Open-Label Study of Pocenbrodib Alone and in Combination With Abiraterone Acetate, Olaparib, or 177Lu-PSMA-617

This is a dose-finding study to assess the safety and preliminary antitumor activity of Pocenbrodib alone or with Abiraterone acetate, Olaparib or 177Lu-PSMA-617 in patients with metastatic castration-resistant prostrate cancer (mCRPC).

This is a Phase 1b/2a multicenter, open-label study to confirm the safety, pharmacokinetics (PK), preliminary antitumor activity, and pharmacodynamics (PD) of pocenbrodib for the treatment of participants with mCRPC who have progressed despite prior therapy and have been treated with at least 1 potent anti-androgen therapy (enzalutamide, apalutamide, abiraterone acetate, or darolutamide). The Phase 1b portion of the study involves pocenbrodib monotherapy at multiple, sequential five rising doses (50, 100, 150, 200, and 250mg) initially using a QD dosing schedule of 5 days on/2 days off. The first dose level (50 mg) will enroll at least 3 participants (with 3 more added if the first 3 participants yield 1 dose-limiting toxicity). Once safety is confirmed through Data Review Committee (DRC), the next higher pocenbrodib dose level cohort can begin enrollment. If both acceptable safety and minimal threshold of efficacy (predefined as 30% PSA50 are achieved, the sponsor will proceed to Phase 2a. Phase 2a will enroll participants in each of 4 cohorts: pocenbrodib monotherapy (2A), and 3 combination therapy cohorts: pocenbrodib + abiraterone acetate (2B), pocenbrodib + olaparib (2C), and pocenbrodib + 177Lu-PSMA-617 (2D). All cohorts may enroll in parallel, but each cohort will be evaluated independently for safety and efficacy.

Key Inclusion Criteria: 1. ≥18 years of age 2. Histologic documentation of prostate adenocarcinoma 3. Metastatic disease, documented by imaging. Imaging performed within 56 days prior to Screening is acceptable Key Exclusion Criteria: 1. Current or prior evidence of any small cell or neuroendocrine histology on the most recent prostate biopsy 2. Any liver metastases confirmed by biopsy or evidence of lesions \>1 cm consistent with liver metastases on imaging 3. Intervention with any chemotherapy, investigational agent, or other anticancer drug, including enzalutamide, apalutamide, or darolutamide, 14 days prior to Screening or 5 half-live20. 4. Any other serious underlying medical, psychiatric, psychological, familial, or geographical condition, which in the judgment of the Investigator may interfere with study participation and compliance or place the participant at high risk from treatment-related complicationss from the last dose (whichever is shorter)