Fasting opens a metabolic window that favors anti-tumor immunity.

Short-term fasting reshapes the metabolic landscape of the tumor microenvironment, creating a transient window of altered nutrient availability that cytotoxic CD8⁺ T cells can exploit. Chen and colleagues report that intratumoral isoleucine accumulation during fasting supports T cell effector programs, enhancing responses to immune checkpoint blockade in mice and humans.