To explore the mechanism of antitumor activity of anti‐TIM3 therapy, we investigated the CD4+ T cells, CD8+ T cells, TIM3+CD4+ cells, and TIM3+CD8+ cells in both tumor microenvironment and peripheral environment, including spleen, draining LN, and blood of HNSCC mice as shown by representative pictures (Fig. 6A,B). Here, HAVCR2 is linked to head and neck squamous cell carcinoma.