Haploidentical Hematopoietic Stem Cell Transplantation for Acquired Severe Aplastic Anemia

Objective: To evaluate the efficacy and safety of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) in patients with acquired severe aplastic anemia (SAA), who lacked suitable related or unrelated HLA-matched donors.

Methods: 39 SAA patients underwent haplo-HSCT from Jul 2012 to Jun 2015 at our center. There were 23 males and 16 females at a median follow-up of 11 (range, from 0 to 36) months. The median time from diagnosis to transplantation was 1 (range, from 0.5 to 52) months. The median ages of SAA patients and related haploidentical donor were 23 years (range, 9 to 51years) and 45 (range, from 21 to 61) years, respectively. All patients were given BuCy plus ATG conditioning regimen. GVHD prophylaxis regimen consisted of cyclosporine A (CsA), mycophenolate motetil (MMF), and short-term methotrexate.

Results: Stem cells were collected from bone marrow in 23.08% (n=9) of patients, peripheral blood in 2.56% (n=1), bone marrow plus peripheral blood in 74.36% (n=29) patients. 36 patients received haplo-HSCT combined with the third part of cord blood transfusion 92.31%. The median stem cell dose transplanted was 9.76 (range, from 4.02 to 20.10)×10⁸/kg for mononuclear cells, while 3.4 (range, from 1.05 to 8.60)×10⁸/kg for CD34 cells. 36 patients achieved neutrophil engraftment at a median of 12 (range, from 9 to 28) , and 29 patients achieved platelet engraftment at a median of 29 (range, from 10 to 26) days. Cumulative incidence of III°~IV° acute graft versus host disease (aGVHD) was 8.9±4.9%. 6 patients died of transplant-related mortality (TRM), including 4 from severe infection, and 1 from TMA. The overal survival rate of all patients was 83.2%±6.4%

Conclusions: Haplo-HSCT is likely to be an option for SAA patients without suitable related or unrelated HLA-matched donors, in consideration of the acceptable TRM and severe GVHD incidences.