EGFR and head and neck squamous cell carcinoma: Additionally, exosomal EGFR, ANXA1 and programmed cell death (PD)-1/PD-ligand 1 (PD-L1) pathway (tumor suppressor in HNSCC) have been identified as potential biomarkers for predicting prognosis and therapeutic monitoring in tumor derived exosomes of HNSCC patients (92).