camrelizumab + apatinib + nab-paclitaxel + S-1

This is a multi-agent investigational anti-cancer regimen combining four drugs with distinct mechanisms of action: **Camrelizumab** is a humanized IgG4 monoclonal antibody that targets programmed cell death protein 1 (PD-1) on T cells. By blocking PD-1 from binding to its ligands PD-L1 and PD-L2, it prevents tumor-induced immune suppression and enhances anti-tumor immunity[1][2][3][4][5]. **Apatinib** is an oral small molecule tyrosine kinase inhibitor that selectively inhibits vascular endothelial growth factor receptor 2 (VEGFR2), thereby blocking angiogenesis required for tumor growth. **Nab-paclitaxel** (nanoparticle albumin-bound paclitaxel) is a microtubule-stabilizing chemotherapeutic agent formulated with albumin nanoparticles to improve delivery and reduce toxicity compared to conventional paclitaxel. It disrupts mitosis in rapidly dividing cancer cells[6][8]. **S-1** is an oral fluoropyrimidine derivative composed of tegafur (a prodrug of 5-fluorouracil), gimeracil, and oteracil potassium. It acts as an antimetabolite by inhibiting thymidylate synthase, leading to impaired DNA synthesis in cancer cells[9]. The combination aims to synergistically enhance anti-tumor efficacy by integrating immunotherapy (camrelizumab), targeted therapy against angiogenesis (apatinib), cytotoxic chemotherapy targeting microtubules (nab-paclitaxel), and antimetabolite chemotherapy affecting DNA synthesis (S‑1). This regimen has been explored primarily in advanced solid tumors such as hepatocellular carcinoma and gastric/gastroesophageal cancers.