A Clinical Trial of CAP-002 Gene Therapy in Pediatric Patients With Syntaxin-Binding Protein 1 (STXBP1) Encephalopathy

This is a Phase 1/2a, FIH, open-label, multi-center, dose-escalation trial to assess the safety, tolerability, and efficacy of a single intravenous (IV) dose of CAP-002 administered to participants with syntaxin-binding protein#1 (STXBP1) encephalopathy ages ≥18 months to \<8 years of age. Approximately 12 participants will be dosed in this trial. Phase 1 is a dose escalation phase that will dose approximately 6 participants divided into 2 cohorts (Cohort 1 and Cohort 2) while Phase 2a will have 1 dose cohort and dose approximately 6 participants. Participants in Phase 1 will be dosed sequentially in each cohort. Phase 2a will allow participants to be dosed concurrently if safety and tolerability data from Phase 1 are deemed acceptable. Participants will receive a single intravenous infusion of CAP-002 and will then be followed for 2 years with safety measures, assessments to measure changes from Baseline in development, language, cognition, motor skills and behavior, a seizure diary and structured caregiver interviews. Upon completion of the study or at the participant's final visit they will be invited to participate in a 3 year safety follow up study.