The improvement in overall survival from unrelated donor transplantation in Australia and New Zealand is driven by a reduction in non-relapse mortality: A study from the ABMTRR.

ABSTRACT

Unrelated donors (UDs) are the commonest source for allogeneic transplantation (alloSCT), with higher non-relapse mortality (NRM) than siblings. We analyzed data from the Australasian Bone Marrow Transplant Recipient Registry from adults receiving a first UD alloSCT during 2001-2015, to determine whether and how NRM has changed. Predictors of outcome were determined using cox regression, accounting for time-interactions and competing risks. A total of 2308 patients met inclusion criteria. Changes over time included increasing age, utilization of peripheral blood cells, reduced intensity conditioning, and T-cell depletion. Three-year OS increased significantly from 44% in 2001-2005 to 58% in 2011-2015 (p < 0.001). This was attributed to a reduction in NRM from 35% to 24% (p < 0.001) with no change in relapse. Factors associated with increased NRM included age, male sex, CMV seropositivity, HLA mismatch, transplant more than 6 months from diagnosis, and T-cell depletion when administered during 2001-2005. Survival following UD SCT has improved by almost 15% over the past decade, driven by improvements in NRM. This has occurred despite increasing recipient age and appears to be due to better donor selection, reduced delays to transplantation, and improved prevention and management of GVHD.