Melbourne (Australia) | 25 February 2025
Telix announces that the Biogenix Molecular Research Center in Miami, FL, is recruiting and dosing patients in the ProstACT Global Phase 3 trial[1] of TLX591 for patients with advanced prostate cancer, as part of a wider United States (U.S.) roll-out.
ProstACT Global is trialling a promising new treatment option for prostate cancer, which is the most commonly diagnosed cancer and the second leading cause of cancer-related death for U.S. men. This month, Biogenix Molecular Research Center successfully administered two doses of TLX591, 14 days apart, to a local Miami-based patient, and continues to recruit eligible patients in the Miami area.
The trial – sponsored by Telix – will investigate and confirm the benefits and risks associated with TLX591 as first-line and second-line therapy in metastatic castration resistant prostate cancer (mCRPC) in combination with standard of care. The innovative trial design is differentiated by a patient-friendly dosing regimen (two doses, 14 days apart) and integrates with real-world standards of care (abiraterone, enzalutamide, or docetaxel chemotherapy), reflective of Telix’s continued innovation in prostate cancer care and commitment to patient outcomes.
ProstACT Global is the first trial to combine the synergistic effects of prostate-specific membrane antigen- (PSMA)- targeted radio antibody-drug conjugate (rADC) therapy in combination with androgen receptor pathway inhibition (ARPI), and docetaxel sensitization. This approach differs from commercially available PSMA-targeted monotherapy and previous or active studies being conducted with small molecule peptide carrier radioligand therapies (RLTs).
Dr. Frankis Almaguel, Director of the Molecular Imaging and Therapeutics Nuclear Oncology Program at Biogenix Molecular Research Center in Miami, FL, and a Principal Investigator on the ProstACT Global trial, stated, “The team at Biogenix is pleased to be dosing patients on this ground-breaking study of Telix’s lead investigational rADC, TLX591, which has delivered such encouraging results in previous Phase 1 and 2 trials. There remains significant unmet need for effective combination treatment intensification in this first- and second-line mCRPC patient population, to improve long-term outcomes without sacrificing quality of life.”
Dr. David N. Cade, Group Chief Medical Officer, Telix, added, “We are very pleased to see Biogenix Molecular Research Center participating in Telix’s international ProstACT Global trial. This study builds on an already extensive data set for TLX591, and we believe it will demonstrate the benefits of an antibody-based approach in combination with real world standards of care.”
About TLX591
TLX591 (lutetium (177Lu) rosopatamab tetraxetan) is Telix’s lead rADC candidate, which comprises a therapeutic isotope (177Lu) attached to an antibody called rosopatamab. TLX591 uses the antibody as both a homing device and a carrier to deliver therapeutic radiation to PSMA.
TLX591 shows high PSMA tumor antigen specificity with low rates of off-target organ exposure, while a simple two-dose regimen, administered over 14 days, offers patient convenience versus commercially available PSMA-targeted RLT therapy of up to six cycles over 30 weeks. There is an unmet need for products that offer lower radiation exposure compared to existing RLTs for prostate cancer[2]. The PSMA-targeted rADC approach demonstrates different targeting and pharmacology to that observed in certain anti-PSMA small peptide RLT molecules. In contrast to these therapies[3], collective long-term follow-up of patients administered with TLX591 has not observed significant acute or delayed kidney toxicity, as the agent is cleared through the liver, instead of the kidneys[4]. Due to its large molecular weight, TLX591 also demonstrates minimal salivary and lacrimal gland uptake, reducing dry mouth and dry eyes, common adverse effects of existing PSMA-targeted RLTs[5].
The ProstACT Global trial design consists of an international, multicenter trial in two parts: Part 1, safety and dosimetry run-in with 30 patients; and Part 2, 2:1 randomized global expansion with an overall target enrolment of approximately 490 patients. Eligible patients must have confirmed progressive mCRPC assessed with a 68Ga-PSMA-11 PET[6] imaging agent (such as Illuccix®) following prior treatment with an ARPI.
Watch the interview with Dr. Almaguel here
Read the full media release here
[1] ClinicalTrials.gov ID: NCT06520345.
[2] 152 mCi cumulative radiation exposure with TLX591 compared with up to 1200 mCi with current approved RLT, based on prescribing information.
[3] Steinhelfer et al. JNM. 2024.
[4] Tagawa et al. Cancer. 2019.
[5] Pepin et al. Pract Radiat Oncol. 2025.
[6] Positron emission tomography.