A Phase II Study of AAA617 Alone and AAA617 in Combination With ARPI in Patients With PSMA PET Scan Positive CRPC

All participants will be assessed for eligibility and will undergo baseline disease assessments including a mandatory gallium \[68Ga\] gozetotide (hereinafter referred to as AAA517) or piflufolastat (18F) (also known as\[18F\]DCFPyL) PET/CT scan and conventional imaging (i.e., CT/MRI and bone scans). Piflufolastat- (18F) PET/CT scan will be performed in US only. The treatment duration will be up to 6 cycles of AAA617, treatment will be administered once every 6 weeks (duration of 1 cycle). Participants randomized to Arm B may continue to receive ARPI after second end of treatment (EOT2) outside the study protocol at the investigator's discretion and in accordance with local guidelines. The visit frequency will be every week 1 and week 4 of each of the 6 cycles and every 16 weeks thereafter (for both arms) until the first event of disease progression (RECIST 1.1) or until global end of study (EOS), whichever comes first. After cycle 1 the safety visit at week 4 is optional onsite and could be paired with efficacy assessments or handled remotely. No biomarker collections are expected after the last end of trial (EOT) visit is completed. The study duration will be approximately 36 months.