gemcitabine + oxaliplatin + sintilimab + bevacizumab

This is a four-drug combination regimen consisting of gemcitabine, oxaliplatin, sintilimab, and bevacizumab. - **Gemcitabine** is a nucleoside analog that inhibits DNA synthesis, acting as an antimetabolite chemotherapeutic agent. - **Oxaliplatin** is a platinum-based chemotherapeutic that forms DNA crosslinks and inhibits DNA replication and transcription. - **Sintilimab** is a monoclonal antibody immune checkpoint inhibitor targeting the programmed cell death protein 1 (PD-1) receptor on T cells, thereby enhancing anti-tumor immune responses. - **Bevacizumab** is a monoclonal antibody targeting vascular endothelial growth factor A (VEGF-A), inhibiting angiogenesis required for tumor growth. This combination leverages cytotoxic chemotherapy (gemcitabine and oxaliplatin), immunotherapy (sintilimab), and antiangiogenic therapy (bevacizumab). It has been investigated in various advanced solid tumors such as biliary tract cancer and gallbladder carcinoma[4][10]. The rationale for this regimen includes synergistic effects between chemotherapy-induced immunogenic cell death, immune checkpoint blockade to enhance T-cell activity against tumors, and inhibition of tumor vasculature to improve drug delivery and reduce tumor growth.