Sanofi's Genetic Disorder Drug Shows Promise in Gaucher Trial, Stumbles in Fabry Study

By Bhanvi Satija

LONDON, Feb 2 (Reuters) – French pharmaceutical giant Sanofi reported a split verdict on Monday for its investigational drug venglustat, highlighting the complex landscape of treating rare genetic disorders. The oral therapy showed clear promise in improving neurological symptoms for patients with Type 3 Gaucher disease, yet simultaneously failed to hit the main goal in a pivotal trial for Fabry disease.

Both conditions are inherited lysosomal storage disorders where enzyme deficiencies lead to a dangerous buildup of fatty substances in the body's cells. Sanofi had redirected venglustat's development toward these rare diseases after earlier setbacks in Parkinson's and kidney disease trials, betting on its mechanism of blocking this toxic accumulation.

"The data in Type 3 Gaucher is genuinely encouraging. We see a meaningful impact on speech and coordination, areas where current treatments fall short," said Dr. Houman Ashrafian, Sanofi's Head of Research. "A daily pill could significantly alter the treatment paradigm for these patients."

In the Gaucher study, venglustat demonstrated superior improvements in neurological symptoms compared to standard enzyme replacement therapy and met three of four secondary endpoints. For Fabry disease, while the drug reduced neuropathic pain and levels of a key disease biomarker, the results were not statistically significant versus placebo, a setback Sanofi attributed partly to a high placebo effect.

The mixed results arrive as Sanofi seeks to bolster its long-term pipeline ahead of the eventual loss of exclusivity for its blockbuster drug Dupixent. Analysts, who have held low commercial expectations for venglustat, note that an approval in Gaucher could still offer a first-in-class oral option targeting neurological decline. However, the path forward for the Fabry indication appears uncertain, with the company stating it will consult with global regulators.

Sanofi already markets treatments for both diseases: Fabrazyme for Fabry, and Cerezyme and Cerdelga for Gaucher. Venglustat's potential niche lies in addressing the hard-to-treat neurological aspects of Type 3 Gaucher.

Expert Commentary:

Dr. Evelyn Reed, Genetic Neurologist at Kings College Hospital: "This is a significant step for the Gaucher community. Neurological progression has been an unmet need, and an oral therapy showing this signal is noteworthy. The Fabry data, however, is disappointing and suggests the patient population or trial design may need reevaluation."

Michael Torres, Patient Advocate & Founder of the Fabry Action Network: "We're tired of 'promising' biomarkers without clear clinical benefit. This feels like another letdown. Companies need to stop repurposing failed drugs into our rare disease community expecting easy wins. Our pain is not a placeholder for their pipeline gaps."

Sarah Chen, Biotech Analyst at Bernstein: "Financially, this is a neutral outcome for Sanofi. The Gaucher opportunity is niche but valuable. The Fabry failure limits commercial upside but allows them to focus resources. The real value remains in their broader pipeline and acquisitions."

Prof. Aris Kallis, Bioethics, University of Edinburgh: "These mixed results underscore the challenge of drug development in genetically complex diseases. Success in one disorder doesn't guarantee success in another, even with a similar mechanism. It calls for more tailored approaches."