Human Genome Sciences, Inc. (HGSI) announced that it has received preliminary written feedback from the US Food and Drug Administration (FDA) regarding the company's Biologics License Application (BLA) seeking approval in the United States to market 900-mcg Zalbin (albinterferon alfa-2b, known in Europe as Joulferon) dosed every two weeks for the treatment of chronic hepatitis C. FDA has expressed concerns regarding the risk benefit assessment of Zalbin dosed at 900-mcg every two weeks. Although the BLA review is ongoing, HGS has concluded that licensure of this dosing regimen is unlikely.

The FDA feedback was provided via a Discipline Review letter, which is a standard vehicle for review disciplines (e.g., clinical) to convey early thoughts on possible deficiencies of an application. In April 2010, HGS announced that Novartis withdrew its Marketing Authorization Application for Joulferon from the European Medicines Agency.

Zalbin (Joulferon) is being developed by HGS and Novartis under an exclusive worldwide co-development and commercialization agreement entered into in 2006. HGS and Novartis are considering development of Zalbin dosed every four weeks, and HGS previously reported the positive interim results of a phase 2b study of this Zalbin regimen.

Zalbin (also known as Joulferon) is a genetic fusion of human albumin and interferon alfa created using proprietary HGS albumin-fusion technology. Human albumin is the most prevalent naturally occurring blood protein in the human circulatory system, persisting in circulation in the body for approximately 19 days. Research has shown that genetic fusion of therapeutic proteins to human albumin decreases clearance and prolongs the half-life of the therapeutic proteins.