In Keynote-012 clinical trial (84, 85), the average levels of six interferon-gamma-related genes (CXCL9, CXCL10, IDO1, IFNG, HLA-DRA, and STAT1) were associated with OS (p=0.0047) and PFS (p=0.0009) in patients with head and neck squamous cell carcinoma and gastric cancer treated with pembrolizumab. Here, IFNG is linked to head and neck squamous cell carcinoma.