Sanofi's SAR446268 Receives FDA Fast Track Designation for Myotonic Dystrophy Type 1
The US Food and Drug Administration (FDA) has granted Fast Track designation to Sanofi's investigational gene therapy, SAR446268, for the treatment of non-congenital myotonic dystrophy type 1 (DM1). This designation aims to expedite the development of therapies for serious conditions with unmet medical needs.
Paris, September 23, 2025 – Sanofi announced today that the US Food and Drug Administration (FDA) has granted Fast Track designation to SAR446268, an investigational one-time AAV gene therapy for the treatment of non-congenital myotonic dystrophy type 1 (DM1).
DM1 is a rare, genetic disorder that leads to progressive muscle weakness and wasting. Currently, there are no approved treatments available for the condition. SAR446268 utilizes a vectorized RNA interference (RNAi) approach designed to silence the expression of the DMPK gene with a single administration. The therapy aims to reduce toxic RNA foci responsible for splicing defects in muscle tissue, potentially restoring normal splicing and improving muscular function.
The therapy is currently being evaluated in a first-in-human Phase 1-2 study assessing safety, tolerability, and efficacy, with patient enrollment anticipated to begin in late 2025. Sanofi has previously received Orphan Drug designation for SAR446268 in both the US (July 2024) and the EU (October 2024).
Myotonic dystrophy type 1 affects approximately 1 in 2,300 people worldwide. It is characterized by progressive muscle weakness, myotonia (difficulty relaxing muscles), and can impact multiple organ systems, including the heart and lungs. The disease significantly affects patients' quality of life, with no existing approved treatments.