US regulators will undertake an accelerated assessment of Sanofi unit Genzyme's Gaucher disease pill Cerdelga (eliglustat), having stamped the application with a six-month priority review.

Gaucher disease is a genetic disorder in which lipids build up in cells and certain organs, causing a whole host of problems. Type 1 patients often live well into adulthood, but life expectancy is much shorter in those with the rarer type II and type III forms of the condition.

The company is hoping to market its twice-daily oral therapy for patients with the most common Type I form of the disease, occurring in around 1 in 50,000 live births, to offer a more convenient alternative to its current standard-of-care treatment Cerezyme (imiglucerase), which is given via intravenous infusions.

Cerdelga is a novel ceramide analogue designed to partially inhibit the enzyme glucosylceramide synthase and thereby slash the production of glucosylceramide, the substance that builds up in the cells and tissues of people with Gaucher. Thereby it differs from current treatments on the market, which largely focus on lengthy enzyme replacement therapy as a means to keeping the disease under control.

Phase III studies of the drug, part of the largest clinical programme ever focused on Gaucher involving some 400 patients treated in 30 countries, showed non-inferiority with Cerezyme as well as an improvement in spleen size, and thus formed the basis of the marketing application.

If approved, Cerdelga will be vying for market share with Shire's Vpriv (velaglucerase alfa) and Pfizer/Protalix Biotherapeutics' Elelyso (taliglucerase alfa), though these are both injected. Actelion also has an oral offering on the market for type I Gaucher - Zavesca (miglustat) - but this is only used in people who cannot be treated with enzyme replacement therapy.

Analysts from Thomson Reuters Cortellis are expecting Cerdelga to generate annual sales of about $517 million by 2018. 

The drug is also under review in Europe.