Detection of Prostate Cancer Genomic Signatures in Blood

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DESCRIPTION (provided by applicant): This grant application addresses the Broad Challenge Area "03 - Biomarker Discovery and Validation" as described within this FAO (RFA-OD-09-003) and the Specific Challenge Topic "03-CA- 101 - Fingerprints for the early detection and treatment of cancer". The diagnosis of prostate cancer (PC) is usually subsequent to routine prostate-specific antigen (PSA) determination in blood and/or discovery of a palpable mass within the prostate (following rectal examination) that may be visualized by anatomic (US, CT) imaging. The nature of the primary masses is generally affirmed by histopathologic characterization following an invasive transrectal, ultrasound-directed, prostatic biopsy. At presentation, the majority of these tumors are localized in the prostate and surgical removal/radiation of these primary tumors can be curative. However, for many of the patients who develop metastases, despite current therapies, the outcome is death. A principal factor contributing to the high mortality rate is our inability to identify the presence of primary and metastatic occult PC lesions in men at the earliest/most curable stage, prior to the manifestation of pathologic signs and symptoms. While current blood-based assays (e.g., PSA) continue to play some role in diagnosis and in treatment monitoring, their specificity, sensitivity, and accuracy continue to be inadequate. We postulate that the false-positive and false-negative rates which have plagued this and other cancer assays are a consequence of their inadvertent dependence on population-derived, average genomic/ proteomic signature profiles that are obtained from the blood of "healthy" men, i.e., the baseline/ background signature(s) is/are NOT specific to the genetic makeup of the individual being tested. Recently, we proposed that phagocytic and nonphagocytic WBC - obtained from the same individual - are ideally suited to the facile identification and differentiation of "tumor-specific" and "normal- specific" signatures and, therefore, the elimination of the "inequality of baseline" consequent to the intrinsic interindividual (e.g., age, gender, ethnic background, health status) and temporal variation in gene expression. Uniquely, the approach does not depend on population-derived average signature profiles and/or biomarker values obtained from "healthy" controls. The approach claims that the analysis of DNA, RNA, protein, and/or lipid expression profiles of phagocytic WBCs and their comparison with those from nonphagocytic WBCs of the same donor will lead to the identification of tumor-specific signatures within the phagocytic cells (patient-specific signal) that are not expressed or minimally expressed in the nonphagocytic cells (patient-specific noise). Our preliminary studies in tumor-bearing mice and in a few cancer patients fully support our expectations and show that (i) multiple oncogenes and tumor-specific genomic signatures are selectively acquired/expressed within phagocytic cells; (ii) these genes are not expressed or are minimally expressed in nonphagocytic cells; and (iii) the assay - thus far in all instances - differentiates (a) tumor-bearing mice from non-tumor bearing mice, and (b) cancer patients from normal blood donors. In the studies proposed in this grant application, we plan to validate this unique approach in blood samples obtained from men known to have PC and demonstrate that the newly-developed novel blood assay (i) can differentiate between patients known to have PC and healthy individuals (blood donors), and (ii) will lead to the identification of genomic signatures that are specific to PC and are universally predictive of the presence of occult and/or recurring disease. We trust that our studies - upon successful verification of the blood assay in PC patients - will lead to the discovery of a gene array (spotted with the identified genomic signatures) that will (i) be used for the routine detection/diagnosis of PC, and (ii) be employed to identify disease recurrence. Consequently, we expect the blood test to have an unprecedentedly high impact on, and contribute significantly to, the goal of eradicating PC in the USA and worldwide. PROJECT NARRATIVE: The specificity, sensitivity, reproducibility, and/or accuracy of current blood-based cellular and molecular assays are inadequate. We postulate that the false-positive and false-negative rates that have plagued these assays are a consequence of their dependence on population-derived, average signature profiles obtained from the blood of "healthy" controls, i.e., the baseline/background signature(s) is/are NOT specific to the genetic makeup of the individual being tested. In this Challenge grant application, we describe methods for the identification of tumor-specific signatures within the WBCs of men known to have prostate cancer.