Tolerability, pharmacokinetics and antiviral activity of rHSA/IFNα2a for the treatment of chronic hepatitis B infection.

AIMS: A recombinant human serum albumin-interferon alpha2a fusion protein (rHSA/IFNα2a) is expected to extend the half-life of IFNα2a. This study aims to evaluate the tolerability, safety and efficacy of rHSA/IFNα2a.

METHODS: This is an open, randomized, positive control, multiple-dose ascending Phase Ib study. A panel of 32 treatment naïve and non-cirrhotic chronic hepatitis B patients were divided into four cohorts, and each received 600, 750 or 900 μg of rHSA/IFNα2a or 180 μg of PEG-IFNα2a for 3 months. Tolerability, pharmacokinetics and antiviral responses were assessed.

RESULTS: Thirty-one of 32 enrolled patients completed the treatment study. The rHSA/IFNα2a treatment was better tolerated than the PEG-IFNα2a 180 μg treatment, as evidenced by blood cell counts and higher serum albumin levels. Half-life (t1/2 ) of rHSA/IFNα2a was estimated to be 120-140 h, and is potentially suitable for a dosing interval of 2 weeks or longer. Pharmacokinetics of the last dose between rHSA/IFNα2a 750 μg and PEG-IFNα2a 180 μg, with the exception of t1/2 , was comparable, and a similar kinetics of inhibiting HBV DNA replication was observed in both groups. Mean reductions in serum HBV DNA levels after treatment were -1.32, -2.13, -1.10 and -2.48 log10 IU/ml in the 600, 750 and 900 μg rHSA/IFNα2a groups and PEG-IFNα2a group, respectively.

CONCLUSIONS: The rHSA/IFNα2a treatment was well tolerated and can be administered biweekly. Similar efficacy in inhibiting HBV replication was observed in both PEG-IFNα2a and rHSA/IFNα2a 750 μg groups.