ERBB2 and breast cancer: Pertuzumab targets the extracellular domain II of HER2, effectively inhibiting the formation of HER2 dimers, particularly HER2-HER3 heterodimers, and blocking downstream signal transduction pathways (34).Studies have revealed that, in comparison with the combination of trastuzumab and chemotherapy, the addition of pertuzumab can significantly enhance the prognosis of patients with advanced HER2-positive breast cancer (BC) (35).