Human Genome Sciences, Inc. (HGS) announced that GlaxoSmithKline (GSK) has exercised its option under a 1996 agreement to co-develop and commercialize LymphoStat-B (belimumab), a human monoclonal antibody (created through a collaboration with Cambridge Antibody Technology) that neutralizes the activity of B-lymphocyte stimulator, or BlyS^TM, a protein required for the development of B-lymphocytes into mature plasma B cells.

The 1996 agreement with GSK granted the company a 50/50 co-development and co-promotion option for certain therapeutic candidates that successfully complete Phase IIa clinical studies. For these therapeutic candidates, GSK and HGS will share equally in both Phase III/IV clinical development costs and in sales and marketing expenses and profits.

Earlier this year HGS reported that LymphoStat-B, which is administered intravenously, met the primary efficacy and safety endpoints in a Phase II clinical trial in patients with rheumatoid arthritis (RA). In this double-blind, placebo-controlled, multicenter study, 283 patients with active moderate-to-severe RA who had failed prior treatment (including, in some cases, at least one tumor necrosis factor-alpha inhibitor) were enrolled and randomly assigned to one of three different doses of LymphoStat-B. Results showed that 36% in the 1 mg/kg low-dose cohort and 31% in the all active-treatment group achieved an ACR20 response at week 24, compared with 17% in the placebo group.

The results of a Phase II clinical trial in patients with systemic lupus erythematosus are expected in later this year. -- Nicholas K. Zittell