Radiopharm Theranostics Ltd (ASX:RAD, OTC:RDPTF, NASDAQ:RADX) has dosed the first patient in a Phase 1 clinical trial of its lead prostate cancer candidate RAD 402, marking the company’s entry into first-in-human studies for the program.
The trial is evaluating RAD 402 in patients with advanced prostate cancer, with a focus on safety, tolerability, biodistribution and early signs of clinical activity. It will also seek to establish the maximum tolerated dose and a recommended Phase 2 dose as the study progresses.
KLK3-targeting radiotherapy approach
RAD 402 is a monoclonal antibody targeting KLK3 — the gene responsible for prostate-specific antigen (PSA) expression — and is radiolabelled with Terbium-161, a radionuclide that emits both beta particles and Auger electrons. This dual emission profile is designed to enhance tumour cell killing while limiting damage to surrounding healthy tissue.
Preclinical studies have shown promising characteristics, including strong tumour targeting, minimal uptake in bone and marrow, and a hepatic clearance profile consistent with antibody-based therapies.
“Dosing the first patient in our Phase 1 study of RAD 402 marks an important step forward for Radiopharm and for patients with advanced prostate cancer,” said Radiopharm CEO and managing director Riccardo Canevari.
“RAD 402 is a differentiated, first-in-class, next-generation radiotherapeutic designed to selectively target KLK3-expressing tumours while minimising off-target exposure,” he added. “With preclinical data demonstrating strong tumour uptake and minimal bone or marrow involvement, we are optimistic about its potential clinical profile.”
Data milestones and broader pipeline
Radiopharm is targeting initial data readouts from the first two dose cohorts in the second half of 2026, providing an early indication of RAD 402’s clinical profile.
The company is advancing a broader pipeline of radiopharmaceutical programs across multiple cancer types, with several assets currently in Phase 1 and Phase 2 development.