A randomised trial to compare the pharmacokinetic, pharmacodynamic, and antiviral effects of peginterferon alfa-2b and peginterferon alfa-2a in patients with chronic hepatitis C (COMPARE)

Background/Aims To compare the pharmacokinetics, pharmacodynamics, and antiviral activity of peginterferon alfa-2b and peginterferon alfa-2a in patients with chronic hepatitis C virus genotype 1. Methods Thirty-six patients were randomised to peginterferon alfa-2b (1.5 μg/kg/week) or peginterferon alfa-2a (180 μg/week) for 4 weeks, then in combination with ribavirin (13 mg/kg/day) for a further 4 weeks. The pharmacokinetic profile of both peginterferons, mRNA expression of a selected group of interferon-induced gene transcripts, and serum HCV-RNA levels were assessed. Results Patients receiving peginterferon alfa-2b had significantly greater up-regulation of interferon-alfa response genes compared with those receiving peginterferon alfa-2a. Correspondingly, patients treated with peginterferon alfa-2b also had a significantly greater log10 maximum and log10 time-weighted average decrease in serum HCV-RNA. A greater proportion of peginterferon alfa-2b patients achieved a 2.0 log10 reduction in serum HCV-RNA levels by week 8 (72% vs 44% of peginterferon alfa-2a patients, P = 0.09). There was an approximately 16-fold greater exposure to peginterferon in the serum of patients treated with peginterferon alfa-2a. Conclusions These findings suggest that the biological activity, measured by early interferon-induced gene transcripts and early antiviral responsiveness, may have been greater in patients treated with peginterferon alfa-2b despite their lower exposure to the drug compared with patients treated with peginterferon alfa-2a.