Long-term efficacy and limitations of cyclophosphamide in myasthenia gravis

Myasthenia gravis (MG) is a chronic autoimmune disorder with a fluctuating clinical course. The aim of immunotherapy is to bring about long-term remission. We evaluated the safety and efficacy of cyclophosphamide in generalized MG. We also highlight the limitations of cyclophosphamide therapy in inducing long-term remission. Data from 22 patients with generalized MG who received cyclophosphamide therapy were analyzed in terms of its safety and outcome. Twelve patients completed at least six pulses of intravenous cyclophosphamide therapy, and all improved symptomatically at 6 months. At 1 year, only seven patients reported sustained benefit and five had discontinued oral pyridostigmine. During a follow-up period of 56.67 months, all but one patient relapsed and required alternative immunomodulatory therapy. The average time to remission after the initiation of intravenous pulse cyclophosphamide (n=12) was 3.6 months (standard deviation [SD] 1.6 months, range 1-6 months), while the mean duration of remission was 20.3 months (SD 8.8 months, range 12-39 months). Forty-six adverse events were documented in 11 patients over 127 cyclophosphamide pulses. Most of the adverse events were managed symptomatically. In four patients, cyclophosphamide had to be discontinued due to adverse events. Intravenous pulse cyclophosphamide is effective in the management of MG; however remission may be short, necessitating long-term follow-up and alternative immunomodulation. Careful monitoring for adverse events should be mandatory.