Lower baseline eosinophil counts are associated with inferior survival in Mantle cell lymphoma

Mantle cell lymphoma (MCL) is characterized by heterogeneous clinical outcomes, highlighting the need for additional biomarkers to refine risk stratification beyond established prognostic models. We evaluated the prognostic value of baseline absolute eosinophil count (EOZ) in 144 adults with newly diagnosed MCL treated with first-line immunochemotherapy. The median EOZ was 0.10 × 109/L. Patients with EOZ above the median had longer OS (84.8 vs. 31.6 months; log-rank p = 0.004) and PFS (64.6 vs. 18.5 months; p = 0.002). In multivariable analyses, each doubling of EOZ was associated with lower hazards of death (HR 0.73, 95% CI 0.61–0.87; p < 0.001) and progression or death (HR 0.76, 95% CI 0.65–0.89; p < 0.001). At 3 years, the incident/dynamic AUC increased from 0.674 to 0.707 for OS (p = 0.042) and from 0.653 to 0.680 for PFS (p = 0.057). Higher baseline EOZ was independently associated with favorable outcome in MCL, supporting further evaluation and validation in independent cohorts.