Telix Pharmaceuticals (TLX) Status update summary

Portfolio strategy and therapeutic approach

• Two advanced-stage PSMA-targeting agents, TLX591-Tx and TLX597-Tx, are being developed for different prostate cancer stages, focusing on patient-centric care and minimizing off-target toxicity.

• TLX591-Tx, a radioantibody-drug conjugate, is designed for metastatic castration-resistant prostate cancer (mCRPC), enabling combination with standard therapies and high tumor selectivity.

• TLX597-Tx, a next-generation small molecule, targets metastatic hormone-sensitive prostate cancer (mHSPC), showing minimal kidney and salivary gland uptake, high tumor targeting, and suitability for dose intensification.

• The portfolio aims to address limitations of first-generation agents, such as over-treatment and quality-of-life impacts, by enabling adaptive dosing and reducing late toxicities.

• Integration with standard of care and flexible treatment algorithms are central to the next-generation portfolio approach.

Clinical trial insights and dosimetry findings

• The OPTIMAL-PSMA phase II trial evaluates dose intensification versus standard dosing, focusing on deeper and more durable responses in heavily pretreated patients, with over 85 patients dosed.

• Early dosimetry data show TLX597-Tx delivers significantly lower radiation to kidneys and salivary glands compared to PSMA-617 and PSMA-I&T, while maintaining high tumor uptake and prolonged retention.

• Imaging demonstrates reduced salivary gland activity and increased tumor uptake after intensified dosing, supporting the agent's favorable safety and efficacy profile.

• Up-front dose intensification leverages PSMA upregulation after initial dose, increasing subsequent tumor uptake and maximizing cell kill.

• Patient case studies demonstrate substantial PSA reductions and lesion shrinkage, even in heavily pretreated individuals.

Adaptive dosing and future development

• Adaptive dosing strategies are being explored, allowing treatment pauses when disease markers are low and resumption upon recurrence, aiming to minimize toxicity and maximize quality of life.

• The OPTIMAL-E trial will test TLX597-Tx in mHSPC, combining it with ARPI and ADT, and using imaging to guide adaptive dosing.

• Benchmarks for future pivotal trials include achieving high rates of deep PSA response and the ability to stop treatment in a significant proportion of patients without compromising outcomes.

• Early results warrant further exploration of TLX597-Tx in mHSPC, with potential for use of novel isotopes such as alpha emitters.

• Integration with standard of care and adaptive, response-driven dosing regimens are being tested to optimize outcomes and quality of life.