The FDA has lifted the partial clinical hold on Idenix Pharmaceutical’s IDX184, a hepatitis C virus (HCV) nucleotide inhibitor. The action allows Idenix to continue its 12-week phase IIb study evaluating the drug in combination with pegylated interferon and ribavirin (PegIFN/RBV).

The clinical hold, originally issued in September 2010, was in response to three cases of elevated liver function tests observed during a drug-drug interaction study in healthy volunteers of the combination of IDX184 and IDX320, an investigational HCV protease inhibitor. At the beginning of 2011, the FDA removed the full clinical hold on IDX184, and the program was placed on partial clinical hold allowing Idenix to initiate the 12-week phase IIb study for IDX184 in July 2011. Recently released interim phase IIb data demonstrated favorable antiviral activity and no serious adverse events.

"After review of the interim safety and antiviral activity results from the IDX184 phase IIb clinical trial, the FDA removed the partial clinical hold and has allowed us to continue enrollment of this study," said Ron Renaud, president and CEO of Idenix. "This allows us to expand the phase IIb program and evaluate IDX184 in interferon-free combination regimens with other direct-acting antivirals. We are working toward beginning all-oral combination trials as quickly as possible."