Fig. 1
From: Looking beyond the cancer cell for effective drug combinations
The tumor microenvironment. Many cells and tissue components interact with cancer cells to influence tumor progression and response. These include cytotoxic (CD8+) T cells and regulatory T (Treg) cells, regulatory B cells (Breg), dendritic cells (DCs), natural killer (NK) cells, myeloid-derived suppressor cells (MDSCs), and mast cells, which are involved in the immune response against the tumor and communicate with tumor cells through receptor–ligand interactions such as those between programmed cell death protein 1 (PD-1) and PD-1 ligand 1 (PD-L1). In addition, the extracellular matrix (ECM), cancer-associated fibroblasts (CAFs), and endothelial cells of the vasculature are critical to tumor growth, transformation, and angiogenesis. In addition to targeting the tumor itself, all of the described components of the tumor microenvironment represent potential therapeutic targets. Figure produced with permission of Acerta Pharma and copyright is reserved