Refractory myasthenia gravis treated with autologous hematopoietic stem cell transplantation

Objectives

Patients with refractory myasthenia gravis (MG) have few treatment options. Autologous hematopoietic stem cell transplantation (HSCT) has been used to treat immune diseases; however, its use in the treatment of MG is not broadly considered. Our objective is to report on the efficacy and safety of HSCT in refractory MG.

Methods

Twenty-one patients who underwent HSCT for MG were retrospectively reviewed. All patients had severe MG refractory to multiple therapies. Stem cells were mobilized with cyclophosphamide and granulocyte colony-stimulating factor. The grafts were depleted of immune cells by selecting CD34+ cells. HSCT conditioning consisted of high-dose cytoreductive therapy and anti-thymocyte globulin. The primary efficacy outcome was achieving clinically stable remission or minimal manifestations without treatment and remaining as such until most recent follow-up.

Results

The median time from MG diagnosis to HSCT was 4.0 years. The primary outcome was reached in 16 of 18 evaluable patients (89%) at a median of 1.7 years and maintained with a median follow-up of 6.7 years (range 1.0–21.9 years). Three patients were not evaluable for the primary outcome: one due to confounding illness and two died within 12 months of transplant. The transplant-related mortality at 100 days was 9.5%. Two late deaths occurred, with uncertain relation to the HSCT.

Interpretation

After HSCT for refractory MG, most patients achieved sustained disease remission. However, HSCT-related mortality in medically complex MG patients may be high. Prospective studies investigating the efficacy and safety of HSCT in the treatment of refractory MG are warranted.