atezolizumab + docetaxel + pertuzumab + trastuzumab

This is a four-drug combination regimen consisting of atezolizumab, docetaxel, pertuzumab, and trastuzumab. It is used as a neoadjuvant (pre-surgical) therapy for patients with HER2-positive (ERBB2-positive) early breast cancer, particularly in stage II or III disease. - **Atezolizumab** is an immune checkpoint inhibitor targeting PD-L1, enhancing anti-tumor immune responses by blocking the interaction between PD-L1 and its receptors on T cells. - **Docetaxel** is a taxane-class cytotoxic chemotherapy agent that inhibits microtubule depolymerization, leading to cell cycle arrest and apoptosis in rapidly dividing cells. - **Pertuzumab** and **trastuzumab** are monoclonal antibodies targeting different domains of the HER2 receptor; their dual blockade prevents HER2 dimerization and downstream signaling critical for tumor growth in HER2-positive cancers. The combination aims to maximize anti-tumor efficacy by integrating immunotherapy with targeted anti-HER2 therapy and cytotoxic chemotherapy[1][2][3][4]. The Neo-PATH phase 2 clinical trial demonstrated that this regimen achieved a pathologic complete response rate of 61% in patients with stage II/III HER2-positive breast cancer[1][3]. The safety profile was considered acceptable with manageable toxicities.