What is "belimumab"

n. A human monoclonal antibody that inhibits the biological activity of B-lymphocyte stimulator (BLyS).

Belimumab (trade name Benlysta, previously known as LymphoStat-B) is a human monoclonal antibody that inhibits B-cell activating factor (BAFF), also known as B-lymphocyte stimulator (BLyS). B cells are responsible for part of the normal immune response, and also for the over-aggressive immune response in autoimmune diseases like systemic lupus erythematosus (SLE).

Belimumab is approved in the United States, Canada and Europe for treatment of SLE. However, the major phase III trials excluded the more severe cases of SLE with kidney and brain damage, so its effectiveness has not been demonstrated in those cases. A Phase III study for SLE patients with kidney disease is now recruiting.

U.S. F.D.A. reviewers were concerned that belimumab is only "marginally" effective, and that there were more deaths in the treatment group.

Belimumab's defenders said that in addition to its modest efficiency, belimumab allowed patients to significantly reduce their use of corticosteroids.

Belimumab is expensive, typically $28,000 for the first year. The UK National Institute for Health and Care Excellence (NICE) calculated the cost of belimumab at £61,200 per quality-adjusted life year (QALY), which is more than the normally accepted £20,000 to £30,000.

Phase II trials of belimumab for rheumatoid arthritis were unsuccessful. Phase II trials for Sjögren’s Syndrome were more successful.

Belimumab was developed by Human Genome Sciences (HGS) and Cambridge Antibody Technology. GlaxoSmithKline acquired HGS, took belimumab through Phase III clinical trials, and markets belimumab.