Used in the treatment of non-small cell lung cancer (NSCLC), particularly for patients with EGFR T790M mutation who have progressed after prior EGFR-targeted therapy. It acts as a third-generation EGFR tyrosine kinase inhibitor, selectively targeting resistant mutant forms of EGFR while sparing wild-type EGFR, thereby reducing side effects. Its oral formulation allows for convenient outpatient treatment, contributing to improved patient compliance and disease management.