Study to Assess [177Lu]Lu-PSMA-R2 (AAA602) and [225Ac]Ac-PSMA-R2 (AAA802) in Participants With PSMA-positive HRLPC

This Phase I/II study is intended to determine the safety, tolerability, anti-tumor activity, pharmacokinetics, and dosimetry of neoadjuvant treatment with the radioligand therapies (RLT) \[177Lu\]Lu-PSMA-R2 (AAA602) and \[225Ac\]Ac-PSMA-R2 (AAA802) before surgery, i.e., radical prostatectomy (RP) and pelvic lymph node dissection (PLND), in participants with Prostate-Specific Membrane Antigen (PSMA)-positive high-risk localized prostate cancer (HRLPC). Study CAAA802B12101 is a Phase I/II open-label, multi-center study investigating AAA602 and AAA802 as neoadjuvant RLTs before surgery in participants with PSMA-positive HRLPC. In Phase I, participants will be assigned to AAA602 or AAA802 dose escalation cohorts to determine the respective maximum tolerated dose (MTD) and/or the recommended dose for Phase II (RP2D). In Phase II, participants will be randomized to one or two investigational arms, i.e., the RP2D of AAA602 or AAA802, or to the control arm. Therefore, Phase II will have two or three treatment arms. In the control arm, participants will be treated with the standard of care (SoC), i.e., they will not receive any neoadjuvant treatment. Supportive care will be allowed. Following the last dose of completed RLT, participants will complete a post-treatment imaging/Safety follow-up visit. Upon discontinuation of RLT, participants will complete an end of treatment (EOT) visit prior to the post-treatment imaging/Safety follow-up visit. If participants undergo surgery, the post-treatment imaging/Safety follow-up visit will be performed before undergoing surgery. After surgery, participants will complete a post-surgery visit and enter the LTFU. No adjuvant treatment is allowed between surgery and biochemical recurrence (BCR). The investigational treatments in both Phases I and II are neoadjuvant treatment with AAA602 or AAA802 before surgery (RP and PLND). Surgery is to be performed as per the SoC and is not part of the investigational treatment in this study. The control treatment in Phase II is SoC, i.e., no neoadjuvant treatment.