Belimumab

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). It is approved in the United States, Canada, and Europe to treat systemic lupus erythematosus (SLE). 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). It is approved in the United States, Canada, and Europe to treat systemic lupus erythematosus (SLE). Belimumab is primarily used in patients with systemic lupus erythematosus. When it was introduced in 2011, it was the first new drug approved to treat lupus in 56 years. Sales rose to $31.2 million in the first quarter of 2012. Clinical trials found belimumab to be safe in treating SLE, but the magnitude of benefit was small, and Phase III trials excluded the most severe cases of SLE, involving kidney and brain damage. Reviewers at the United States Food and Drug Administration expressed concern that the drug was only 'marginally' effective, and that there were more deaths in the treatment group. Defenders said that in addition to its modest efficiency, belimumab allowed patients to significantly reduce their use of corticosteroids. Belimumab was not effective in Phase II clinical trials for rheumatoid arthritis. It was moderately effective in Phase II trials for Sjögren syndrome. Common adverse effects reported with belimumab include nausea, diarrhea, and fever, as well as hypersensitivity and infusion-site reactions, which were severe in 0.9% of patients. Regulatory agencies recommend that patients be treated with an antihistamine prior to a belimumab infusion. Because belimumab is an immunosuppressant, more serious infections and deaths were reported among patients treated with the drug than among those treated with placebo. No interaction studies have been carried out, but combining belimumab with other immunosuppressants—especially those targeting B lymphocytes, such as anti-CD20 therapies—could increase the risk of severe infections. Likewise, combining belimumab with intravenous cyclophosphamide or live vaccines is not recommended. B lymphocytes (B cells), which are part of the normal immune response, are also responsible for the over-aggressive response seen in autoimmune diseases like SLE. B cells develop in the bone marrow and continue to mature peripherally in secondary lymphoid organs and in the gut. When autoimmune B cells attack the body's own tissues, they are normally destroyed by cell suicide (apoptosis). Researchers theorize that SLE is caused when autoimmune B cells proliferate and survival factors protect them from cell suicide.