Spatial distribution of B cells and lymphocyte clusters as a predictor of triple-negative breast cancer outcome

Abstract

While tumor infiltration by CD8+ T cells is now widely accepted to predict outcomes, the clinical significance of intratumoral B cells is less clear. We hypothesized that spatial distribution rather than density of B cells within tumors may provide prognostic significance. We developed statistical techniques (fractal dimension differences and a box-counting method ‘occupancy’) to analyze the spatial distribution of tumor-infiltrating lymphocytes (TILs) in human triple-negative breast cancer (TNBC). Our results indicate that B cells in good outcome tumors (no recurrence within 5 years) are spatially dispersed, while B cells in poor outcome tumors (recurrence within 3 years) are more confined. While most TILs are located within the stroma, increased numbers of spatially dispersed lymphocytes within cancer cell islands are associated with a good prognosis. B cells and T cells often form lymphocyte clusters (LCs) identified via density-based clustering. LCs consist either of T cells only or heterotypic mixtures of B and T cells. Pure B cell LCs were negligible in number. Compared to tertiary lymphoid structures (TLS), LCs have fewer lymphocytes at lower densities. Both types of LCs are more abundant and more spatially dispersed in good outcomes compared to poor outcome tumors. Heterotypic LCs in good outcome tumors are smaller and more numerous compared to poor outcome. Heterotypic LCs are also closer to cancer islands in a good outcome, with LC size decreasing as they get closer to cancer cell islands. These results illuminate the significance of the spatial distribution of B cells and LCs within tumors.

Dissecting Tumor-Immune Microenvironment in Breast Cancer at a Spatial and Multiplex Resolution

“…In concordance with H&E sTILs, the vast majority of immune markers is enriched in stromal compartments of BC [74][75][76]. Indeed, T cells (CD3+, CD4+ or CD8+), B cells (CD20+) and macrophages (CD68+) are commonly found in stroma [62,63,73,77]. However, tumoral compartments seem to be more infiltrated by T cells (CD3+, CD8+) and NK cells (CD56+) [62,73,77,78].…”

“…This is more apparent for B cells, as 75% of density differences is attributed to ROI examination within a slide. Besides this, B cells seem to be distributed in TIME independently of their stromal density [73].…”

Prognostic impact of tertiary lymphoid structures in breast cancer prognosis: a systematic review and meta-analysis

“…The complex interactions among immune and tumor cells are crucial for tumor progression [ 29 ]. A recent study reported that lymphocyte clusters (LCs), like TLSs, are closer to tumor cell islands in patients with a good outcome, with a decrease in the LC size with decreasing distance to tumor cell islands [ 30 ]. Thus, it is crucial to identify the clinicopathological impact of TLSs in BCa.…”

Clinical Significance of Tumor-Infiltrating Conventional and Plasmacytoid Dendritic Cells in Pancreatic Ductal Adenocarcinoma

“…High densities of TS-infiltrating CD4 + T cells favored DSS of non-small-cell lung carcinoma patients, whereas their frequency in the tumor islands did not have any effect on DSS [ 72 ]. In contrast, an increased frequency of tumor island-associated CD3 + T cells was linked to improved relapse-free survival in triple negative breast cancer [ 73 ]. Here, we showed that in contrast to IET-infiltrating cDC1s, a higher density of TS-associated cDC1s was significantly correlated with prolonged DFS.…”