Chronic GVHD induced GVL effect after unmanipulated haploidentical hematopoietic SCT for AML and myelodysplastic syndrome.

The aim of this study was to investigate the impact of occurrence of chronic GVHD (cGVHD) and its severity on transplantation outcomes in a consecutive cohort of AML and myelodysplastic syndrome (MDS) patients who received unmanipulated haploidentical hematopoietic SCT (haplo-HSCT; n=324). The cumulative incidence of relapse was significantly decreased in patients with cGVHD compared with the non-cGVHD group (1 year: 3.2% vs 11.9%, P=0.002; 3 years: 6.0% vs 16.3%, P=0.002), particularly in those with mild cGVHD. The cumulative incidence of non-relapse mortality was comparable between patients with and without cGVHD. The probabilities of disease-free survival (DFS) were significantly better in patients with cGVHD than in those in the non-cGVHD group (1 year: 90.5% vs 78.5%, P=0.002; 3 years: 86.5% vs 71.5%, P<0.001), particularly in those with mild or moderate cGVHD; however, no significant impact of severe cGVHD on DFS was seen. Our findings highlight the close relationship between cGVHD and the immune-mediated GVL effect in patients with AML and MDS receiving unmanipulated haplo-HSCT; however, only mild or moderate cGVHD was associated with a lower risk of relapse translating into improved DFS.