Starve-Pc: Biomarker-Driven Phase 2 Study Of Ipilimumab Plus Nivolumab For Ar-V7-Expressing Metastatic Castration-Resistant Prostate Cancer (Mcrpc).

TPS5089Background: AR-V7 is an AR splice variant present in ~20% of men with mCRPC, and is associated with poor responses to abiraterone and enzalutamide. Developing effective treatments for AR-V7+ mCRPC is an unmet medical need, and combined immune checkpoint blockade may be a fruitful approach in such pts. Previous studies have shown benefits using ipilimumab in a subset of mCRPC pts. Given that treatment of prostate cancer cells with potent anti-androgens may induce PD-L1 expression, and given that the AR-V7+ phenotype may be associated with DNA repair defects (mismatch repair, homologous recombination), we hypothesize that the addition of nivolumab in AR-V7+ mCRPC men will improve the response rates seen with ipilimumab, and that the combination will be safe and tolerable. We also hypothesize that successful treatment with this combination may correlate with conversion of AR-V7 from positive to negative, and with baseline PD-L1 expression in CTCs and tumor biopsies. Methods: STARVE-PC is a single-arm ...