surufatinib + camrelizumab + nab-paclitaxel + S-1

This is a combination regimen consisting of four agents: - **Surufatinib** is an oral small molecule tyrosine kinase inhibitor targeting vascular endothelial growth factor receptors (VEGFR) 1/2/3, fibroblast growth factor receptor 1 (FGFR1), and colony-stimulating factor 1 receptor (CSF-1R). It inhibits angiogenesis and modulates the tumor microenvironment. - **Camrelizumab** is a humanized monoclonal antibody that targets programmed cell death protein 1 (PD-1) on T cells, acting as an immune checkpoint inhibitor to enhance anti-tumor immunity. - **Nab-paclitaxel** is an albumin-bound formulation of paclitaxel that stabilizes microtubules and inhibits cell division; it improves drug delivery and reduces hypersensitivity reactions compared to conventional paclitaxel. - **S-1** is an oral fluoropyrimidine derivative composed of tegafur (a prodrug of 5-fluorouracil), gimeracil, and oteracil potassium. It acts as a cytotoxic antimetabolite by inhibiting DNA synthesis. This combination brings together targeted therapy, immunotherapy, cytotoxic chemotherapy via microtubule inhibition, and antimetabolite activity. The regimen has been explored in clinical trials for advanced solid tumors—especially gastrointestinal cancers such as pancreatic cancer or gastric cancer—though no direct trial data for this exact four-drug combination was found in the provided sources. Each component has demonstrated efficacy in various combinations for these indications.