OPTIMAL-PSMA Trial of TLX597-Tx Next Generation RLT Presented at IPCS 2026 Highlighting Therapeutic Potential in Prostate Cancer

Melbourne (Australia) and Indianapolis, IN (United States) | April 30, 2026

  • TLX597-Tx is a PSMA[1]-targeting small molecule radioligand therapy (RLT) candidate, designed to improve quality-of-life and efficacy in earlier-stage prostate cancer.
  • OPTIMAL-PSMA[2] initial dosimetry data demonstrate low salivary gland and kidney uptake, supporting dose intensification.
  • Telix is developing two distinct prostate therapeutic programs, tailored to disease stage and patient condition: TLX591-Tx radio antibody-drug conjugate (rADC) in combinations with standard of care (Phase 3 in mCRPC[3]) and TLX597-Tx intended for earlier-stage mHSPC[4].

Telix today announces dosimetry results from the randomized Phase 2 OPTIMAL-PSMA trial of TLX597-Tx in metastatic castration-resistant prostate cancer (mCRPC), presented at the 2026 International Prostate Cancer Symposium (IPCS 2026) held in Lugano, Switzerland. These findings support TLX597-Tx’s potential to deliver a treatment that overcomes quality-of-life challenges that currently limit the clinical utility of existing RLTs in earlier-stage metastatic prostate cancer.

TLX597-Tx (177Lu-DOTA-HYNIC-panPSMA) is a novel PSMA-targeting small molecule RLT candidate with a highly favorable dosimetry profile. Significantly reduced radiation exposure to healthy organs, including the salivary glands and kidneys[5], may lower the incidence of xerostomia (dry mouth) and renal toxicity and support better tolerability for patients. This dosimetry profile combined with higher tumor uptake compared to existing PSMA RLTs may deliver a wider therapeutic window and enable dose intensification to maximize tumor control while preserving patient quality-of-life.

OPTIMAL-PSMA is an open-label, multi-center, randomized, Phase 2 investigator-initiated trial (IIT) led by Professor Louise Emmett at St Vincent’s Hospital in Sydney, Australia. The study is evaluating the safety, dosimetry, and efficacy of an intensified dosing regimen of TLX597-Tx compared with a standard dose schedule in 120 men with advanced mCRPC, randomized on a 2:1 basis. The novel dose-intensification regimen delivers higher activity per cycle (8.5 GBq), delivered on day 1, day 3 and day 15, followed by 10-weekly dosing for three further cycles. The study aims to confirm that a dose intensified TLX597-Tx regimen will maximize the radiation dose to cancerous lesions when they are most vulnerable to damage and therefore improve overall response to treatment.

Telix believes these dosimetry data support further evaluation of TLX597-Tx in earlier-stage disease and is initiating OPTIMAL-E, a Phase 2 study in androgen pathway-sensitive prostate cancer (mHSPC).

Principal Investigator for OPTIMAL-PSMA, Professor Louise Emmett, commented, “The goal of OPTIMAL-PSMA is to identify a dose regimen for TLX597-Tx that leads to deeper and longer responses without increasing toxicity for men with metastatic prostate cancer. We look forward to starting the Phase 2 OPTIMAL-E trial soon.”

Dr. David N. Cade, Group Chief Medical Officer at Telix, added, “These encouraging dosimetry results from OPTIMAL-PSMA, combined with earlier exploratory work[6], are very promising and highlight TLX597-Tx’s potential to substantially increase the tumor dose while minimizing radiation to sensitive organs. For people living with earlier-stage metastatic disease, preserving quality-of-life alongside effective cancer control is mandatory. These findings support further study in mHSPC and reinforce Telix’s strategy to develop differentiated PSMA-targeting therapies, so clinicians may be able to tailor treatment choice to the patient’s disease stage and individual condition.”

TLX597-Tx is being developed alongside TLX591-Tx (lutetium-177 (177Lu) rosopatamab tetraxetan), Telix’s lead antibody-based prostate cancer therapy candidate, currently the subject of the Phase 3 ProstACT Global[7] trial in mCRPC, which is actively dosing patients in jurisdictions with regulatory approval and recently reported data from a safety and dosimetry lead-in[8]. TLX591-Tx and TLX597-Tx exhibit complementary modes-of-action, suggesting the potential for distinct applications in mCRPC and mHSPC settings as part of Telix’s portfolio approach to treating prostate cancer.

TLX591-Tx and TLX597-Tx have not received marketing authorization in any jurisdiction.

To view the webcast slides, click here.

[1] Prostate-specific membrane antigen.

[2] Australian New Zealand Clinical Trials Registry ID: ACTRN12625000971437.

[3] Metastatic castration-resistant prostate cancer.

[4] Metastatic hormone-sensitive prostate cancer.

[5] Steinhelfer et al. J Nucl Med. 2024.

[6] Omar et al., presented at the European Association of Nuclear Medicine 2025 Annual Congress.

[7] ClinicalTrials.gov ID: NCT06520345.

[8] Telix ASX disclosure March 10, 2026.