Stem cell transplantation from identical twins in patients with myelodysplastic syndromes

In a multicentre retrospective EBMT database study, we analysed factors influencing outcome in 38 patients with MDS/sAML who were transplanted with stem cells from their syngeneic twin and compared those to 1444 patients who were transplanted from an HLA-identical sibling. The median time to leukocyte and platelet engraftment was faster in the twin group: 14 vs 17 (P=0.02) and 16 vs 26 days (P=0.09), respectively. The 5 years cumulative incidence of treatment-related mortality (TRM) was higher in the sibling than in the twin group (38 vs 27%; P=0.05). The 5 year cumulative incidence of relapse was 32% (95% CI: 29-35%) for the siblings and 39% (95% CI: 26-60%; P=0.6) for the twins. A trend for better 5-years disease-free and overall survival was observed in the twin group: 34% (95% CI: 14-54%) vs 28% (95% CI: 25-31%; P=0.2) and 36% (95% CI: 15-57%) vs 32% (95% CI: 29-35%; P=0.09), respectively. In a multivariate analysis, stem cell transplantation from identical twins had a lower TRM: HR: 0.4 (95% CI: 0.2-0.9; P=0.03). The relapse rate was similar for both groups with a HR of 1.2 (95% CI: 0.07-2.1; P=0.5), with a better survival for the twins: HR 0.6 (95% CI: 0.4-1.0; P=0.07). We conclude that twin transplantation in MDS/sAML is associated with a similar relapse risk, a lower TRM and a trend for better overall survival in comparison to transplantation from HLA-identical siblings.