Yu et al., 2006, Cancer Res, 66: 4795-47801) microvesicles to blood and the pericellular milieu.

Oncogenic receptors often reside within the regions of the plasma membrane, from which microvesicles originate in cancer cells (e.g. lipid rafts). It is disclosed herein that the oncogenic receptors can themselves become included in the microvesicle cargo. This is of particular interest for example in malignant brain tumors (gliomas) where activation of membrane associated EGFR represents a major transforming event, and in nearly 30% of cases with glioblastoma multiforme (GBM) expression of the EGFRvlll oncogenic mutant is readily detectable.

In order to explore this phenomenon further, the production of microvesicles by cultured U373 glioma cells lacking the activated EGFR and their counterparts, engineered to express EGFRvlll (U373vlll cells) was examined. Interestingly, the presence of the EGFRvlll oncogene in the latter cell line resulted in formation of multiple vesicular protrusions on the cell surface, an effect that was accompanied by an increase in recovery of protein from the microvesicular fraction of the culture media (see Fig. 1A, B). This material contained a proportional quantity of flotilin-1 , a protein associated with membrane lipid rafts and often found in raft-related microvesicles from various sources. Collectively, it demonstrates that EGFRvlll-related transformation observed in U373vlll cells is coupled with increased production of microvesicles derived from membrane lipid rafts. In a particular embodiment, proteins enriched in microvesicles, such as EGFRvlll, HER-2, and MET, can be detected by various techniques known in the art. For example, lysates of microvesicles can be analyzed by immunoblotting using antibodies such as anti-EGFRvlll or anti-EGFR. Concentration of the microvesicles by centrifugation is necessary, but also provides a considerable quantitative and qualitative advantage over the analysis of the whole plasma. This is because microvesicle isolation can improve the sensitivity of detection of certain molecules, e.g. EGFRvlll (due to their enrichment in microvesicles), increase the specificity (as microvesicles are not random collections of plasma membrane molecules), protect the cargo from proteolysis, dephosphorylation or degradation (owing to the microvesicle membrane), and broaden the scope of the analysis (owing to the presence of unique and diagnostically informative combinations of proteins in microvesicle cargo). In this regard, the sensitivity of microvesicle analysis can be increased by switching from ultracentrifugation to microfiltration, the latter of which may simplify and improve the recovery of microvesicles. Another technique to detect microvesicular proteins is immunoprecipitation of microvesicle-related material from magnetic beads coated with e.g. Annexin V (as the MVs express large amounts of phosphatidyl serine) or an antibody binding an oncogenic protein that is expressed on the surface of the MV, such as anti-EGFRvlll antibody. Further, an ELISA assay based on two antibodies (e.g. 2 x anti-EGFRvlll or anti-EGFRvlll + anti-EGFR) or a radioimmune assay (RIA) based on two antibodies (e.g. 2 x anti-EGFRvlll or anti-EGFRvlll + anti-EGFR) can also be used. In addition, ELISA based on binding of microvesicles to surfaces coated with Annexin V (as e.g. in commercial TF assays) or with EGFRvlll/EGFR antibodies could be used in conjunction with a detection component based on the anti-EGFRvlll antibody. Other techniques that can be used include flow cytometry, where microvesicles are captured by beads coated with e.g. Annexin V, or antibodies specific to molecules (proteins, carbohydrates and other) present on their surfaces, or with non-antibody affinity reagents (receptors, aptamers, lectins, nucleic acid sequences, and so on), and stained with e.g. anti-EGFRvlll antibody, and mass spectrometry, where EGFR is detected in the proteome of microvesicle preparations. All such reagents and capture methods could also be used to isolate microvesicles using affinity purification columns and multiplex platforms. It is contemplated that standard techniques known in the art for preparation of microvesicles and for detection of proteins can be used in the methods described herein. The present invention is based, at least in part, on the observation that abundant expression of EGFRvlll protein is detected in lysates not only of U373vlll cells themselves, but also in their derived microvesicles, demonstrating that the intact oncoprotein is released in this fashion into the circulation. Although the parental U373 cells did release detectable quantities of flotilin-1 containing microvesicles, they contained only trace amounts of wild type EGFR (wtEGFR) and no EGFRvlll. These results were validated against EGFR-negative endothelial cells (HUVEC) and A431 cells expressing only wtEGFR, as well as their respective microvesicle preparations (Fig. 1C). While U373 cells exhibit indolent phenotype in vivo, their U373vlll counterparts readily form subcutaneous tumors in immunodeficient (SCID) mice, in a manner susceptible to inhibition by daily doses of an irreversible, small molecule pan- Erb inhibitor CI-1033 (Fig. 1 D). U373vlll tumors stained strongly for EGFRvlll but not for wtEGFR and, interestingly, emitted EGFRvlll-containing microvesicles into the systemic circulation (Fig. 1 E, F). Thus, expression of mutant EGFRvlll gene leads to the increased aggressiveness of glioma cells coupled with extracellular release of microvesicles containing an intact EGFRvlll oncoprotein.

Heterogenous EGFRvlll expression in human glioma suggests that different tumor cell subsets could shed EGFRvlll-containing microvesicles into the common intercellular space. Since microvesicles can readily fuse with cellular membranes via a phosphatidylserine-dependent mechanism, it is here demonstrated that oncogenic EGFRvlll can be transferred in this manner from more aggressive to indolent glioma cells. EGFRvlll-negative U373 cells were, therefore, incubated with preparations of microvesicles obtained from either their U373vlll counterparts harboring EGFRvlll, or from U373vlll-GFP cells engineered to express a green fluorescent protein (GFP)-tagged EGFRvlll oncogene (EGFRvlll-GFP). Interestingly, this resulted in an extensive uptake of the microvesicular content by U373 cell, as demonstrated by their de novo surface expression of the EGFRvlll antigen and GFP fluorescence, respectively (Fig. 2A-D).

The apparent intercellular microvesicle-mediated transfer of the ostensibly intact EGFRvlll receptor raises the question, as to the signaling consequences (if any) of this event for the 'acceptor' (U373) cells. To address this question, U373 cells 24 hours after their exposure to EGFRvlll-containing microvesicles were examined for activation of the MAPK and Akt cascades, both known to mediate transforming effects downstream of this oncogene. Indeed, incorporation of EGFRvlll into the U373 plasma membrane resulted in a consistent increase in Erk1/2 phosphorylation. This event was dependent on the transfer of active EGFRvlll, as U373-derived microvesicles, containing no EGFRvlll were ineffective. Moreover, the irreversible blockade of this receptor by preincubation of U373vlll-derived microvesicles with pan-ErbB inhibitor (Cl- 1033) markedly reduced Erk1/2 phosphorylation (Fig. 3A). Phosphorylation of Erk1/2 was also abrogated by preincubation of these microvesicles with annexin V, which blocks their exposed phosphatidylserine residues and thereby their uptake by U373 cells. These results demonstrate that not just mere contact between the EGFRvlll containing microvesicles with the surface of U373 cells, but rather their actual (phosphatidylserine-dependent) integration and EGFRvlll transfer are required for triggering the activation of MAPK pathway in the acceptor cells (Fig. 3B). Incorporation of U373vlll-derived microvesicles also induced phosphorylation of Akt in U373 cells, in a manner inhibitable by annexin V (Fig. 3C), and triggered several other events, notably phosphorylation of PDK1 and Raf.

The transforming effects of EGFRvlll-dependent pathways are ultimately mediated by deregulation of several genes responsible for tumor growth, survival and angiogenesis. With regard to the latter, it was noted that U373 cells exposed to U373vlll-derived microvesicles exhibited a marked (2-3 fold) increase in production of vascular endothelial growth factor (VEGF), a potent mediator of brain tumor angiogenesis and a known EGFR target. EGFRvlll activity was essential for this effect as U373-derived microvesicles (devoid of EGFRvlll), or those from U373vlll, but preincubated with CI-1033 were unable to induce this release of VEGF (Fig. 4A). In these settings, EGFRvlll containing microvesicles also robustly stimulated VEGF promoter activity and this effect was abrogated by their pretreatment with annexin V (Fig. 4B). Collectively, these observations demonstrate that incorporation of U373vlll microvesicles triggers an EGFRvlll-dependent increase in VEGF gene expression and protein production by U373 cells, via activation of the MAPK and Akt pathways.

While VEGF upregulation often heralds activation of oncogenic pathways, cellular transformation downstream of EGFRvlll is mediated by changes in expression of genes directly involved in cellular proliferation and survival. In this regard, U373 cells treated with EGFRvlll-containing microvesicles revealed an increase in expression of the antiapoptotic protein BclxL and decrease in levels of p27/Kip1 cyclin dependent kinase inhibitor, both known EGFR targets (Fig. 4C, D). Again, these effects were inhibited by annexin V-mediated blockade of the microvesicle uptake by the acceptor U373 cells. Similar EGFRvlll- dependent changes in expression of other EGFRvlll target genes, e.g. p21/Cip, were also observed.

The functional consequences of the aforementioned repertoire of molecular responses evoked by incorporation of EGFRvlll-containing microvesicles can lead to a higher degree of cellular transformation, as demonstrated by more spindle morphology of U373 cells exposed to this material (Fig. 2B). U373 cells were preincubated with EGFRvlll containing microvesicles and tested for growth in semisolid media, a paradigmatic transformation assay. Remarkably, incorporation of the oncoprotein in this manner caused a twofold increase in anchorage independent soft agar colony formation of by U373 cells, while exposure to equivalent amounts of microvesicles devoid of EGFRvlll content was inconsequential (Fig. 4 D, E). It is well recognized that in human GBMs, only a small sub-population of tumor cells harbor the primary genetic mutation leading to EGFRvlll expression, though there is increased growth of the entire tumor. In this regard, it is disclosed herein that EGFRvlll expression provokes formation of cellular microvesicles, to which this transmembrane protein becomes incorporated and shed to the pericellular micromilieu (Figs. 6 and 7) and blood (Fig. 1F). The experiments disclosed herein demonstrate that microvesicles containing such an active oncogene (oncosomes) may serve as vehicles for rapid intercellular transfer of the transforming activity between cells populating brain tumors. This could lead to a horizontal propagation of an increased proliferative, survival and angiogenic capacity even without (prior to) enrichment in cells harbouring the respective mutation. This hitherto unappreciated form of intercellular interaction is fundamentally different than the previously postulated transfer of DNA fragments containing oncogenic sequences from apoptotic cancer cells to their non-transformed (phagocytic) counterparts. Microvesicle exchange is also different from paracrine effects induced by secretion of tumor-stimulating soluble ligands, but it could amplify/modulate the latter effects by intercellular sharing of membrane-associated (and thereby insoluble) active receptors.

Confirming that in human GBMs, only a small sub-population of tumor cells harbor the primary genetic mutation leading to EGFRvlll expression, both wild type EGFR and EGFRvlll bands were detected at the expected sizes and resolved using a standard SDS-PAGE protocol in microvesicles collected from human plasma of patients with GBM (Fig. 5).

It is encompassed that similar microvesicular transfer can also involve other transforming, mutant, upregulated, or otherwise activated membrane- associated oncogenic tyrosine kinases (e.g. HER-2, wtEGFR, cKit or MET) and proteins operative in a variety of human tumors. Host cells (e.g. endothelium) may also be targets of oncogene-containing microvesicles. In one aspect, the tumor promoting functions (e.g. angiogenesis) of a host cell could be exacerbated by microvesicular transfer. Conversely, tumor-associated host cells are often profoundly altered or even contain overt cytogenetic alterations (Akino et al Am. J. Pathol. 2009), and their derived microvesicles (e.g. containing tumor endothelial markers (TEMs) of endothelial cells) could possess diagnostic, prognostic and predictive value.

It is also encompassed herein that agents capable of blocking exchange of microvesicles between cells (e.g. annexin V derivatives) may be useful as therapeutic agents, e.g. to inhibit cancer spreading and growth by inhibiting the fusion of microvesicles with cells. In an embodiment, methods for treating cancer are provided comprising administration of a microvesicle exchange blocking agent, e.g. annexin V and/or derivatives thereof, to a subject in need thereof. It is contemplated that any agent that could be used for blocking microvesicle, microparticle, ectosome or exosome transfer can be used in the methods of the inventions described herein. Other non-limiting examples of such agents include agents blocking P-selectin or its ligand, PSGL.

In another aspect, the invention provides methods of diagnosing cancer by allowing detection of multiple oncogenic proteins and/or multiple phosphorylation sites within them by performing the analysis in microvesicles. For example, a cancer could be characterized by determining whether it carries EGFRvlll, HER-2, wtEGFR, cKit or MET, alone or in combination, by analyzing the protein composition of the microvesicles. The number of oncogenic protein- containing microvesicles found in a bodily fluid can also be used as a way of determining the aggressiveness of a tumor, i.e. its tendency to spread or metastasize. The methods of the invention can thus aid in diagnosis and/or prognosis. In one embodiment, diagnosis and/or prognosis of breast cancer can be determined by detecting the presence of EGFR and/or HER-2. In another embodiment, diagnosis and/or prognosis of tumors is determined by detecting the presence of HER-2 and/or HER-3. In another embodiment, diagnosis and/or prognosis of colorectal cancer is determined by detecting the absence of a tumour-related protein such as the tumour suppressor PTEN and/or p53 and the presence of an oncogenic protein such as K-ras and/or c-Met, which is indicative of an aggressive tumor. In another embodiment, the invention provides methods of monitoring the progression of a cancer and/or monitoring the effectiveness of a treatment or therapeutic regimen. For example, the size and the nature of a tumor can be followed by monitoring the amount and composition of an oncogenic protein or proteins, e.g. EGFRvlll, HER-2, HER-3, cKit or MET, released in microvesicles. It would be expected, for example, that a larger tumor would include more cells and therefore release more microvesicles than a smaller one. This could be used to monitor therapy by providing a means to measure a change in size of a tumor, which may either shrink, grow, or stay the same. Such methods would be valuable in evaluating the effectiveness of a therapy in a patient population as a whole, or in an individual patient. It is also contemplated that the progression of a cancer and/or the response to treatment can be monitored by measuring a combination of oncogenic proteins found in microvesicles. In an embodiment, EGFR and HER-2 can be measured in combination, for example in breast cancer, thereby providing indication as to genetic status (e.g. genotype) and progression (or recurrence) of malignancy, in some aspects irrespectively of the actual tumor size. In other embodiments, HER-2 and HER- 3 or HER-2 and EGFR can be measured in combination, for example. Furthermore, as microvesicles may contain intact oncoproteins, in another embodiment the phosphorylation status of the oncoproteins can be determined to monitor or measure the efficacy of targeted treatments. For instance, monitoring the phosphorylation status of the EGFR/HER-2 combination in microvesicles derived from breast cancer could indicate the efficacy of a HER- 2-directed drug such as Herceptin ^® , an EGFR-directed drug such as Tarceva ^® , or similar anti-cancer treatments, alone or in combination. In another aspect, the molecular environment surrounding an oncogenic protein in the microvesicles, e.g. other molecules, the entire proteome, or the phosphoproteome, may be used to monitor the progression of cancer and/or efficiacy of an anti-cancer treatment. For example, the presence or absence or phosphorylation status of PTEN in the microvesicles may be indicative of progression or cancer and/or efficacy of an anti-cancer treatment. In a further aspect, the invention provides methods of monitoring the progression of a cancer and/or monitoring the efficacy of an anti-cancer treatment or therapeutic regimen. It is contemplated that any anti-cancer treatment or therapeutic regimen known in the art could be used in the methods described herein. Non-limiting examples of treatments and therapeutic regimens encompassed herein include surgery, radiology, chemotherapy, and administration of targeted cancer therapies and treatments, which interfere with specific mechanisms involved in carcinogenesis and tumour growth. Non- limiting examples of targeted cancer therapies include therapies that inhibit tyrosine kinase associated targets (such as Iressa ^® , CI-1033, Tarceva ^® and Gleevec ^® ), inhibitors of extracellular receptor binding sites for hormones, cytokines, and growth factors (Herceptin ^® , Erbitux ^® ), proteasome inhibitors (Velcade ^® ) and stimulators of apoptosis (Genasense ^® ). Such targeted therapies can be achieved via small molecules, monoclonal antibodies, antisense, siRNA, aptamers and gene therapy. A subject may also receive a combination of treatments or therapeutic regimens. Any other treatment or therapeutic regimen known in the art can be used in the methods described herein, alone or in combination with other treatments or therapeutic regimens.

In another aspect, the invention provides methods of diagnosing cancer by allowing detection of multiple phosphorylated oncogenic proteins and/or multiple phosphorylation sites within them by performing the analysis in microvesicles. In another embodiment, the invention provides methods of monitoring the progression of a cancer and/or monitoring the effectiveness of a treatment or therapeutic regiment by measuring the phosphorylation state of an oncogenic protein in the microvesicles.

Receptor tyrosine kinases (RTKs), such as EGFR, contain an extracellular ligand binding domain connected to a cytoplasmic domain by a single transmembrane helix. The cytoplasmic domain contains a conserved protein tyrosine kinase core and additional regulatory sequences that are subject to autophosphorylation and phosphorylation by heterologous protein kinases. When a ligand binds to the extracellular domain of an RTK, dimerisation of the RTK with other adjacent RTKs is triggered. Dimerisation leads to a rapid activation of the proteins' cytoplasmic kinase domains, the first substrate for these domains being the receptor itself. As a result the activated receptor becomes autophosphorylated on multiple specific intracellular tyrosine residues. The phosphorylation of specific tyrosine residues within the activated receptor creates binding sites for Src homology 2 (SH2) and phosphotyrosine binding (PTB) domain containing proteins. Specific proteins containing these domains include Src and phospholipase Cy, and the phosphorylation and activation of these two proteins upon receptor binding leads to the initiation of signal transduction pathways. Other proteins that interact with the activated receptor act as adaptor proteins and have no intrinsic enzymatic activity of their own. These adaptor proteins link RTK activation to downstream signal transduction pathways, such as the MAP kinase signalling cascade. The activity of virtually all RTKs can be enhanced, even in the absence of ligand binding, by treatment of cells with protein tyrosine phosphatase inhibitors. Thus, the persistent activation of a RTK, or an oncogenic receptor, that triggers abnormal expression of genes involved in cell proliferation, survival and angiogenesis, is positively regulated by one or several phosphotyrosine sites in the activation loop.

Phosphorylation of RTKs can be measured using a number of methods. Non- limiting examples of such methods include phosphospecific antibodies, phosphoantibody arrays, staining with antibodies against phosphotyrosine residues, and direct kinase assays with phosphorylatable substrates. Another way to determine the phosphorylation status of multiple receptors on microvesicles could be to assess their total phosphoproteome using mass spectrometer (MS) related methods. It is contemplated that standard techniques known in the art for measuring and detecting phosphorylated proteins (also referred to as phospho-proteins) and the phosphorylation state of a protein can be used in the methods described herein.

We further report herein that oncogenic transformation may impact a cancer cell in such a way as to cause a change in the wider spectrum of MV- associated proteins, the linkages of which to the triggering oncogene may or may not be mechanistically obvious, but may be meaningful for use as biomarkers. Thus we report herein the identification of cancer-associated proteins present in circulating MVs of mice harbouring subcutaneous human tumour xenografts or in MVs from the culture medium of human tumour cell lines. These proteins represent biomarkers which can be used, for example, to monitor progression of a tumour or response to anti-tumour therapy. The biomarkers can also be used for diagnosis and prognosis of a tumour in a subject. We demonstrate herein that many proteins related to malignancy, such as oncogenes, tumour suppressors, receptor tyrosine kinases, and mediators of cellular signaling are detected in MVs derived from several types of human cancer cells. Examples of such cancer-associated proteins and phosphoproteins found in tumour-derived MVs which can be used as biomarkers are given in Tables 1-4 below. It is noted that the cancer-associated proteins and phosphoproteins found in MVs include both known oncogenic proteins such as HER-2 and unexpected proteins such as VEGFR2 or Tie 2, which are angiogenic receptors usually found on epithelial cells. Thus, analysis of the protein content of tumour- derived MVs as demonstrated herein will aid the characterization, prognosis and diagnosis of tumours, including the complexities of their microenvironment and host stroma. Determining the protein content of tumour-derived MVs may also lead to the potential identification of new therapeutic targets. For example, the human VEGFR3 phosphoprotein was identified in MVs from mice harbouring PANC-1 xenografts, suggesting that the cancer cell associated VEGFR3 phosphoprotein may be a hitherto unappreciated biomarker and/or therapeutic target for at least a subset of pancreatic cancers (see Table 4). In addition, the combination of proteins present in MVs may be characteristic of the tumour from which the MVs are derived (see Table 4, for example). Thus the protein or phosphoprotein profile, or a subset thereof, of the MVs may be used in the methods provided herein, e.g. for monitoring anti-tumour therapy or for diagnosis or prognosis of a tumour.

As many of the proteins identified herein are phosphoproteins which are known to be activated or inactivated by phosphorylation, the activation or functional state of the cancer-associated proteins can be assessed by monitoring their phosphorylation status. Thus the phosphorylation status of MV-associated proteins, alone or in combination, can also be used in the methods provided herein, e.g. for monitoring anti-tumour therapy or for diagnosis or prognosis of a tumour.

It should be understood that the MV-associated proteins and phosphoproteins identified herein, and combinations thereof, can be used in the methods and kits of the invention.

In an aspect, there is provided herein a microvesicle-based blood test, wherein MVs are isolated from a sample of blood from a subject and assayed for MV- associated proteins, or assayed to assess the phosphorylation status of MV- associated proteins. Such methods are demonstrated below, for example in MVs expressing EGFRvlll and wild type EGFR, in mice bearing a xenograft of a human tumour cell line, and in glioblastoma (GBM) patients. We have demonstrated the feasibility of this approach in numerous cancer cell types (such as breast cancer, glioma, brain cancer, lung cancer, pancreatic cancer, skin cancer, prostate cancer and colorectal cancer). It is noted that another potential advantage of using circulating MVs rather than a biopsy specimen is the problem of tumor heterogeneity: we have observed on one occasion that a tumor biopsy sample was negative for EGFRvlll, whereas the corresponding blood MV sample was positive (see Example 3). Thus, by obtaining a tissue biopsy sample that is not representative of the overall tumor phenotype/genotype, the result is misleading, whereas the blood sample is representative of the entire tumor, and thus more reliable.

In an embodiment, there are provided herein methods of detecting the presence of an oncogenic protein or a tumor-related protein in a tumor in a subject, wherein MVs are isolated from a sample of a bodily fluid, e.g., blood, from the subject and assayed for the oncogenic or tumor-related protein, and wherein the presence of the protein in the MVs indicates the presence of the protein in the tumor. In some embodiments, the methods provided herein can detect an oncogenic protein or a tumor-related protein which is not detected in a biopsy specimen from the subject. These methods may be particularly useful for analyzing heterogeneous tumors, where an oncogenic protein or tumor- related protein can be missed by standard tissue biopsy methods and histopathological sampling. Thus in an aspect, the methods provided herein reduce or eliminate the risk of not detecting an oncogenic or tumor-related protein in a biopsy specimen obtained from a subject. These methods also provide a non-invasive alternative to tissue biopsy.

In another embodiment, there are provided methods of detecting cancer in a subject wherein an oncogenic protein or a tumor-related protein is detected in microvesicles obtained from a sample of bodily fluid, e.g., blood, collected from the subject. In an embodiment, said oncogenic or tumor-related protein is not detected in a biopsy specimen obtained from said subject. In other

embodiments, there are provided methods of detecting metastatic cancer in a subject, wherein an oncogenic protein or a tumor-related protein is detected in microvesicles obtained from a sample of bodily fluid, e.g., blood, collected from the subject. In some cases where it is impractical or impossible to obtain biopsy specimens from all the metastatic sites in a subject, the analysis of microvesicles can be used to determine the presence of oncogenic or tumor- related proteins in the tumors and/or to reduce or eliminate the risk of not detecting an oncogenic or tumor-related protein. In another aspect, there are provided methods of determining the phosphorylation state of an oncogenic protein or tumor-related protein in a tumor in a subject, comprising collecting a sample of a bodily fluid from the subject; isolating microvesicles from the sample; and detecting the phosphorylation state of the oncogenic protein or the tumor-related protein in the microvesicles, wherein the phosphorylation state of the oncogenic protein or the tumor-related protein in the microvesicles indicates the phosphorylation state of the oncogenic protein or the tumor-related protein in the tumor. In an aspect, the bodily fluid is blood. In a further aspect, there are provided methods of diagnosing or determining prognosis of a cancer in a subject, comprising collecting a sample of a bodily fluid, e.g., blood, from the subject; isolating microvesicles from the sample; and determining the oncogenic and/or tumor-related proteins in the microvesicles. In an aspect, the oncogenic, tumor-related and/or MV-associated proteins in the microvesicles is diagnostic, e.g., of the cancer type, and/or prognostic.

The present invention will be more readily understood by referring to the following examples, which are given to illustrate the invention rather than to limit its scope.

EXAMPLE 1

Cell culture and isolation of microvesicles (MVs) U373 (human astrocytoma) cells, their stable variant U373vlll expressing Tet- off regulated EGFRvlll or EGFRvlll fused at C-terminus to green fluorescent protein (pEGFPNI) cassette (U373vlll-GFP) and A431 are maintained as described previously (Viloria-Petit et al Am. J. Pathology, 1997, 6:1523-1530; Yu et al., 2005, Blood, 105: 1734-1741 ) in medium containing microvesicle- depleted fetal bovine serum FBS. HUVEC cells are maintained in EGM-2 (Cambrex Bioscience, Walkesville, MD, USA). Microvesicles are collected from conditioned media or mouse plasma, as previously described (Yu & Rak, J. Thromb. Haemost, 2004, 2:2065-67; Al-Nedawi et al., 2005, Arterioscler. Thromb. Vase. Biol., 25: 1744-1749). Briefly, media are subjected to two successive centrifugations at 300g and 12000g to eliminate cells and debris. Microvesicles are pelleted by ultracentrifugation for 2 hours at 100 OOOg and quantified by protein content and analyzed for EGFR or EGFRvlll content. For scanning electron microscopy (SEM) the cells are grown on cover slips, fixed with 2.5% gluteraldehyde, stained with 1 % Os04, covered with gold and visualized using the JEOL 840A instrument. For in vivo analyses tumors are generated by injection of 1-10 x 10 ⁶ U373vlll or U373 cells into immunodeficient (SCID) mice (Charles River, Canada). In some cases mice are treated daily with the pan-ErbB inhibitor CM 033 as indicated. Blood is collected from tumor bearing, or control mice by cardiac puncture into heparinized syringes. Platelet- free plasma is used to prepare microvesicles.

Flow cytometry (FACS) is employed to detect EGFRvlll, or EGFRvlll-GFP on the surface of viable not permeabilized cells and is carried out either with cells that expressed these receptors endogenously, or with those that have acquired such expression upon transfer of microvesicles. Typically, U373 cells are treated, with microvesicles (MVs) obtained from U373vlll or U373vlll-GFP cells for 24 hours. The cells are then detached using 2 mM EDTA (ethylenediaminetetraacetic acid) to obtain a single-cell suspension the aliquots of which (1.5 x 10 ⁶ /sample) are washed in phosphate-buffered saline (PBS) with 1% FBS and 0.1% sodium azide. The cells treated with U373vlll derived MVs are then stained for 30 minutes at 4°C with for example a monoclonal antibody against EGFRvlll (Zymed). After washing, samples are incubated with Alexa Fluor 488 goat anti-mouse secondary antibody (Molecular Probes, Eugene, OR) for 30 minutes at 4°C, washed with phosphate buffered saline (PBS) and analyzed. In the case of treatment with MVs derived from U373vlll- GFP cells fresh cell suspensions are directly analyzed for GFP fluorescence. The data can be acquired using FACScalibur flow cytometer (BD Biosciences, Mountain View, CA). All in vivo experiments are performed in 6- to 8-week-old severe combined immunodeficiency (SCID) mice (Charles River, Saint-Coustant, QC, Canada). Briefly, 1 to 10 x 10 ⁶ of U373vlll or U373, cells are injected subcutaneously in 0.2 ml PBS. Blood is collected from mice by cardiac puncture, into heparin sodium solution. Platelet-free plasma was prepared by centrifugation at 2000g for 5 minutes, 2000 g for 5 minutes, and 16,000g for 5 minutes to isolate microvesicles.

EXAMPLE 2

Microvesicle transfer assays

U373 (acceptor) cells are treated with microvesicles for 24 hours and a single- cell suspension is analyzed by flow cytometry or fluorescent microscopy for expression of EGFRvlll or GFP. To detect signaling events, U373 are starved in 0.5% FBS (DMEM) before addition of microvesicles, which are either intact or preincubated with annexin-V, or CI-1033, at the concentrations as indicated. The expression of microvesicle associated molecules (EGFRvlll, TF), and expression of total and activated MAPK and Akt as well as other changes are assayed by immunoblot (BclxL, p27/Kip1), ELISA (VEGF, R&D Systems), or promoter activity assays (VEGF), as described elsewhere (Lopez-Ocejo et al. 2000, Oncogene, 40:4611-4620). For soft agar colony formation assays single cell suspensions are prepared in 0.3% agarose from equal numbers of cells pretreated with microvesicles or control media. Cultures are established in plates precoated with 0.5% agarose and all colonies containing more than 4 cells are counted.

EXAMPLE 3

Detection of circulating EGFRvlll in patients with glioblastoma multiforme

Microvesicles are collected from human plasma in a similar manner as previously described for plasma of tumor bearing mice (Al-Nedawi et al., 2008, Nature Cell Biology, 10: 619-624). Briefly, archival blood samples are subjected to two consecutive centrifugations at 300g for 5 minutes, and then at 12000g for 20 minutes to eliminate cells and debris. Finally, microvesicles are obtained after centrifugation for 2 hours at 100 OOOg, washed twice with a large volume of phosphate buffered saline (PBS). The protein lysates are prepared in the lysis buffer containing: 10 mMTris, pH 6.8, 5 mM EDTA, 50 mM NaF, 30 mM sodium pyrophosphate, 2% (wt/vol) SDS, 1 mM phenylmethylsulfonyl fluoride (PMSF), and 1 mM Na ₃ VO ₄ , for 10 minutes on ice. Unless otherwise indicated the lysates are resolved by SDS-PAGE and subjected to immunoblotting with for example a mouse or a sheep anti-human EGFR polyclonal antibody or appropriate mouse monoclonal antibodies. Immunodetection is accomplished using the appropriate HRP-conjugated secondary antibody and chemiluminescence plus kit (ECL kit; Amersham Pharmacia, Buckinghamshire, United Kingdom), after which the blots are scanned and protein bands quantified using for example the Storm 860 scanner (GE healthcare). Both wild type EGFR and EGFRvlll bands are detected in this manner at the expected sizes and resolved using a standard SDS-PAGE protocol.

The EGFRvlll oncoprotein was also detected in circulating MVs collected from a cohort of 24 GBM patients from the Toronto Tumor Bank using Western analysis (Fig. 8). Detection of the oncoprotein in MVs correlated well with detection of the EGFRvlll oncogene in tumor samples from the same patients (Fig. 8). These results demonstrate the feasibility of oncoprotein detection in circulating MVs in cancer patients. Notably, for patient #4 the oncoprotein was detected in MVs even though the oncogene was not detected in the tumour sample using PCR. This result indicates that in some cases MV analysis may be more sensitive than PCR for the detection of cancer-associated biomarkers such as EGFRvlll. It is also possible that the MV-related EGFR signal could have emanated from tumour cells that have not been removed and are expected to cause a recurrence.

The EGFR signal was detected in MVs collected from blood of human xenograft bearing SCID mice using an ELISA assay (Fig. 9). A commercial EGFR ELISA kit (R & D, Systems, DYC 1854-5) containing the anti-EGFR antibody cross- reacting with EGFRvlll was used to detect EGFRvlll in MVs from mice harbouring xenotransplants of glioma-derived U373vlll cells and wild type EGFR in squamous cell carcinoma (SCC)-derived A431 cells. These results indicate that both forms of EGFR are readily detected by ELISA assay, and confirm the feasibility of MV-based biomarker detection.

EXAMPLE 4

Detection of multiple cancer-related molecular targets in MVs

We isolated microvesicles released by human tumour cell lines into culture media and used Western analysis to detect several proteins related to malignancy, such as oncogenes, tumour suppressors, and mediators of cellular signalling, in the cargo of the microvesicles. Glioma cell lines (U373, U373vlll, U87 and U87vlll), lung cancer cells (A549), breast cancer cells (MDA-MB-231), prostate cancer cells (PC-3), and colorectal cancer cells (DLD-1 , HCT116 and CaCo2) were used. The putative oncoproteins K-ras, c-Met, beta-catenin and PDGFR and the tumour suppressor gene products PTEN, TP53 and E-cadherin were tested in the microvesicles. Results are shown in Fig. 10A, where (+) indicates robust reactivity, (+/-) indicates faint reactivity and (-) indicates no detectable reactivity. Examples of Western blot analysis are shown in Fig. 10B. Western blot analysis was performed on total cell lysates of MV preparations, obtained from the cultured cell lines, as indicated. The antibodies used included the following: Pan Ras: Rabbit monoclonal [Y131], Cat. No. (ab32442), Abeam; K-ras: Mouse monoclonal Ab., Cat. No. AT2650a, Biolynx Inc.; C-Met: Rabbit monoclonal (EP145Y], Cat. No. (ab51067), Abeam; PDGFR-b2: Mouse monoclonal, Cat. No. (ab10847-100), Abeam; Beta-catenin: Mouse monoclonal, Cat. No. (MA 1-301), ABR; E-Cadherin: Mouse monoclonal [MB2], Cat. No. (ab8993), Abeam; PTEN: Rabbit monoclonal, Cat. No. (#9188), Cell Signaling; P53: Rabbit monoclonal, Cat. No. (#2527), Cell Signaling. It is noted that cell lines used in this study represent stocks currently used in the laboratory and obtained from various sources (ATCC, collaborators), and may therefore differ in their molecular status from similarly named cell lines maintained elsewhere. These results demonstrate the large scope of molecular targets relevant to cancer that are present and detectable in MVs. For example, phosphorylated MV-associated RTKs in vivo can be detected. The results also demonstrate that a multiplicity of human tumour types can be analysed in this manner.

EXAMPLE 5

Demonstration of the Sustained Functional Status

(phosphorylation/activation) of MV-associated Cancer-related Proteins

We detected, in vitro, multiple phospho-RTKs in microvesicles released into culture medium by several types of human tumour cell lines, using a Phospho- Protein Antibody Array containing probes for 42 RTKs (R & D Systems) (Fig. 11). Fig. 11A lists examples of RTKs for which relative phosphorylation can be simultaneously detected in a single sample using the phospho-RTK antibody array; the array has 119 spots and can detect 42 different phosphorylated RTKs. Fig. 11 B shows major phospho-RTKs detected in MVs from the indicated cell lines. Examples of the assay output are given in Fig. 11C. The results indicate that numerous MV-associated phospho-proteins can be detected. Major MV-associated phospho-proteins include, for example, EGFR, FGFR3, EphB2, ROR1 , EphA2 and EphA4.

The cell lines used in this study represent stocks currently used in the laboratory and obtained from various sources (ATCC, collaborators), and may therefore differ in their molecular status from similarly named cell lines maintained elsewhere. In addition, it is noted that the results obtained depend on the specific antibodies used for this detection and the phospho-epitopes they target. The antibodies used in the array are unique and may have non- overlapping reactivity with other phospho-specific antibodies directed at the same RTKs. These results demonstrate that the receptor tyrosine kinases (RTKs) contained in microvesicles of cancer cells have sustained phosphorylation and therefore have a sustained activation and functional status.

We also performed large scale in vitro profiling of phospho-proteins contained or enriched in MVs released from EGFRvlll-driven GBM cells. A Kinex™ Antibody Microarray composed of over 650 different phospho site-specific antibodies for profiling cell signaling protein expression and phosphorylation was used (Kinexus, Inc.) The array can detect 248 unique phospho-specific antibody phosphorylation sites, 121 kinase phosphorylation sites, 2 phosphatase phosphorylation sites and 125 phosphorylation sites in regulatory subunits and other proteins. Using the KinexTM Antibody Microarray, we analyzed the phosphoproteome of MVs produced by human GBM cells. In order to identify EGFRvlll-dependent changes in the phosphoproteome of the MVs, both U373P (also referred to as parental U373) cells (non-transfected, non-tumorigenic cells) and U373vlll cells were used. In each case, the values obtained from MVs were normalized to values obtained from cells. Exemplary results are given in Tables 1 and 2 below, where the phospho-protein (P- Protein) is given in the left column and the Normalized Net Median Signal (NNMS) is given in the right column. The most abundant proteins found in the MVs are shown in Tables 1 and 2. Table 3 gives further examples of phosphoproteins detected in U373-MVs using the Kinex™ Antibody Array; these proteins represent a sampling of the over 200 phosphoproteins detected. Table 3.1 shows that phosphorylation of distinct sites, e.g. Y1068 or Y1110 of EGFR, can be monitored in the MVs.

The results indicate that there are numerous phosphorylated, and therefore activated, proteins in MVs, many of which are known to have a role and/or predictive value in cancer. In addition, the results presented herein using both the Kinex™ antibody array and the phospho-protein antibody array from R & D systems demonstrate that multiple oncogenic, signalling and biologically active molecular targets can be detected simultaneously in cancer cell derived MVs, both for MVs recovered from cell culture conditioned medium and for MVs recovered from the blood of mice harbouring human tumour xenografts.

Table 1. Kinex Arrays - MV-Associated Phosphoproteins with the Highest Net Normalized Median Signal (U373P-Cells vs U373P-MVs).

P-Protein Normalized Net Median Signal

BLNK 5079

BAD 8520

CrystalliaB 8499 elF4E 6455

MKK1 6244

PKB/Akt 5505

PKCg 5316

PLCgl 5025

Progesterone Receptor 5013

VEGFR2(KDR) Y1214 5065

VEGFR2(KDR) Y1214 5252

ZAP70/Syk 7160

ZAP70/Syk 7031 Table 2. Kinex™ Arrays - MV-Associated Phosphoproteins with the Highest Net Normalized Median Signal ( U373vlll-Cells vs. U373vlll-MVs).

P -Protein NNMS

MEK1 6003

MEK 8459

MARCK 6202

Tau (mtub)5270

IRS1 5064

IRS1 5947

Ret 5861

Jun 8782

Jun 6743

BAD 12142

BAD 5055

Erk-1 5314

MKK1 9113

HER-2 6389

HER-2 6252

HER-2 5779

HER-2 5399

PKCd 9078

PKCg 14431

PKCg 5999

PKCg 15696

PKCg 17197

PKCg 7949

PKCg 7013

Tau 5264

Tau 5117

Chk2 6002

EGFR 5929

EGFR 5958

EGFR 5250

VEGFR2 5117

Zap70/Syk 8242

Zap70/Syk 5796

FAK 5242

BLNK(lin) 1 1480 Table 3. Examples of phosphoproteins detected in U373-MVs. Antibody Target Protein Phospho Site Full Target Protein Name NNMS Codes Name (Human)

PN011 Bad S91 Bcl2-antagonist of cell death protein 8520.4

N024 CREB1 S133 cAMP response element binding protein 4935.8

PK121 EGFR T693 Epidermal growth factor receptor-tyrosine kinase 4807.0

PN030-1 elF4E S209 Eukaryotic translation initiation factor 4 (mRNA cap 6554.6 binding protein)

PK125 ErbB2 (HER2) Y877 ErbB2 (Neu) receptor-tyrosine kinase 4922.7

PK014- Erk1 T202+Y204; Extracellular regulated protein-serine kinase 1 (p44 4199.1 PK015-2 T185/Y187 MAP kinase)

PK019-1 FAK Y577 Focal adhesion protein-tyrosine kinase 3457.4

PN048-1 Jun S73 Jun proto-oncogene encoded AP1 transcription 5879.4 factor

PK046-3 MEK1 T291 MAPK ERK protein-serine kinase 1 (MKK1) 6244.5

PK116 mTOR (FRAP) S2448 Mammalian target of rapamycine (FRAP) 1 183.9

PN053 NFkappaB p65 S276 NF-kappa-B p65 nuclear transcription factor 1503.1

PK060-3 P38a APK T180+Y182 Mitogen-activated protein-serine kinase p38 alpha 1171.6

PK063 PDGFRa Y754 Platelet-derived growth factor receptor kinase alpha 2315.3

PK065 PDGFRb Y716 Platelet-derived growth factor receptor kinase beta 3369.6

PK073 PKCa S657 Protein-serine kinase C alpha 3019.3

PK079 PKCd S645 Protein-serine kinase C delta 4061.2

PK082-2 PKCg T514 Protein-serine kinase C gamma 4857.1

NN143 PLCg2 Y753 1-phosphatidylinositol-4,5-bisphosphate 2472.8 phosphodiesterase gamma-2

PN104 Progesterone S294 Progesterone receptor 5013.0

Receptor PP003 PTEN S380+S382+ Phosphatidylinositol-3,4, 5-trisphosphate 3- 1623.7

S385 phosphatase and protein phosphatase and tensin

homolog deleted on chromosome 10

PK098 Raf1 S259 Raf1 proto-oncogene-encoded protein-serine 2463.0 kinase

PN065 Rb T356 Retinoblastoma-associated protein 1 1331.6

PN074-2 Shd Y349+Y350 SH2 domain-containing transforming protein 1 2088.9

PN077 SOX9 S181 SRY (sex determining region Y)-box 9 3355.7

(campomelic dysplasia, autosomal sex-reversal)

PN078 STAT1 S727 Signal transducer and activator of transcription 1 2016.7

PK1 10 VEGFR2 Y1054 Vascular endothelial growth factor receptor- 3542.7

(KDR) tyrosine kinase 2 (Flk1 )

Histone H1 phospho Histone H1 phosphorylated 663.2

CDK1 sites

P27 Kip1 S10 p27 cyclin-dependent kinase inhibitor 1 B 27.9

Histone H2A.X S139 Histone H2A variant X 1558.5

BRCA1 S1423 Breast cancer type 1 susceptibility protein 4698.6

Hsp27 S15 Heat shock 27 kDa protein beta 1 (HspB1 ) 1428.5

Lck S157 Lymphocyte-specific protein-tyrosine kinase 2049.3

Caveolin 2 S36 Caveolin 2 977.9 p53 S392 Tumour suppressor protein p53 (antigen NY-CO- 1535.4

13)

IRS1 S639 Insulin receptor substrate 1 5064.2

Ret S696 Ret receptor-tyrosine kinase 5861.1

Rac1 S71 Ras-related C3 botulinum toxin substrate 1 2791.5

FAK S843 Focal adhesion protein-tyrosine kinase 4081.5

SMC1 S957 Structural maintenance of chromosomes protein 470.1

1A

Integrin a4 S988 Integrin alpha 4 (VLA4) 2846.1 p38a MAPK T180+Y182 itogen-activated protein-serine kinase p38 1817.2 alpha

ML 3 T277+S281 Mixed-lineage protein-serine kinase 3 2096.6

PKBa (Akt1 ) T308 Protein-serine kinase B alpha 2339.6

RSK 1/3 T359+S363/ Ribosomal S6 protein-serine kinase 1/3 130.0

T356+S360

MEK1 T385 MAPK/ERK protein-serine kinase 1 (MKK1 ) 4256.4 (MAP2K1)

C k2 T68 Checkpoint protein-serine kinase 2 6002.0

IR/IGF1 R Υ1 189ΛΊ 190 Insulin receptor/lnsulin-like growth factor 1 3420.7 (INSR) receptor

Met Y1230+Y123 Hepatocyte growth factor (HGF) receptor- 2459.8

4+Y1235 tyrosine kinase

CDK1/2 Y15 Cyclin-dependent protein-serine kinase 1/2 4737.5

Lck Y191 Lymphocyte-specific protein-tyrosine kinase 2272.8

Shd Y239 SH2 domain-containing transforming protein 1 2557.0

GSK3a Y279/Y216 Glycogen synthase-serine kinase 3 alpha 4249.1

Src Y529 Src proto-oncogene-encoded protein-tyrosine 3564.0 kinase

Kit Y703 Kit/Steel factor receptor-tyrosine kinase 1653.3

IR (INSR) Y972 Insulin receptor 2594.7

Table 3.1. Kin ex - Examples of Redundant and Non-Redundant Detection of Receptor (EGFR) Phosphorylation Sites In MVs Released by Cancer Cells (U373).

Target Protein Phospho Site Full Target Protein Name NN S

Name (Human) EGFR T693 Epidermal growth factor receptor-tyrosine kinase 4807.0

EGFR Y11 10 Epidermal growth factor receptor-tyrosine kinase 3966.1

EGFR Y11 10 Epidermal growth factor receptor-tyrosine kinase 3806.9

EGFR Y1197 Epidermal growth factor receptor-tyrosine kinase 1971.5

EGFR Y1 197 Epidermal growth factor receptor-tyrosine kinase 3521.4

EGFR T678 Epidermal growth factor receptor-tyrosine kinase 4535.8

EGFR T678 Epidermal growth factor receptor-tyrosine kinase 4001.3

EGFR T693 Epidermal growth factor receptor-tyrosine kinase 5929.1

These results indicate the spectrum of types of molecules that can be found in MVs in phosphorylated form. While this is an in vitro assay, it is noted that the spectrum of oncogene-related changes in MVs (some of which may be MV- associated but not necessarily oncogenic) is unexpectedly large.

The results also show that not only phosphorylation-dephosphorylation can be determined, but also the status of distinct phosphorylation sites can be monitored (e.g. Y1068 or Y1110 of the EGFR), which are responsible for different functions of the molecule (interactions with different targets, recycling etc). This information is readily available from analysis of MVs, whereas it would be difficult, and perhaps not possible, to obtain this information using a comparable analysis of tumour samples.

EXAMPLE 6

Determination of phosphoprotein profiles of MVs circulating in mice with

human tumour xenografts

Next, the human phosphoprotein profiles of MVs circulating in blood of mice harbouring human tumour xenografts was analyzed in vivo (Table 4; Figure 12). Xenografts of the indicated human cancer cell lines were generated in SCID mice by subcutaneous inoculation of cells. Tumours were allowed to form. When the tumours reached the endpoint of 17 mm in diameter, the mice were sacrificed and MVs were isolated from pooled plasma of 4-5 tumour bearing mice. Protein lysate was generated and used to probe the anti-human RTK Phosphoprotein Antibody Array from R & D Systems.

The results are given in Table 4 below, and an example of the RTK assay for circulating MVs from mice with an A431 xenograft is shown in Fig. 12. The results demonstrate that multiple phosphorylated RTKs are contained in circulating MVs in mice harbouring tumour xenografts representative of several types of human tumours, such as breast, colon, pancreas, prostate, lung, skin and brain tumours, and that these phosphorylated RTKs can be easily detected in the MVs.

Table 4. Phosphoprotein profiles of MVs circulating in blood of mice harbouring human tumour xenografts.

EXAMPLE 7

Demonstration that phosphorylation status of MV-associated RTKs is responsive to targeted therapy

In order to determine whether MVs can be used as biomarkers to monitor response to oncogene-directed therapeutics in vivo, we treated mice bearing EGFR-driven subcutaneous tumours with the EGFR inhibitor CI-1033 (Fig. 13). After 7 days of treatment with 20 mg/kg of CI-1033 administered intraperitoneally, the tumour size was measured in the mice (Fig. 13A) and Western blot analysis using anti-phospho-EGFR antibody was used to determine the phosphorylation status of EGFR in MVs circulating in the mice (Fig. 13B, with MVs from mice bearing A431 subcutaneous tumours shown on the top, and MVs from mice bearing U373vlll tumours shown on the bottom). Both A431 and U373vlll tumours were responsive to exposure to daily dosing of CI-1033. Moreover, there was a diminished presence of phosphorylated human EGFR in MVs circulating in blood of mice bearing EGFR-driven subcutaneous tumours and treated with the EGFR inhibitor CI-1033, as seen by Western analysis. The degree of EGFR inhibition was lower in the case of the mutant receptor EGFRvlll (U373vlll) compared to wild type EGFR (A431 cells), and this is reflected in differential antitumour effects. Our results demonstrate that the phosphorylation status of MV-associated active RTKs, which are oncogenic, is responsive to systemic targeted therapy directed at these receptors, and that status of these oncogenic targets may be monitored using a blood test based on isolating MVs and analyzing their content. These findings indicate that the circulating MVs can be used as biomarkers to monitor response to oncogene-directed therapeutics in vivo,

The contents of all documents and references cited herein are hereby incorporated by reference in their entirety.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.