EGFR and non-small cell lung carcinoma: Furthermore, several molecular mechanisms of resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs), such as hepatocyte growth factor (HGF), c-MET amplification, and EGFR-T790M mutation, were associated with upregulation of PD-L1 expression in EGFR-mutant NSCLC.