Successful outcomes of second hematopoietic stem cell transplantation with total nodal irradiation and ATG conditioning for graft failure in adult patients with severe aplastic anemia.

Data regarding the optimal approach for second allogeneic hematopoietic stem cell transplantation (HSCT) after graft failure (GF) in acquired severe aplastic anemia (SAA) are still limited and heterogeneous. We examined 24 patients who underwent second HLA-matched sibling donor (MSD) peripheral blood HSCT for GF. The reconditioning regimen (TNI-750/ATG) consisted of a single dose of total nodal irradiation (TNI, 750 cGy) and antithymocyte globulin (ATG; Thymoglobulin®, 1.25 mg/kg/day for 3 days). All but one patient achieved successful engraftment of neutrophils (median 12 days, range 5-21) and platelets (median 15 days, range 9-316). Two patients with subsequent secondary GF achieved successful engraftment after a third HSCT from the same MSD. After a median follow-up of 57.4 months (range, 11.2-155.2), the 5-year overall survival and failure-free survival were 95.7% (95% confidence interval [CI] 87.7-100%) and 87.5% (95% CI 75.2-100%), respectively. One patient developed grade II acute graft-versus-host disease (GVHD), and the 2-year cumulative incidence of chronic GVHD was 23.5% (95% CI 8.1-43.5%). This study demonstrated successful outcomes following a second MSD HSCT in SAA after GF, and the results suggest TNI-750/ATG is a feasible reconditioning option. Future studies with larger cohorts will validate our results.