Human Genome Sciences Inc announced that results from a Phase 1 clinical trial demonstrate that LymphoStat-B (a human monoclonal antibody to B-lymphocyte stimulator, BLyS) is well tolerated and biologically active in patients with systemic lupus erythematosus. Human Genome Sciences plans to initiate Phase 2 clinical trials of LymphoStat-B for the treatment of lupus and for the treatment of rheumatoid arthritis in 2003.

The company also announced that LymphoStat-B has received a Fast Track Product designation for the treatment of systemic lupus erythematosus from the U.S. Food and Drug Administration (FDA). The Fast Track Drug Development Programs of the FDA were established in response to the Food and Drug Administration Modernization Act of 1997, which authorized the FDA to take actions to facilitate the development and expedite the review of new drugs designated by the FDA as demonstrating the potential to address serious unmet medical needs. For a new drug to be designated a Fast Track Product, the condition it is designed to treat must be serious or life-threatening, and must represent an unmet medical need. In addition, the FDA must determine that the drug has the potential to address the unmet medical need and that the development program is designed to evaluate this potential.

The multi-center, double-blind, placebo-controlled, dose-escalation Phase 1 clinical trial was designed to determine the safety and pharmacology of LymphoStat-B in adult patients with systemic lupus erythematosus who were receiving standard therapies. Seventy patients were enrolled and randomized in the study. LymphoStat-B or placebo was administered intravenously at 1 milligram (mg)/kilogram (kg), 4 mg/kg, 10 mg/kg, or 20 mg/kg. Patients received a placebo, a single dose of LymphoStat-B, or two doses of LymphoStat-B twenty-one days apart. Safety was the primary endpoint of the study. Pharmacology of LymphoStat-B and biological markers of B-cell function also were evaluated.

Results show that LymphoStat-B is well tolerated with no clinically significant differences from placebo in adverse events or laboratory abnormalities. No drug-related serious adverse events were reported. The half-life of LymphoStat-B was shown to be consistent with that of other human monoclonal antibodies, and a dose-proportional pharmacokinetic profile was observed. As expected based on preclinical research, results show that LymphoStat-B significantly reduces the levels of circulating B (CD 20) cells, the precursor cells to those that produce the body's normal and abnormal antibodies. Full results of the Phase 1 clinical trial will be disclosed in upcoming scientific meetings and publications as appropriate.

LymphoStat-B is a human monoclonal antibody that specifically recognizes and inhibits the biological activity of B-lymphocyte stimulator, or BLyS. BLyS is a naturally occurring protein discovered by Human Genome Sciences that stimulates B-lymphocyte cells to develop into mature plasma B cells. Plasma B cells produce antibodies, the body's first line of defense against infection. Laboratory studies have indicated that higher than normal levels of BLyS may contribute to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis. Autoimmune diseases are diseases in which the body is attacked by its own immune system.