[Reduced intensity of BuCy conditioning regimen for transplantation in the treatment of malignant hematologic diseases].

OBJECTIVE

To evaluate the use of a new reduced intensity of BuCy conditioning regimen for the treatment of malignant hematologic diseases in aged or intolerable patients receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT) from the siblings.

METHODS

Twelve patients with acute lymphoblastic leukemia (ALL, n = 4), acute myelogenous leukemia (AML-M(2), n = 2), chronic myelogenous leukemia (CML, n = 4), and myelodysplastic syndromes-refractory anemia with excess blasts (MDS-RAEB, n = 2) were intolerant of conventional myeloablative therapy because of age (older than 50 years) or having severe concurrent diseases. The median age was 49 years (range 42-64 years). Seven were males and five females. Two of the 12 patients were HLA one antigen-mismatched and the rest HLA identical with their donors. The low dosage conditioning regimen consisted of busulfan (2 mg.kg(-1).d(-1) for 3 days), Ara-C (2 g.m(-2).d(-1) for 1 or 2 times), cyclophosphamide (1.0 g.m(-2).d(-1) for 2 days) and anti-T-lymphocyte globulin (ATG 2.5 mg.kg(-1).d(-1) for 4 days, -5 - -2 day). Granulocyte colony-stimulating factor mobilized bone marrow and peripheral blood stem cells (PBSC) were harvested (1 patient using PBSC alone). All patients received cyclosporin A, short-term MTX and mycophenolate mofetil (MMF) for prophylaxis of acute graft-versus-host disease (aGVHD). DNA short tandem repeat (STR) sequence analysis, cytogenetics and molecular-biologic technique were used to analyze chimerism.

RESULTS

All the patients were well tolerated the regimen, with no severe regimen related toxicity. In all the 12 patients, absolute neutrophil count > or = 0.5 x10(9)/L was achieved in 11 to 17 (median 15) days and platelet count > 20 x 10(9)/L in 10 to 23 (median 15) days after transplantation. Complete chimerism was achieved in 11 patients and 1 patient was in mixed chimerism at one month after HSCT. With a median follow-up of 14.5 (4.0-24.0) months, 7 of the 12 patients (58.0%) were alive and 5 (42.0%) of the 7 were disease-free. The probabilities of OS and DFS at 12 months were 75.0% and 48.1%. Five patients (41.6%) had aGVHD and four had local chronic GVHD with a cumulative probability of chronic GVHD of 41.5%.

CONCLUSION

This reduced intensity conditioning regimen is well tolerated and safe for HSCT in the older patients or patients with severe concurrent medical conditions and can achieve full chimerism and long-term disease-free survival.