Human Genome Sciences Inc. has been searching for the better part of this decade to find a regimen and dose for its Zalbin albinterferon alfa-2b that would provide administration advantages over pegylated interferon for HCV. Last week it had yet another setback, as the company acknowledged the 900 µg twice monthly dose wouldn't likely get FDA approval based on concerns about the compound's risk-benefit profile.

Indeed, the therapeutic window keeps narrowing, and HGS now hopes to thread the needle with a slightly higher monthly dose than one previously tested, while avoiding the respiratory side effects seen in Phase III trials using twice-a-month dosing.