Enzalutamide Plus Talazoparib for the Treatment of Hormone Sensitive Prostate Cancer (ZZ-First)

Men age ≥ 18 years with high-volume mHNPC that are not candidates for curative intent and have not received previous systemic treatment with any other agent for unresectable locally advanced or mHNPC. After signing ICF and confirm eligibility, patients will start treatment with enzalutamide in addition to standard ADT. After 2 cycles of enzalutamide-containing regimen, patients will be randomized in a 1:2 ratio to: Cohort A - Enzalutamide 160 mg orally daily continuously; Cohort B - Enzalutamide 160 mg in combination with talazoparib (PF-06944076) 0.5 mg, both orally daily and continuously in 28-day cycles. In either arm, patients will be requested to continue ADT throughout trial participation (unless surgical castration). Randomization will be stratified based on HR gene alterations (presence versus absence/unknown) detected in the baseline biopsy. Patients will receive treatment until disease progression, unacceptable toxicity, death, or discontinuation from the study treatment for any other reason. Patients discontinuing the study treatment period will enter a post-treatment follow-up period during which survival and at least the first two new anti-cancer therapies will be collected every six months (± 14 days) from the last dose of investigational product until the end of study (EoS).