Telix wins FDA alignment to open ProstACT Global Phase 3 in US
Telix Pharmaceuticals has secured a positive outcome from a Type B meeting with the US Food and Drug Administration, clearing the path for the company to expand Part 2 of its ProstACT Global Phase 3 trial into the United States. The Melbourne and Indianapolis-based radiopharmaceutical company said the FDA confirmed that safety and dosimetry data from Part 1 of the study are sufficient to support US enrolment of the randomised cohort.
The candidate at the centre of the trial is TLX591-Tx, generically known as lutetium-177 rosopatamab tetraxetan, which targets prostate-specific membrane antigen (PSMA) via an antibody-based mechanism. Part 2 of the trial randomises approximately 490 patients with metastatic castration-resistant prostate cancer (mCRPC) in a 2:1 ratio, with TLX591-Tx administered in two doses 14 days apart in combination with one of three standard-of-care regimens: abiraterone, enzalutamide, or docetaxel.
FDA alignment and next steps
The FDA and Telix agreed on the Part 2 clinical protocol, statistical analysis plan, and ongoing safety monitoring framework. Telix now needs to file an Investigational New Drug amendment before US recruitment can formally begin, and the company said the IND submission will be aligned with a parallel regulatory filing to open the study in Europe.
Part 2 is already recruiting in Australia, New Zealand, Canada, Türkiye, and the United Kingdom, and has received regulatory approval to commence in China, Singapore, and South Korea.
David N. Cade, Group Chief Medical Officer at Telix, said the outcome "enables submission of our IND amendment for initiation of Part 2 of ProstACT Global in the US," and noted that enrolment is proceeding strongly in regions where recruitment is already open.
Neeraj Agarwal, Professor of Medicine and Presidential Endowed Chair of Cancer Research at Huntsman Cancer Institute, and ProstACT Global Principal Investigator, argued that the candidate's compressed dosing window could make it easier to sequence into existing regimens: "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."
Competitive context in the PSMA radioligand space
The radiopharmaceutical therapy segment for mCRPC has grown sharply since Novartis's lutetium-177 PSMA-617 (Pluvicto) received FDA approval in 2022. That programme demonstrated the commercial viability of PSMA-targeted radioligand therapy but uses a small-molecule targeting vector, which Telix argues differs meaningfully from TLX591-Tx's antibody-based approach. Telix's own published follow-up data suggest the antibody format offers a differentiated excretion profile, with hepatic rather than renal clearance, and reduced uptake in salivary and lacrimal glands. Those properties, if confirmed in the Phase 3 setting, could translate into a more favourable tolerability profile relative to existing PSMA-targeted therapies, though a head-to-head comparison has not been conducted.
The broader PSMA-targeted pipeline is expanding, with several academic centres and smaller biotechs pursuing next-generation constructs. Telix's decision to combine TLX591-Tx with three distinct standard-of-care backbones in a single randomised trial is an ambitious design that, if successful, could support broad commercial positioning across different treatment sequences in mCRPC.
Telix's commercial base currently rests on its PSMA-PET imaging portfolio, Illuccix and Gozellix, which are approved across 22 countries. The company also has pivotal-stage programmes in recurrent glioblastoma and kidney cancer. Investors will track the IND amendment timeline and US site activation as the next near-term milestones for ProstACT Global.