Used in the treatment of HER2-positive breast cancer, particularly in patients with advanced or metastatic disease. It is effective in combination with trastuzumab and capecitabine, helping to slow tumor growth and improve survival outcomes. Shows activity in brain metastases, making it valuable for patients with central nervous system involvement. Works by selectively inhibiting the HER2 tyrosine kinase, minimizing damage to healthy cells. Also being studied in other HER2-driven cancers, including colorectal and non-small cell lung cancer.