Schering-Plough reported results from a planned interim analysis of an ongoing Phase II study of boceprevir, its investigational oral hepatitis C protease inhibitor, in 595 treatment-naive patients with chronic hepatitis C virus (HCV) genotype 1. The ongoing study evaluates boceprevir in 28-week and 48-week treatment regimens.
   
In the 28-week treatment regimen, patients received 4 weeks of Pegintron (peginterferon alfa-2b) and Rebetol (ribavirin, USP) prior to the addition of boceprevir. The rate of sustained virological response at 12 weeks after the end treatment (SVR 12) was 57%. This treatment regimen provided an indication of early predictability of response with patients who had undetectable virus (HCV-RNA) in plasma after 4 weeks of boceprevir treatment achieving an SVR 12 rate of 86%.
   
In the ongoing study, HCV SPRINT-1 (HCV Serine Protease Inhibitor Therapy-1), boceprevir is being evaluated in three treatment regimens: 4 weeks of Pegintron and Rebetol therapy followed by the addition of boceprevir to the combination for 24 or 44 weeks (totaling 28 or 48 weeks of treatment); boceprevir in combination with Pegintron and Rebetol for 28 or 48 weeks (triple combination); and boceprevir in combination with Pegintron and low-dose Rebetol for 48 weeks, compared to a control of Pegintron and Rebetol alone for 48 weeks (an approved treatment regimen). The primary endpoint of the study is sustained virologic response after 24 weeks of follow up.