β-hydroxybutyrate enhances the metabolic fitness of CAR T cells in cancer.

The influence of lifestyle factors, such as diet, on the effectiveness of T cell-mediated cancer immunotherapies remains unclear. Here, we demonstrate that the ketogenic diet (KD)-induced ketone metabolite β-hydroxybutyrate (BHB) augments chimeric antigen receptor (CAR) T cell function across multiple preclinical cancer models. Mechanistically, BHB supports the tricarboxylic acid (TCA) cycle in CAR T cells, driving oxidative phosphorylation and energy generation. This metabolic enhancement is associated with CAR T cell proliferation and cytokine production, thereby leading to superior tumor control. Furthermore, BHB induces global transcriptional and epigenetic reprogramming in activated CAR T cells, which promotes an enhanced effector and metabolic profile. Lastly, in a prospective cohort of healthy volunteers, administration of BHB enhanced peripheral T cell oxygen consumption, mitochondrial membrane potential, and ATP production. Our results suggest that metabolite intervention via BHB supplementation is a promising, readily implementable strategy to improve adoptive T cell function against various cancers.