Telix Pharmaceuticals (ASX:TLX) has taken another step in its push to bring novel radiopharmaceutical therapies to men with advanced prostate cancer, confirming that the first patient has now been treated in the randomised expansion phase of its pivotal ProstACT Global Phase 3 trial.
The patient was dosed at the Australian Prostate Centre in Melbourne, marking the official start of Part 2 of the study, which will recruit around 490 patients across Australia, New Zealand and Canada, with further global expansion planned.
The trial is evaluating Telix’s lead therapeutic candidate TLX591, a PSMA-targeted radio antibody drug conjugate, in men with metastatic castration-resistant prostate cancer (mCRPC).
ProstACT Global is the first Phase 3 clinical study to combine a PSMA-targeting radio-antibody therapy with standard of care treatments such as abiraterone, enzalutamide or docetaxel, comparing performance against standard care alone.
Telix said preliminary data from Part 1, the safety and dosimetry lead-in component, will be presented to both the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) “in the coming months” as part of regulatory engagements to support the trial’s geographic expansion.
“Dosing the first patient into Part 2 of the randomised treatment expansion of ProstACT Global is a significant milestone for Telix’s late-stage prostate cancer therapeutics pipeline,” said Dr David N. Cade, Telix’s Group Chief Medical Officer. “We look forward to presenting the preliminary data from Part 1 of the study to the FDA and EMA in the coming months.”
The company has approvals to commence the study in multiple additional jurisdictions, including China, Japan, Singapore, South Korea, Türkiye and the United Kingdom, and will soon file a clinical trial application with the EMA to allow European sites to join.
TLX591 is distinct from existing small-molecule PSMA radioligand therapies. Due to its large-molecule antibody structure, TLX591 shows minimal salivary and lacrimal gland uptake, potentially reducing side effects such as dry mouth and dry eyes that are commonly associated with current PSMA-targeted radiotherapies. TLX591 is cleared through the liver rather than the kidneys, meaning long-term follow-up of treated patients has not shown the kidney toxicity often seen with other radioligand therapies.