FDA removes clinical hold on trial of Idenix's investigational HCV therapy

Idenix Pharmaceuticals Inc. said the Food and Drug Administration removed the partial clinical hold that was placed on a midstage trial of IDX184, the company's lead product candidate for hepatitis C virus (HCV). The firm can now proceed with its double-blind, Phase IIb study in which investigators are evaluating IDX184, a pangenotypic oral nucleotide polymerase inhibitor, in combination with pegylated interferon and ribavirin. The clinical hold was originally issued in September 2010...

Idenix Pharmaceuticals Inc. said the Food and Drug Administration removed the partial clinical hold that was placed on a midstage trial of IDX184, the company's lead product candidate for hepatitis C virus (HCV).

The firm can now proceed with its double-blind, Phase IIb study in which investigators are evaluating IDX184, a pangenotypic oral nucleotide polymerase inhibitor, in combination with pegylated interferon and ribavirin.

The clinical hold was originally issued in September 2010 after three cases of elevated liver function tests were observed during a drug-drug interaction study in healthy volunteers who received a combination of IDX184 and IDX320, which is another of Idenix's investigational HCV protease inhibitors.

Subsequently, Idenix reviewed available data and conducted additional preclinical studies. Along with independent experts and an external safety committee, the company concluded that the observed toxicity was likely caused by IDX320 and submitted all relevant data to the FDA. The agency removed the full hold on IDX184 at the beginning of last year and placed the program on partial hold, thereby allowing Idenix to start enrollment for the Phase IIb study of IDX184 last July.

Recently, Idenix submitted to the FDA interim study data for the first 31 patients in the trial, along with a recommendation from the independent Data and Safety Monitoring Board to continue the study.

With the removal of the partial clinical hold, the company can initiate dosing of an additional 30 patients in the trial and begin a broad Phase IIb program with IDX184 in the months ahead. Idenix noted that although the original protocol called for 100 patients to be enrolled in the current trial, the FDA agreed to truncate the study to 60 patients and expand the enrollment criteria.

The ongoing study involves treatment-naive patients with HCV genotype 1 who are being randomized to undergo once-daily treatment with IDX184 at a dose of 50 mg or 100 mg in combination with pegylated interferon and ribavirin for 12 weeks. The study investigators are evaluating the compound's safety and tolerability, along with antiviral activity as a secondary endpoint.