RAD 101 Imaging Agent Achieves Concordance with MRI in Suspected Brain Mets

Positive interim results were released from a single-dose, single-arm phase 2b trial (NCT06777433) evaluating RAD 101, a novel, small-molecule imaging agent targeting fatty acid synthase and radiolabeled with Fluorine-18, in patients with suspected brain metastases, according to a press release from the developer, Radiopharm Theranostics.¹

Among the first 12 patients enrolled in the trial and treated with RAD 101, 11 (92%) achieved concordance with MRI as assessed by PET imaging of brain metastases. Concordance was defined as the agreement or correlation between MRI and Pivalate images; pivalate technology is the term granted to the technology utilizing a novel radiopharmaceutical, which is used in PET to detect and monitor brain metastases. The results also demonstrated significant and selective tumor uptake in brain metastases. The images confirmed metabolic activity in brain metastases compared with equivocal MRI findings.

The trial also recently achieved 50% patient enrollment. Previously, RAD 101 was granted fast track designation by the FDA to distinguish between recurrent disease and the treatment effect of brain metastases originating from solid tumors of different origins.²

“These compelling interim data significantly strengthen confidence in the success of our phase 2 trial of RAD 101 and provide a strong foundation for initiating a pivotal study by the end of 2026,” Riccardo Canevari, chief executive officer and managing director of Radiopharm Theranostics, stated in the press release.¹ “Integrating RAD 101 PET (Pivalate) with standard MRI has the potential to transform patient management and enable better treatment decisions for the more than 300,000 patients in the US diagnosed with brain metastases each year. Independent commercial assessments estimate RAD 101’s US market opportunity at more than $500 million annually, positioning it to become one of the top 3 imaging agents in the market.”

As of November 24, 2025, the trial had an estimated enrollment of 30 patients. Treatment was a single dose of RAD101 at a maximum of 370 mBq (10 mCI) administered as a slow intravenous bolus injection over a maximum of 30 seconds, followed by a saline flush.³

Eligible patients were 18 years or older with suspected recurrent brain metastases from solid tumors; notably, a maximum of 15 patients per tumor type—lung, breast, colon, kidney, or melanoma—will be enrolled to avoid overrepresentation of a specific tumor type. Each lesion suspected of possessing recurrent brain metastases must have been at least 5 mm in longest diameter seen on 2 slices on the volumetric MRI analyzed at 2.5 mm slice thickness, and did not meet complete response criteria or unequivocal progressive disease criteria in the opinion of the evaluating provider. Additional enrollment criteria include prior receipt of stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT) for their brain metastases prior to study screening, an ECOG performance status from 0 to 2, and a life expectancy of at least 4 months.

Patients with a history of known additional malignancy that is progressing or requires treatment, brain surgery for the target lesion within 4 weeks before the screening MRI, and receipt of whole brain radiation therapy, SRS, or SRT within 6 weeks of day 1 were all reasons for exclusion.

The primary end point was the concordance between RAD 101 positive lesions and those seen in conventional imaging. Secondary end points included accuracy, sensitivity, and specificity of RAD 101 for identifying tumor recurrence compared with radiation necrosis in previously SRS-treated brain metastases.

References

1. Radiopharm Theranostics achieves primary endpoint in 92% of patients at interim analysis of RAD 101 phase 2b imaging trial in brain metastases. News release. Radiopharm Theranostics. December 15, 2025. Accessed December 16, 2025. https://tinyurl.com/hby2tzk
2. Radiopharm Theranostics granted U.S. Food and Drug Administration fast track designation for RAD101 imaging in brain metastases. News release. Radiopharm Theranostics. June 11, 2025. Accessed December 16, 2025. https://tinyurl.com/3ankvc2u
3. Phase 2b imaging study of RAD101 in participants with suspected recurrent brain metastases (RAD101). ClinicalTrials.gov. Updated November 24, 2025. Accessed December 16, 2025. https://tinyurl.com/24fsb6z5