Telix ProstACT Phase 3 Part 1 meets safety goals

Telix's TLX591-Tx combination therapy shows acceptable safety profile in mCRPC patients

Published on Mar. 9, 2026

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Telix Pharmaceuticals Limited announced that Part 1 of its ProstACT Global Phase 3 study for its therapeutic candidate TLX591-Tx (lutetium-177 rosopatamab tetraxetan) has achieved its primary objectives, demonstrating an acceptable safety and tolerability profile with no new safety signals observed. The study treated 36 patients with TLX591-Tx combinations, and the results will be presented to the FDA to seek an Investigational New Drug amendment to progress Part 2 of the study in the U.S.

Why it matters

Telix's TLX591-Tx is a first-in-class lutetium radio antibody-drug conjugate therapy that could provide a new treatment option for men with advanced prostate cancer. The positive Part 1 results support the feasibility of integrating TLX591-Tx with current standard of care therapies and demonstrate its potential to become a new first-line option for patients facing this aggressive disease.

The details

Part 1 of the ProstACT Global Phase 3 study confirmed the safety profile, biodistribution and dosimetry of TLX591-Tx administered in two doses, 14 days apart, in combination with one of three standard of care therapies: abiraterone, enzalutamide or docetaxel. The study showed an acceptable safety profile across the combination cohorts, with mostly low-grade non-hematologic events and transient and manageable hematologic events. Dosimetry data indicated no difference in absorbed dose profile across cohorts and no evidence of drug-drug interactions.

  • Part 1 of the ProstACT Global Phase 3 study dosed 36 patients.
  • Telix has already advanced the study into Part 2 - a 2:1 randomized treatment expansion - in jurisdictions where the clinical trial has obtained approval from health authorities.

The players

Telix Pharmaceuticals Limited

A global biopharmaceutical company focused on the development and commercialization of therapeutic and diagnostic radiopharmaceuticals and associated medical technologies.

Neeraj Agarwal, MD

Professor of Medicine and Presidential Endowed Chair of Cancer Research at Huntsman Cancer Institute, Salt Lake City, and ProstACT Global Principal Investigator and Steering Committee member.

David N. Cade, MD

Group Chief Medical Officer at Telix.

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What they’re saying

“These results reinforce the feasibility of integrating TLX591-Tx with current standard of care therapies for mCRPC, including ARPIs such as enzalutamide or abiraterone, or docetaxel. Hematologic events align with those typically seen in this patient population and therapeutic class, and these cases resolved quickly. The dosimetry profile, along with the low-grade nature of non-hematologic adverse events, further supports the tolerability profile of this investigational therapy.”

— Neeraj Agarwal, MD, Professor of Medicine and Presidential Endowed Chair of Cancer Research at Huntsman Cancer Institute, Salt Lake City, and ProstACT Global Principal Investigator and Steering Committee member (Telix Pharmaceuticals Limited)

“Despite advances in clinical practice, men with advanced prostate cancer still need improved first and second line treatment options. These results build on prior findings and highlight the potential for TLX591-Tx in combination with contemporary standard of care, to become a new first-line option for patients facing this aggressive disease. We are encouraged by the data and look forward to engaging with the FDA at the earliest opportunity, while continuing to advance enrollment in Part 2 in regions where clinical trial initiation has already been approved.”

— David N. Cade, MD, Group Chief Medical Officer, Telix (Telix Pharmaceuticals Limited)

What’s next

Telix plans to present the Part 1 data to the U.S. Food and Drug Administration (FDA) to seek an Investigational New Drug (IND) amendment to progress Part 2 of the ProstACT Global Phase 3 study in the U.S.

The takeaway

Telix's TLX591-Tx combination therapy has shown a promising safety profile in the first part of its Phase 3 ProstACT study, supporting its potential as a new first-line treatment option for men with advanced prostate cancer. The company is now poised to engage with the FDA and advance the study to the next stage in the U.S. and other regions where regulatory approvals have been obtained.