[Efficacy and safety of low-dose cyclophosphamide plus corticosteroids for type I/II myasthenia gravis]

To evaluate the efficacy and safety of low-dose cyclophosphamide plus corticosteroids for type I/II myasthenia gravis (MG).

This trial was prospective, non-random and open-labeled. We selected 160 patients with steroid-insensitive MG from January 1999 to October 2011. Each patient received an oral dose of prednisone 0.5 mg×kg(-1)×d(-1), cyclophosphamide 8 mg×kg(-1)×time(-1) once weekly intravenously and oral pyridostigmine 36 mg×kg(-1)×d(-1). The efficacies were assessed by absolute and relative MG scores. The clinical treatment cycle was 30 weeks.

(1) Among them, 74/106 type I MG patients (69.9%) reached clinical relative scores ≥ 95% in 30 weeks. The total dose of cyclophosphamide was 12 g. And 35/54 type II MG patients (64.8%) reached clinical relative scores ≥ 95% in 30 weeks. No statistically significant difference existed between two groups (P = 0.521). (2) All patients had various degrees of improvement in 30 weeks. The difference was statistically significant by Mann-Whitney U test (P ≤ 0.05). (3) There were minor side effects in these all patients. (4) When the total dose of cyclophosphamide reached 4 g, the cure rate in type I patients was higher than that of in type II patients (P = 0.000). When the total dose of cyclophosphamide reached 12 g, the cure rate in type II patients was higher than that of in type I patients (P = 0.001). (5) The cure dose of cyclophosphamide was 4-8 g in 58.4% of type I patients versus 8 - 12 g in 61.1% of type II patients.

The combined treatment of low-dose cyclophosphamide and corticosteroids in glucocorticoid-insensitive type MG (type I/II) is both effective and safe. And the sensitivity to cyclophosphamide varies for different clinical types. It is higher in type I than type II patients.