Prognostic significance of monocytic-like phenotype in patients with AML treated with venetoclax and azacytidine

The prognostic impact of monocytic differentiation in patients with acute myeloid leukemia (AML) receiving venetoclax (Ven) and azacitidine (Aza) remains unclear. In a prospective cohort of 86 newly diagnosed patients with AML treated with Ven-Aza, we used multiparametric flow cytometry (MFC) to define monoblasts as AML blasts coexpressing ≥2 monocytic markers (CD4, CD36, and CD64) per European LeukemiaNet (ELN) guidelines. Patients with higher monoblasts/CD45+ proportions had lower complete response rates (odds ratio, 0.24; P = .005) and significantly shorter overall survival (OS; 4.0 vs 14.9 months; P = .003). A ≥10% monoblasts/CD45+ threshold, identified via maximally selected rank statistics, stratified patients into monoblasthigh (≥10%) and monoblastlow (<10%) groups. MFC reclassified 20% of French-American-British (FAB) non-M4/5 and 15% of FAB M4/5 cases into monoblasthigh and monoblastlow groups, respectively. Multivariable analysis confirmed monoblasthigh status as an independent adverse prognostic factor for OS (hazard ratio [HR], 1.95; P = .023), with a particularly strong impact in ELN 2024 favorable-risk patients (HR, 2.81; P = .024). Our findings highlight monocytic differentiation, assessed via MFC, as a key predictor of Ven-Aza resistance and poor survival, independent of genetic classification. Given its availability in routine diagnostics, MFC-based monocytic assessment could improve AML risk stratification and treatment decisions in patients eligible for less intensive therapies. This trial was registered at www.clinicaltrials.gov as #NCT05326919.