pembrolizumab + albumin paclitaxel + 5-fluorouracil + cisplatin

This is a multi-agent combination therapy consisting of four agents: **pembrolizumab** (a monoclonal antibody checkpoint inhibitor targeting PD-1), **albumin-bound paclitaxel** (nab-paclitaxel, a microtubule-stabilizing taxane chemotherapeutic), **5-fluorouracil** (a pyrimidine analog antimetabolite), and **cisplatin** (a platinum-based cytotoxic chemotherapeutic). - **Pembrolizumab** blocks the PD-1 receptor on T-cells, enhancing immune-mediated tumor cell destruction. - **Albumin-bound paclitaxel** disrupts microtubule function, leading to cell cycle arrest and apoptosis. - **5-fluorouracil** inhibits thymidylate synthase, interfering with DNA synthesis and function. - **Cisplatin** forms DNA crosslinks, causing DNA damage and inducing apoptosis. This regimen leverages both immune checkpoint inhibition and broad cytotoxic effects, and has been investigated in various squamous cell carcinomas, esophageal cancers, and cancer of unknown primary origin as a first-line or subsequent therapy, especially in aggressive or advanced disease settings[2][7].