Telix Pharmaceuticals Ltd Wins FDA Alignment for US ProstACT Phase 3 Trial
Telix secures FDA alignment to advance ProstACT Global Phase 3 into the US
Telix Pharmaceuticals (ASX: TLX, NASDAQ: TLX) has secured alignment with the United States Food and Drug Administration (FDA) to advance into Part 2 of its ProstACT Global Phase 3 trial in the US, following a successful Type B meeting.
The agreement covers TLX591-Tx (lutetium-177 (177Lu) rosopatamab tetraxetan), a therapeutic candidate targeting metastatic castration resistant prostate cancer (mCRPC). The FDA confirmed that safety and dosimetry data from Part 1 is sufficient to enable progression into the next stage of the study.
ProstACT Global Phase 3 Part 1 confirmed an acceptable safety and tolerability profile across all 36 patients, with no new safety signals observed across the three standard-of-care combinations and a differentiated biodistribution profile showing liver-based clearance and minimal salivary and kidney uptake.
For investors, the outcome de-risks a pivotal-stage asset and opens the pathway toward recruitment in the world’s largest pharmaceutical market. It marks a clear regulatory step forward for one of Telix’s three late-stage therapeutic programmes.
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What the FDA alignment covers
The Type B meeting produced alignment across several core elements of the study’s execution. According to Telix, the FDA agreed on the following points:
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Part 1 safety data is sufficient to progress to Part 2 in the US
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Alignment on the Part 2 clinical trial protocol
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Alignment on the statistical analysis plan
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Alignment on the ongoing safety monitoring plan
Under the Part 2 regimen, TLX591-Tx is administered in two doses, 14 days apart, in combination with one of three randomised standard-of-care (SOC) therapies: abiraterone, enzalutamide or docetaxel. The result is a consistent framework as enrollment continues internationally and expands into the US.
Importantly, US initiation remains subject to the FDA’s review of an Investigational New Drug (IND) amendment. The IND amendment will also be aligned with a pending regulatory submission to initiate the ProstACT Global study in Europe.
David N. Cade, MD, Group Chief Medical Officer, Telix
“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.”
Understanding radiopharmaceutical therapy and why TLX591-Tx stands apart
Telix operates in the field of theranostics, which pairs a precision diagnostic with a targeted therapy to both diagnose and treat disease. In prostate cancer, this involves imaging a tumour to confirm a specific target, then delivering a treatment designed to act on that same target.
A key target in prostate cancer is prostate-specific membrane antigen (PSMA), a protein found on the surface of cancer cells. PSMA-targeted radioligand therapy (RLT) delivers a radioactive payload directly to cells carrying that protein.
TLX591-Tx uses an antibody-based approach, which Telix states demonstrates differentiated targeting and pharmacology compared to PSMA-targeted small-molecule RLTs. According to the company’s clinical data and cited references, the differentiators include:
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No significant acute or delayed kidney toxicity observed in collective long-term follow-up, as the agent is hepatically (liver) excreted, a comparatively radioresistant organ
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Minimal salivary and lacrimal gland uptake, reducing the prevalence of xerostomia (dry mouth) and dry eye, which are typical adverse effects of existing PSMA-targeted RLTs
Neeraj Agarwal, MD, Professor of Medicine and Presidential Endowed Chair of Cancer Research, Huntsman Cancer Institute, and ProstACT Global Principal Investigator and Steering Committee member
“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.”
Inside the ProstACT Global trial design
The ProstACT Global study is structured as a two-part international trial. The snapshot below outlines its key parameters.
| Parameter | Detail |
|---|---|
| Trial name / ID | ProstACT Global (NCT06520345) |
| Design | International, multicentre, two-part study |
| Part 1 | Safety and dosimetry lead-in, 36 patients (complete) |
| Part 2 | 2:1 randomised global expansion |
| Target enrollment | Approximately 490 patients |
| Eligibility | Confirmed progressive mCRPC, assessed with 68Ga-PSMA-11 PET imaging (such as Illuccix® or Gozellix®), following prior treatment with one ARPI |
Part 2 is currently enrolling patients across several jurisdictions, with additional regions approved to commence recruitment.
Currently enrolling:
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Australia
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New Zealand
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Canada
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Türkiye
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United Kingdom
Approved to commence:
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China
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Singapore
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South Korea
Notably, trial eligibility utilises 68Ga-PSMA-11 PET imaging agents, such as Telix’s Illuccix® or Gozellix®, to confirm patient suitability.
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Why this matters for the Telix investment case
The FDA alignment reinforces Telix’s position as a commercial-stage global radiopharmaceutical company advancing targeted theranostics across the cancer patient journey. The advancement of TLX591-Tx sits within a broader late-stage pipeline of pivotal-stage assets:
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TLX591-Tx — prostate cancer
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TLX101-Tx — recurrent glioblastoma
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TLX250-Tx — kidney cancer
This therapeutic pipeline is complemented by an established commercial franchise anchored in prostate cancer imaging. Illuccix® is commercially available in 22 countries including the US, while Gozellix®, the company’s next-generation PSMA-PET imaging agent, has been approved by the US FDA.
Looking ahead, the disclosed regulatory steps centre on three areas:
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Submission of the IND amendment for US Part 2 initiation
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Continued international enrollment while awaiting FDA review of the IND amendment
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A pending regulatory submission to initiate ProstACT Global in Europe
With Part 1 complete and the Part 2 framework now aligned with the FDA, Telix has moved a pivotal-stage asset a step closer to the US market. The next milestones rest on the IND amendment and the pending European submission, keeping the ProstACT Global programme on a defined regulatory pathway.
For investors exploring how ProstACT Global fits within Telix’s broader operational momentum, our full explainer on Telix Q1 2026 revenue and pipeline milestones walks through the US$230 million Q1 result, full-year guidance of US$950 million to US$970 million, and the concurrent progress across all four active clinical programmes.
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