Here, we evaluated synergistic antitumor efficacy of EGFR × MET targeting bispecific antibody, amivantamab with PD-L1 immunotherapy, pembrolizumab in head and neck squamous cell carcinoma (HNSCC) and lung squamous cell carcinoma tumor–bearing humanized patient-derived xenograft (PDX) models. This evidence concerns the gene EGFR and head and neck squamous cell carcinoma.