Study of AMG 509 in Participants With Metastatic Castration-Resistant Prostate Cancer

Inclusion criteria

• ✓. Dose exploration phase: Novel antiandrogen therapy must have been given for treatment of metastatic disease.
• ✓. Dose-expansion phase: participants must not have had more than 2 NHTs and 2 taxane regimens in any setting, and an additional up to 2 other systemic anti-cancer treatments are allowed (eg, anti-PD1, PARP inhibitors, radioligand therapies, sipuleucel-T, experimental agents) Note: Combinations are considered one systemic anti-cancer treatment.
• ✓. Participants with histologically or cytologically confirmed mCRPC who have received no or 1-2 prior NHTs (given in any disease setting depending on the part), and no or 1 taxane regimen (for HSPC).
• ✓. Dose-expansion phase: at least 1 prior NHT must have been given; 0-1 prior PARP inhibitors are acceptable.
• ✓. 4A: Participants planning to receive abiraterone acetate for the first time (participants who received prior abiraterone acetate are not eligible). Participants may have had exposure to up to 2 NHTs with a similar mechanism of action (apalutamide, enzalutamide or darolutamide) in the non-mCRPC and mCRPC setting.
• ✓. Prior disease progression on 1, and only 1, NHT (either enzalutamide, apalutamide, or darolutamide) is required. NOTE: Prior progression on or intolerance to abiraterone is not allowed.
• ✓. No prior treatment with any chemotherapy regimen in the mCRPC setting; ≤ 6 cycles of docetaxel treatment in the mHSPC setting is allowed.
• ✓. mCRPC with ≥ 1 RECIST v1.1 measurable lesion that is present on baseline computed tomography (CT) or magnetic resonance imaging (MRI).