Gene expression profiles of microdissected tumor epithelium and stroma from TN breast tumors

Engaging the immune system promises to be key for optimal cancer therapy, especially in hard-to-treat disease such as triple-negative breast cancer (TNBC). However, the immune microenvironment remains poorly understood. Using gene expression based on laser capture microdissection, we identify three distinct tumor microenvironments associated with CD8+ T cell localization patterns and outcome in TNBC. An immunoreactive microenvironment is defined by granzyme B-positive CD8+ T cell infiltration, a type I interferon signature, tumor expression of PD-L1 and good outcome. In contrast, tumors with an immune-cold microenvironment display restriction of CD8+ T cells to tumor margins, elevated tumor expression of the immunosuppressive marker B7-H4, a signature of desmoplastic stroma and poor outcome. A third distinct immunomodulatory microenvironment associated with poor outcome is enriched for IL-17-producing cells and neutrophils, as well as stroma-restricted localisation of CD8+ T cells. These distinct immune microenvironments have implications for TNBC patient stratification for current and future therapies. 38 patient samples, tissue compartments isolated by laser capture microdissection to yield 38 samples of tumor epithelium, 38 samples of tumor stroma; each subjected to gene expression profiling in a common reference design using Agilent whole human genome oligonucleotide arrays.