FDA scientists provide rationale behind Vosevi indications

Last Updated: 2017-11-23

By Reuters Staff

NEW YORK (Reuters Health) - Food and Drug Administration (FDA) scientists explain why the indication for Vosevi is narrower for NS5A inhibitor-naive hepatitis C virus (HCV) patients in a new report.

The FDA approved sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) in July 2017, stating that the fixed-dose combination (FDC) was indicated for patients with genotype 1, 2, 3, 4, 5, or 6 HCV infection treated previously with NS5A inhibitor-containing regimens. But in patients not exposed to NS5A inhibitors who had taken sofosbuvir previously, SOF/VEL/VOX was only indicated for patients with genotype 1a or 3 HCV, the authors explain in Hepatology, online October 23.

The approval was based on results of the POLARIS-1 and POLARIS-4 trials, which included patients who had already been treated with direct-acting antivirals (DAAs). Sustained viral response at 12 weeks after the end of treatment (SVR12) was 96% in POLARIS-1 and 98% in POLARIS-4.

"A key and challenging question in evaluating the data was determining the contribution of VOX to SOF/VEL and how this differed depending on the genotype and patient population," Dr. Kimberly Struble, who leads the FDA's Division of Antiviral Products, and her colleagues note in their report.

Several DAA regimens have been approved since 2013, with SVR12 rates higher than 90% overall and above 95% for some populations and genotypes. SOF/VEL is recommended for genotypes 1-6; VOX, developed by Gilead, is an NS3/4A protease inhibitor active against HCV genotypes 1-6.

POLARIS-1 included patients with any HCV genotype who had failed treatment including an NS5A inhibitor, and were randomized to a placebo or to SOF/VEL/VOX.

In POLARIS-4, patients were randomized to SOF/VEL or SOF/VEL/VOX. SVR-12 rates were higher with the three-drug combination for patients with HCV genotype 1a (98% vs. 89%) and those with genotype 3 (96% vs. 85%). But there was no significant difference in SVR-12 with the two treatment combinations in patients with genotypes 1b and 2. There was not enough data to determine whether response was different for HCV genotypes 4, 5 and 6.

"Emerging subpopulations of individuals with chronic hepatitis C viral infection who have failed prior DAA therapy now have an approved treatment option with the fixed-dose combination of SOF/VEL/VOX," Dr. Struble and colleagues write.

The drug is safe and efficacious in non-cirrhotic and compensated cirrhotic patients, they add, but its safety and efficacy have not been established in patients with moderate to severe cirrhosis.

Dr. Struble was not available for an interview by press time.

SOURCE: http://bit.ly/2iGrWsP

Hepatology 2017.