First Patients Dosed in Optimal-e Trial for Earlier Stage Prostate Cancer

Melbourne (Australia) and Indianapolis, IN (United States) | July 16, 2026

  • First patients dosed in OPTIMAL-e[1] Phase 2 study evaluating TLX597-Tx for metastatic hormone-sensitive prostate cancer at St Vincent’s Hospital Sydney.
  • OPTIMAL-e will evaluate TLX597-Tx in earlier prostate cancer treatment setting, building on the OPTIMAL-PSMA[2] study which recently completed patient enrollment.
  • TLX597-Tx is Telix’s next generation PSMA[3]-targeting small molecule radioligand therapy candidate designed to improve efficacy and quality of life in earlier-stage prostate cancer.

Telix and St Vincent’s Hospital today announced that the first patients have been dosed with TLX597-Tx (177Lu-DOTA-HYNIC-panPSMA) in the OPTIMAL-e trial, led by Professor Louise Emmett for patients with metastatic hormone-sensitive prostate cancer (mHSPC) at St Vincent’s Hospital in Sydney, Australia.

OPTIMAL-e is a single-arm, open-label trial, evaluating adaptive-dosed TLX597-Tx in combination with androgen deprivation therapy (ADT) and an androgen receptor pathway inhibitor (ARPI) in men with mHSPC. The study will evaluate the impact of TLX597-Tx on PSA[4] response rate in an earlier treatment setting, assessing its potential to improve both the depth and durability of PSA response, while further evaluating the safety of dose intensification.

TLX597-Tx is a highly-targeted next generation small molecule RLT[5] designed to improve efficacy and quality of life in earlier-stage metastatic prostate cancer. It has demonstrated a favorable biodistribution and dosimetry profile in prior studies including OPTIMAL-PSMA[6], suggesting low exposure to salivary glands and the kidneys, the healthy organs of concern with PSMA RLT, and high uptake in PSMA-expressing tumors.

Louise Emmett, MD, Director of Theranostics and Nuclear Medicine, St. Vincent’s Hospital, and Lead Investigator of the OPTIMAL-e study, said, “I am excited to lead the OPTIMAL-e trial, which is evaluating an adaptive treatment approach designed to tailor therapy to each patient’s response. By using PSMA-PET[7] imaging and PSA measurements to monitor disease burden, treatment can be continued when the PSMA target persists, and paused when there is a significant reduction in tumor burden. This individualized strategy aims to maintain disease control while minimizing unnecessary treatment exposure, with the potential to keep patients in a low-volume disease state for longer and support quality of life. The findings from OPTIMAL-e may help shape future treatment strategies and advance precision medicine for men living with prostate cancer.”

David N. Cade, MD, Group Chief Medical Officer, Telix, said, “The initiation of OPTIMAL-e marks an important evolution of PSMA-targeted radioligand therapy for earlier metastatic prostate cancer, where maintaining quality of life is paramount. While the currently approved radioligand therapy has demonstrated a modest improvement in overall survival in advanced-stage disease, we believe earlier intervention may offer the potential to further improve outcomes and prolong quality of life for patients.”

TLX597-Tx has not received marketing authorization in any jurisdiction.

[1] Australian New Zealand Clinical Trials Registry ID: ACTRN12626000034336.

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

[3] Prostate-specific membrane antigen.

[4] Prostate-specific antigen.

[5] Radioligand therapy.

[6] Telix media release April 30, 2026.

[7] Imaging of prostate-specific membrane antigen with positron emission tomography.