Telix Pharmaceuticals Limited (NASDAQ: TLX) presented dosimetry results from its Phase 2 OPTIMAL-PSMA trial of TLX597-Tx at the 2026 International Prostate Cancer Symposium in Lugano, Switzerland. The trial is evaluating the experimental radioligand therapy in metastatic castration-resistant prostate cancer.

TLX597-Tx is a PSMA-targeting small molecule radioligand therapy candidate designed for prostate cancer treatment. The dosimetry data showed reduced radiation exposure to salivary glands and kidneys compared to existing treatments, which the company states may lower the incidence of dry mouth and kidney toxicity.

The OPTIMAL-PSMA trial is an open-label, multi-center, randomized Phase 2 study led by Professor Louise Emmett at St Vincent's Hospital in Sydney, Australia. The study enrolled 120 men with advanced metastatic castration-resistant prostate cancer, randomized on a 2:1 basis to compare an intensified dosing regimen against a standard dose schedule.

The intensified regimen delivers 8.5 GBq on days 1, 3, and 15, followed by 10-weekly dosing for three additional cycles. The study aims to determine whether this dose intensification approach will improve treatment response by maximizing radiation dose to cancerous lesions.

Based on these results, Telix plans to initiate OPTIMAL-E, a Phase 2 study evaluating TLX597-Tx in androgen pathway-sensitive prostate cancer. The company is developing TLX597-Tx alongside TLX591-Tx, its antibody-based therapy currently in Phase 3 trials for metastatic castration-resistant prostate cancer.

Principal investigator Professor Louise Emmett stated the goal is to identify a dose regimen that produces deeper and longer responses without increasing toxicity. Neither TLX591-Tx nor TLX597-Tx have received marketing authorization in any jurisdiction, according to the company's statement.