Merck has announced the final results from its Phase III open-label study of Victrelis, used for the treatment of patients with chronic hepatitis C virus (HCV) genotype 1 infection.

Victrelis is the first in a class of hepatitis C virus protease inhibitors approved by the US Food and Drug Administration for use in combination with Pegintron (peginterferon alfa-2b) and ribavirin (P/R).

The multinational open-label trial enrolled 687 treatment-naïve adult patients with chronic HCV genotype 1 who had baseline haemoglobin levels of less than or equal to 15g/dL to compare the impact of two anaemia management strategies on sustained virologic response (SVR) when treated with Victrelis in combination with P/R.

In the study, patients were treated with a four-week lead-in of peginterferon alfa-2b (1.5mcg/kg/week) and an investigational dose of ribavirin (600-1,400mg/day), followed by the addition of Victrelis at a dose of 800mg three times a day after week four for 24 or 44 weeks based on HCV-RNA levels at treatment week eight.

The trial’s primary endpoint was the comparison of SVR in patients who were randomised to receive ribavirin dose reduction or the addition of erythropoietin (EPO).

The data demonstrated that the rates of SVR were 71% for both groups; those patients whose anaemia was managed by ribavirin dose reduction and those patients whose anemia was managed by the addition of EPO. The rates of relapse were the same at 10% in both groups.

Chief of hepatology and liver transplantation at Cedars-Sinai Medical Center, US, Fred Poordad said the results showed that there was no difference in SVR rates among the anaemia management strategies and that ribavirin dose reduction should be the primary strategy for managing anaemia in patients taking Victrelis combination therapy.

In the pivotal clinical trials, the proportion of patients who experienced haemoglobin values less than 10g/dL and less than 8.5g/dL was higher in subjects treated with Victrealis combination therapy compared to those treated with P/R alone, respectively.