Fig. 2. Metabolic pathways under nutrient-replete and nutrient-deprived conditions.

Accessibility to nutrients within solid tumors is regulated by proximity to the vasculature. Cells located adjacent to the vasculature use nutrients and oxygen to fuel anabolic pathways that support proliferation. However, cells distant from the vasculature have diminished accessibility to nutrients and oxygen and may engage in alternative forms of metabolism including oxidation of fatty acids and BCAAs as well as macromolecular degradation through autophagy and macropinocytosis to support cell viability.