FDA awards breakthrough status to Grin Therapeutics' radiprodil

The US Food and Drug Administration (FDA) has recognized Grin Therapeutics' radiprodil as a breakthrough therapy for managing seizures linked to GRIN-related neurodevelopmental disorders with gain-of-function mutations. This recognition comes after promising results from the Phase Ib Honeycomb trial, which evaluated the treatment's effectiveness in pediatric patients with specific genetic mutations affecting the GRIN genotypes.

In the Honeycomb trial, radiprodil demonstrated good tolerability among participants and provided significant relief from seizures. Data from the study revealed an impressive median reduction of 86% in countable motor seizure (CMS) frequency when compared to baseline measurements. Additionally, 71% of the participants experienced a reduction in CMS of more than 50%. Remarkably, six out of seven patients were seizure-free for at least 80% of the days during the trial's eight-week maintenance phase.

The trial also highlighted positive feedback from both clinicians and caregivers, utilizing assessment tools like the Clinician and Caregiver Global Impressions of Change and the Aberrant Behavior Checklist – Community. These assessments further supported the observed benefits of radiprodil in managing the disorder.

Radiprodil functions as a potent negative allosteric modulator specifically targeting the N-methyl-D-aspartate receptor subtype 2B. This investigational drug now benefits from fast-track privileges and the FDA’s thorough guidance on drug development, which aims to expedite its path to availability.

Mutations in GRIN genes are known to cause GRIN-related neurodevelopmental disorders. Grin Therapeutics, a subsidiary of Neurvati Neurosciences, is backed by a significant $200 million capital investment from Blackstone Life Sciences. The company is poised to initiate a Phase III pivotal trial by mid-2025 to further assess radiprodil’s efficacy in managing seizures and addressing behavioral and functional abnormalities in affected individuals.

Bruce Leuchter, President and CEO of Neurvati Neurosciences and Grin Therapeutics, emphasized the promising outcomes observed in the Phase Ib study. He noted that radiprodil, by targeting the root cause of the disorder, has shown significant reduction in seizures and holds potential for addressing non-seizure symptoms associated with GRIN-related neurodevelopmental disorders. Leuchter expressed the company’s commitment to advancing the Phase III study with urgency, aiming to deliver this novel treatment to patients swiftly. He also highlighted the importance of collaborating closely with the FDA to ensure a comprehensive and efficient development process.

This latest FDA designation marks an important milestone for Grin Therapeutics and offers hope for improved therapeutic options for individuals dealing with GRIN-related neurodevelopmental disorders. As the company prepares for the upcoming Phase III trial, there is cautious optimism within the medical community about the potential impact of radiprodil on this challenging condition.