French healthcare company Sanofi S.A. (Euronext Paris:SAN) (Nasdaq:SNY) announced on Tuesday that it has received fast track designation from the US Food and Drug Administration for its one-time AAV gene therapy SAR446268, targeting non-congenital myotonic dystrophy type 1 (DM1).

This designation aims to accelerate development and review of therapies for serious conditions with unmet medical needs.

SAR446268 uses vectorised RNA interference to silence DMPK expression in a single administration, reducing toxic RNA foci responsible for splicing defects in muscle tissue. The therapy is designed to address progressive muscle weakness, difficulty relaxing muscles (myotonia), and multi-system effects on heart, lungs, and endocrine functions.

Currently the only investigational therapy in clinical development for DM1, SAR446268 is under evaluation in a first-in-human phase 1-2 study, with first patient enrolment planned for late 2025. The therapy has also received orphan drug designation in the USA and European Union.

DM1 (also known as Steinert's disease) is a rare, inherited disorder affecting about 1 in 2,300 people worldwide. Caused by mutations in the DMPK gene, the condition has a significant impact on patient quality of life and independence. There are no currently approved treatments.