A new Phase II/III clinical trial, designated as study CAAA817A12201, is underway to assess the efficacy and safety of the investigational Actinium-based drug AAA817 (225Ac-PSMA-617) in adult patients with prostate-specific membrane antigen (PSMA)-positive metastatic castration-resistant prostate cancer (mCRPC). This study targets individuals who have previously undergone treatment with androgen receptor pathway inhibitors (ARPI) and taxane-based chemotherapy, and whose disease has progressed following 177Lu-PSMA targeted therapy.

The trial is structured in two parts:

1. Phase II: A randomized, open-label, international, multicenter study aimed at gathering additional data to support the proposed dosing regimen of AAA817.
2. Phase III: A randomized, open-label, international, multicenter, two-arm study designed to evaluate the efficacy and safety of the proposed AAA817 dose compared to the investigator’s choice of standard of care (SoC) treatments.

Participants in the investigational arm will receive AAA817, while those in the control arm will receive the investigator’s choice of SoC therapy. The primary objective is to determine the recommended Phase III dose of AAA817 and to assess its effectiveness relative to current standard treatments.