French drugmaker Sanofi SASY.PA said on Monday that its experimental genetic disorder treatment showed promise in a late-stage study of patients with a type of Gaucher disease, but failed to meet the main goal in a separate trial.

The oral drug, venglustat, was being tested in patients with Fabry disease and type 3 Gaucher disease. Both inherited conditions are caused by enzyme deficiencies that lead to the accumulation of toxic substances in the body.

Previous failures in trials of patients with Parkinson's disease and a type of acute kidney disease have prompted Sanofi to prioritize testing the drug in rare genetic disorders, where its mechanism of blocking the buildup of harmful fatty molecules has yielded promising early-stage results.

Analysts have not projected future sales for venglustat as market expectations for its success remain low.

Sanofi is banking on its late-stage pipeline and recent acquisitions to help drive sales growth in the next decade, after the top-selling eczema and asthma drug Dupixent it shares with Regeneron REGN.O loses exclusivity.

Sanofi's bet could pay off if venglustat is eventually approved, making it the first such drug to target neurological symptoms and giving patients an oral dosing option.

"A daily pill could make a serious difference for Gaucher patients facing neurological challenges," said Sanofi research chief Houman Ashrafian.

But the drug's path to regulatory approval looks murky, especially for Fabry disease. Ashrafian said data from the Fabry disease study was still being analysed, while the company said it would work with global regulators to determine next steps.

STUDY DETAILS

The drug showed superior improvements in neurological symptoms such as speech and limb coordination for type 3 Gaucher disease patients, compared to those who received enzyme replacement therapy. It also demonstrated statistically significant improvements on three of four secondary goals of that study.

In patients with Fabry disease, venglustat helped reduce neuropathic and abdominal pain, but not enough to declare statistical success. Sanofi suggested that may be due to a large placebo effect. The company said it helped reduce levels of plasma lyso-GL-3 in patients, which is an indicator of accumulated harmful fat molecules.

Sanofi already sells Fabrazyme, an enzyme‑replacement therapy for Fabry disease, and markets Cerezyme and the oral drug Cerdelga for Gaucher disease.

-Reporting by Bhanvi SatijaEditing by Bill Berkrot/Reuters