Long-Term Follow-Up of the Baltimore Experience with Hematopoietic Cell Transplantation for Severe Aplastic Anemia Using Post-Transplantation Cyclophosphamide

Severe aplastic anemia (SAA) is a marrow failure disorder with high morbidity and mortality. It is increasingly treated with hematopoietic cell transplantation (HCT) upfront or at relapse after immunosuppressive therapy with alternative donor options. We report the outcomes of pediatric and adult recipients of HCT using reduced-intensity conditioning regimens, related HLA-haploidentical or unrelated donors, and post-transplantation cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis. One hundred eleven transplantation-eligible patients with treatment-naïve or relapsed/refractory SAA were treated uniformly at our center in Baltimore, Maryland. These 111 patients included 65 males (59%), and the median age was 27 years (range, 3 to 71 years; interquartile range [IQR], 19 to 53 years). The median age of the predominantly haploidentical (68%) donors was 32 years (range, 13 to 56 years; IQR, 24 to 42 years). The overall median follow-up for these SAA patients was 61.3 months (95% confidence interval [CI], 47.5 to 76.6 months). Overall survival for all patients at 3 years was 92% (95% CI, 86% to 97%). Graft failure-free survival was 80% (95% CI, 73% to 88%), 79% (95% CI, 72% to 87%) at 2 years, and 79% (95% CI, 72% to 87 %) at 3 years. Rates of acute and chronic graft-versus-host disease (GVHD) were low, and the majority of patients stopped all immunosuppressive therapy for GVHD by 6 months. Surviving patients also returned to premorbid functional status, indicative of the meaningful benefit of this curative approach.