Gilead Sciences, Inc, a biopharmaceutical company, has submitted a New Drug Application (NDA) to Japan’s Pharmaceutical and Medical Devices Agency (PMDA) for approval of sofosbuvir, a once-daily nucleotide analog polymerase inhibitor for the treatment of chronic hepatitis C virus (HCV) infection. The data in the NDA support the use of sofosbuvir with ribavirin (RBV) for 12 weeks in patients with genotype 2 HCV infection. If approved, sofosbuvir would form the basis of the first all-oral, interferon-free treatment regimen for genotype 2 patients in Japan.

Primarily due to HCV, Japan has one of the highest rates of liver cancer of any industrialised country. Of the more than one million people chronically infected with HCV, 20-30 percent have the genotype 2 strain of the virus. Currently approved therapies in Japan for genotype 2 HCV infection involve 24-48 weeks of injections with pegylated interferon, which may not be suitable for certain patients.

“There is an urgent need in Japan for new HCV treatment options that are more effective, well-tolerated and simpler for patients,” said Norbert Bischofberger, PhD, Gilead’s executive vice president of research and development and chief scientific officer. “Based on Phase 3 studies, we believe that sofosbuvir has the potential to provide high cure rates among genotype 2 patients in just 12 weeks of interferon-free therapy. We look forward to working with the PMDA as the agency reviews our application.”

The NDA is based primarily on data from a Phase 3 clinical trial conducted in Japan (Study GS-US-334-0118) among 153 treatment-naïve and treatment-experienced genotype 2 patients. In the study, 97 per cent (n=148/153) of genotype 2 HCV-infected patients receiving 12 weeks of an all-oral regimen of sofosbuvir plus RBV 600–1,000 mg/day achieved a sustained virologic response 12 weeks after completing therapy (SVR12). Patients who achieve SVR12 are considered cured of HCV infection. The NDA is also supported by SVR12 results from four international Phase 3 studies (FISSION, FUSION, POSITRON and VALENCE), which included genotype 2 HCV patients.

Sofosbuvir represents Gilead’s first drug application in Japan, and if approved, would be the first product to be launched and marketed by Gilead in the country. The company established operations in Japan in November 2012.

Gilead also has conducted a second Phase 3 clinical trial in Japan (Study GS-US-337-0113) that is evaluating a once-daily fixed-dose combination of sofosbuvir 400 mg and the NS5A inhibitor ledipasvir 90 mg, with and without RBV, for the treatment of genotype 1 HCV infected patients. Genotype 1 is the most common strain of HCV in Japan. Gilead announced SVR12 results from this study on June 15 and plans to file for approval of the ledipasvir/sofosbuvir combination in Japan in the second half of 2014.

Sofosbuvir is an investigational product in Japan and its safety and efficacy has not yet been established. The compound has been approved by regulatory authorities in the United States, European Union and Canada and is commercialised under the tradename Sovaldi. The ledipasvir/sofosbuvir fixed-dose combination is an investigational product and its safety and efficacy has not yet been established.