FDA approved Merck’s Victrelis™ (boceprevir) drug for treating chronic hepatitis C genotype 1. Approval covers use of the drug in combination with peginterferon alfa and ribavirin in adult patients with compensated liver disease who have previously either not been treated or failed previous treatment with interferon and ribavirin.
“Victrelis is the first major advancement for the treatment of chronic hepatitis C approved in a decade,” comments Victrelis trial investigator Bruce Bacon, M.D., professor of internal medicine at Saint Louis University School of Medicine. “Compared to current standard therapy, Victrelis can significantly increase a patient’s chance of achieving undetectable levels of the virus. For many patients, Victrelis may allow for a shorter total duration of treatment.”
Clearance of the drug in the U.S. was based on data from two large-scale Phase III studies involving about 1,500 patient with chronic HCV genotype 1 infection. In both studies patients were initially treated with peginterferon alpha-2b and ribavirin (P/R) in a four-week lead-in phase prior to the addition of Victrelis therapy. Two Victrelis treatment arms were included: a 48-week treatment arm, and a response-guided therapy (RGT) arm in which patients with undetectable virus at treatment week eight were eligible for a shorter duration of therapy.
Results from the Phase III HCV Respond-2 study in 403 treatment-failure patients showed that addition of Victrelis to P/R therapy boosted sustained virologic response (SVR) rates from 23% in the P/R-treated control arm to 59% in the RGT arm and 66% in the 48-week treatment arm. The addition of Victrelis to P/R therapy in addition halved relapse rates. Forty-six percent of Victrelis-treated patients In the RGT arm and 52% of those in the 48-week treatment arm had undetectable virus at treatment week eight and were considered early responders compared with 9% of control patients. Early responders in the RGT arm were eligible to stop all treatment at week 36. Among patients with less than a 1 log decline in virus during the four-week lead-in, SVR rates were boosted to 33% and 34% among RGT and treatment arm patients, respectively, whereas SVR among control patients was 0%.
Data from the Phase III HCV Sprint-2 trial involving 1,097 treatment-naïve patients showed that adding Victrelis to P/R therapy increased SVR rates from 38% among control patients to 63% for the RGT arm and 66% for the 48-week treatment cohort. Relapse rates were 9% for both RGT and treatment cohorts, and 22% for control patients. Fifty-six percent and 57% of RTG and 48-week treatment cohort patients, respectively, had undetectable virus at treatment week eight and were considered early responders, compared with 17% of control patients. Early responders in the RGT arm were eligible to stop all treatment at week 28.