A two part, Phase 1 dose escalation and expansion followed by randomized Phase 2, multicenter, study to assess the safety and efficacy of the combination of tulmimetostat (DZR123) and JSB462 (ARV-766) vs standard of care in participants with progressive metastatic castrate resistant prostate cancer

The Phase I study, comprised of Parts 1a and 1b, aims to assess the safety and tolerability of the combination of tulmimetostat (DZR123) and JSB462 (also known as luxdegalutamide). Part 1a is the parallel dose escalation that aims to determine the recommended dose(s) of tulmimetostat and JSB462, in combination, for further exploration. Part 1b is the dose expansion/optimization that aims to determine the recommended dose of the combination for Phase II. The purpose of the Phase II study (Part 2) is to compare the combination of tulmimetostat with JSB462 in terms of the biochemical response as assessed by PSA50 compared to the standard of care (SoC) in adult men with progressive, taxane-naive mCRPC