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Gilead Drug Combo Could Be Indicated for All Forms of Hepatitis C
A new Gilead Sciences drug combination that targets six genotypes of the hepatitis C virus (HCV) has achieved promising results in four international phase III clinical studies.
Gilead has announced results from ASTRAL-1, ASTRAL-2, ASTRAL-3, and ASTRAL-4. The studies evaluated a once-daily, fixed-dose combination of the nucleotide analog polymerase inhibitor sofosbuvir (SOF) with velpatasvir (VEL), an investigational pan-genotypic NS5A inhibitor, for the treatment of genotype 1 to 6 chronic HCV infection.
In the ASTRAL-1, ASTRAL-2, and ASTRAL-3 studies, 1,035 patients with genotype 1 to 6 HCV infection received 12 weeks of SOF/VEL. Among these patients, 21%% had compensated cirrhosis and 28% had failed prior treatments. The ASTRAL-4 study randomized 267 patients with decompensated cirrhosis (Child-Pugh class B) to receive 12 weeks of SOF/VEL with or without ribavirin (RBV), or 24 weeks of SOF/VEL. The primary endpoint for all studies was a sustained virological response at week 12 post-treatment (SVR12).
Of the 1,035 patients treated with SOF/VEL for 12 weeks in the ASTRAL-1, ASTRAL-2, and ASTRAL-3 studies, 1,015 (98%) achieved the primary efficacy endpoint of SVR12. Of the 20 patients who did not achieve SVR12, 13 patients (1.3%) experienced virological failure and seven did not complete an SVR12 visit (that is, they were lost to follow-up). Twelve of the 13 virological failure patients relapsed (two genotype 1 HCV-infected patients and 10 genotype 3 HCV-infected patients). One patient had a documented reinfection. No patients with genotype 2, 4, 5, or 6 HCV infection had virological failure.
Patients treated with SOF/VEL for 12 weeks in these three studies had similar adverse events compared with placebo-treated patients in ASTRAL-1. Two patients (0.2%) treated with SOF/VEL for 12 weeks, one each in ASTRAL-1 and ASTRAL-2, discontinued treatment due to adverse events. The most common adverse events were headache, fatigue, and nausea.
In ASTRAL-4, patients with Child-Pugh class B cirrhosis receiving SOF/VEL plus RBV achieved higher SVR12 rates than patients receiving SOF/VEL for 12 or 24 weeks. Among genotype 1 and 3 patients treated with SOF/VEL plus RBV for 12 weeks, the SVR12 rates were 96% and 85%, respectively.
The most common adverse events across all arms of ASTRAL-4 were fatigue, nausea, and headache. Anemia, a common side effect associated with RBV, was reported in 31% of patients in the SOF/VEL plus RBV arm and in 4% and 3% of patients treated with SOF/VEL for 12 or 24 weeks, respectively. Treatment-emergent serious adverse events occurred in 18% of patients; nine patients died. The majority of serious adverse events and deaths were associated with advanced liver disease.
According to Reuters, Gilead expects to file marketing applications for the combination—which could eliminate the need for HCV genotype testing altogether—by the fourth quarter of 2015.
Sources: Gilead; September 21, 2015; Reuters; September 21, 2915.