French healthcare company Sanofi S.A. (Euronext Paris:SAN) (Nasdaq:SNY) announced on Wednesday that the US Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to venglustat, an investigational oral glucosylceramide synthase inhibitor (GCSi), for the treatment of neurological symptoms in type 3 Gaucher disease (GD3).

The designation is based on results from the LEAP2MONO phase 3 study, in which patients receiving venglustat showed statistically significant improvements in neurological symptoms -- including ataxia and cognition -- compared with enzyme replacement therapy (imiglucerase; p=0.007). Venglustat was well tolerated, with the most common adverse events being headache, nausea, spleen enlargement, and diarrhoea.

GD3 is a rare lysosomal storage disorder in which accumulation of glycosphingolipids in the central nervous system causes neurological symptoms alongside systemic manifestations such as liver and spleen enlargement, anaemia, low platelet counts, and bone disease. Current treatments address systemic symptoms, but no approved therapies target the neurological effects.

Venglustat is designed to cross the blood-brain barrier to reduce glycosphingolipid accumulation and address the underlying neurological pathology. The drug has previously received FDA fast-track designation and orphan designation in the USA, EU, and Japan.

Sanofi plans to pursue global regulatory filings for venglustat in GD3 in 2026.