Reduced-intensity vs myeloablative conditioning allogeneic hematopoietic SCT for patients aged over 45 years with ALL in remission: a study from the Adult ALL Working Group of the Japan Society for Hematopoietic Cell Transplantation (JSHCT)

In this study, outcomes for 575 adult ALL patients aged >= 45 years who underwent first allo-SCT in CR were analyzed according to the type of conditioning regimen (myeloablative conditioning (MAC) for 369 patients vs reduced-intensity conditioning (RIC) for 206 patients). Patients in the RIC group were older (median age, 58 vs 51 years, P<0.0001). There were no statistically significant differences in 3-year OS, disease-free survival (DFS) and non-relapse mortality (NRM): 51% vs 53%, 47% vs 39% and 38% vs 36%, respectively. Multivariate analysis showed that CR2 and HLA mismatching were associated with poor OS (P = 0.002 and P = 0.019, respectively). HLA mismatching was associated with lower rate of relapse (P = 0.016), but was associated with higher rate of NRM (P = 0.001). RIC was associated with good OS and DFS in patients who received HLA-mismatch transplantation and were aged >= 55 years compared with MAC by multivariate analysis for each event with interaction (hazard ratio (HR) and 95% confidence interval 0.35 and 0.15-0.81, P = 0.014 for OS and 0.36 and 0.16-0.81, P = 0.013 for DFS). Therefore, patients >= 55 years of age with HLA-mismatch transplantation should be candidates for RIC rather than MAC.