Efficacy of Rituximab in Refractory Generalized anti-AChR Myasthenia Gravis.

Abstract

Several retrospective case series have suggested rituximab (RTX) might improve patients with refractory Myasthenia Gravis (MG). In this study, we aimed to evaluate prospectively the efficacy of RTX on muscle function in refractory generalized anti-acetylcholine receptor (AChR) MG patients. Enrolled patients received 1 g of RTX at day 0, day 14, and 6-month follow-up (M6). The primary endpoint was improvement of muscle function at 12-month (M12) based on myasthenic muscle score (MMS). Secondary endpoints were an improvement of the MG Foundation of America Postintervention Status (MGFA-PIS), respiratory forced vital capacity, occurrences of acute MG exacerbation and requirement of associated immunosuppressants and immunomodulatory agents. Twelve patients were enrolled, and 11 completed the study. Only a single patient presented an improvement of at least 20 points on MMS at M12, although 2 patients displayed an increase of at least 18 points at M12. MGFA-PIS had improved in 55% of patients by M12. The clinical improvement was not associated with a reduction of immunosuppressant burden. These results provide data on the effect of RTX in patients with severe, refractory anti-AChR Abs generalized MG. Even though primary outcome was only reached in a single patient at M12, a beneficial effect of RTX on muscle function was seen in half of the patients at M12 and persisted in a third of patients at M18.