Avitinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor primarily used in the treatment of non-small cell lung cancer (NSCLC), especially in patients who have developed resistance to first- and second-generation EGFR inhibitors. It is particularly effective against tumors harboring the T790M mutation, a common resistance mechanism. Avitinib selectively targets mutant forms of EGFR while sparing the wild-type receptor, which helps reduce side effects. Its ability to cross the blood-brain barrier also makes it valuable in managing brain metastases in NSCLC patients. Ongoing clinical studies continue to evaluate its efficacy, safety, and optimal dosing in advanced stages of EGFR-positive lung cancer.