MELBOURNE, Australia & INDIANAPOLIS, IN, April 30, 2026
Telix Pharmaceuticals has announced encouraging dosimetry results from its Phase 2 OPTIMAL-PSMA trial evaluating TLX597-Tx, a next-generation PSMA-targeting small molecule radioligand therapy (RLT) for metastatic castration-resistant prostate cancer (mCRPC). The data presented at the 2026 International Prostate Cancer Symposium (IPCS 2026) demonstrate significantly low salivary gland and kidney uptake, supporting dose intensification while preserving patient quality-of-life. This milestone strengthens Telix’s strategy to expand radioligand therapy options for patients with earlier-stage metastatic prostate cancer.
Improved Dosimetry Profile Supports Better Tolerability
TLX597-Tx (177Lu-DOTA-HYNIC-panPSMA) is designed to improve both treatment efficacy and tolerability compared with currently available PSMA-targeting radioligand therapies. The initial dosimetry results showed significantly reduced radiation exposure to healthy organs, particularly the salivary glands and kidneys, which are common sites of off-target toxicity in traditional radioligand therapy.
This reduced organ uptake may help lower the risk of xerostomia (dry mouth) and renal toxicity, two major quality-of-life limitations associated with existing treatments. Combined with stronger tumor uptake, TLX597-Tx may offer a wider therapeutic window, enabling physicians to deliver higher treatment intensity while minimizing unwanted side effects. This is especially important for patients with earlier-stage metastatic disease where preserving long-term quality-of-life is a major clinical priority.
Phase 2 OPTIMAL-PSMA Trial Uses Intensified Dosing Strategy
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The OPTIMAL-PSMA trial is an open-label, multi-center, randomized Phase 2 investigator-initiated study 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 compared to standard dose scheduling in 120 men with advanced mCRPC, randomized on a 2:1 basis.
The intensified regimen delivers 8.5 GBq per cycle on day 1, day 3, and day 15, followed by additional dosing every 10 weeks for three more cycles. This strategy aims to maximize radiation delivery during periods when cancer lesions are most vulnerable, potentially improving tumor control and generating deeper, longer-lasting responses without increasing toxicity.
Expansion Into Earlier-Stage Disease With OPTIMAL-E
Based on these positive findings, Telix is initiating OPTIMAL-E, a new Phase 2 study in metastatic hormone-sensitive prostate cancer (mHSPC), further expanding the role of TLX597-Tx into earlier treatment settings. The company believes the improved dosimetry profile makes the therapy particularly suitable for patients requiring long-term disease control with lower treatment burden.
TLX597-Tx is being developed alongside TLX591-Tx, Telix’s antibody-based prostate cancer therapy currently in the Phase 3 ProstACT Global trial for advanced mCRPC. Together, the two therapies provide a differentiated portfolio approach, allowing treatment selection based on disease stage and individual patient condition.
With strong Phase 2 data, dose intensification potential, and expansion into earlier-stage prostate cancer, Telix is positioning TLX597-Tx as a potentially transformative radioligand therapy, offering improved efficacy and better quality-of-life outcomes for prostate cancer patients worldwide.
Source: Telix Pharmaceuticals press release
