Mixed Ph IIb data for Idenix' HCV combo

USA-based Idenix Pharmaceuticals presented mixed results from two Phase IIb studies of its novel HCV polymerase inhibitor, valopicitabine (NM283) and pegylated interferon alfa-2a, in treatment-naive and treatment- experienced patients infected with genotype-1 hepatitis C virus, at the 42nd annual meeting of the European Association for the Study of the Liver, held in Barcelona, Spain. In a press statement, the firm said that the treatment combination showed encouraging results in one trial but missed its primary endpoint in a similar study. On the day of the presentation, April 12, shares in Idenix fell 4.8% to $7.76.

The first study evaluated the safety and efficacy of various doses of valopicitabine plus pegylated interferon in 173 HCV genotype-1, treatment-naive patients over 48 weeks. At the end of the treatment period, 53% of patients on 200mg/day valopicitabine plus pegylated interferon achieved undetectable HCV levels by the TaqMan assay (<20 IU/mL). "These data are encouraging," said Eric Lawitz, medical director, Alamo Medical Research. "It is important to remember that ribavirin was not used in this study. The addition of ribavirin to the combination of valopicitabine and pegylated interferon may increase on-treatment response and may help to prevent post-treatment relapse. I look forward to the results from the company's ongoing study exploring the triple combination," he added.

The second Phase IIb clinical trial evaluated various doses of valopicitabine plus pegylated interferon versus pegylated interferon and ribavirin in 178 patients for up to 72 weeks. The end-of-treatment response rates and post-treatment SVR rates were comparable for patients receiving valopicitabine and pegylated interferon and those receiving pegylated interferon and ribavirin. Of patients treated with valopicitabine in combination with pegylated interferon, none achieved an SVR, compared to one patient re-treated with pegylated interferon and ribavirin, Idenix noted.