# Lutetium-177 rosopatamab tetraxetan

Source: https://nuclide.cc/drugs/tlx-591/  
Nuclide record `tlx-591` (Agent). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

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.

By 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.

The 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.

## Fields

- Kind: Agent
- Status: phase-3
- Last checked: 2026-09-22
- Also known as: TLX591; TLX591-Tx; 177Lu-rosopatamab tetraxetan
- Tags: PSMA; radio-antibody-drug conjugate; prostate cancer; phase 3
- 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.
- Dosing: Intravenous infusion; Two doses of 76 mCi, 14 days apart, per treatment course

## Sources

- Telix: first patient dosed in ProstACT GLOBAL Phase 3: https://telixpharma.com/news-views/first-patient-dosed-in-phase-iii-prostact-global-study-of-antibody-based-prostate-cancer-therapy-candidate-tlx591/
- Telix: ProstACT Global Part 1 achieves primary objectives, 9 March 2026: https://telixpharma.com/news-views/prostact-global-phase-3-study-part-1-achieves-primary-objectives/
- Telix: positive rPFS data from ProstACT SELECT trial: https://telixpharma.com/wp-content/uploads/2024/05/TLX_ProstACT_SELECT_Study_of_TLX591_rADC_Therapy_Positive_rPFS.pdf
- ClinicalTrials.gov: ProstACT Global (NCT06520345): https://clinicaltrials.gov/study/NCT06520345

## Connected records

- drugs: [Illuccix (kit for Ga-68 gozetotide)](https://nuclide.cc/drugs/illuccix/), [Lutetium-177 vipivotide tetraxetan](https://nuclide.cc/drugs/pluvicto/)
- isotopes: [Lutetium-177](https://nuclide.cc/isotopes/lu-177/)
- indications: [Metastatic castration-resistant prostate cancer](https://nuclide.cc/indications/prostate-mcrpc/)
- technologies: [Radio-antibody & radio-ADC](https://nuclide.cc/technologies/radioimmunotherapy/)
- targets: [PSMA](https://nuclide.cc/targets/psma/)
- companies: [Telix Pharmaceuticals](https://nuclide.cc/companies/telix/)
- trials: [The Study of 177Lu-TLX591 Plus SOC Versus SOC Alone in Patients With mCRPC (ProstACT Global)](https://nuclide.cc/trials/nct06520345/)

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