pertuzumab + trastuzumab + cisplatin + capecitabine

A combination regimen composed of **pertuzumab** (a humanized monoclonal antibody targeting HER2 domain II), **trastuzumab** (a humanized monoclonal antibody targeting HER2 domain IV), **cisplatin** (a platinum-based chemotherapy agent causing DNA crosslinking), and **capecitabine** (an oral fluoropyrimidine carbamate prodrug of 5-fluorouracil). Pertuzumab and trastuzumab are dual anti-HER2 therapies designed to interrupt HER2-dependent cell signaling by blocking different epitopes and inhibiting both homodimerization and heterodimerization of HER2, increasing antitumor efficacy via direct inhibition of proliferation and antibody-dependent cell-mediated cytotoxicity. Cisplatin is a DNA-damaging agent with broad cytotoxic activity, while capecitabine is converted to 5-FU selectively within tumors, inhibiting thymidylate synthase and thereby DNA synthesis. This regimen is investigated in the treatment of HER2-positive cancers, especially metastatic breast cancer, and is studied as an alternative to taxane-based regimens to reduce toxicity or in pretreated settings[1][3][5].