Immune-phenotyping of peripheral blood mononuclear cells from patients with early triple-negative breast cancer: Identification of a systemic immunosuppressive CD3+ CD4+ CD39+ Treg subset.

Abstract

3040 Background: Cells of the immune system and malignant cells interact in the tumor microenvironment, influencing response to treatment and survival. The current study was undertaken to assess the prevalence of these immune cells systemically in patients with early triple-negative breast cancer (TNBC). Methods: Multi-parameter flow cytometry was used to examine the percentages and phenotypes of cytotoxic T cells, natural killer (NK) cells, monocyte subsets, and regulatory T cell (Treg) subsets in the peripheral blood of 19 TNBC patients (pts) and 10 controls (cnt). Multicolor flow cytometry was carried out using DURAClone IM phenotyping (basic and Treg tubes) with a CytoFLEX Flow Cytometer (Beckman Coulter, California, USA), and data analyzed with FlowJo v 10.10.0 software (BD Life Sciences, USA). The Mann-Whitney U-test was used to compare non-parametric data where appropriate. Results: Significant increases in the percentages of immunosuppressive CD3+ CD4+ CD39+ Tregs cells in the setting of a significant decrease of CD19+ B cells were observed in pts with TNBC (Table).Tumour size, nodal status, age and ki-67 did not correlate with the percentages of any type of circulating immune cell. Conclusions: TNBC is associated with severe immunosuppression. In this context, percentages of circulating CD19+ B cells were significantly lower, while CD3+ CD4+ CD39+ Tregs were significantly higher in early TNBC pts. The peripheral blood immunome of TNBC pts identified a subset of immunosuppressive Tregs. A study is ongoing to identify the prognostic and predictive values of this systemic subset of Tregs for pCR in early TNBC pts undergoing neoadjuvant chemotherapy. [Table: see text]