OBJECTIVETo observe the effects of increased-intensity conditioning regimen with FBCA (Fludarabine, Busulfan, Cyclophosphamide, and Antithymocyte globulin) for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in acquired severe aplastic anemia (SAA).

METHODSFrom January 2000 to June 2011, twenty-two patients (male 12, female 10) with SAA underwent allo-HSCT with FBCA conditioning regimen which consisted of fludarabine (30 mg·m⁻²·d⁻¹×5 d), busulfan (3 mg/kg×2 d), cyclophosphamide (60 mg·kg⁻¹·d⁻¹×2 d) and ATG (2.5 mg·kg⁻¹·d⁻¹×5 d). GVHD prophylaxis was performed by cyclosporine and short-term course methotrexate. Nine patients received mobilized peripheral blood stem cells transplantation and 13 patients underwent mobilized peripheral blood combined with bone marrow stem cells. Fourteen cases were human leukocyte antigen (HLA)-matched related donors, while the other 8 cases were HLA-haploidentical transplantation. Engraftment was documented by short tandem repeats with polymerase chain reaction (STR-PCR) on approximately day + 30, + 90, + 180, + 1 year and + 2 year, respectively. Long-term survival and transplantation-related complications were analyzed.

RESULTSAll patients obtained prompt and sustained hematopoietic reconstitution. Median time for neutrophil and PLT engraftment was 15 (range: 11-22) days and 16 (range: 12-27) days, respectively. All patients were full donor chimerism identified by STR-PCR. 2 of the total 22 cases (9.1%) had grade I-III acute GVHD and 3 (15.8%) was chronic GVHD. Three patients (13.6%) died of transplantation related mortality and the other 19 cases were disease-free survival with a median time of 24 (range: 0.5-140.5) months. The causes of death were cytomegalovirus pneumonia (n=1), acute GVHD (n=1) and severe pulmonary infection (n=1).

CONCLUSIONIncreased-intensity of FBCA conditioning regimen could favor donor stem cell sustained engraftment for allo-HSCT in SAA.