Among the piles of data pouring out of the European Association for the Study of the Liver congress in Amsterdam, detailed results from four Phase III trials evaluating Gilead Sciences' investigational hepatitis C drug sofosbuvir have caught the eye.

In the four trials, sofosbuvir, a once-daily nucleotide NS5B inhibitor, was administered to nearly 1,000 patients with chronic HCV infection as part of an all-oral 12-week or 16-week treatment regimen in combination with ribavirin (RBV) in genotypes 2 and 3, or with RBV and pegylated interferon (peg-IFN) for 12 weeks in genotypes 1, 4, 5 and 6. Overall SVR12 rates (ie sustained viral response 12 weeks after completing therapy and considered cured) from 50% to 90% percent were observed.

In one of the studies, 207 patients were enrolled in the clinical trial who either did not respond to interferon, could not tolerate it (due to serious side effects) or were unwilling to use it. After three months of combined therapy with sofosbuvir and RBV, the patient response rate for those with genotype 2 was 93%, and 61% in patients with genotype 3; these two subtypes account for 25% of HCV infection in the USA.

The study's lead investigator, Ira Jacobson of Weill Cornell Medical College, said that "we have dreamed for years of being able to eliminate interferon from our HCV regimens and this study is one of several that are finally bringing us very close to realising that goal". He added that sofosbuvir represents "a paradigm shift in the way that HCV is going to be treated," noting that "we are achieving the same or higher cure rates in many patients with sofosbuvir, compared to interferon, and we are doing it in half the time with a drug that has a remarkable safety profile".

The drug was filed in the USA in April and submissions in other geographies, including the European Union, are planned for the second quarter. The European Medicines Agency has accepted Gilead’s request for accelerated assessment for sofosbuvir, which could shorten the EMA’s review time by two months.

J&J's simeprevir filed in EU

Meantime, Johnson & Johnson has submitted a marketing authorisation application to the European Medicines Agency seeking approval for simeprevir for the treatment of genotype 1 (the most prevalent form of HCV worldwide) or genotype 4.

Simeprevir is a new generation NS3/4A protease inhibitor and has been developed with Sweden's Medivir. It is administered as one capsule once daily with peg-IFN and RBV.