MRD abnormal expression predict poor outcomes for refractory or relapsed acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation

We retrospectively analyzed data from 197 patients with refractory or relapsed acute myeloid leukemia (r/rAML) who underwent allo‐HCT between January 2013 and February 2020 in our center (patients with promyelocytic leukemia were excluded). Of all patients, 86 achieved a complete morphological remission (CR) before transplant, while 111 failed to do so (NR). In the CR group, 32 patients displayed minimal residual disease (MRD‐positive). According to their immunophenotype pre‐HCT, we divided the MRD‐positive group and NR group into three subgroups: MRD 0+ group (without any antigen abnormal expression of CD7+, CD56+, CD38−, or HLA‐DR−) 28 patients, MRD 1+ group (with one abnormal antigen expression of CD7+, CD56+, CD38−, or HLA‐DR−) 63 patients, MRD 2+ group (with two or more abnormal antigens expression of CD7+, CD56+, CD38‐, or HLA‐DR‐) 52 patients. 3‐year estimates of disease‐free survival (DFS) for MRD 0+, MRD 1+ and MRD 2+ patients were 59.5 ± 9.5%, 29.9 ± 6.1%, and 9.4 ± 5.1%, and 3‐year estimates of overall survival (OS) were 59.5 ± 9.5%, 34.5 ± 6.3%, and 14.5 ± 10.8%, respectively. Multivariate analysis adjusted for genetic risk, blast cell level, secondary disease, age, sex, and donor relationship pre‐HCT, the hazard ratios of abnormal expression of CD7+, CD56+, HLA‐DR−, and CD38(‐) were 6.69 (range 2.08–21.52; p = 0.001) for DFS, 2.24 (range 1.21–4.14; p = 0.010) for OS, and 7.18 (range 2.23–23.10; p = 0.001) for relapse compared with CD7−, CD56−, HLA‐DR+, and CD38+ patients. Our finding suggested that abnormal expression of CD7+, CD56+, HLA‐DR−, and CD38− is associated with poor outcomes, and the more number of abnormal antigens expression predict worse outcomes.