CHARACTERIZATION AND CLINICAL IMPACT OF THE CIRCULATING IMMUNE CELL PROFILE IN PATIENTS WITH FOLLICULAR LYMPHOMA

Abstract

L. Magnano equally contributing author.

Introduction: FL is characterized by a heterogeneous clinical course. Although the importance of the microenvironment in its pathogenesis is well established, detailed information on the immune profile in peripheral blood (PB) has not been previously investigated. The aim of this study was to characterize immune profile in PB of FL patients (pts) at diagnosis (dxFL) and at relapse (rFL) and compare it with that of healthy controls (HC). Correlation with baseline clinical features was also explored.

Methods: We prospectively collected PB samples from FL pts (median age: 61 y; 41M/33F) at dxFL (n = 42) and at rFL (n = 40), as well as from 10 HC (median age: 51 y; 4M/6F) from 2019 to 2024. The identification of the main subsets of T-cells, B-cells, NK-cells, monocytes, neutrophils, dendritic cells (DC) and myeloid suppressor cells was performed by multiparameter flow cytometry. At least 150.000 events were acquired and analysed using Infinicyt software. A Cox regression was performed to identify immune biomarkers that had an impact on time to first treatment (> / < 6 months). In 18 dxFL pts, RNA expression was measured in PB with the nCounter technology.

Results: Compared with HC, dxFL pts exhibited a lower CD4⁺/CD8⁺ ratio due to depletion of CD4⁺ cells with an increase in CD8⁺ lymphocytes. Furthermore, dxFL pts were characterized by a decrease in naïve CD4⁺ and CD8⁺ (p < 0.0001), along with an increase in effector (E) and effector memory (EM) lymphocytes (p < 0.05), both CD4⁺ and CD8⁺. Of note, total regulatory T lymphocytes (Treg) and Th1 cells were increased in FL pts, while NK-cells were decreased, likely indicating an immunosuppressive environment. FL pts showed a decrease in total DC, but with an increase in myeloid DC subset (p = 0.015). These differences remained and became more marked in the relapse setting (Figure 1a). Subsequently, these data were correlated with the main clinical features. Pts with high tumour burden according GELF criteria at diagnosis were enriched in EM (p = 0.001) and activated CD8⁺ cells (p = 0.031), but a significantly decrease in Th1 (p = 0.042). Of note, pts with high-risk features as bulky disease (> 7 cm), higher LDH and int/high FLIPI showed an expansion in Treg (Figure 1b). Genes involved in Treg expression (CCL17, FOXP3, SOCS1, NFKBIA and DUSP4) and T EM phenotype (CCL3, CD70) were upregulated in high tumour burden pts. In dxFL pts, immune predictive variables for early treatment initiation (< 6 m) were lower CD3⁺, E CD4⁺ and myeloid DC; and higher EM CD4⁺ and activated CD8⁺. Multivariate analysis showed that higher EM CD4⁺ lymphocytes was the most important variable to predict time to first therapy (p = 0.03).

Conclusions: FL pts showed an immune profile in PB significantly different from that observed in HC, and are more pronounced at relapse. Knowledge of these immune alterations may enhance the understanding of FL behavior and aid in designing patient-tailored strategies based on immune profile in the era of immunotherapy.

Research funding declaration: Fondo de Investigaciones Sanitarias, Instituto de Salud Carlos III (PI19/00925 to LM and PI23/01207 to LM). Andrea Rivero was supported by a “Emili Letang-Josep Font” grant (Hospital Clinic Barcelona).

Keywords: microenvironment; diagnostic and prognostic biomarkers; indolent non-Hodgkin lymphoma

No potential sources of conflict of interest.