August 5, 2010
On Wednesday, Merck & Co. reported promising news about its experimental hepatitis C virus (HCV) treatment boceprevir, a protease inhibitor. In two late-stage clinical trials, patients taking boceprevir in addition to standard pegylated interferon and ribavirin had higher rates of sustained virological response than those taking standard therapy alone, Merck said. Sustained virological response (SVR) is defined as undetectable HCV 24 weeks after treatment ends.
The "Respond-2" study enrolled 403 patients who had previously failed HCV therapy and divided them into three groups: standard therapy plus boceprevir for 48 weeks; the same combination but treatment shortened to 36 weeks if HCV fell to certain levels; and those on standard therapy plus placebo.
SVR was achieved by 66 percent of patients in the boceprevir 48-week group, 59 percent in the short-term boceprevir group, and 21 percent taking the standard drugs with placebo.
The "Sprint-2" trial enrolled 1,097 patients with no prior treatment history. Though divided by similar groups, patients in the short-term arm could stop taking the boceprevir combination therapy after 28 weeks. SVR was achieved by 66 percent of patients in the 48-week arm, 63 percent of the short-term group, and 38 percent of the standard therapy group.
The results mean some HCV patients could shorten treatment by 12-20 weeks, said Peter Kim, president of Merck's research unit.
The most common side effects in the trials were fatigue, headache, and nausea.
Vertex Pharmaceuticals Inc. and Johnson & Johnson also are developing an HCV protease inhibitor, telaprevir, which had a 75 percent SVR rate among treatment-naive patients. The firm has not yet announced late-stage data for treatment-experienced patients. Vertex could seek U.S. approval of telaprevir this year. Boceprevir's SVR rate among previously untreated patients was 66 percent.
Merck plans to present its data in more detail at a medical conference in November, and anticipates submitting boceprevir for regulatory approval in the United States and Europe this year.