LATE EFFECTS OF IMMUNOSUPPRESSIVE THERAPY IN ACQUIRED BONE MARROW FAILURE: LONG-TERM FOLLOW-UP OF CZECH PATIENTS WITH APLASTIC ANEMIA AND REFRACTORY CYTOPENIA

Methods: We analyzed pediatric SAA patients from the EWOG-SAA 2010 registry who received a second HSCT following GF.Results: Of 229 patients who underwent a first HSCT, 25 (11%) received a second HSCT for primary (n=13) or secondary (n=12) GF.One patient received two unsuccessful stem cell boosts before the second HSCT, while 24 patients were directly retransplanted.Conditioning regimens were primarily fludarabine-based (n=21, 88%), most frequently combined with cyclophosphamide (42%) or another alkylating agent.Total body irradiation (2-4 Gy) or total lymphoid irradiation (7-7.5 Gy) was administered in 5 and 3 patients, respectively.Serotherapy included antithymocyte globulin (ATG) in 12 patients (50%) and alemtuzumab in 8 (33%).Donor types at second HSCT included mismatched related donors (MMRD, n=8; 32%), matched unrelated donors (MUD, n=8; 32%), matched sibling donors (MSD, n=7; 28%), and mismatched unrelated donors (MMUD, n=1; 4%).The same donor was reused in 13 cases (54%).Neutrophil engraftment was achieved in 92% of patients at a median of 19 days .Two patients required a third HSCT, both achieving complete remission.Grade III-IV acute graft-versus-host disease (GVHD) occurred in 1 patient (4%), and moderate-to-severe chronic GVHD in 3 patients (12%).The estimated 5-year overall survival (OS) was 92%, with 8% treatment-related mortality (TRM).Conclusions: Second HSCT is a feasible and effective salvage strategy for pediatric SAA patients experiencing GF.Favorable engraftment and survival rates, along with a low GVHD incidence, support its use in this high-risk setting.Further research is needed to optimize conditioning regimens and donor selection.