docetaxel + cyclophosphamide + trastuzumab + pertuzumab

This drug combination is a neoadjuvant chemo-immunotherapy regimen evaluated in the PETREMAC trial (NCT02624973) for the treatment of high-risk, HER2-positive breast cancer. It consists of two cytotoxic agents—docetaxel (a taxane that stabilizes microtubules) and cyclophosphamide (an alkylating agent that cross-links DNA)—and two HER2-targeted monoclonal antibodies—trastuzumab and pertuzumab. Trastuzumab binds to the extracellular domain IV of the HER2 receptor to inhibit downstream signaling and induce antibody-dependent cellular cytotoxicity (ADCC), while pertuzumab binds to domain II, preventing HER2 from dimerizing with other HER family members (notably HER3). This dual HER2 blockade, combined with chemotherapy, aims to maximize pathological complete response (pCR) rates in patients with HER2-amplified tumors by simultaneously disrupting cell division and blocking oncogenic growth signaling.