Capsida Receives FDA IND Clearance for Its First-in-Class, IV-administered Gene Therapy for STXBP1 Developmental and Epileptic Encephalopathy

Business Wire

12-05-2025

THOUSAND OAKS, Calif.--(BUSINESS WIRE)--Capsida Biotherapeutics ('Capsida') today announced the U.S. Food and Drug Administration (FDA) has cleared the Investigational New Drug (IND) application for CAP-002, its wholly owned first-in-class, intravenously (IV) administered gene therapy to enter clinical trials for syntaxin-binding protein 1 developmental and epileptic encephalopathy (STXBP1-DEE). This is the first program entering a human clinical trial utilizing an IV-administered, blood brain barrier-crossing engineered capsid that also is detargeted from off-target tissues, like liver and dorsal root ganglia (DRG). CAP-002 is enabled by one of Capsida's proprietary engineered capsids and optimized cargo. In addition, Capsida uses a proprietary manufacturing process and CAP-002 is manufactured in Capsida's state-of-the-art wholly owned Good Manufacturing Practice (GMP) facility.
STXBP1-DEE is estimated to affect up to one in 26,000 births globally, equating to approximately 5,000 pediatric patients in U.S. and Europe. The STXBP1 protein is present in every neuron and is essential for normal neurotransmission. A mutation in the STXBP1 gene is associated with early-onset seizures, severe developmental delay and intellectual disability, motor abnormalities, and a risk of sudden unexpected death in epilepsy (SUDEP). There are no approved treatments.
"STXBP1-related disorders present devastating challenges in communication, development, motor function and seizures. We are in dire need of targeted therapies that can improve the lives and functioning of our children and families," said Charlene Son Rigby, STXBP1 Foundation President and Cofounder.
Gene therapy for STXBP1-DEE had not been possible because wild-type adeno-associated viruses (AAVs), such as AAV9, cannot achieve the level of widespread neuronal transduction required to modify the disease. In non-human primate (NHP) studies to date, CAP-002 has established transduction of more than 70% of neurons across critical brain areas, while simultaneously detargeting the liver and DRGs. This brain-wide expression of STXBP1 has the potential to correct seizures, developmental disabilities, and motor abnormalities, after a single IV infusion. The NHP Good Laboratory Practice (GLP) toxicology study has shown a well-tolerated safety profile with no adverse histopathology. CAP-002 received Orphan Drug Designation (ODD) from the FDA in October 2024. Capsida is now initiating study start-up activities for the SYNRGY Phase 1/2a clinical trial, with the first patient expected to be dosed in the third quarter of this year.
"This is the first potentially disease-modifying treatment for STXBP1-DEE, and we are excited to be part of the SYNRGY clinical trial," said Ingo Helbig, M.D., Pediatric Neurologist and Clinical Director of Clinical Research at the Center for Epilepsy and Neurodevelopmental Disorders (ENDD) at Children's Hospital of Philadelphia (CHOP), and paid consultant to Capsida.
'The FDA clearance of the CAP-002 IND is a significant milestone for Capsida, the STXBP1 community, and the field of genetic medicine,' said Swati Tole, M.D., Chief Medical Officer of Capsida. "We look forward to initiating the SYNRGY clinical trial and dosing patients starting in the third quarter of this year with this potential first targeted therapy for STXBP1-DEE.'
About Capsida Biotherapeutics
Capsida Biotherapeutics is a fully integrated next-generation genetic medicines company with a central nervous system (CNS) pipeline consisting of disease-modifying and potentially curative treatments for rare and more common diseases across all ages. Capsida's wholly owned pipeline includes its first-in-class treatment for STXBP1 developmental and epileptic encephalopathy (STXBP1-DEE), which has received Investigational New Drug clearance (IND) to initiate clinical trials from the U.S. Food and Drug Administration (FDA). Capsida's pipeline also includes potential best-in-class treatments for Parkinson's disease associated with GBA mutations (PD-GBA) and Friedreich's ataxia (FA). The PD-GBA program is also on track to enter clinical development this quarter. In addition to its wholly owned programs, the Company has validating partnerships with AbbVie, Lilly, and CRISPR Therapeutics. Capsida was founded in 2019 by lead investors Versant Ventures and Westlake Village BioPartners and originated from groundbreaking research in the laboratory of Viviana Gradinaru, Ph.D., a neuroscience professor at Caltech. Visit us at www.capsida.com.