Objective      To determine the clinica1 efficacy of infusions of donor-derived cytokine induced killer (CIK) cells in the patients having minimal residual disease (MRD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).       Methods      Ten refractory/relapsed patients

including acute lymphoblastic leukemia (ALL

n=5)

acute myelogenous leukemia (AML

n=4)

and chronic myelomonocytic leukemia (CMML

n=1) admitted in our department from November 2012 to November 2015 were enrolled in this retrospective analysis. All the patients were achieved molecular remission

then relapsed again after allo-HSCT

and 7 of them achieved MRD positive status and 3 relapsed. They had received salvage treatments including stopping immunosuppressive

chemotherapy and donor lymphocytes infusion. All patients were achieved remission but had MRD positive before CIK infusion.       Results      The median number of CIK infusions was 3 (ranged from 2 to 8) times. However

1 case was no response to the twice infusions of CIK and died finally due to relapse. Nine patients of them achieved molecular responses after accepting the infusions of CIK. One of the 9 patients relapsed again and died 10 months after the infusions

one died of grade Ⅳ graft versus host disease after stopping immunosuppressive therapy

and the left 7 patients had stayed continuous complete remission (CCR). The median time of follow-up after CIK infusion was 10 (ranging from 3 to 14) months. The median time of overall survival (OS) was 8 months (ranging from 3 to 14)

and that of event-free survival (EFS) was 8 months (ranging from 0 to 14). Five patients had longer remissions after infusion of CIK cells than after allo-HSCT.       Conclusion      Infusion of donor-derived CIK cells is an effective therapy for the MRD-positive patients after allo-HSCT

with well tolerance

achieving molecular remission

reducing relapse

and improving efficiency of hematopoietic stem cell transplantation.