A distinct subgroup of AML resembling the APL immunophenotype is associated with DIC

The complexity of acute myeloid leukemia (AML) is increasingly recognized through the identification of distinct subgroups, including those with an APL-like immunophenotype characterized by the absence of CD34 and HLA-DR expression, which is widely recognized as a representative immunophenotype in acute promyelocytic leukemia (APL). This study sought to understand the clinical, molecular, and prognostic differences between AML patients with and without this phenotype.

This study retrospectively analysed 191 de novo non-M3 AML patients and identified 32 patients with the CD34^-HLA-DR^- phenotype resembling APL-like immunophenotype, considered as the experimental group. Clinical data, including complete blood count, leukemic blasts, coagulation analysis DIC score, and OS, were collected, and immunophenotypic and molecular data were compared between this group and a control group of patients without this immunophenotype.

Patients with the CD34^-HLA-DR^- immunophenotype in the AML cohort had a significantly greater risk of developing disseminated intravascular coagulation (DIC) than did patients in the control group. Additionally, a lower rate of expression of immunophenotypic clusters of differentiation (CD markers) associated with poor prognosis was observed in the CD34^-HLA-DR^- group. At the molecular level, an increased frequency of nucleophosmin 1 (NPM1) mutations and increased expression of the Wilms' tumor 1 (WT1) gene were noted in this subgroup. However, contrary to patients with an expected favourable prognosis, patients in the favourable risk group with the CD34^-HLA-DR^- immunophenotype had significantly shorter overall survival than did patients in the control group.

The findings highlight the patients exhibiting the CD34^-HLA-DR^- immunophenotype as a unique AML subgroup with specific clinical and molecular traits, notably a predisposition to DIC, which affecting prognosis. This finding has implications for risk stratification and potential targeted therapies for AML management.