GlaxoSmithKline has decided to develop and commercialize LymphoStat-B (belimumab) jointly with Human Genome Sciences.

LymphoStat-B, a human monoclonal antibody that specifically recognizes and inhibits the biological activity of B-lymphocyte stimulator (BLyS), is in clinical development as a potential treatment for rheumatoid arthritis and systemic lupus erythematosus (SLE).

In April 2005, Human Genome Sciences reported that LymphoStat-B met the primary efficacy and safety endpoints in a Phase 2 clinical trial in patients with rheumatoid arthritis. The Phase 2 results demonstrated that LymphoStat-B is safe and well tolerated, biologically active, and reduces the signs and symptoms of rheumatoid arthritis at a level of statistical significance. It is anticipated that the full presentation of data from the Phase 2 trial will take place at an appropriate scientific meeting later in 2005. The results of a separate Phase 2 clinical trial in patients with SLE are expected in Fall 2005, a Human Genome Sciences release said.

As part of its June 1996 agreement with GSK, Human Genome Sciences granted a 50/50 co-development and co-promotion option to GSK for certain Human Genome Sciences human therapeutic products that successfully complete Phase 2a clinical trials. Under the terms of the agreement, GSK and Human Genome Sciences will share equally in Phase 3/4 development costs, and will share equally in sales and marketing expenses and profits of any product that is commercialized under the agreement, under a co-development and co-promotion agreement, the remaining terms of which are being negotiated by the parties.

H. Thomas Watkins, CEO, said, “We are very pleased that GSK has exercised its option to develop and commercialize LymphoStat-B jointly with Human Genome Sciences. Autoimmune diseases such as rheumatoid arthritis and lupus cause suffering to millions of people. It is our hope that LymphoStat-B will one day become an important treatment option for those who suffer from these diseases. We are confident that GSK’s decision to exercise its option to LymphoStat-B will lead to a productive collaboration between the parties that will greatly facilitate its development and eventual commercialization.”

LymphoStat-B is a Human Genome Sciences drug, created through a collaboration with Cambridge Antibody Technology.