Clinical evaluation of a staphylococcal protein A immunoadsorption system in the treatment of myasthenia gravis patients

BACKGROUND: The role of plasma exchange is well established in the management of myasthenia gravis, an autoimmune disorder characterized by muscle weakness and caused by circulating IgG antibodies with specificity against the acetylcholine receptor. Plasma antibody removal by conventional means, however, is nonselective and uses replacement fluids (chiefly, albumin solution) derived from human plasma. STUDY DESIGN AND METHODS: The Canadian Apheresis Group undertook a study at two Canadian apheresis centers to clinically evaluate a staphylococcal protein A immunoadsorption system (EXCORIM) in myasthenia gravis patients. RESULTS: The immunoadsorption system was safe and well tolerated. Ten of 12 patients had improvement in their neurologic status, as measured by a 20-point scoring system. The mean improvement in the weakness score was significant for the group (p = 0.0013). CONCLUSION: Patients with myasthenia gravis respond to treatment with plasma immunoadsorption. Further studies are required for a cost-benefit analysis.