ORLANDO – Adding a protease inhibitor to pegylated interferon and ribavirin increased the rate of sustained virologic responses in patients with chronic hepatitis C infections for whom prior interferon/ribavirin therapy had failed, an investigator reported at the annual Digestive Disease Week.
Among patients with hepatitis C virus (HCV) infections who received only pegylated interferon and ribavirin (peg-IFN/RBV) in the control arms of phase II and III studies of boceprevir (Victrelis), more than 90% of those who had relapsed had a sustained virologic response for at least 24 weeks after therapy (SVR24) with combined boceprevir and peg-IFN/RBV, reported Dr. John Vierling, chief of hepatology at Baylor College of Medicine in Houston.
Dr. John Vierling
"Overall, the data from this final analysis lead to the conclusion that boceprevir combined with pegylated interferon/ribavirin therapy is efficacious in subjects with all three categories of nonresponse: relapsers, partial responders, and most importantly, null responders," Dr. Vierling said.
The PROVIDE study Included 168 patients (mean age, 52 years) in an intention-to-treat analysis whose peg-IFN/RBV therapy was considered a failure. The cohort included treatment-experienced patients with detectable HCV RNA after 12 weeks of peg-IFN/RBV and treatment-naive patients after 24 weeks of therapy, as well as those who had experienced virological breakthrough or relapse after having an end-of-treatment response.
Patients who had completed peg-IFN/RBV therapy within the previous 2 weeks were enrolled for 44 weeks. Those patients who had completed peg-IFN/RBV more than 2 weeks earlier were assigned to a 4-week lead-in phase with peg-IFN/RBV prior to starting on the study combination.
All participants were given boceprevir 800 mg orally three times daily with food, pegylated interferon-alpha-2b (Intron A) 1.5 mcg/kg subcutaneously once weekly, and weight-based ribavirin 600-1,400 mg daily divided into two oral doses.
Four patients dropped out of the study during the lead-in phase and thus did not receive any boceprevir, leaving 164 for a prespecified full-analysis set. A total of 60 patients discontinued therapy (including the 4 who dropped out in the lead-in phase). Of these patients, 14 stopped due to adverse events, 33 had treatment failure, and 13 dropped out for nonmedical reasons.
In the full analysis set, 27 of 28 (96%) patients who had had a relapse after prior peg-IFN/RBV had an SVR24, the primary endpoint, as did 57 of 85 (67%) prior partial responders and 20 of 49 (41%) prior null responders. Overall, 65% of patients in the full-analysis population and 63% of those in an intention-to-treat population had an SVR24.
In a breakdown by baseline characteristics of patients who had an SVR24, the authors found that SVR occurred more frequently in men than in women, in nonblack vs. black patients, among those with a viral load of 800,000 copies/mL or fewer, HCV genotype 1a vs. 1b (except among those with prior relapse), and patients with platelet counts of 200,000/mcL.
The most frequently reported adverse events were anemia in 45% of patients, dysgeusia in 35%, and neutropenia in 23%. The safety profile was similar to that reported for the combination in phase II and III studies, Dr. Vierling said.
The study was sponsored by Merck. Dr. Vierling disclosed serving in an advisory capacity and receiving grants and research support from the company. Three of his coauthors are employees of Merck, and one is a board member.