Successful Result of 113 Patients for Refractory/Recurrent Leukemia By Allogeneic Hematopoietic Cell Transplantation and Prophylactic Immunotherapy

Objective: To retrospectively evaluate the results of allogeneic hematopoietic stem cell transplantation for Refractory/Recurrent leukemia. Methods: From July 2012 to May 2016, total 113 patients with Refractory/Recurrent leukemia were enrolled, including 31 cases of ALL, 73 cases of AML and 8 cases of CML-BP, 1 case of Prolymphocytic leukemia. The average leukemia burden was 51% (10-99) in bone marrow before conditioning. Myeloablative conditioning regimens consisted of 13 cases of BuCy, 47 cases of TBI/FLAG, 28 cases of TBI/Cy, and 16 cases of FLAG that followed by reduced-intensified BUCY, 9 cases of CLAG/BuCy. Transplant types included sibling HLA-identical allo-HSCT (n=22) and relative HLA-haploidentical HSCT (n=91). All patients received cyclosporine A, MMF and methotrexate for GVHD prophylaxis. Analyzed outcomes were hematological engraftment, incidence of acute and chronic GVHD, incidence of CMV/EBV infecton, 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 8.83 (7.02-11.64) ×108/Kg and 2.91 (0.8-8.32) ×106/Kg. 111 patients achieved stable engraftment, 2 patients died of infection before engraftment. The median time of ANC≥0.5×109/L was 16 days(8-29) and the median time of platelet ≥20×109/L was 22 days (8-150). On day 28postallogeneic transplant, 110 patients were in complete remission of bone marrow, 1 patient was in hematologic relapse. Immunity residue were negative in 107 patients and positive in 4 patients. 62 patients developed acute GVHD, the accumulative incidence of aGVHD was (57.6±4.8)%, the accumulative incidence of II-IV grade aGVHD was (47.2±4.8)%, and the accumulative incidence of III-IV grade aGVHD was (25.2±4.1)%. 62 patients developed cGVHD (43 patients extensive, 19 patients limited), the accumulative incidence of cGVHD was (70.2±6.6)% and for extensive type, the accumulative incidence was (43.6±5.2)%. The accumulative incidence of CMV infection was (42.3±4.7)%, and the accumulative incidence of EBV infection was (4.5±2)%. 10 patients developed virus cystitis, and the accumulative incidence was (9.1±2.1)%. The median follow-up time post transplantation was 10 months (1-46), 35 patients occurred hematologic relapsed and the accumulative incidence of relapse was (39.7±5.9)%. For AML, ALL and CML-BP patients, the accumulative incidence of relapse were (33.8±6.9)%, (56.6±11.7)% and (25±15.3)%respectively (p>0.05). On median follow up (10 months), 49 patients died and 64 patients survived. The cause of death included relapse (28 cases), infection (6 cases), GVHD (11 cases) diffuse alveolar hemorrhage (2cases), radiation enteritis (1 case), and TMA (1 case).Among 64 survirors, two-year accumulative incidences of OS were (49.3±5.7)%, and two-year accumulative incidences of LFS were (45.1±5.4). The two-year accumulative incidences of OS for AML, ALL and CML-BP patients were ( 52.4±7.1)%, (28.1±9.7)%,and (87.5±11.7)%respectively (p>0.05). The two-year accumulative incidence of LFS for AML, ALL and CML-BP patients were (49.8±6.5)%, (24.7±9.1)%, and (70±18.2)%respectively (p>0.05). Incidence of relapse, OS and LFS were similar in different conditioning cohorts (p>0.05). There was no significant difference in the incidence of relapse, OS and LFS over two years among patients with C-Kit, FLT3, MLL and without such genes(p>0.05). There is significant difference in incidence of relapse, OS and LFS among patients with different leukemia burdens(p<0.01). Patients with leukemia burden at 10-19% has lower relapse rate but higher OS and LFS compared to patients with leukemia burden at 80%. Incidence of relapse, OS and LFS for the prophylactic immunotherapy cohort were 32.9%, 61.1% and 57.6% respectively, compared to 45.2%, 35.8% and 35% for non prophylactic immunotherapy cohort (p<0.01). Incidence of relapse , OS and LFS for the cGVHD cohort were 12.9%, 68.4% and 66.2% respectively, compared to 78.7%, 13.9% and 12.8% for non cGVHD(p<0.01). Incidence of relapse , OS and LFS for extensive cGVHD cohort were 12.3%, 62.1% and 61.8% respectively, compared to 58.8%, 31.4% and 31.2% for non extensive cGVHD(p<0.01) Conclusion: Our clinical results have shown that the salvaged HSCT is a promising modality for treatment of Refractory/Recurrent leukemia. Especially for Refractory/Recurrent AML and CML-BP. Disclosures No relevant conflicts of interest to declare.