Peripheral blood stem cell graft compared to bone marrow after reduced intensity conditioning regimens for acute leukemia–A report from the ALWP of the EBMT

Increasing numbers of patients are receiving reduced-intensity-conditioning regimen allogeneic hematopoietic stem-cell transplantation. We hypothesized that the use of bone-marrow graft might decrease the risk of graft-versus-host-disease compared to peripheral-blood after reduced-intensity-conditioning regimens without compromising graft-versus-leukemia effects.
Patients who underwent reduced-intensity-conditioning regimen allogeneic hematopoietic stem-cell transplantation from 2000-2012 for acute leukemia and reported to the acute-leukemia-working-party of the EBMT were included in the study.
Eight hundred thirty-seven patients receiving bone-marrow grafts were compared with 9011 peripheral-blood transplant recipients after reduced-intensity conditioning regimen. Median follow-up of surviving patients was 27 months. Cumulative incidence of engraftment (neutrophil≥0.5x109/L at day 60) was lower in bonemarrow recipients, 88 vs. 95% (p<0.0001). Grade II to IV acute graft-versus-hostdisease was lower in bone-marrow recipients, 19% vs. 24% for peripheral-blood (p=0.005). In multivariate analysis, after adjusting for differences between both groups, overall survival (HR 0.90; p=0.05) and leukemia-free-survival (HR 0.88;
p=0.01) were higher in patients transplanted with peripheral-blood compared to bone-marrow grafts. Furthermore, peripheral-blood graft was also associated with decreased risk of relapse (HR 0.78; p=0.0001). Non-relapse-mortality was not significantly different between recipients of bone-marrow and peripheral-blood grafts, and chronic graft-versus-host-disease was significantly higher after peripheral blood grafts (HR 1.38; p<0.0001).
Despite the limitation of a retrospective registry based study, we found that peripheral-blood grafts after reduced-intensity-conditioning regimens had better overall and leukemia-free survival than bone-marrow grafts. However, there is an increase in chronic graft-versus-host-disease after peripheral-blood grafts. Long-term follow-up is needed to clarify if chronic graft-versus-host-disease related deaths might increase the risk of late morbidity and mortality.