Gilead Sciences has been boosted by the news that regulators in the USA have granted a priority review to its investigational hepatitis C pill sofosbuvir.

The company filed a New Drug Application for sofosbuvir plus ribavirin in April as an all-oral therapy for genotype 2 and 3 HCV infection, and for sofosbuvir, RBV and pegylated interferon combination for treatment-naive patients with genotype 1, 4, 5 and 6 infections. The priority review, granted to drugs that may provide major advances over existing options,  means that the US Food and Drug Administration has set a target date under the Prescription Drug User Fee Act of December 8, four months earlier than usual.

Recently, the European Medicines Agency accepted Gilead’s request for accelerated assessment for sofosbuvir, a once-daily nucleotide NS5B inhibitor, which could shorten the EMA’s review time by two months. The drug has shown impressive SVR12 rates (ie sustained viral response 12 weeks after completing therapy and considered cured) in a number of trials.

The HCV market has been attracting huge interest since the approval a couple of years ago of Vertex Pharmaceuticals' Incivek (telaprevir) and Merck & Co's Victrelis (boceprevir). Both have impressive cure rates but there are concerns about side effects, so the race is on for an all-oral treatment which can eliminate or reduce the need for interferon.

As well as Gilead, other companies in that race include AbbVie and its all-oral triple direct-acting antiviral combination and a combo from Bristol-Myers Squibb centred around daclatasvir and asunaprevir. Johnson & Johnson filed simeprevir earlier this year, while another company looking at the HCV market is Boehringer Ingelheim.