European initiation advances global registrational program for investigational radiprodil in GRIN-NDD; initiation augments sites already enrolling in the US and UK

NEW YORK, May 4, 2026 /PRNewswire/ — GRIN Therapeutics, Inc., a leader in the development of targeted, disease-specific therapies for serious neurodevelopmental disorders, today announced the initiation of its pivotal Phase 3 Beeline study in Europe, further advancing its global clinical program evaluating investigational radiprodil for GRIN-related neurodevelopmental disorder (GRIN-NDD).

The Phase 3 Beeline trial is a global, registrational study designed to evaluate the efficacy and safety of radiprodil, a selective negative allosteric modulator of the NMDA receptor GluN2B subunit, in patients with GRIN-NDD caused by gain-of-function (GoF) variants. By targeting the underlying biology of NMDA receptor overactivation, radiprodil has the potential to address core aspects of the disease, including seizures, behavioral manifestations, and functional outcomes.

“This is an exciting and meaningful milestone for GRIN Therapeutics and, more importantly, for the GRIN-NDD community,” said Bruce Leuchter, MD, President and Chief Executive Officer of GRIN Therapeutics. “Expanding the Beeline study into Europe brings us closer to delivering what we hope will be the first targeted, disease-modifying therapy for patients living with this complex and life-altering condition. We are deeply motivated by the families and caregivers who have helped shape this program, and we are committed to advancing radiprodil with urgency, rigor, and a clear focus on making a meaningful difference for patients and their families.”

The Beeline trial builds on results from the open-label Phase 1b/2a Honeycomb study, which demonstrated encouraging clinical activity and tolerability of radiprodil in patients with GRIN-NDD caused by GoF variants. In that study, patients with countable motor seizures experienced a median reduction of 86% in seizure frequency, and clinicians and caregivers also observed signs of a favorable effect on clinical outcomes regardless of the occurrence of seizures, as measured by Clinician and Caregiver Global Impressions of Change. These data supported the granting of Priority Medicines (PRIME) designation by the European Medicines Agency.

The Honeycomb data, together with insights from patients, caregivers, and investigators, informed the design of the Phase 3 program, including a disease-specific endpoint designed to capture behavioral symptoms that clinicians and caregivers consider meaningful, and a cohort that enables enrollment of patients with behavioral symptoms, not requiring countable motor seizures.

The initiation of sites in Belgium, France, Germany, Italy, Poland, the Netherlands, Slovenia, and Spain represents the next step in the global expansion of the Beeline trial, which is already enrolling in the United States and the United Kingdom. European activation includes both experienced centers that participated in earlier studies and new clinical sites across multiple countries, supporting efficient study execution and broader patient access. Further EU countries are anticipated to come online in September 2026.

The addition of European sites is expected to accelerate progress of the Phase 3 study while expanding access for European patients and families seeking new treatment options. Families can reach out to international groups like GRIN Europe (grineurope.org) and CureGRIN (curegrin.org), or their national advocacy groups, for more information.

About Radiprodil 

Radiprodil is an investigational, potent negative allosteric modulator that selectively targets the GluN2B subunit of the N-methyl-D-aspartate (NMDA) receptor and is being assessed for the treatment of GRIN-related neurodevelopmental disorder (GRIN-NDD). Radiprodil has not been approved for use; its safety and efficacy has not been established. It has been awarded Breakthrough Therapy, Orphan Drug and Rare Pediatric Disease designations by the U.S. Food and Drug Administration as well as Priority Medicines (PRIME) designation by the European Medicines Agency (EMA) and a positive opinion for orphan designation from the EMA Committee for Medicinal Products for Human Use (CHMP). The global Phase 3 Beeline trial for radiprodil in patients with GRIN-NDD gain-of-function variants is designed to evaluate the impact of a targeted disease-specific treatment on core aspects of the disease, including seizures, behavioral manifestations and functional outcomes. Radiprodil is also being assessed for the treatment of tuberous sclerosis complex (TSC) and focal cortical dysplasia (FCD) type II, two disorders associated with NMDA receptor overexpression. The Astroscape trial (ClinicalTrials.gov identifier: NCT06392009) is an ongoing, open-label Phase 1b/2a clinical trial assessing the safety, tolerability, pharmacokinetics (PK), and potential efficacy of radiprodil in patients with TSC or FCD type II. 

About GRIN Therapeutics 

GRIN Therapeutics, Inc. is dedicated to the research and development of precision therapeutics for neurodevelopmental disorders with the goal of bringing hope to patients and caregivers. In late 2024, GRIN Therapeutics reported promising topline data from a Phase 1b/2a clinical trial (the Honeycomb Trial, ClinicalTrials.gov identifier: NCT05818943) evaluating investigational radiprodil in GRIN-related neurodevelopmental disorder (GRIN-NDD) in patients with gain-of-function (GoF) variants, leading to the decision to advance to the global pivotal Phase 3 Beeline trial (ClinicalTrials.gov identifier: NCT07224581). The company has an additional ongoing clinical trial to evaluate radiprodil for the potential treatment of focal cortical dysplasia type II (FCDII) and tuberous sclerosis complex (TSC). GRIN Therapeutics is an affiliate of Neurvati Neurosciences, a portfolio company of Blackstone Life Sciences. For more information, please visit www.grintherapeutics.com. 

About Neurvati Neurosciences 

Neurvati Neurosciences is the neuroscience development platform of Blackstone Life Sciences, created to bridge the gap that has long constrained progress in the field. Neurvati identifies and advances high-potential neuroscience assets through a disciplined, scalable model that establishes and funds fit-for-purpose affiliate companies—each designed to drive development with precision, dedicated capital, and experienced leadership. By addressing the challenges that have historically impeded neuroscience drug development, Neurvati offers a differentiated solution that creates durable value across the neuroscience ecosystem and accelerates the delivery of new therapies for patients with complex neurological and psychiatric disorders. 

About Blackstone Life Sciences 

Blackstone Life Sciences is an industry-leading private investment platform with capabilities to invest across the life cycle of companies and products within key life science sectors. By combining scale investments and hands-on operational leadership, Blackstone Life Sciences helps bring to market promising new medicines and medical technologies that improve patients’ lives and currently has more than $17 billion in assets under management. 

Corporate Contact  
Elliott Ruiz
+1 201.674.5417
elliott.ruiz@neurvati.com 

For general inquiries, please reach out to info@grintherapeutics.com.

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SOURCE GRIN Therapeutics Inc.