EGFR and head and neck squamous cell carcinoma: More importantly, while examining the combination regimens of inhibitors of PI3K and the epidermal growth factor receptor (EGFR) for the treatment of HNSCC, the combination of HS-173 and afatinib, an irreversible EGFR/ERBB2 dual inhibitor, exhibited the highest synergistic effect in most models tested [14].