CD8A and obesity due to melanocortin 4 receptor deficiency: Ringel et al. (2020) found that obesity accelerated MC38 tumor growth, which was associated with a reduction in CD8 T cell function. Interestingly, they showed that tumor cells and CD8 T cells differentially adapted to the HFD with only the tumor cells increasing their lipid uptake, while CD8 T cells became lipid starved. In contrast, Manzo et al. (2020) reported that CD8 T cells accumulated lipids in a pancreatic cancer model in a nonobese setting, leading to T cell exhaustion.