Outcome of medium-dose VP-16/CY/TBI superior to CY/TBI as a conditioning regimen for allogeneic stem cell transplantation in adult patients with acute lymphoblastic leukemia

The choice of conditioning regimen before allogeneic stem cell transplantation (SCT) in patients with acute lymphoblastic leukemia (ALL) is important. We retrospectively compared outcomes of medium-dose VP-16/cyclophosphamide/total body irradiation (VP/CY/TBI) regimen and CY/TBI. Five hundred and twenty-nine patients (VP/CY/TBI: n = 35, CY/TBI: n = 494) who met all of the following criteria were compared: first time for SCT, aged 15-59 years; first or second complete remission at SCT; bone marrow or peripheral blood as stem cell source; and HLA phenotypically matched donor. Median age of the patients was 34 years, and patients who received VP/CY/TBI were younger (28 vs. 34 years, P = 0.02). Cumulative incidences of relapse and non-relapse mortality (NRM) were higher for patients who received CY/TBI (P = 0.01 for relapse, P < 0.01 for NRM). After a median follow-up period of 36.9 months, 5-year overall survival (OS) rates were 82.2% in the VP/CY/TBI group and 55.2% in the CY/TBI group. OS, and disease-free survival (DFS) in the VP/CY/TBI group were shown to be significantly better by multivariate analysis [hazard ratio: 0.21 (95% confidence interval: 0.06-0.49) for DFS, hazard ratio: 0.25 (95% confidence interval: 0.08-0.59) for OS]. VP/CY/TBI was associated with a lower relapse rate and no increase in NRM, resulting in better survival than that in CY/TBI for adult ALL patients.