Research conducted by Baylor College of Medicine and Texas Children’s Hospital has led to the U.S. Food and Drug Administration (FDA) granting Orphan Drug Designation (ODD) to a new treatment for developmental and epileptic encephalopathy (DEE) caused by syntaxin-binding protein 1 (STXBP1) mutations. The treatment, named CAP-002, was developed by Capsida Biotherapeutics.
DEE due to STXBP1 mutations is estimated to affect up to one in 26,000 children worldwide. It is associated with treatment-resistant seizures, severe developmental delay, intellectual disability, motor abnormalities, and sudden unexpected death in epilepsy (SUDEP).
“Receiving Orphan Drug Designation is an important milestone for our program, and for the patients and families affected by STXBP1 developmental and epileptic encephalopathy,” said Peter Anastasiou, Chief Executive Officer of Capsida Biotherapeutics. “There are no disease-modifying therapies available for this devastating disorder, and FDA’s granting ODD signals the significant potential that CAP-002 demonstrates based on non-clinical data."
CAP-002 is described as a novel gene therapy administered intravenously. It aims to achieve widespread neuronal expression of the STXBP1 protein while minimizing liver exposure. Currently undergoing IND-enabling studies, it has shown promising results in adult mice lacking one functional copy of the STXBP1 gene. These studies indicated that intravenous administration of the gene encoding STXBP1 could rescue key phenotypic defects such as seizures, motor deficits, and cognitive impairments in a dose-dependent manner with long-lasting effects.
“This milestone moves us one step closer to our goal of transforming the lives of people living with STXBP1 developmental and epileptic encephalopathy,” said Swati Tole, M.D., Chief Medical Officer at Capsida. “We are committed to advancing CAP-002, with our IND filing in the first half of 2025, and bringing novel gene therapies to people with high unmet medical needs.”
The FDA's Orphan Drug Designation aims to encourage treatments for rare diseases affecting fewer than 200,000 people in the United States. This designation can potentially shorten clinical development through closer collaboration with the FDA and offers benefits such as tax credits for qualified clinical trials, exemption from user fees, and possible seven-year market exclusivity upon approval.
