Used primarily in the treatment of non-small cell lung cancer (NSCLC), especially in patients with specific epidermal growth factor receptor (EGFR) mutations. It functions as a tyrosine kinase inhibitor, blocking signals that promote tumor growth. Administered orally, it offers a targeted therapy option with improved tolerability compared to traditional chemotherapy. Commonly prescribed in China, it is used in both first-line and later-stage treatments for advanced or metastatic disease.