Pyrotinib is primarily used in the treatment of HER2-positive breast cancer. It functions as an irreversible tyrosine kinase inhibitor, targeting both HER2 and EGFR receptors to block the signaling pathways that promote cancer cell growth and proliferation. This dual inhibition makes it particularly effective in patients who have not responded well to other HER2-targeted therapies, such as trastuzumab. It is administered orally, either as monotherapy or in combination with other chemotherapeutic agents like capecitabine, to enhance treatment efficacy. Clinical studies, including the PHENIX trial, have demonstrated significant improvements in progression-free survival and objective response rates in advanced or metastatic HER2-positive breast cancer. Its targeted mechanism helps minimize damage to healthy cells, potentially reducing side effects compared to traditional chemotherapy.