TALAPRO-2: A two-part, placebo-controlled phase III study of talazoparib (TALA) with enzalutamide (ENZA) in metastatic castration-resistant prostate cancer (mCRPC).

TPS337Background: ENZA is approved to treat men with CRPC. TALA is a poly(ADP-ribose) polymerase (PARP) inhibitor that inhibits PARP1/PARP2 and traps PARP on DNA, preventing DNA damage repair (DDR), and causing cell death in BRCA1/2-mutated cells. TALA is approved in the US to treat germline BRCA1/2-mutated HER2- locally advanced/metastatic breast cancer. A combination of TALA with ENZA in mCRPC may improve clinical outcomes. Methods: Eligible patients (pts) in parts (P) 1 and 2 of this study are aged ≥18 years; have asymptomatic/mildly symptomatic mCRPC, ECOG PS ≤1, and no brain metastases; and have not received taxanes/novel hormonal therapy (NHT). P1 is an open label study to confirm the starting dose of TALA to be given in combination with ENZA. P2 is a randomized double-blind study that will evaluate the safety, efficacy and pt reported outcomes of TALA (0.5 mg QD) + ENZA (160 mg QD) vs placebo + ENZA in 2 cohorts (C). C1: pts with mCRPC (all comers) (N = 560); C2: pts with DDR gene mutations likely ...