Antiviral activity was observed at all dose levels tested either as single agent or in combination with ribavirin. Treatment was well-tolerated with reversible, dose-dependent increases in liver enzyme levels and bilirubin. There was no evidence for potentiation of ribavirin-induced toxicities in the combination groups, the two companies said.
The Phase Ib clinical trial was designed to evaluate the safety and antiviral activity of PEG-Interferon lambda as a single agent or in combination with ribavirin in genotype 1 hepatitis C virus (HCV) patients with relapsed disease. The single agent part of the study, designed to assess PEG-Interferon lambda administered subcutaneously either with a weekly or every other week dose-escalation schedule at 1.5mcg/kg and 3mcg/kg for four weeks, is complete.
In the combination part of the study, data are available for the first 10 subjects who have received weekly subcutaneous administration of PEG-Interferon lambda at doses of 0.75mcg/kg (three patients) or 1.5mcg/kg (seven patients) with daily oral ribavirin administered per the package insert over a four-week period.
Antiviral activity was seen in all cohorts, with a mean maximum decrease in HCV RNA viral load of at least 3.0log10 in all single agent and combination cohorts receiving weekly dosing. Of the 22 patients dosed weekly, 86% showed a 2log10 or greater decrease in HCV RNA at day 29 and 50% had less than 1,000 HCV RNA copies. Of the six patients treated weekly with 3mcg/kg single agent, 50% achieved a rapid virologic response. PEG-Interferon lambda was well tolerated over four weeks of treatment with minimal hematologic effects or constitutional symptoms.
Mitchell Shiffman, managing director of Virginia Commonwealth Medical Center, said: “PEG-Interferon lambda showed antiviral effects as a single agent and also in combination with ribavirin. The lack of hematologic adverse effects in the trial is very encouraging.”