The data, which were presented in Philadelphia at the 73rd Annual Scientific Meeting of the American College of Rheumatology (ACR), demonstrate that in BLISS-52, belimumab plus standard of care achieved a clinically and statistically significant improvement in patient response rate, as measured by the systemic lupus erythematosus (SLE) Responder Index at Week 52, compared with placebo plus standard of care.

‘The BLISS-52 Phase 3 results presented at ACR demonstrate that the efficacy of treatment with BENLYSTA plus standard of care was superior to that of placebo plus standard of care,’ said David C. Stump, MD, Executive Vice President, Research and Development, HGS. ‘These data were statistically significant and were strongly supported across multiple measures of clinical effect and multiple time-points. Of note, a greater percentage of patients receiving BENLYSTA were able to reduce their use of steroids.’

Belimumab is an investigational drug and the first in a new class of drugs called BLyS-specific inhibitors. Belimumab is being developed by HGS and GSK under a co-development and commercialization agreement entered into in August 2006. Results from BLISS-76, the second Phase III trial of belimumab, will be announced on November 2, 2009. Assuming the results from BLISS-76 are positive, HGS and GSK plan to submit marketing applications in the United States, Europe and other regions in the first half of 2010.

Among 865 patients randomized and treated, belimumab met its primary efficacy endpoint by achieving a superior SLE patient response rate at Week 52 vs placebo. A clinically and statistically significant improvement was shown in patient response rate for belimumab plus standard of care vs placebo plus standard of care: 57.6% for 10 mg/kg belimumab, 51.4% for 1 mg/kg belimumab, and 43.6% for placebo (p=0.0006 and p=0.013 for 10 mg/kg and 1 mg/kg belimumab, respectively). The BLISS-52 patient response rate was based on the SLE Responder Index (SRI), which defines patient response by an improvement in SELENA SLEDAI score of 4 points or greater, with no clinically significant BILAG worsening and no clinically significant worsening in Physician’s Global Assessment. The improvement in patient response rate was generally consistent across subgroups.

Key findings of the BLISS-52 study also included the following:

• Belimumab significantly delayed time to first SLE disease flare, reduced the risk of having severe SLE disease flares and reduced the risk of having 1 BILAG A (severe flare) or more than 1 BILAG B (moderate flare) organ domain score vs placebo.
• A significantly greater percentage of patients receiving belimumab achieved a reduction in SELENA SLEDAI score of at least 4 points by Week 52, and a significantly greater improvement in Physician’s Global Assessment (PGA) at Week 52 was observed in the belimumab treatment groups.
• Improved fatigue scores were observed in the 10 mg/kg belimumab treatment group vs the placebo group within 4–8 weeks, and both belimumab treatment groups achieved statistically significant improvement of fatigue by Week 52 using the FACIT-Fatigue Scale.
• Belimumab was generally well tolerated. Serious infections were reported in 5.9% of patients on placebo and 6.1% of patients on belimumab. The most common adverse events were headache, arthralgia, upper respiratory tract infections, urinary tract infection and influenza and were comparable between belimumab and placebo treatment groups.

To view the full results of the Phase III BLISS-52 study of BENLYSTA (S. Navarra et al.), click here.

Belimumab is an investigational human monoclonal antibody drug that specifically recognizes and inhibits the biological activity of B-lymphocyte stimulator, or BLyS®. BLyS is a naturally occurring protein discovered by HGS that is required for the development of B-lymphocyte cells into mature plasma B cells. Plasma B cells produce antibodies, the body’s first line of defense against infection. In lupus and certain other autoimmune diseases, elevated levels of BLyS are believed to contribute to the production of autoantibodies – antibodies that attack and destroy the body’s own healthy tissues. The presence of autoantibodies seems to correlate with disease severity. Preclinical and clinical studies suggest that belimumab can reduce autoantibody levels in SLE, and BLISS-52 results suggest that belimumab can reduce SLE disease activity.