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

Background: Several retrospective case series have suggested rituximab (RTX) might improve patients with refractory Myasthenia Gravis (MG).
Objective: In this study, we aimed to evaluate prospectively the efficacy of RTX on muscle function in refractory generalized anti-acetylcholine receptor (AChR) MG patients.
Methods: 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.
Results: 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.
Conclusions: 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.