FDA Grants Breakthrough Therapy Designation to GRIN Therapeutics' Radiprodil
GRIN Therapeutics that the FDA has awarded Breakthrough Therapy designation to its investigational drug radiprodil for treating seizures in patients with GRIN-related neurodevelopmental disorder driven by gain-of-function mutations.
Radiprodil is a potent negative allosteric modulator that selectively targets the NR2B (GluN2B) subunit of the NMDA receptor, and it is being developed as a first-in-class treatment aimed at addressing the underlying disease mechanism rather than merely alleviating symptoms.
In a Phase 1b open-label study, radiprodil significantly reduced seizure frequency and showed promise in improving other clinical features of the disorder.
The Breakthrough Therapy designation is intended to speed up the development and review of drugs for serious conditions where early clinical evidence suggests a substantial improvement over current therapies on key clinical endpoints.
This designation provides radiprodil with the benefits of Fast Track status and grants it enhanced FDA guidance and organizational support from senior managers.
Support for the designation came from the positive results of the Phase 1b Honeycomb study, which involved pediatric patients with confirmed gain-of-function mutations across various GRIN genotypes.
In this study, radiprodil was generally well tolerated, with the qualifying seizure cohort showing a median 86% reduction in countable motor seizure frequency compared to baseline. Seventy-one percent of patients experienced more than a 50% reduction in seizures, and six out of seven were seizure-free for at least 80% of the days during an eight-week maintenance period.
Clinician and caregiver assessments also indicated overall clinical improvement. The most frequently observed adverse events were linked to infections or the underlying disease, with three serious adverse events related to infections—none of which were attributed to radiprodil.
