MICROENVIRONMENT IMMUNE CELLS IN BONE MARROW AND LYMPH NODE MEASURED BY FLOW CYTOMETRY CAN PREDICT SURVIVAL IN DIFFUSE LARGE B CELL LYMPHOMA

Abstract

Introduction: Tumor microenvironment (TME) in diffuse large B-cell lymphoma (DLBCL) has recently been in the spotlight. The predictive role of immune cells (IC) in peripheral blood (PB), bone marrow (BM) and lymph nodes (LN) has been individually assessed, often using techniques not widely available. However, data regarding the relative prognostic impact of TME in each compartment evaluated simultaneously in DLBCL is still lacking. Aims: To determine the prognostic impact on survival of the Monocyte-Lymphocyte prognostic score (MLS) in PB and the percentage (%) of IC in the BM and LN measured by flow cytometry (FC) in DLBCL. Methods: We retrospectively collected information of patients (pts) with DLBCL and available BM aspiration and LN FC data at diagnosis, treated at our center between 2012 and 2019. Pts were stratified according to the MLS (Wilcox et al, leukemia 2011) in two groups: low (PB monocyte counts <630/ml and lymphocyte counts ≥1000/ml) and intermediate-high. FC analysis was performed with 8-color panels according to Euroflow protocols. % of BM and LN IC by FC were compared to normal values determined by Matarraz (Cytometry part B 2010) and Battaglia et al (Immunology 2003), and analyzed in 3 categories: low, normal and high. Survival analysis was performed with Kaplan-meier (variables compared with log-rank) and Cox regression. Results: 71 pts were included with a median age of 59 years. 49.3% had poor R-IPI. All pts received immunochemotherapy. Complete remission rate was 82%. Median overall survival (OS) was 120.5 months (m), with a median follow up time of 34.7 m. On univariate analysis TME variables from all the compartments showed prognostic impact on OS. BM IC levels did not statistically differ in involved vs not involved BM. Both low LN TL % and high and low BM Mo % remained independent predictors of survival on multivariate analysis. Moreover, pts with both of these unfavorable variables had a HR for death of 40.22 (CI 95% 5.16-313.04, p < 0.001) with a median OS of only 22.19 m. Variables Univariate analysis Multivariate analysis HR (95% CI) P-value HR (95% CI) P-value LN T lymphocytes (TL) low 3.98 (1.31-12.06) 0.014 5.44 (1.48-20.04) 0.011 BM B lymphocytes low 4.73 (1.62-13.79) 0.004 3.36 (0.99-11,34) 0.0501 BM Monocytes (Mo) High 10.53 (3.66-30.26) <0.001 4.66 (1.34-16.25) 0.015 BM Monocytes Low 3.87 (1.28-11.7) 0.016 3.40 (1.05-10.99) 0.04 PB MLS intermediate-high 2.59 (1.12-6) 0.02 1.05 (0.4-2.77) 0.91 Conclusion: Abnormal BM Mo % and low LN TL % measured by FC were associated with inferior OS in our cohort of DLBCL pts. These two TME variables presented at diagnosis could be easily translated into prognostic biomarkers in DLBCL, identifying a subgroup of pts with a dismal short term prognosis. In the future, therapies that target the crosstalk between lymphoma cells and the LN and BM ME might represent an encouraging strategy to improve outcomes in this high risk subset of pts. Kaplan-meler estimates of overall survival stratified by number of adverse prognosis tumor microenviroment varaibles present(low lymph node T-lymphocytes and high low bone marrow monocytes) Keywords: Diagnostic and Prognostic Biomarkers No conflicts of interests pertinent to the abstract. On univariate analysis TME variables from all the compartments showed prognostic impact on OS. BM IC levels did not statistically differ in involved vs not involved BM. Both low LN TL % and high and low BM Mo % remained independent predictors of survival on multivariate analysis. Moreover, pts with both of these unfavorable variables had a HR for death of 40.22 (CI 95% 5.16-313.04, p<0.001) with a median OS of only 22.19 m. Variables Univariate analysis Multivariate analysis HR (95% CI) P-value HR (95% CI) P-value LN T lymphocytes (TL) low 3.98 (1.31-12.06) 0.014 5.44 (1.48-20.04) 0.011 BM B lymphocytes low 4.73 (1.62-13.79) 0.004 3.36 (0.99-11,34) 0.0501 BM Monocytes (Mo) High 10.53 (3.66-30.26) <0.001 4.66 (1.34-16.25) 0.015 BM Monocytes Low 3.87 (1.28-11.7) 0.016 3.40 (1.05-10.99) 0.04 PB MLS intermediate-high 2.59 (1.12-6) 0.02 1.05 (0.4-2.77) 0.91