ProstACT Global Phase 3 Study (Part 1) Achieves Primary Objectives

Core Viewpoint - Telix Pharmaceuticals Limited has successfully achieved the primary objectives of Part 1 of the ProstACT Global Phase 3 study for its therapeutic candidate TLX591-Tx, demonstrating an acceptable safety and tolerability profile with no new safety signals observed [1][5]. Study Findings - Part 1 confirmed the safety profile, biodistribution, and dosimetry of TLX591-Tx administered in two doses, 14 days apart, in combination with standard of care therapies: abiraterone, enzalutamide, or docetaxel [2][5]. - The patient population consisted of prostate-specific membrane antigen (PSMA) positive metastatic castration-resistant prostate cancer (mCRPC) patients previously treated with one androgen receptor pathway inhibitor (ARPI) [2][5]. Trial Design - ProstACT Global is a differentiated Phase 3 trial comparing PSMA-targeted 177Lu-rADC therapy administered with standard of care versus standard of care alone, reflecting current global clinical practice [3]. - The study has advanced into Part 2, a 2:1 randomized treatment expansion, in regions where clinical trial approval has been obtained [3]. Expert Commentary - Neeraj Agarwal, MD, noted that the results support the feasibility of integrating TLX591-Tx with current standard therapies for mCRPC, with hematologic events aligning with expectations and resolving quickly [4]. - David N. Cade, MD, emphasized the need for improved treatment options for advanced prostate cancer and highlighted the potential of TLX591-Tx to become a new first-line option [4]. Summary Results - A total of 36 patients were dosed in Part 1, with an acceptable safety profile observed across combination cohorts [5][6]. - The tolerability profile was supported by dosimetry and low-grade non-hematologic events, with no adverse drug-drug interactions observed [6][15]. Dosimetry and Biodistribution - Lesion dosimetry indicated no difference in absorbed dose profile across cohorts, and radiation exposure to key organs was well below established safety limits [6][15]. - Pharmacokinetics demonstrated sustained activity at 15 days, corroborated by imaging showing prolonged tumor retention [15]. Additional Information - ProstACT Global is an international, multicenter trial with an overall target enrollment of approximately 490 patients, focusing on confirmed progressive mCRPC assessed with a 68Ga-PSMA-11 PET imaging agent [9][24]. - TLX591-Tx has not yet received marketing authorization in any jurisdiction [12].