Two Phase 2 Trials Report Positive Sofosbuvir Data in HCV

Gilead Sciences announced promising efficacy results of sofosbuvir (SOF) in combination with ledipasvir (LDV) and GS-5816 from two Phase 2 clinical trials on chronic hepatitis C virus (HCV) infection at the International Liver Congress 2014.

ELECTRON2 (Oral #6) is an ongoing, open-label Phase 2 clinical trial analyzing sustained virologic response (SVR) in treatment-naïve patients with HCV genotype 1 and 3. Patients were randomized to receive once-daily, fixed-dose combinations of SOF 400mg and LDV 90mg, with or without twice-daily ribavirin (1000mg or 1200mg/day). After 12 weeks of therapy, all treatment-naïve genotype 3 recipients of combination therapy with ribavirin achieved SVR12 compared to 64% of those without ribavirin. All genotype 1-infected patientsreceiving triple therapy achieved SVR12; 65% of genotype 1 patients had decompensated or Child-Turcotte-Pugh Class B cirrhosis.

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Study GS-US-342-0102 (Oral #111), another ongoing randomized Phase 2 clinical trial, is evaluating SVR12 in treatment-naïve, non-cirrhotic patients with genotypes 1–6 HCV infection. Patients were randomized to a 12-week course of SOF 400mg plus 25mg or 100mg doses of GS-5816, an investigational pan-genotypic NS5A inhibitor. SVR12 was achieved in 94.8% of patients in the GS-5816 25mg treatment arm and in 96.1% of the 100mg treatment arm.

Gilead has developed a once-daily, fixed-dose formulation of SOF and GS-5816 which will be evaluated in an additional Phase 2 trial, Study GS-US-342-0109, enrolling treatment-experienced cirrhotic and non-cirrhotic patients with genotype 1 or 3 HCV infection. Phase 3 trials analyzing the efficacy and safety of this combination are pending on the full results of studies GS-US-342-0102 and GS-US-342-0109.

Sofosbuvir, a NS5B polymerase inhibitor, is currently available as Sovaldi (Gilead) and indicated as a component of combination antiviral therapy for chronic HCV genotype 1, 2, 3, or 4 infection.

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