ASCO 2026: Promising Phase 3 Data on Telix’s TLX591-Tx for mCRPC
Telix Pharmaceuticals recently presented notable findings from the first part of their global Phase 3 ProstACT trial at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting. The trial investigates TLX591-Tx, a lutetium-177 (177Lu) labeled radioantibody-drug conjugate developed for metastatic castration-resistant prostate cancer (mCRPC). The data presented focused on safety, dosimetry, and pharmacokinetics, showing favorable results for the candidate therapy in conjunction with standard-of-care (SoC) treatments.
Safety and Tolerability Insights
Presented by Dr. Pedro C. Barata from the University Hospitals Seidman Cancer Center, the data indicated that TLX591-Tx, when combined with either abiraterone, enzalutamide, or docetaxel, exhibited an acceptable safety and tolerability profile. No new safety signals emerged during the study. The patient cohort for this trial phase included 36 individuals with PSMA-positive mCRPC, previously treated with one androgen receptor pathway inhibitor. Among these, almost all adverse events, such as fatigue, nausea, and dry mouth, were low-grade. Hematologic adverse events such as thrombocytopenia and neutropenia occurred as expected and were largely transient.
Dosimetry and Pharmacokinetics Findings
The dosimetry data revealed that radiation exposure remained well below established safety limits, with the liver receiving the highest absorbed dose. Importantly, lesion dosimetry confirmed a broad uptake of TLX591-Tx across tumor sites in all treatment cohorts. Pharmacokinetic analyses showed sustained TLX591-Tx activity by Day 15 post-administration, with imaging further validating prolonged tumor retention. No significant drug-drug interactions affecting TLX591-Tx's pharmacological properties were observed.
Next Steps in the Trial
The positive outcomes from Part 1 set the stage for the randomized expansion planned in Part 2, which has now begun in multiple regions. Discussions with the U.S. Food and Drug Administration are in progress to advance the trial under an Investigational New Drug amendment in the country. The expansion seeks to further assess the potential of TLX591-Tx as a new therapeutic option for mCRPC, a condition still in need of improved treatment strategies.
Expert Commentary
Dr. Barata emphasized the potential of TLX591-Tx as a feasible addition to existing mCRPC therapies, noting that the therapy demonstrated promising tumor retention and manageable adverse event profiles during this initial phase. Dr. David N. Cade, Telix’s Chief Medical Officer, highlighted the urgent need for new therapeutic options in mCRPC and expressed optimism about TLX591-Tx’s potential, given the participant compliance and solid data presented.