PDCD1 and neoplasm: Besides, it has been reported that galectin‐9 can interact with PD‐1, which helps to stabilize the PD‐1+/TIM3+ exhausted T cell subset in the tumor microenvironment.[40] Therefore galectin‐9 might also induce CD8+ T cell exhaustion through up‐regulation of PD‐1, which is worthy for future study.