Efficacy, safety, and factors predicting response in rituximab therapy for generalised myasthenia gravis

We evaluated the efficacy, safety, and factors predicting response in Rituximab (RTX) therapy for refractory generalised Myasthenia Gravis (gMG). A retrospective observational study was conducted in patients treated from 2019 to 2023. Positive outcomes were recorded if, a) a reduction of at least 2 points in MG Activities of Daily Living (ADL) or 3 points in MG composite scale occurred, b) if treatment escalation was not required, or c) if either prednisolone or intravenous immunoglobulin were weaned. Out of 32 patients, 26 (81.2%) were female and 6 were male. Eighteen (56.2%) patients were acetyl-choline receptor antibody positive (AchR) and thirteen were muscle-specific kinase (MuSK) antibody positive. Mean age at start of treatment was 46.8 years (range 25 – 76) and mean disease duration was 13.2 (+/-10) (range 1 to 47). An average of 4 other immunosuppressive agents had been tried previously (range 1–7). Twenty (62.5%) patients responded to RTX. 76.9% (10/13) of MuSK positive and 50% (9/18) of AchR positive patients improved. Age and thymectomy were unrelated to outcomes while less than 10 years to treatment correlated to positive outcome. One multi-morbid patient died from Covid19. Rituximab is effective in MuSK positive gMG but variably effective in AchR positive gMG.