Mismatched related donors of hematopoietic SCT (HSCT) for severe aplastic anemia (SAA) present challenges mainly associated with graft failure and GVHD. The greater the HLA disparity, the poorer the OS. About 19 consecutive SAA/very SAA (VSAA) patients who received HSCT from haploidentical family donors in our center are reported in this study, 18/19 pairs had 2-3 loci mismatched. All 19 cases failed to respond to previous therapy and were heavily transfused before transplantation. The conditioning regimen before HSCT included BU, CY and thymoglobulin. The recipients received CsA, mycophenolate mofetil (MMF) and short-term MTX for GVHD prophylaxis. The source of stem cell grafts was a combination of G-CSF-primed BM and G-CSF-mobilized peripheral blood stem cells. All patients achieved 100% donor myeloid engraftment; the median time for myeloid engraftment was 12 days (ranging from 10-29 days) and for platelets was 18 days (ranging from 8-180 days) with a cumulative platelet engraftment incidence of 84.21 ± 10.53%. The cumulative incidence was 42.1 ± 11.3% for grade II-IV acute GVHD and 56.2 ± 12.4% for chronic GVHD. The OS was 64.6 ± 12.4% with a median 746-day (90-1970) follow-up for surviving patients. These limited retrospective analysis data suggest that HLA-haploidentical HSCT for SAA patients without an HLA-identical sibling donor might be feasible. Further research to increase OS by decreasing GVHD while maintaining stable engraftment will be needed in the future.

Techniques for haploidentical hematopoietic stem cell transplantation (haplo-HSCT) to treat severe aplastic anemia (SAA) have recently improved, but no protocol has been evaluated in a large number of pediatric patients. Fifty-two children with SAA received haplo-HSCT in our center. The treatment protocol used G-CSF-primed bone marrow with G-CSF-mobilized PBSCs without in vitro T-cell depletion. The conditioning regimen included busulfan/cyclophosphamide and antithymocyte globulin. Fifty-one patients achieved primary engraftment; one child died of regimen-related toxicity on the day +1. Secondary graft failure occurred in three patients. The cumulative incidences of aGVHD grade II-IV and grade III-IV were 39.2±0.5 and 13.7±0.2%, respectively. The cumulative incidence of cGVHD was 34.2±0.5%. The 3-year overall and failure-free survival rates were 84.5±5.0 and 82.7±5.2%, respectively, with a median follow-up time of 744.5 days (100-3294) for surviving patients. The Eastern Cooperative Oncology Group score was the only predictor of overall and failure-free survival rates. Clinical outcomes were similar between the upfront and salvage group. This result suggests that both newly diagnosed and refractory pediatric SAA patients benefit from haplo-HSCT, especially when patients are in good general condition. Therefore, haplo-HSCT might be an alternative therapy for pediatric SAA patients without HLA-matched sibling donors.