Differential impact of graft-versus-host disease on post-transplant outcomes of chronic myelomonocytic leukemia according to transplant procedures.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) provides curative outcomes for chronic myelomonocytic leukemia (CMML). We conducted a retrospective study to clarify the protective impact of acute and chronic graft-versus-host disease (aGVHD and cGVHD) on relapse by transplant procedures in 314 CMML patients. Interaction effects of conditioning intensity were observed with aGVHD (Pinteraction=0.181) and cGVHD (Pinteraction=0.256) for the cumulative incidence of relapse (CIR), whereas interaction effects of donor type were not detected with GVHD. In patients with the myeloablative conditioning regimens, the multivariate analysis showed that the development of aGVHD was not associated with overall survival (OS). The development of limited cGVHD correlated with better OS (HR [95 % CI], 0.34 [0.14-0.81]; P = 0.015); and that of extensive cGVHD correlated with better OS (HR, 0.44 [0.21-0.91]; P = 0.026) and lower CIR (HR, 0.28 [0.08-0.94]; P = 0.040). In patients with the reduced-intensity conditioning regimens, the development of grade I-II aGVHD correlated with better OS (HR, 0.39 [0.20-0.76]; P = 0.005) and lower CIR (HR, 0.30 [0.13-0.70]; P = 0.006). The development of extensive cGVHD correlated with better OS (HR, 0.44 [0.20-0.96]; P = 0.039). The present results suggest that the type and severity of GVHD mediating graft-versus-leukemia effects against relapse were influenced by conditioning intensity in CMML patients.