Figure 5. The tumor microenvironment (TME) is composed of tumor and stromal cells that compete for nutrients.

Schematic of cells and nutrients in the TME. Nutrients are circulated throughout the body, and the TME imports these nutrients from the blood. In the TME, stromal cells (immune cells, fibroblasts, endothelial cells, and more) and tumor cells have distinct metabolic requirements. Depending on the cellular composition, local metabolite concentration can be increased or decreased. The further into the TME (away from the circulation) the sparser nutrients and oxygen become resulting in cells competing for available nutrients.