ERBB2 and head and neck squamous cell carcinoma: Since trastuzumab, an anti-ERBB2 antibody for the treatment of breast cancer, was approved in 1998, various selective inhibitors (antibodies or small molecules) of ERBB TK have been shown to be effective in different tumor entities either overexpressing EGFR (e.g., head and neck squamous cell carcinoma (HNSCC)) [15] or exhibiting activating EGFR mutations (e.g., non-small cell lung cancer (NSCLC)) [16].