trifluridine + tipiracil + bevacizumab + camrelizumab

This is a four-drug combination regimen consisting of trifluridine, tipiracil, bevacizumab, and camrelizumab. - **Trifluridine** is a cytotoxic nucleoside analog that incorporates into DNA and causes DNA damage leading to cancer cell death. - **Tipiracil** inhibits thymidine phosphorylase, preventing the degradation of trifluridine and thereby increasing its bioavailability. The fixed-dose combination of trifluridine and tipiracil is marketed as Lonsurf for metastatic colorectal cancer[2][3][5]. - **Bevacizumab** is a monoclonal antibody targeting vascular endothelial growth factor A (VEGF-A), inhibiting angiogenesis (the formation of new blood vessels) required for tumor growth[5][8]. It is marketed as Avastin. - **Camrelizumab** is an immune checkpoint inhibitor targeting programmed cell death protein 1 (PD-1), enhancing T-cell mediated anti-tumor immunity[7]. The combination aims to attack tumors through multiple mechanisms—direct cytotoxicity (trifluridine/tipiracil), inhibition of tumor angiogenesis (bevacizumab), and immune system activation against tumor cells (camrelizumab). This regimen has been explored in clinical studies for metastatic colorectal cancer, particularly in patients with microsatellite stable or mismatch repair proficient disease where immunotherapy alone has limited efficacy[7].