Lymphocyte-to-Monocyte Ratio as a Novel Tumor Microenvironment Marker of Adverse Prognosis in Adults with Acute Myeloid Leukemia.

Abstract

Background: The Lymphocyte-to-Monocyte Ratio (LMR) is an inexpensive complete blood count-derived marker that may reflect the balance between host immune status and the leukemia-associated microenvironment. This prospective cohort study evaluated baseline LMR as an exploratory prognostic biomarker in adults with de novo non-M3 Acute Myeloid Leukemia (AML). Methods: We prospectively enrolled 100 treatment-naive adults with de novo non-M3 AML at the Clinical Hematology Unit, Zagazig University Hospitals. Receiver operating characteristic analysis identified an LMR cutoff of 3 for survival outcomes (Area Under the Curve [AUC], 0.613; 95% Confidence Interval [CI], 0.511-0.709; sensitivity, 73.33%; specificity, 55%; p = 0.047). Overall Survival (OS) and Disease-Free Survival (DFS) were estimated using Kaplan-Meier analysis. Cox proportional hazards models were used to assess prognostic factors. Results: Over a median follow-up of 7.7 months (range: 0.5-33.2 months), patients with LMR ≤3 demonstrated significantly inferior outcomes compared with those having LMR >3: lower Complete Remission (CR) rates (51.6% vs. 73.7%; p = 0.029), worse 3 year OS (0 vs. 44.9%; p = 0.03) and poorer 3 year DFS (0 vs. 45%; p = 0.021). Mortality and relapse rates were significantly elevated in the low LMR group (71.0 vs. 42.1%, p = 0.004; 62.5 vs. 12.6%, p = 0.009, respectively). Multivariate Cox regression identified low LMR as an independent adverse prognostic factor for DFS (HR 4.51; 95% CI: 1.57-12.97; p = 0.005). Conclusions: Low baseline LMR was associated with adverse DFS in this exploratory cohort. LMR should be considered a candidate supplementary biomarker rather than a replacement for established molecular and cytogenetic risk stratification. Multicenter validation is required before routine clinical use.