Allogeneic Halpo-Identical Hematopoietic Stem Cell Transplantation for High-Risk Leukemia

Objective To retrospectively evaluate the results of allogeneic halpo-identical hematopoietic stem cell transplantation for high-risk leukemia.

Methods From June 2012 to January 2015, total 60 patients with high-risk leukemia were enrolled, including 18 cases of ALL, 37cases of AML and 5 case of CML-BP. Including criterions: 1) ≥CR1; 2) relapse within 6 months after remisson. The average leukemia burden was 53% in bone marrow. All patients received HLA haplo-identical stem cells transplantation from parent or sibling donors. Myeloablative conditioning regimens consist of 7cases of BuCy, 26 cases of TBI/FLAG, 15 cases of TBI/Cy, and 12 cases of FLAG that followed by reduced-intensified BUCY. All patients received cyclosporine A, MMF and methotrexate for GVHD prophylaxis. Analyzed outcomes were hematological engraftment, incidence of acute and chronic GVHD, incidence of relapse, and nonrelapse mortality (NRM), Overall survival (OS) and Disease-free survival (DFS).

Results The median mononuclear cells and CD34+ for transfusion were 9.08(7.02-24.4)*108/Kg and 3.42(0.8-12.1)*106/Kg. All 60 patients achieved stable engraftment. The median time of ANC≥0.5*10^9/L was 16 (8-23) days. And for platelet ≥20*10^9/L, the median was 22 (8-150) days. 38 patients developed acute GVHD, the accumulative incidence of aGVHD was 66.4%, the accumulative incidence of II-IV grade aGVHD was 35%, and the accumulative incidence of III-IV grade aGVHD was 15%. 26 patients developed cGVHD (12 patients extensive, 14 patients limited), the accumulative incidence of cGVHD was 88.2% and for extensive type, the accumulative incidence was 67.4%. The accumulative incidence of CMV infection was 54.1%, and the accumulative incidence of EBV infection was 16.3%. 10 patients developed virus cystitis. The number of Bacterial and fungal infected patients were 51 and 27, respectively. The median follow-up time post transplantation was 11(1-36) months, 14 patients relapsed and the accumulative incidence of relapse was 27%. For AML, ALL and CML-BP patients, the accumulative incidence of relapse were 26.6%, 34.8% and 0%, respectively. The median follow-up time post transplantation was 11months, 21 patients died and the main causes were relapse (11 cases), infection (5 cases), cGVHD (2 cases) and diffuse alveolar hemorrhage (3 cases). Among 60 patients, 39 patients survived. The one-year and two-year accumulative incidences of OS were 61.8% and 49.5%, respectively. The one-year and two-year accumulative incidences of DFS were 53.8% and 47.8%, respectively. For AML, ALL and CML-BP patients, the two-year accumulative incidence were 52.6%, 34.4% and 66.7%, respectively. The non-relapse mortality was 10. The one-year and two-year accumulative incidences of NRM were 19.4% and 28.4%, respectively.

Conclusion Our clinical results have shown that the salvaged HSCT is a promising modality for treatment of high-risk AL with high leukemia burden.