EGFR and head and neck squamous cell carcinoma: However, the treatment efficacy of cetuximab is low, with an objective response rate of 13% as a monotherapy and 36% in combination with chemotherapy 44,45.] Friederike et al. 46 reported that after chemotherapy or radiotherapy combined with cetuximab, HNSCC patients with higher EGFR-K521 (k-allele) expression levels had a significantly shorter progression-free survival period compared with those without expression of EGFR-K521.