Background: Prostate cancer is the second-leading cause of cancer death for men in the United States in 2013. Although relatively indolent compared to other epithelial malignancies, prostate cancer is lethal when untamed metastatic castration-resistant dissemination occurs. Mounting evidence suggests that non-mutated tyrosine kinase activation may be an important driver in metastatic castration-resistant prostate cancer (CRPC). We have previously identified a strong correlation between increased global tyrosine phosphorylation and prostate cancer progression both in a mouse model of prostate cancer and in human clinical samples. We identified several activated kinases using unbiased quantitative phosphopeptide proteomic analysis by tandem mass spectrometry of human metastatic CRPC tissues. Several of these identified kinases are direct targets of current Food and Drug Administration (FDA)-approved kinase inhibitors opening the door to investigate these kinases as viable therapeutic options.Objective/Hypothesis: Due to the overwhelming evidence for kinase activation in metastatic CRPC tissues, our objective is to utilize a targeted mass spectrometry (MS) approach known as selected-ion monitoring (SIM) for the evaluation of current druggable kinases in human CRPC biopsies that will ultimately guide personalized therapy decisions. We hypothesize that SIM MS can be effectively used for the stratification of CRPC patients based on detection of activated kinases in preclinical and biopsy tissues.Specific Aims: Aim 1: To establish quantitative methods to detect activated kinases for clinical diagnostics. Aim 2: To measure activated kinases in pre-clinical xenograft models of prostate cancer. Aim 3: To assess efficacy of targeted SIM MS in clinical CRPC tissues for personalized therapy.Study Design: In Aim 1, we plan to evaluate the kinases most potently inhibited by FDA-approved kinase inhibitors. We will synthesize over 50 and up to 100 phosphopeptide standards corresponding to these kinase activation sites, and we will establish methods to analyze these standards via SIM MS to set up our diagnostic pipeline. In Aim 2, we will use preclinical xenograft and the human primary tissue recombination cancer models to generate tumors and evaluate kinase activity using our phosphopeptide standards and SIM methods developed in Aim 1. The tumors will be harvested and biopsies will be taken and analyzed using targeted MS methods and will serve as valuable preclinical resources for the evaluation of resistance mechanisms to pharmacological inhibitors. In Aim 3, we will obtain metastatic CRPC biopsies in collaboration with an interventional radiologist and orthopedic surgeon from the University of California, Los Angeles (UCLA) using already established protocols from previous work that acquired biopsies from the Stand up to Cancer West Coast Dream Team (SU2C-WCDT). Activated kinases will be assessed in these tissues using targeted mass spectrometry to determine druggable kinase signatures.Clinical Impact: Metastatic CRPC represents the final stage of prostate cancer where successful treatment options are limited. Despite the recent approval of several novel therapies directed at androgen receptor function, these agents only extend overall survival by a modest 4-5 months, and predictive biomarkers for response to these treatments have not been established. To date, biopsy-driven, therapeutic efforts aimed at wild-type kinases that are activated for reasons other than genetic lesions to the kinase gene itself have not been undertaken. Because metastatic CRPC does not manifest frequent genetic mutations of kinase genes but does manifest kinase activation patterns that are common to a large proportion of cases, metastatic CRPC constitutes an ideal clinical model to test the notion that inhibition of activated wild-type kinases is a viable and effective treatment approach. In addition, advanced predictive tools and effective therapies are necessary to improve the clinical care of patients with metastatic CRPC. The development of a targeted mass spectrometry approach to measure a large panel of druggable, activated kinases in clinical tissues will represent a new clinical paradigm supporting phospho-kinase profiling to determine optimal treatment combinations in patients with metastatic CRPC.
Androgen Receptor; base; Biological Markers; Biological Markers; Biopsy; California; Cancer Etiology; Cancer Model; Cancer Patient; Castration; castration resistant prostate cancer; Cessation of life; Clinical; clinical care; Collaborations; Detection; Development; Diagnostic; DNA Sequence Alteration; Dreams; effective therapy; Epithelial; Evaluation; Genes; Harvest; Human; improved; Indolent; inhibitor/antagonist; kinase inhibitor; Lesion; Los Angeles; Malignant neoplasm of prostate; Malignant Neoplasms; Mass Spectrum Analysis; Measures; men; Methods; Modeling; mouse model; Mutate; novel; Orthopedics; Other Genetics; Patients; Pattern; personalized medicine; Phosphopeptides; Phosphotransferases; pre-clinical; Protein Tyrosine Kinase; Proteomics; Protocols documentation; radiologist; receptor function; Research Design; Resistance; resistance mechanism; Resources; response; Sampling; selected ion monitoring; Site; Staging; Stratification; Surgeon; tandem mass spectrometry; Testing; Therapeutic; Tissue Recombination; Tissues; tool; tumor; tumor progression; Tyrosine Phosphorylation; United States; United States Food and Drug Administration; Universities; Work; Xenograft Model; Xenograft procedure