paclitaxel + pembrolizumab + trastuzumab

This is a combination regimen consisting of three drugs—paclitaxel, pembrolizumab, and trastuzumab—used primarily in the treatment of HER2-positive cancers such as metastatic breast cancer and advanced gastric or gastroesophageal junction adenocarcinoma. - **Paclitaxel** is a small molecule chemotherapeutic agent that stabilizes microtubules, inhibiting cell division and inducing apoptosis in rapidly dividing cells. - **Pembrolizumab** is a monoclonal antibody immune checkpoint inhibitor targeting programmed cell death protein 1 (PD-1), thereby enhancing T-cell–mediated antitumor immune responses. - **Trastuzumab** is a monoclonal antibody that targets the human epidermal growth factor receptor 2 (HER2), blocking downstream signaling pathways involved in tumor growth and survival. The combination leverages cytotoxic chemotherapy (paclitaxel), targeted therapy against HER2 (trastuzumab), and immunotherapy via PD-1 inhibition (pembrolizumab). This regimen has been studied for patients with HER2-positive metastatic breast cancer who have failed prior anti-HER2 therapies[1], as well as for first-line treatment of locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma[3][5]. The addition of pembrolizumab to trastuzumab plus chemotherapy has demonstrated improved outcomes in these populations.