Anti-leukaemic role of acute GvHD after unrelated haematopoietic stem cell transplantation in intermediate- to high-risk acute myelogenous leukaemia.

Little is known about the role of acute GvHD (aGvHD) based on the concept of graft-versus-leukaemia effect (GVLE) after unrelated donor haematopoietic stem cell transplantation (uHSCT). We evaluated 67 uHSCTs performed with multinational unrelated donors for patients with AML. The median follow-up duration was 18 months (range 7-61). The majority of patients had intermediate- or high-risk cytogenetic findings. The conditioning regimen for most patients consisted of cyclophosphamide plus total body irradiation (n=56) with our standard GvHD prophylaxis containing tacrolimus plus a short course of methotrexate. The incidence of aGvHD and chronic GvHD was 50 and 52%, respectively. Eight patients (12%) have relapsed to date. The estimated overall disease-free survival (DFS) rate at 5 years was 67%. Notably fewer relapses were seen when aGvHD developed (P=0.008). Specifically, high-risk AML patients had a much lower relapse rate when they developed aGvHD (P=0.01), compared with the intermediate-risk group. Therefore, the development of aGvHD after uHSCT in AML patients is closely related to a lower relapse rate, probably in association with GVLE.