The association of graft-versus-leukemia effect and graft-versus host disease in haploidentical transplantation with post-transplant cyclophosphamide for AML

The association of graft-versus-host disease (GVHD) and graft-versus-leukemia effect after stem-cell transplantation (SCT) is well established but with limited data in the setting of haploidentical SCT (haploSCT) with post-transplant cyclophosphamide (PTCy). We used a series of landmark analyses to investigate this association in 805 AML patients following haploSCT. On day +100, 707 patients were alive and leukemia-free, 500 had no prior acute GVHD, 137 had acute GVHD grade II and 70 had grade III-IV. Subsequent relapse rates were 20.3%, 23.2% and 15.0%, respectively (P = 0.52). Subsequent non-relapse mortality (NRM) was 8.6%, 17.8% and 38.6%, respectively (P < 0.0001). Leukemia-free survival (LFS) was 71.0%, 59.0% and 46.3%, respectively (P < 0.0001). Multivariate analysis showed that acute GVHD grade II and grade III-IV were not associated with relapse (HR 1.21, P = 0.37 and HR 1.03, P = 0.94), but were associated with increased NRM (HR 2.09, P = 0.005 and HR 6.41, P < 0.0001) and lower LFS (HR 1.47, P = 0.02 and HR 2.59, P = < 0.0001). Chronic GVHD was not associated with subsequent relapse. Extensive chronic GVHD was associated with higher NRM (HR 6.72, P < 0.0001) and inferior LFS (HR 3.29, P = < 0.0001). GVHD of any type or grade is not associated with lower relapse after haploSCT with PTCy. Severe forms are associated with higher NRM and lower survival.