Sporadic Inclusion-Body Myositis (sIBM) is the most common inflammatory muscle disease in people above the age of 50 years. It progresses steadily, leading to severe weakness and wasting of the muscles in the arms and legs. The cause of s-IBM is not known, but it may be an autoimmune disease. In this study, the effectiveness of alemtuzumab in suppressing endomysial inflammation and arresting sIBM progression was investigated. Alemtuzumab is an immunosuppressant medication currently approved to treat certain leukemias. It results in severe peripheral blood lymphocyte reduction up to 6 months. Thirteen sIBM patients with a 12-month natural history were treated with 0.3 mg/kg/day Alemtuzumab for 4 days. Primary end-points were the disease stabilization or increased strength 6 months after treatment, assessed by bi-monthly Quantitative Muscle Strength Testing (QMT) and Medical Research Council (MRC) strength measurements. During a 12-month observation, patients' total strength had declined by a mean of 14.9% on QMT, while six months after therapy, only by 1.9 %. Six of 13 patients improved by 15.7% and reported improvement in activities of daily living, and the other 7 declined by 6%. Total MRC scores declined during observation by 13.8% but improved after 6 months by 11.4. Peripheral blood lymphocyte depletion persisted for 6 months after treatment. Alemtuzumab significantly reversed disease progression, improved the strength of some patients, and reduced the inflammatory and degeneration-associated molecules in the patients' muscles. The observations are encouraging and necessitate further study.

Références : Brain. 2009 Jun;132(Pt 6):1536-44. Epub 2009 May 19