Decitabine Plus mBU/CY Preconditioning for Relapse/Refractory Acute Leukemia

Overview

Allogeneic haematopoietic stem cell transplantation (allo-HSCT) remains one of the currently available curative therapies for acute leukemia (AL). Leukemia relapse is one of the mainly causes of transplant failure. We reported previously that patients with relapse or refractory AL were at very high risk of relapse post allo-HSCT, with cumulative relapse rate of 50-80%. Decitabine has been demonstrated efficacy in the treatment of patients with recurrent or refractory leukemia and myelodysplastic syndrome. It was reported that the combination of decitabine, with busulfan and cyclophosphamide as a preparative regimen for allo-HSCT using HLA-matching donors was safe and effective. In this prospective, single-arm clinical trial, we aimed to examine the efficacy of combining decitabine with modified busulfan and cyclophosphamide (mBU/CY) as a preparative regimen for allo-HSCT in recurrent and refractory AL patients.

Patients enrolled in this study would receive decitabine 200mg·m-2·d-1 on day -12 and -11 pre-HSCT. The conditioning therapy for human leukocyte antigen (HLA)-mismatched HSCT patients was modified BU/CY plus ATG (thymoglobulin; Sang Stat, France) consisting of cytarabine (Ara-C 4 g·m-2·d-1) intravenously on days -10 to -9, busulfan (BU 3.2 mg·kg-1·d-1) intravenously on days -8 to -6, cyclophosphamide (CY 1.8 g·m-2·d-1), intravenously on days -5 to -4, semustine (Me-CCNU, 250 mg·m-2), orally once on day -3, and ATG (2.5 mg·kg-1·d-1) intravenously on days -5 to -2. In matched sibling transplantations, patients received hydroxycarbamide (80 mg·kg-1) orally on day -10 and a lower dose of Ara-C (2 g·m-2·d-1) on day -9, but otherwise an identical regimen to the HLA-mismatched patients without ATG. BM(bone marrow) samples from patients were obtained to assess leukemia status after HSCT. The time points that we monitored BM samples included at time of allo-HSCT; 1 month, 2 months, 3 months, 4.5 months, 6 months, 9 months, and 12 months after allo-HSCT; and every 6 months thereafter to the defined endpoints or for at least until 5 years after transplantation.