FDA Awards Orphan Drug Status to Capsida Biotherapeutics for STXBP1 Encephalopathy Treatment

Capsida Biotherapeutics announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to CAP-002, the company's leading investigational gene therapy. CAP-002 is designed to treat developmental and epileptic encephalopathy (DEE) caused by mutations in the syntaxin-binding protein 1 (STXBP1) gene. This novel gene therapy is administered intravenously and uses Capsida's proprietary engineered capsids aimed at achieving widespread neuronal expression of the STXBP1 protein in the brain while significantly reducing its impact on the liver. Currently, CAP-002 is in the stage of studies needed to file for an Investigational New Drug (IND) application.

Peter Anastasiou, CEO of Capsida Biotherapeutics, expressed that the FDA's ODD recognition highlights the significant potential of CAP-002, based on preclinical data. There are currently no disease-modifying therapies available for STXBP1-related DEE, making CAP-002 a promising candidate for providing hope to affected patients and their families.

The STXBP1 protein is vital in every neuron for normal neurotransmission. Mutations in the STXBP1 gene are linked to treatment-resistant seizures, severe developmental delays, intellectual disabilities, motor abnormalities, and sudden unexpected death in epilepsy (SUDEP). Preclinical studies have indicated the potential to treat or even fully correct the disease through gene supplementation. These studies showed that rescuing these neurological conditions depends on the supplementation of STXBP1 in neurons throughout the brain at levels unattainable with wild-type serotypes like AAV9. Capsida conducted these studies using a proprietary murine disease model in collaboration with Mingshan Xue, Ph.D., an associate professor of neuroscience and molecular and human genetics at Baylor College of Medicine, and a member of the Cain Foundation Laboratories and the Duncan Neurological Research Institute at Texas Children's Hospital.

Swati Tole, M.D., Chief Medical Officer at Capsida, stated that receiving Orphan Drug Designation brings them closer to their goal of transforming the lives of individuals with STXBP1-related DEE. Capsida remains committed to advancing CAP-002, with an IND filing anticipated in the first half of 2025, aiming to bring novel gene therapies to those with high unmet medical needs.

The FDA's Orphan Drug Designation is meant to encourage the development of treatments for rare diseases, which are defined as those affecting fewer than 200,000 people in the United States. This designation can shorten the clinical development timeline through closer FDA collaboration and potential qualification for expedited development programs. Additionally, the designation offers certain benefits to the company, such as tax credits for qualified clinical trials, exemption from user fees, and potential seven-year market exclusivity upon FDA approval.

Developmental and epileptic encephalopathy caused by STXBP1 mutations is estimated to affect up to one in 26,000 children worldwide. It is characterized by treatment-resistant seizures, severe developmental delays, intellectual disabilities, motor abnormalities, and SUDEP. No approved treatments currently exist for this condition.

Capsida Biotherapeutics is a fully integrated gene therapy company focusing on the central nervous system (CNS) with a pipeline of disease-modifying and potentially curative treatments for both rare and common diseases across all ages. Their gene therapies are administered intravenously and utilize proprietary engineered capsids to achieve high transduction levels in target tissues and cells while limiting their effects on non-target organs, such as the liver. Capsida has three wholly owned programs, including a potential first-in-class treatment for STXBP1-related DEE and a best-in-class treatment for Parkinson's disease associated with GBA mutations, both in IND-enabling studies and expected to enter clinical trials in the first half of 2025. Capsida also has partnerships with AbbVie, Lilly, and CRISPR Therapeutics, with the AbbVie partnership expanding to include ophthalmology disorders. Founded in 2019 by Versant Ventures and Westlake Village BioPartners, Capsida originated from groundbreaking research in the laboratory of Viviana Gradinaru, Ph.D., a neuroscience professor at Caltech.