{"entity":{"id":"tlx-591","kind":"drug","name":"Lutetium-177 rosopatamab tetraxetan","aka":["TLX591","TLX591-Tx","177Lu-rosopatamab tetraxetan"],"tldr":"A cancer-targeting antibody carrying a radioactive metal is being tested as a two-dose treatment for advanced prostate cancer, on top of the usual hormone or chemotherapy drugs.","summary":"TLX591 (INN lutetium Lu 177 rosopatamab tetraxetan; also referred to as TLX591-Tx) is Telix Pharmaceuticals' lead PSMA-targeted radio-antibody-drug conjugate for metastatic castration-resistant prostate cancer (mCRPC). Unlike small-molecule PSMA ligands (e.g. PSMA-617, PSMA-I&T), TLX591 uses a full-length PSMA-targeting monoclonal antibody, given as two 76 mCi intravenous infusions 14 days apart; its hepatic (rather than renal) clearance means long-term follow-up has not shown significant acute or delayed nephrotoxicity.\n\nBy the ProstACT SELECT trial (NCT04786847), 242 patients had been treated with TLX591 across eight phase 1/2 studies; SELECT itself reported a median radiographic progression-free survival of 8.8 months in 23 evaluable mCRPC patients, and an earlier single-arm phase 2 study reported 42.3-month overall survival in 17 patients dosed under a fractionated regimen with concurrent docetaxel.\n\nThe pivotal phase 3 ProstACT Global trial (ClinicalTrials.gov NCT06520345) compares TLX591-Tx plus standard of care (abiraterone, enzalutamide or docetaxel) against standard of care alone in PSMA-positive mCRPC patients who progressed on one prior ARPI, with an initial 36-patient safety/dosimetry lead-in (Part 1) followed by a 2:1 randomised expansion (Part 2, target enrolment approximately 490). Part 1 results (reported March 2026) showed an acceptable safety and tolerability profile across all three standard-of-care combination cohorts, with no new safety signals; the main non-haematological toxicities were fatigue, nausea and dry mouth, and haematological toxicity (thrombocytopenia, neutropenia) was transient and manageable. Part 2 is enrolling in Australia, New Zealand, Canada, Türkiye, the UK and other jurisdictions; TLX591 has not yet received marketing authorisation anywhere.","status":"phase-3","asOf":"2026-09-22","links":[{"label":"Telix: first patient dosed in ProstACT GLOBAL Phase 3","url":"https://telixpharma.com/news-views/first-patient-dosed-in-phase-iii-prostact-global-study-of-antibody-based-prostate-cancer-therapy-candidate-tlx591/"},{"label":"Telix: ProstACT Global Part 1 achieves primary objectives, 9 March 2026","url":"https://telixpharma.com/news-views/prostact-global-phase-3-study-part-1-achieves-primary-objectives/"},{"label":"Telix: positive rPFS data from ProstACT SELECT trial","url":"https://telixpharma.com/wp-content/uploads/2024/05/TLX_ProstACT_SELECT_Study_of_TLX591_rADC_Therapy_Positive_rPFS.pdf"},{"label":"ClinicalTrials.gov: ProstACT Global (NCT06520345)","url":"https://clinicaltrials.gov/study/NCT06520345"}],"tags":["PSMA","radio-antibody-drug conjugate","prostate cancer","phase 3"],"related":["illuccix","pluvicto","lu-177"],"indications":["prostate-mcrpc"],"sections":[],"technologies":["radioimmunotherapy"],"targets":["psma"],"drugs":[],"companies":["telix"],"institutions":[],"pathways":[],"terms":[],"trials":["nct06520345"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"code":"TLX591","modality":"radioimmunotherapy","mechanism":"A radio-antibody-drug conjugate (rADC): a high-specificity PSMA-targeting monoclonal antibody, linked via a chelator to cytotoxic lutetium-177, given intravenously. Because it is a full antibody rather than a small molecule, it has longer tumour retention and different biodistribution to small-molecule PSMA radioligands, with lower observed uptake in kidneys, salivary and lacrimal glands.","approvals":[],"mechanismSteps":[],"dosing":{"route":"Intravenous infusion","schedule":"Two doses of 76 mCi, 14 days apart, per treatment course","source":"https://telixpharma.com/wp-content/uploads/2024/05/TLX_ProstACT_SELECT_Study_of_TLX591_rADC_Therapy_Positive_rPFS.pdf"},"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/tlx-591/","neighbours":{"drug":[{"id":"illuccix","kind":"drug","name":"Illuccix (kit for Ga-68 gozetotide)","route":"/drugs/illuccix/"},{"id":"pluvicto","kind":"drug","name":"Lutetium-177 vipivotide tetraxetan","route":"/drugs/pluvicto/"}],"isotope":[{"id":"lu-177","kind":"isotope","name":"Lutetium-177","route":"/isotopes/lu-177/"}],"indication":[{"id":"prostate-mcrpc","kind":"indication","name":"Metastatic castration-resistant prostate cancer","route":"/indications/prostate-mcrpc/"}],"technology":[{"id":"radioimmunotherapy","kind":"technology","name":"Radio-antibody & radio-ADC","route":"/technologies/radioimmunotherapy/"}],"target":[{"id":"psma","kind":"target","name":"PSMA","route":"/targets/psma/"}],"company":[{"id":"telix","kind":"company","name":"Telix Pharmaceuticals","route":"/companies/telix/"}],"trial":[{"id":"nct06520345","kind":"trial","name":"The Study of 177Lu-TLX591 Plus SOC Versus SOC Alone in Patients With mCRPC (ProstACT Global)","route":"/trials/nct06520345/"}]}}