CD4 T-cell immune stimulation of HER2+ breast cancer cells alters response to trastuzumab in vitro

Abstract

Introduction: The HER2+ tumor immune microenvironment is composed of macrophages, natural killer cells, and tumor infiltrating lymphocytes, which produce pro-inflammatory cytokines. Determining the effect of T-cells on HER2+ cancer cells during therapy could guide immunogenic therapies that trigger antibody-dependent cellular cytotoxicity. This study utilized longitudinal in vitro time-resolved microscopy imaging to measure T-cell influence on trastuzumab in HER2+ breast cancer.Methods: Fluorescently-labeled breast cancer cells (BT474, SKBR3, MDA-MB-453, and MDA-MB-231) were co-cultured with CD4+ T-cells (Jurkat cell line) and longitudinally imaged to quantify cancer cell viability when treated with or without trastuzumab (10, 25, 50 and 100 mg/mL). The presence and timing of T-cell co-culturing was manipulated to determine immune stimulation of trastuzumab-treated HER2+ breast cancer. HER2 and TNF-a expression were evaluated with western blot and ELISA, respectively. Significance was calculated using a two-tailed parametric t-test. Results: The viability of HER2+ cancer cells significantly decreased when exposed to 25 mg/mL trastuzumab and T-cells, compared to cancer cells exposed to trastuzumab without T-cells (p = 0.01). The presence of T-cells significantly increased TNF-a expression in trastuzumab-treated cancer cells (p = 0.02). Conversely, cancer cells treated with TNF-a and trastuzumab had a similar decrease in viability as trastuzumab-treated cancer cells co-cultured with T-cells (p = 0.32).Conclusions: The presence of T-cells significantly increases the efficacy of targeted therapies and suggests trastuzumab may trigger immune mediated cytotoxicity. Increased TNF-a receptor expression suggest cytokines may interact with trastuzumab to create a state of enhanced response to therapy in HER2+ breast cancer, which has potential to reducing tumor burden.