For example, in the treatment of lung cancer, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) such as gefitinib are effective initially, but after long-term use, tumor cells may evade the inhibition of the drug through T790M mutations in the EGFR gene, leading to the development of drug resistance 109. Here, EGFR is linked to lung carcinoma.