US-based Gilead Sciences has reported topline results from a Phase III clinical trial (GS-US-337-0113) of the investigational once-daily fixed-dose combination of the NS5A inhibitor ledipasvir (LDV) 90mg and nucleotide analog polymerase inhibitor sofosbuvir (SOF) 400mg to treat Japanese patients with genotype 1 chronic hepatitis C virus (HCV) infection.
Among patients receiving 12 weeks of LDV/SOF without RBV, 100% of treatment-naive and 100% of treatment-experienced patients achieved a sustained virologic response 12 weeks after completing therapy (SVR12).
In patients receiving LDV/SOF plus RBV, 96% of treatment-naive and 100% of treatment-experienced patients achieved SVR12.
The company said that across all arms of the trial, patients with cirrhosis achieved a 99% SVR12 and those who achieve SVR12 are considered cured of HCV infection.
The trial also met its primary endpoint of superiority compared with a predefined historical SVR12 rate.
Gilead executive vice-president of research and development and chief scientific officer Norbert Bischofberger said: "These results suggest that a once-daily LDV/SOF tablet has the potential to be an efficacious and well-tolerated regimen for many HCV patients in Japan."
In Japan, Genotype 1 is the most common strain of HCV, accounting for around 70% of the more than one million people chronically infected with the disease.
In the trial, 341 patients with genotype 1 HCV infection were randomised (1:1) to receive 12 weeks of all-oral therapy with LDV/SOF, with or without RBV.
Out of these, 166 patients were treatment-naive, 175 were treatment-experienced and 76 had compensated cirrhosis.
Based on these data, the company intends to submit a New Drug Application for the LDV/SOF fixed-dose combination with the Japanese Pharmaceutical and Medical Devices Agency (PMDA) by the end of 2014.
The product is currently under regulatory review in the US and EU.