Induction intravenous cyclophosphamide followed by maintenance oral immunosuppression in refractory myasthenia gravis.

Abstract

Myasthenia gravis (MG) can be refractory to conventional immunotherapy. We report on the efficacy and durability of intravenous (IV) remission-induction cyclophosphamide (CYC) followed by oral immunosuppression in refractory MG. We identified 8 patients from our medical records with moderate or severe refractory MG who were treated with 6 cycles of IV CYC (0.75 g/m(2) ) every 4 weeks followed by oral immunosuppression. Six patients improved within 3 months of treatment. Four patients remained in clinical remission (mean follow-up 31 months). Two patients responded partially, and 1 patient relapsed after 11 months. Two patients were non-responders. CYC was well tolerated. Acetylcholine receptor antibody levels remained below pretreatment levels in patients in clinical remission. The leukocyte nadir was lower in CYC responders. Remission-induction IV CYC followed by oral immunosuppression is a rapid, effective, and durable treatment for refractory MG. Adding a post-CYC immunosuppressant may account for low relapse rates compared with other published series.