Prevalence and clinical impact of CD56 and T-cell marker expression in acute myeloid leukaemia: A single-centre retrospective analysis.

Flow cytometry-based immunophenotyping is a mainstay of diagnostics in acute myeloid leukaemia (AML). Aberrant CD56 and T-cell antigen expression is observed in a fraction subset of AML cases, but the clinical relevance remains incompletely understood. Here, we retrospectively investigated the association of CD56 and T-cell marker expression with disease-specific characteristics and outcome of 324 AML patients who received intensive induction therapy at our centre between 2011 and 2019. We found that CD2 expression was associated with abnormal non-complex karyotype, NPM1 wild-type status and TP53 mutation. CD2 also correlated with a lower complete remission (CR) rate (47.8% vs. 71.6%, p  = 0.03). CyTdT and CD2 were associated with inferior 3-year event-free-survival (EFS) (5.3% vs. 33.5%, p  = 0.003 and 17.4% vs. 33.1%, p  = 0.02, respectively). CyTdT expression was also correlated with inferior relapse-free survival (27.3% vs. 48.8%, p  = 0.04). In multivariable analyses CD2 positivity was an independent adverse factor for EFS (HR 1.72, p  = 0.03). These results indicate a biological relevance of aberrant T-cell marker expression in AML and provide a rationale to further characterise the molecular origin in T-lineage-associated AML.