CXCL9 and head and neck squamous cell carcinoma: Correlation analyses consistently demonstrated a positive correlation between CXCL9 expression and M1 macrophage in the IMvigor210 cohort (R = 0.84, p < 0.0001), mUC‐cohort2 (R = 0.69, p < 0.0001), HCC cohort (R = 0.63, p = 0.0009), and HNSCC cohort (R = 0.85, p < 0.0001) (Figure 4E–H).