Salvage therapy of refractory severe aplastic anemia by decreasing cyclosporine dose regimen.

Optimal modalities for immunosuppressive therapy (IST) for severe aplastic anemia (SAA) have to be determined, and especially cyclosporine (CyA) dosing to promote regulatory T cells (Treg) which are lacking and which account for physiopathological mechanisms. We are reporting on three cases of pediatric patients suffering from SAA, initially without hematological response between 4 and 7 months after IST, and who have responded 2 months after the decrease in CyA target trough blood levels to 100 ng/mL, and one case which has early responded by applying low trough blood levels from the beginning. As it has been demonstrated that Treg increase in IST responders and that Treg are stimulated only by low CyA concentrations, these case series suggest that lower CyA doses than actually recommended could be more efficient to enhance the proportion of responders. This report highlights a new field of perspectives for the treatment for SAA.