Quantitative Assessment of the Immune Microenvironment in African American Triple Negative Breast Cancer: A Case Control Study

Abstract

PURPOSETriple Negative Breast Cancer (TNBC) is more common in African American (AA) than Non-AA (NAA) population. We hypothesize that Tumor Microenvironment (TME) contributes to this disparity. Here we use multiplex quantitative immunofluorescence (QIF) to characterize the expression of immunologic biomarkers in the TME in both populations.PATIENTS AND METHODSTNBC tumor resection specimen tissues from a 100-patient case: control cohort including 49 AA and 51 NAA were collected. TME markers including CD45, CD14, CD68, CD206, CD4, CD8, CD20, CD3, Ki67, GzB, Thy1, FAP, aSMA, CD34, Col4, VWF and PD-L1 we quantitatively assessed in every field of view. Mean expression levels were compared between cases and controlsRESULTSAlthough no significant differences were detected in individual lymphoid and myeloid markers, we found that infiltration with CD45+ immune cells (p=0.0102) was higher in TNBC in AA population. AA TNBC tumors also had significantly higher level of lymphocytic infiltration defined as CD45+CD14- cells (p=0.0081). CD3+T-cells in AA tumors expressed significantly higher levels of Ki67 (0.0066) compared to NAAs, indicating that a higher percentage of AA tumors contained activated T-cells. All other biomarkers showed no significant differences between the AA and NAA group.CONCLUSIONSWhile the TME in TNBC is rich in immune cells in both racial groups, there is a numerical increase in lymphoid infiltration in AA compared to NAA TNBC. Significantly higher activated T cells seen in AA patients raises the possibility that there may be a subset of AA patients with improved response to immunotherapy.