Human Genome Sciences: challenging the pegylated interferons

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Human Genome Sciences: challenging the pegylated interferons

15th March 2006

By Staff Writer

Human Genome Sciences has reported largely positive results for Albuferon in chronic hepatitis C.

Interim results of a phase II trial of Human Genome Sciences' Albuferon in combination with ribavirin showed a significant antiviral effect in non-responders at 48 weeks of treatment. Although its favorable once-monthly dosing puts Albuferon in a strong position to potentially replace pegylated interferon, the drug's success might be delayed by the approval of specific HCV inhibitors.

Chronic hepatitis C (CHC) is currently managed through combination therapy consisting of pegylated interferon (pegIFN) and ribavirin (RBV), marketed by Roche and Schering-Plough as Pegasys/Copegus and PegIntron/Rebetol, respectively. Approximately half of all CHC patients fail to eradicate the viral infection despite completion of the entire course of therapy and are left without an additional therapeutic option. Moreover, pegIFN therapy is associated with significant adverse events.Human Genome Sciences (HGS) is one of a number of companies developing new therapeutics to meet the largely untapped CHC market, which is currently estimated to be worth $3 billion worldwide. The company's candidate CHC drug Albuferon, in development as a pegIFN replacement, is a long-acting form of IFN alfa fused to human serum albumin. The key advantage of this fusion protein is its significantly higher half-life compared to pegIFN, leading to increased bioavailability and hence less frequent dosing. Should Albuferon demonstrate a similar efficacy to pegIFN, its more favorable dosing, and hence lower incidence of side effects, could help the drug to become the preferred option for CHC patients.However, there is some doubt as to how much of a competitive edge this dosing schedule could provide. Furthermore, the monthly Albuferon dose has performed worse than the fortnightly regimen in phase II trials, and HGS is considering upping the dose for the 28-day schedule. This had led to mixed reactions to the results from industry analysts and investors.Albuferon could also face the threat of HCV inhibitors currently in development. Vertex' VX-950 and Idenix' NM283 are being developed as part of combination therapy with Pegasys and, should they demonstrate superior efficacy in conjunction with pegIFN than RBV, there is no doubt that they will quickly replace RBV as the standard of care. To test Albuferon with either VX-950 or NM283, HGS would have to wait until one of the three drugs receives FDA approval, which is unlikely to occur before 2011. This could potentially delay the replacement of pegIFN with Albuferon until at least 2014.

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