Reduced-Intensity Conditioning Versus Conventional Regimen for Allogeneic Peripheral Blood Hematopoietic Stem Cell Transplantation in Patients with Chronic Myeloid Leukemia.

Objective To explore the significance of reduced-intensity conditioning allogeneic peripheral blood hematopoietic stem cell transplantation (PBSCT) in the treatment of chronic myeloid leukemia.

Patients and Methods Twenty-six consecutive patients received reduced-intensity conditioning (Flu 30mg/m².d⁻¹×5d+BU 4mg.kg⁻¹.d⁻¹×3d or CTX 100mg.kg⁻¹+TBI≤6.0Gy) PBSCT(RIC group). Among them, 21 were male and 5 female with median age of 36 (23~49). Twenty three of them were in chronic phase and 3 in progressive phases. The median time from diagnosis to transplantation was 12 (3~84) months. Twenty-four consecutive patients received standard conditioning (CTX 120mg.kg⁻¹+ TBI≥7.0Gy) prior to PBSCT (STAND group) were used as historic controls. In this group of patients, 22 were in chronic phase and 2 in progressive phases. Twenty patiens were male and 4 female with median age of 35 (18~49). The median time from diagnosis to transplantation was 13 (3~48) months. All patients received PBSC from HLA matched related donors. Mycophenolate mofetil (MMF),CsA and MTX were given for prophylaxis of acute graft-versus-host-disease (aGVHD).

Results All patients were successfully engrafted and achieved a complete cytogenetic remission. One patient developed graft rejection 6 months post-transplantation in RIC group. The median time when granulocyte exceeded 0.5 ×10⁹/L and platelets exceeded 20 ×10⁹/L was 15(12–23) days and 19(12–32) days in STAND group and 13(11–18) and 17(11–30) days in RIC group, respectively. The cumulative incidence of aGVHD was 45.83% (11/24) in STAND group and 23.08% (6/26) in RIC group(P>0.05). The incidence of Grade III–IV aGVHD in STAND group and RIC group was 16.67% and 0%, respectively(P<0.05). Chronic GVHD (cGVHD) occurred in 15 out of 20 patients (75%) lived longer than 6 months post-transplantation in STAND group and 18 out of 25 patients (72%) in RIC group(P>0.05). The incidence of extensive cGVHD in STAND group and RIC group was 35% and 0%, respectively(P<0.01). Median follow-up for survivors was 34(14–89)and 18(6–39)months in the STAND and RIC groups, respectively. Relapse occurred in 12.5%(3/24)of the patients in STAND group and 11.54%(3/26)in RIC group (P>0.05). 4 patients experienced a cytogenetic relapse, which was successfully treated with donor PBSC infusions. The Cumulative incidence of TRM was 41.67% (10/24) for the STAND group and 19.23% (5/26) for the RIC group, respectively (P>0.05). GVHD copplicated with interstitial pneumatitis or severe infection were the main causes of death. The estimated 3-year probabilities of disease-free-survival (DFS) was 62% in STAND group and 76% in RIC group, respectively (P>0.05).

Conclusion Our results indicate that reduced-intensity conditioning allogeneic peripheral blood stem cells transplantation is a safe, less toxic and curative approach for patients with chronic myeloid leukemia.