PD-1 Inhibitor Combined With Bevacizumab and FOLFIRI Regimen in the Second-line Treatment of Advanced Colorectal Cancer

MSI-H is a biomarker for solid tumors benefiting from immunotherapy. Recent clinical studies have confirmed that PD-1 inhibitors have a good effect on MSI-H advanced colorectal cancer for first- or second-line treatment. The overall effective rate is 30% to 40%. However, about 30% of patients are resistant to PD-1 inhibitors. Whether PD-1 inhibitors and existing chemotherapeutics and anti-vascular drugs have synergistic effects is worth studying. This study is a phase II prospective clinical study of PD-1 inhibitor combined with bevacizumab and FOLFIRI regimen in the second-line treatment of unresectable recurrent or metastatic MSI-H colorectal cancer.