Used in the treatment of HER2-positive breast cancer, particularly in patients who have progressed after prior therapies 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 enhanced efficacy. Also investigated in clinical settings for other solid tumors with EGFR or HER2 overexpression. Its oral bioavailability allows for convenient outpatient treatment compared to intravenous alternatives.