Neil Canavan
November 30, 2011 (San Francisco, California) — Patients with hepatitis C virus (HCV) infection who previously failed combination treatment with pegylated interferon alfa-2a (peginterferon) and ribavirin achieved up to a 50% sustained viral response (SVR) with the recently approved protease inhibitor boceprevir. This finding, from the preliminary results of the ongoing PROVIDE study, was reported here at The Liver Meeting 2011: American Association for the Study of Liver Diseases 62nd Annual Meeting.
"This study was designed to give boceprevir treatment to patients who were null responders in the control arms of our previous pivotal trials," said Michelle Treitel, PhD, from Merck Research Laboratories in Kenilworth, New Jersey.
Patients were rolled over from the SPRINT-1, SPRINT-2, RESPOND-2, and PEG 2a/BOC studies into PROVIDE. "These are patients who had either met the futility rule or who had relapsed after the end of treatment with peginterferon and ribavirin. After failure, they were immediately started on 44 weeks of boceprevir/peginterferon/ribavirin triple therapy." The aim of the study was to assess SVR after boceprevir, peginterferon, and ribavirin treatment in nonresponders.
Overall, 168 patients from the 4 studies were enrolled in PROVIDE. Patients were eligible if they received 12 or more weeks of peginterferon plus ribavirin treatment and failed to achieve a SVR (HCV RNA levels below the lower limit of detection of +9.3 IU/mL at treatment week 12 in treatment-experienced patients or at treatment week 24 in treatment-naïve patients), had a virologic breakthrough, or relapsed after the end of treatment (undetectable HCV RNA at the end of treatment but no SVR).
The subanalysis presented by Dr. Treitel involved 48 patients from the SPRINT-2 and RESPOND trials.
Patients were treated with boceprevir 800 mg orally twice daily, peginterferon 1.5 µg/kg subcutaneously once daily, and ribavirin 600 to 1400 mg/day (based on weight) orally in 2 divided doses. All patients received 4 weeks of peginterferon plus ribavirin induction therapy prior to receiving boceprevir. Patients received the boceprevir, peginterferon, ribavirin combination for up to 44 weeks, and were followed for an additional 24 weeks to determine SVR.
The PROVIDE cohort was 64.6% male, 68.8% white, had mean age of 51.0 years, and had a mean body mass index of 26.8 kg/m². Among the patients, 87.5% had a baseline viral load greater than 800,000 IU/mL, 64.6% were infected with HCV genotype 1a, and 4.2% had detectable cirrhosis.
The primary end point of PROVIDE was undetectable HCV RNA 24 weeks after therapy.
In this nonresponder subpopulation, 38% of patients treated with the triple combination achieved a SVR. The achievement of SVR differed by race (27% of black subjects and 42% of nonblack subjects), age (50% of those younger than 50 years and 29% of those older than 50 years), alanine transaminase levels (50% of those with normal levels and 34% of those with elevated levels), and genotype (41% of those infected with genotype 1a and 33% of those with genotype 1b).
"The difference by genotype is the reverse of what you would expect," said Dr. Treitel. "That most likely has to do with the small sample size."
The magnitude of decline in HCV RNA after 4 weeks of peginterferon plus ribavirin induction therapy was positively related to the rate of SVR. Dr. Treitel reported a 50% SVR for patients who experienced a reduction of at least 1 log in HCV RNA, compared with 34% SVR for patients who experienced a reduction of less than 1 log.
"This null group has not been specifically studied for boceprevir before, and these patients are really poor interferon responders," said Dr. Treitel. "In these traditionally very hard-to-treat subjects, we're still showing that you can get a 38% SVR."
Taking It to the Street
"I was very interested to see the rate of response to triple therapy in patients who have previously failed treatment or who were nonresponders," said Abu Hamour, MBBS, MSc, FRCP, from the University Hospital of Northern British Columbia in Prince George, Canada.
The lack of patients with cirrhosis in the study was a sticking point for Dr. Hamour. Although this does not reflect the population of patients he sees in his practice, the conclusions give him something valuable to take home.
"I have this information that I can give to my patients — a prognosis," he said. After treatment with this triple therapy, I can tell patients "who failed treatment with peginterferon/ribavirin or who were nonresponders...[that] if you have a more than a 1 log drop, you have a 50% chance of response; if you have less than a 1 log drop, then your response is much lower, around 35%. Patients can then make choices based on that information."
Dr. Treitel is an employee of Merck Research Laboratory. Dr. Hamour has disclosed no relevant financial relationships.
The Liver Meeting 2011: American Association for the Study of Liver Diseases (AASLD) 62nd Annual Meeting. Abstract 931. Presented November 7, 2011.
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