July 7, 2026 —
Epicrispr Biotechnologies announced that it has completed enrollment and dosing in the dose-escalation portion of its first-in-human clinical trial evaluating EPI-321 for facioscapulohumeral muscular dystrophy, or FSHD.
All 12 patients have been enrolled and dosed across two dose cohorts in the ongoing open-label study. The trial is evaluating the safety, tolerability, and preliminary biological and clinical activity of EPI-321 in adults with FSHD.
EPI-321 is an investigational AAV-based epigenetic therapy designed to address the underlying biology of FSHD by suppressing inappropriate expression of DUX4, the gene associated with disease pathology. The dose-escalation portion enrolled six patients at each of two intravenous dose levels: 2 × 10¹³ vg/kg and 4 × 10¹³ vg/kg.
The enrollment milestone follows recently reported interim clinical data showing a favorable safety profile and early evidence of disease modification. Among evaluable patients treated with a single dose of EPI-321, Epicrispr reported statistically significant increases in whole-body lean muscle volume measured by MRI, favorable changes in circulating biomarkers consistent with DUX4 suppression, favorable strength and functional outcomes, and a manageable safety profile.
FSHD is a progressive genetic neuromuscular disease caused by inappropriate DUX4 expression, which leads to skeletal muscle degeneration, weakness, and disability. The disease is estimated by the FSHD Society to affect approximately one million people worldwide. There are currently no approved therapies for FSHD.
Epicrispr said it completed enrollment as rapidly as the study protocol allowed in the complex first-in-human AAV gene therapy trial. The company expects to present additional clinical data at the World Muscle Society Annual Congress in September 2026 and to complete 12-month follow-up across all participants next year.
The EPI-321 program represents a differentiated approach within genetic medicine by using epigenetic regulation rather than conventional gene replacement or gene editing. If further data confirm the interim findings, EPI-321 could support a new therapeutic strategy for FSHD by targeting DUX4-driven disease biology at its source.
