Radiopharm Theranostics (ASX:RAD) has announced encouraging interim results from its U.S.-based Phase 2b clinical imaging trial of RAD 101, reporting that 92 per cent of evaluable patients achieved concordance between RAD 101 PET imaging and MRI, the study’s primary endpoint.
The company said the findings represent a significant step forward for improving the diagnosis and management of recurrent brain metastases, one of the most common and complex complications of advanced cancer.
The analysis is based on data from the first 12 patients enrolled. According to Radiopharm, 11 out of 12 demonstrated strong agreement between MRI findings and RAD 101 PET scans, with PET imaging showing significant and selective tumour uptake in areas of suspected metastasis.
RAD 101 is a novel small-molecule imaging agent that targets fatty acid synthase (FASN), an enzyme overexpressed in many solid tumours. Radiolabelled with Fluorine-18, the agent belongs to Radiopharm's Pivalate technology, designed to more accurately detect metabolic activity in cancer cells, irrespective of the tumour’s tissue of origin. Clinical images from the trial, the company said, highlighted metabolic activity in suspected lesions even when MRI findings were inconclusive.
Radiopharm CEO Riccardo Canevari said the interim results significantly strengthen the company’s confidence in the program and help set the stage for what it hopes will be a pivotal study in 2026.
“These compelling interim data significantly strengthen confidence in the success of our Phase II trial of RAD 101 and provide a strong foundation for initiating a pivotal study by the end of 2026,” he said. “Integrating RAD 101 PET with standard MRI has the potential to transform patient management and enable better treatment decisions for the more than 300,000 patients in the U.S. diagnosed with brain metastases each year.”
Radiopharm noted that independent commercial assessments estimate the potential U.S. market opportunity for RAD 101 at more than US$500 million annually, positioning the agent among the top three imaging products in its category if approved. The company also recently reached 50 per cent patient enrolment in the Phase 2b study and has secured FDA Fast Track Designation to support the development of RAD 101 for distinguishing between recurrent disease and treatment effects in brain metastases, including leptomeningeal disease.
Brain metastases affect more than 300,000 people in the U.S. each year, a figure that continues to rise due in part to improved survival from modern systemic therapies. While contrast-enhanced MRI remains the standard imaging modality, its limitations, particularly in follow-up surveillance, create clinical uncertainty that can delay treatment or lead to unnecessary interventions. RAD 101 aims to provide a clearer, more reliable diagnostic pathway.
The ongoing Phase 2b trial is enrolling 30 patients across multiple U.S. sites in an open-label, single-arm design. Beyond the primary endpoint of concordance with MRI, the study is assessing RAD 101’s ability to distinguish tumour recurrence from radiation necrosis, a notoriously difficult diagnostic challenge in patients previously treated with stereotactic radiosurgery.