Lipid-driven epigenetic exhaustion: linking palmitate metabolism to CD8⁺ T-cell dysfunction in cancer

In a recent study published in Science Immunology, Tiberti and colleagues demonstrate that palmitate, a saturated fatty acid enriched in tumors, directly impairs CD8⁺ cytotoxic T lymphocyte function through mitochondrial and epigenetic reprogramming. Palmitate exposure reduced mitochondrial fitness, oxidative phosphorylation, and adenosine triphosphate production, resulting in defective proliferation, cytokine production, and antitumor activity. Mechanistically, mitochondrial dysfunction decreased intracellular acetyl-CoA availability, leading to reduced histone acetylation and loss of chromatin accessibility at loci that control effector programs. The study further identifies sphingosine kinase 2 as a critical mediator of lipid-induced dysfunction. Importantly, SPHK2 inhibition restored mitochondrial function, histone acetylation, and cytotoxic T lymphocyte antitumor activity, highlighting a potential therapeutic strategy for enhancing cancer immunotherapy.