The changes in cetuximab resistant HNSCC cell lines (e.g., OECM1-cetuximabR and CAL-27 cetuximabR) after being treated with Cetuximab (500 ug/ml) for at least 2 months. We used LC-MS/MS to identify the main phosphorylation sites in resistance cell lines.

Recent clinical trials revealed that prior use of Cetuximab may interfere with ICB efficacy. In this study, STAT1 protein levels changed after continued Cetuximab treatment (500 ug/ml). We used LC-MS/MS to compare the phosphorylation sites in wild-type and resistant cells. We proposed that the phosphorylation of STAT1 may lead to the degradation of the STAT1 protein.