Avitinib maleate is an investigational 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 with EGFR T790M mutations that confer resistance to first- and second-generation EGFR inhibitors. It selectively inhibits mutant EGFR forms, blocking downstream signaling pathways that promote tumor cell proliferation and survival. By targeting these specific mutations, Avitinib maleate helps to slow or halt cancer progression in advanced disease stages where prior therapies have failed. Ongoing studies explore its efficacy in other EGFR-mutated cancers, such as certain brain and colorectal cancers. Its use requires close medical supervision to monitor and manage potential severe side effects and optimize therapeutic outcomes.