Hematopoietic Stem Cell Transplantation for Patients with Chronic Myeloid Leukemia

OBJECTIVE To evaluate the effects of autologous and allogeneic hematopoietic stem cell transplantation (HSCT) for patients with chronic myeloid leukemia(CML).

METHODS Fifty-seven patients with CML were treated by HSCT, including 8 cases treated with autologous transplantation purged in vivo and in vitro of minimal residual disease (MRD), 39 cases with related donor allogeneic HSCT (allo-HSCT) and 10 cases with unrelated donor allo-HSCT. The conditioning regimen was a TBI (total-body Irradiation) +CY (cyclophosphamide, CTX) protocol in 32 patients, a modified BuCY (hydroxyurea, busulfan, Ara-C, CTX) protocal in 24 patients, and a MACC (Melphalan, Ara-C, CTX and chlorethyl cyclohexyl nitrosourea) protocol in one patient. Cyclosporine (CsA) and methotrexate (MTX) were used in patients with related-donor allo-HSCT, and CsA and MTX were added to mycophenolate mofetil (MMF) and antithymocyte globulin (ATG) in unrelated donor allo-HSCT for graft versus host disease (GVHD) prophylaxis. Otherwise, CsA was only used for GVHD prophylaxis in patients with accelerated phase (AP) and blast crisis (BC). The Kaplan-Meier survival analysis model was used to estimate the overall survival (OS) and the disease-free survival (DSF) at 5 years after transplantation.

RESULTS Eight patients with autologous transplantation, except for 1 case who died of transplantation-related complications, obtained cytogenetic part or complete remission (CR) within 3 months after transplantation. One patient, who was in BC and obtained CR in hematology before transplantation, had been in molecular CR for 92 months after autologous transplantation. Among the 49 patients treated with allo-HSCT, all obtained CR, except for one patient who died of hepatic veno-occlusive disease (VOD) and one who had not obtained CR. The incidence of infection and VOD was 33.3% and 7.0%, respectively, during transplantation. After transplantation the incidence of hemorrhagic cystitis (HC) and cytomegalovirus (CMV) interstitial pneumonia (IP) was 22.8% and 8.8%, respectively. VOD, HC and CMV IP did not occur in patients with autologous transplantation. The incidence of acute GVHD and the frequency of chronic GVHD was 41.0% and 48.6%, respectively, In patients with related and unrelated transplantation. The rate of relapse in patients with autologous and allogeneic transplantation was 57.1% and 12.8%, respectively. The DFS at 5 years after transplantation was 25.0% and 61.7%, respectively, in patients with autologous and related donor transplantation. The DFS at 5 years was 70.7% and 34.1%, respectively, in patients with CP (chronic phase) or AP and BC before transplantation.

CONCLUSION Alio-HSCT may have a higher clinical cure rate for CML patients with CP. The CsA +MTX +MMF +ATG protocol is more effective for acute GVHD prophylaxis and can decrease the incidence and degree of GVHD in patients with unrelated donor transplantation. Autologous transplantation with purged bone marrow can prolong the survival time of CML patients and some may be cured with transplants of this type.