Telix Pharmaceuticals reports Phase 2 OPTIMAL-PSMA dosimetry data showing TLX597-Tx reduces radiation to healthy organs while increasing tumor uptake in mCRPC, supporting further studies in earlier-stage disease.
Written By: Karthik Teja Macharla, PharmD
Reviewed By: Pharmacally Editorial Team
Telix Pharmaceuticals has reported dosimetry results from the Phase 2 OPTIMAL-PSMA trial evaluating TLX597-Tx in patients with metastatic castration-resistant prostate cancer (mCRPC). The data were presented at the 2026 International Prostate Cancer Symposium in Lugano, Switzerland.
TLX597-Tx (177Lu-DOTA-HYNIC-panPSMA) is a prostate-specific membrane antigen (PSMA)-targeting radioligand therapy (RLT) designed to deliver radiation directly to tumor cells. The reported findings indicate a favorable dosimetry profile, with reduced radiation exposure to healthy organs such as the salivary glands and kidneys. Lower off-target radiation may help reduce treatment-related toxicities, including xerostomia (dry mouth) and renal effects, while maintaining effective tumor targeting.
The study also showed higher tumor uptake compared to existing PSMA-targeted radioligand therapies. This combination of increased tumor dose and reduced normal tissue exposure suggests a wider therapeutic window, which may allow dose intensification strategies aimed at improving tumor control without compromising patient tolerability.
OPTIMAL-PSMA is an open-label, multi-center, randomized Phase 2 investigator-initiated trial led by Professor Louise Emmett at St Vincent’s Hospital, Sydney. The trial is enrolling 120 men with advanced mCRPC, randomized in a 2:1 ratio to receive either an intensified dosing regimen or a standard dosing schedule. The intensified regimen delivers 8.5 GBq per cycle on day 1, day 3, and day 15, followed by additional cycles every 10 weeks.
The study is designed to assess whether delivering higher radiation doses during periods of tumor vulnerability can improve treatment response while maintaining safety.
Professor Louise Emmett stated that the trial aims to identify a dosing regimen that achieves deeper and longer-lasting responses without increasing toxicity, and confirmed plans to initiate the OPTIMAL-E study in earlier-stage disease.
Telix Pharmaceuticals indicated that these dosimetry findings support further evaluation of TLX597-Tx in metastatic hormone-sensitive prostate cancer (mHSPC). The company has initiated the Phase 2 OPTIMAL-E study in this earlier disease setting.
Dr. David N. Cade, Group Chief Medical Officer, noted that the results demonstrate the potential to increase tumor radiation dose while minimizing exposure to sensitive organs. He emphasized the importance of maintaining quality of life alongside treatment efficacy, particularly in earlier-stage metastatic disease.
TLX597-Tx is being developed alongside TLX591-Tx (lutetium-177 rosopatamab tetraxetan), an antibody-based radioligand therapy currently under investigation in the Phase 3 ProstACT Global trial in mCRPC. The two candidates have different mechanisms of action and are intended to address distinct treatment settings across prostate cancer stages.
Neither TLX597-Tx nor TLX591-Tx has received marketing authorization in any jurisdiction.
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About the Writer
Karthik Teja Macharla, PharmD is a Pharm.D. graduate with a strong interest in clinical research, pharmacovigilance, and medical writing. In his words, he is passionate about converting complex medical information into clear, evidence-based scientific communication, committed to contributing to patient safety and advancing healthcare through accurate and impactful medical content.