Novel SLE Responder Index as the primary endpoint in two Phase 3 clinical trials

Human Genome Sciences, Inc. (NASDAQ:HGSI) today announced publication by the journal Arthritis Care & Research of an article describing the development and use of a novel evidence-based systemic lupus erythematosus (SLE) Responder Index selected as the primary endpoint of two pivotal Phase 3 clinical trials of BENLYSTA™ (belimumab) in serologically active patients with SLE. This primary endpoint was accepted by the FDA under a Special Protocol Assessment agreement for the Phase 3 trials.

“The lack of a gold standard to measure SLE disease activity endorsed by international rheumatology societies or national health authorities has impeded the development of SLE therapies,” said Richard A. Furie, M.D., lead author of the article and Chief, Division of Rheumatology and Allergy-Clinical Immunology, North Shore Long Island Jewish Health System, Lake Success, NY, and Professor of Medicine, Albert Einstein College of Medicine. “In other diseases where manifestations are heterogeneous, combined responder instruments have been used to assess disease activity. We believe the SLE Responder Index may play an important role in drug development for this potentially devastating disease.”

The primary efficacy endpoint of both Phase 3 trials of belimumab is the SLE Responder Index at Week 52, as defined by: (1) a reduction from baseline of at least 4 points on the SELENA SLEDAI disease activity scale (which indicates a clinically important reduction in SLE disease activity); (2) no worsening of disease as measured by the Physician’s Global Assessment (worsening defined as an increase of 0.30 points or more from baseline); and (3) no new BILAG A organ domain score (which indicates a severe flare of lupus disease activity) and no more than one new BILAG B organ domain score (which would indicate a moderate flare of disease activity).

In July 2009, HGS and GSK announced that belimumab met this primary endpoint in BLISS-52, the first of the two Phase 3 trials. Results from BLISS-76, the second Phase 3 trial, are expected in November 2009. Belimumab is being developed by HGS and GSK under a co-development and commercialization agreement entered into in August 2006.

“The SLE Responder Index selected as the primary efficacy endpoint of the BLISS studies of belimumab emerged directly from exploratory analysis of the results of our Phase 2 clinical trial,” said William W. Freimuth, M.D., Ph.D., Vice President, Clinical Research – Immunology, Rheumatology and Infectious Diseases. “This novel and robust index now allows clinical investigators to measure improvement in overall SLE disease activity while at the same time ensuring that the improvement is not accompanied by worsening in other disease manifestations such as organ flares. I am delighted that the validity of the endpoint has now been established with its successful prospective use in the recently completed BLISS-52 study.”