Rational Design of a Potent, Long-Lasting Form of Interferon: A 40 kDa Branched Polyethylene Glycol-Conjugated Interferon α-2a for the Treatment of Hepatitis C

Abstract

A potent, long-lasting form of interferon α-2a mono-pegylated with a 40 kilodalton branched poly(ethylene glycol) was designed, synthesized, and characterized. Mono-pegylated interferon α-2a was comprised of four major positional isomers involving Lys³¹, Lys¹²¹, Lys¹³¹, and Lys¹³⁴ of interferon. The in vitro anti-viral activity of pegylated interferon α-2a was found to be only 7% of the original activity. In contrast, the in vivo antitumor activity was severalfold enhanced compared to interferon α-2a. Pegylated interferon α-2a showed no immunogenicity in mice. After subcutaneous injection of pegylated interferon α-2a, a 70-fold increase in serum half-life and a 50-fold increase in mean plasma residence time concomitant with sustained serum concentrations were observed relative to interferon α-2a. These preclinical results suggest a significantly enhanced human pharmacological profile for pegylated interferon α-2a. Results of Phase II/III hepatitis C clinical trials in humans confirmed the superior efficacy of pegylated interferon α-2a compared to unmodified interferon α-2a.