Interim results from a Phase 2b trial show that RAD 101 may help doctors distinguish true brain tumor recurrence from treatment-related changes. In a study of 30 patients with previously treated brain metastases, RAD 101 PET scans matched biopsy or clinical follow-up results in 90% of cases, demonstrating high accuracy.
RAD 101 works differently from standard MRI by targeting LAT1 and LAT2 amino acid transporters that are overexpressed in cancer cells, mapping tumor metabolism instead of blood-brain barrier disruption. This allows it to differentiate viable tumor tissue from radiation-induced scarring, a problem known as pseudoprogression.
The study reported no serious drug-related side effects. Full results are expected by June 2026, and if confirmed, RAD 101 could advance to a Phase 3 trial. Its approval would support RANO guidelines recommending PET scans to complement MRI, helping patients avoid unnecessary brain biopsies and allowing faster treatment decisions for confirmed tumor recurrences.