LAUSR

We assessed the susceptibility of secondary acute myeloid leukaemia (sAML) to graft‐versus‐leukaemia effects. Data from 2414 sAML patients in first (n = 2194) or second (n = 220) complete remission were included. They were given grafts from human leucocyte antigen (HLA)‐matched sibling (MSD, n = 1085), 10/10 unrelated donor (MUD, n = 1066) or 9/10 mismatched unrelated donor (MMUD, n = 263). The 100‐day incidence of grade II‐IV acute graft‐versus‐host disease (GVHD) was 25% while 2‐year incidence of chronic GVHD was 38%. Relapse rates declined steadily by duration of follow‐up and were significantly lower in patients with chronic GVHD (P < 0·001). Limited (hazard ratio [HR] = 0·66, P < 0·001) and extensive (HR = 0·52, P < 0·001) chronic GVHD were associated with a lower incidence of relapse. Each grade III‐IV acute (HR = 7·04, P < 0·001) as well as limited (HR = 1·42, P = 0·03) and extensive (HR = 3·97, P < 0·001) chronic GVHD were associated with higher non‐relapse mortality (NRM). This translated to better overall survival (OS; HR = 0·61, P < 0·001) in patients with limited chronic GVHD. In contrast, grade III‐IV acute and extensive chronic GVHD were associated with worse OS (HR = 3·16, P < 0·001 and HR = 1·21, P = 0·03, respectively). Further, in comparison to HLA‐identical sibling recipients, MUD recipients had a lower risk of relapse (HR = 0·82, P = 0·03) but higher NRM (HR = 1·38, P = 0·004). In conclusion, these data demonstrate that sAML is susceptible to graft‐versus‐leukaemia effects.