Telix Pharmaceuticals (ASX:TLX) has announced that the first patient has been dosed in its Phase 3 ProstACT GLOBAL study of its investigational prostate-specific membrane antigen (PSMA) targeting radio-antibody drug conjugate (rADC) therapy, TLX591 (177Lu-rosopatamab tetraxetan).
TLX591 is a rADC composed of a high-specificity PSMA-targeting antibody, chelator linker, and cytotoxic lutetium ( 177Lu) payload.
The company said the PSMA-targeted monoclonal antibody (mAb) approach offers significantly different targeting and pharmacology to anti-PSMA small molecules.
ProstACT GLOBAL is the first Phase III trial to evaluate TLX591 in adult patients with PSMA-positive metastatic castrate-resistant prostate cancer (mCRPC) administered together with Standard of Care (SoC, androgen receptor inhibition or taxanes) versus SoC alone.
The company said the ProstACT GLOBAL has an overall target enrolment of around 400 patients, with the first dose successfully administered at GenesisCare's centre at the St John of God Hospital Murdoch campus in Australia.
The study is expected to expand internationally, subject to regulatory approvals, including in Europe and the US.
Telix said the planned US arm of the study will also incorporate a run-in to bridge manufacturing data to a new commercial-scale process. An interim analysis is expected after the first 120 patients.
According to Dr Colin Hayward, Telix group chief medical officer, “Dosing a first patient in the ProstACT GLOBAL study is a significant milestone for Telix and will help build on an already extensive data set for this product candidate. The current TLX591 experience underlines the potential benefits of an antibody-based approach in combination with real world standards of care, including physician choice of ARPI5 or taxane. As we take this potential first-in-class rADC candidate into a large, midstage patient population for the first time, we would like to thank Professor Lenzo and his clinical team, as well as the patients who will contribute to the study.”