Neutrophil to T-Lymphocyte Ratio (NLR) and Neutrophil to Monocyte Ratio (NMR) Are Promising Biomarkers in Chronic Lymphocytic Leukemia Prognostic Assessment

Development of targeted drugs produced a significant changes in the management of patients with Chronic Lymphocytic Leukemia (CLL). The recent advances in molecular diagnostic techniques has provided a better prediction of disease progression but they are not easily accessible to all Institutions.

CLL cells proliferation and survival are sustained by a complex microenvironmental network of cells interactions that are at least partially mediated through B cell receptor signaling.

An increased number of studies describe the role of neutrophils and monocytes as markers of the inflammation and antitumor immunity that support tumorigenesis. Recently, authors published the increased NLR is associated to a prognosis in different cancer type.

In our study we retrospectively evaluated the prognostic significance of peripheral blood neutrophils, monocytes and non-neoplastic lymphocytes in a unicentric, unselected, CLL cohort of 400 CLL patients at diagnosis (median age 64; stage Binet A 76%,B 18%,C 6%).

Using blood count and the flow cytometric analysis reports, absolute neutrophil count (ANC), absolute monocyte count (AMC) and absolute T-lymphocyte count (ALC-CD3+) were evaluated and the neutrophil to T-lymphocyte ratio (NLR), the monocyte to T-lymphocyte ratio (MLR) and the neutrophil to monocyte ratio (NMR) were calculated at diagnosis, follow up and at relapse. Clinical and biological data from all patients were also retrieved to make a better comparison with the major clinical and prognostic markers commonly used.

Compared to normal controls, CLL patients showed an increase AMC value (788±65 vs 469±51 cells/μL, p=0.005) and a slightly increased in the ALC-CD3+ value (2514±63 vs 2189±45 cells/μL, p=0.04). No difference in the ANC. The median NLR ratio was higher in CLL patients compared to healthy individuals (2.32 vs 1.7, p=0.02) and appeared more increased in early stage (2.65, 2.14, 1.95 mean value in Binet A, B, C respectively, p=0.0015). NMR median value was also significantly higher in early stage compared to advanced stage (8.0, 6.7, 5.1 in Binet A, B, C, p=0.0008).

Conversely, MLR showed the opposite trend resulting more elevated in advanced stage at diagnosis, although with a low statistical significance.

We did not found any correlation between these ratio and the IGVH status or genetic abnormalities.

NLR and NMR higher level are associated with the absence of serum prognostic markers, such as CD38, and CD49d (p=0.002).

160 out of 400 patients of our CLL cohort received a treatment during the course of disease. In our analysis, NLR and NMR are significantly higher in untreated patients than treated ones (median NLR 2.42 vs 1.95, p=0.0021; NMR 8.0 vs 7.0, p=0.0002). Among treated patients NLR and NMR significantly correlate with the time to treatment initiation (TTFT): lower NLR and NMR ratio correspond to a shorter TTFT (NLR p=0.03; NMR p=0.0035). For MLR the trend is opposite.

A subgroup analysis conducted only on Rai 0/Binet A patients (n 219, 55%) showed that NLR and specially NMR are significantly associated with the risk of progression: lower NLR and NMR ratio correspond to an increased risk to symptomatic progression (p=0.0017), strengthening the hypothesis that high ratios are associated with a more indolent form of disease.

In the 0/A population, analysis showed that a higher AMC and at a lesser extend a high ALC-CD3+ correlate with the progression rate and treatment initiation (Kaplan-Meier survival curve, p= 0.0001).

Univariate analysis suggested that NLR ≥ 3.0, NMR ≥ 8.0 and AMC <900/mmc predicted a good prognosis in CLL patients. However, only NMR and AMC appeared as independent prognostic factors in multivariable analysis in Rai 0/Binet A patients.

Our in vitro experiments supported these finding confirming: the non "immunosuppressive" role for neutrophils in CLL and the increased ability for monocytes to suppress T-lymphocytes activation and expand T-regulatory cell.

In our study NLR ratio showed a positive prognostic role in CLL. A strongest protective meaning is displayed by NMR value. These combined value and AMC count provide more prognostic information at diagnosis and are associated with clinical outcome in CLL patients.

These simple, cheap and reliable markers could be easily integrated into clinical practice reflecting both inflammatory status, immune response and microenviroment that contribute to disease progression.