Used in the treatment of HER2-positive breast cancer, particularly in patients who have already received prior chemotherapy regimens including anthracyclines, taxanes, and trastuzumab. It functions as a dual tyrosine kinase inhibitor, targeting both HER2 and EGFR pathways to suppress tumor growth. Often administered in combination with capecitabine for advanced or metastatic cases. Also investigated in clinical trials for other solid tumors involving EGFR or HER2 overexpression, such as lung and gastric cancers. Its oral formulation allows for convenient outpatient therapy, improving patient compliance compared to intravenous treatments.