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Grazoprevir appears safe for HCV genotype 1

Grazoprevir dosed at 100 mg was safe and effective among adults for the treatment of hepatitis C virus infection, according to study data published in the Journal of Viral Hepatitis.

In a dose-ranging clinical trial conducted across the UK, Canada, New Zealand and Sweden, researchers, including Martin Lagging, MD, PhD, of the Institute of Biomedicine at Sahlgrenska Academy, University of Gothenburg, Sweden, randomly assigned 87 treatment-naive adults with chronic HCV genotype 1 to a once-daily dose of either 25 mg (n = 24), 50 mg (n = 25) or 100 mg (n = 26) of grazoprevir (MK-5172, Merck) with pegylated interferon alfa-2b (PEG-IFN a-2b) plus ribavirin for 12 weeks. At 4 weeks, any patient with HCV RNA greater than 25 IU/mL received an additional 12 weeks of PEG-IFN a-2b plus ribavirin.

Overall, sustained virologic response at 12 weeks was achieved by 54.2% of patients who received the 25-mg dose, 84% who received 50 mg and 88.5% who received 100 mg. Although SVR rates were similar among the groups, the researchers noted that all 13 patients with IL28B CC genotype and 10 of 11 patients with HCV genotype 1 non-a infection achieved SVR12.

The median time to undetectable HCV RNA was 22 days among patients who received 25 mg or 50 mg compared with 16 days among patients who received 100 mg.

Virologic failure occurred in 16% of patients who received 50 mg of MK-5172 and 15% who received 100 mg compared with 46% of patients who were dosed with 25 mg.

All patients except one had undetectable or unquantifiable HCV RNA at 4 weeks and received only 12 weeks of therapy. Common adverse events included fatigue, headache, or chills, among others, and were reported in 30% of all patients. Three patients discontinued the regimen due to adverse events that were deemed not serious. Three patients overall experienced serious adverse events.

The researchers concluded: “Phase 3 studies with this dose of grazoprevir in combination with elbasvir [MK-8742, Merck] are currently ongoing, with the ultimate goal of providing a safe and effective short-duration regiment for patients with HCV infection.” – by Melinda Stevens

Disclosure: Lagging reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.