Telix Pharmaceuticals has received FDA agreement on the protocol and statistical framework for Part 2 of its global Phase 3 ProstACT trial evaluating TLX591-Tx in patients with metastatic castration-resistant prostate cancer (mCRPC).

The company said a Type B meeting with the FDA reviewed safety and dosimetry data from Part 1 of the study and plans for the randomized Part 2 portion of the trial. The agency confirmed that the Part 1 safety data are sufficient to support progression into Part 2 in the United States, subject to review of an Investigational New Drug (IND) amendment.

Part 2 of ProstACT Global is designed to evaluate TLX591-Tx, also known as lutetium-177 rosopatamab tetraxetan, administered in two doses 14 days apart alongside one of three standard-of-care therapies: abiraterone, enzalutamide or docetaxel.

According to Telix, the FDA also agreed with the Part 2 clinical protocol, statistical analysis plan and ongoing safety monitoring framework. The company said this alignment will allow a consistent approach as patient recruitment continues internationally and expands into the US.

David Cade, group chief medical officer at Telix, said: “This is an excellent outcome that enables submission of our IND amendment for initiation of Part 2 of ProstACT Global in the U.S. Part 2 continues to enroll strongly in regions where recruitment is open.”

The ProstACT Global study is an international multicentre trial being conducted in two parts. Part 1 enrolled 36 patients in a safety and dosimetry lead-in phase, which has now been completed. Part 2 is a 2:1 randomized expansion phase targeting approximately 490 patients worldwide.

Eligible participants must have progressive mCRPC confirmed using a PSMA PET imaging agent following previous treatment with an androgen receptor pathway inhibitor.

The trial is investigating whether the antibody-based radiopharmaceutical approach can provide an additional treatment option for patients with advanced prostate cancer. Radiopharmaceutical therapies have become an increasingly important area of oncology research, particularly in prostate cancer, where PSMA-targeted treatments are being evaluated across multiple stages of disease.

Neeraj Agarwal, professor of medicine and presidential endowed chair of cancer research at Huntsman Cancer Institute and principal investigator of ProstACT Global, said: “TLX591-Tx has the potential to redefine how radiopharmaceutical therapy is integrated into clinical practice. Because the complete treatment course is delivered over approximately two weeks, physicians can layer it into an existing regimen with minimal interruption, providing greater flexibility to sequence therapies while preserving future treatment options in patients with metastatic prostate cancer.”

Initiation of Part 2 in the US remains dependent on FDA review of the IND amendment. Telix said the submission will also be aligned with a planned regulatory filing intended to support the study’s expansion into Europe.