The prognostic significance of CD11b⁺CX3CR1⁺ monocytes in patients with newly diagnosed diffuse large B-cell lymphoma

Despite their critical roles in angiogenesis and host immunosuppression within the tumor microenvironment, the prognostic significance of myeloid-lineage cells expressing CD11b and CX3CR1 in diffuse large B-cell lymphoma (DLBCL) has not been well studied. We prospectively enrolled newly-diagnosed DLBCL patients at two Korean institutions between May 2011 and Aug 2015. CD11b⁺CX3CR1⁺ cells were analyzed by flow cytometry using peripheral blood (PB) and bone marrow (BM) aspirate samples before treatments. Eighty-nine patients (52 males) were enrolled. The median age was 65 years (range, 19-88 years). Thirty-seven patients (42%) were classified as high-intermediate or high risk according to the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI). Patients were categorized into either high or low PB-/BM-CD11b⁺CX3CR1⁺ monocyte group according to the cutoffs identified by the receiver-operating-characteristics analysis (PB, 3.68%; BM, 3.45%). The high PB-CD11b⁺CX3CR1⁺ monocyte group was significantly associated with highintermediate and high risk NCCN-IPI group (P = 0.004). With a median follow-up of 27.7 months (range, 1.7-60.4 months), the low PB-CD11b⁺CX3CR1⁺ monocyte group showed significantly better overall survival (OS) than the high PB-CD11b⁺CX3CR1⁺ monocyte group (3-year, 92.3% vs. 51.2%, respectively; P < 0.001). In contrast, no significant difference was observed between the high and low BM-CD11b⁺CX3CR1⁺ monocyte groups. Among patients with high-intermediate to high risk NCCN-IPI, the high PB-CD11b⁺CX3CR1⁺ monocyte group showed significantly worse OS than the low PB-CD11b⁺CX3CR1⁺ monocyte group (3-year, 29.3% vs. 80.2%, respectively; P = 0.008). Taken together, PB-CD11b⁺CX3CR1⁺ monocyte percentage correlates with the NCCN-IPI risk stratification, which enables identification of subgroups with extremely poor clinical outcomes.