This study is a single-center, prospective, observational study. This study plans to enroll 50 patients with mCRC who received immunotherapy. Stool and blood samples were collected from patients with mCRC before receiving immunotherapy (baseline) and after one cycle of immunotherapy and stored immediately in a -80°C freezer. Six months after treatment with a PD-1 inhibitor in combination with fruquintinib, patients with mCRC were evaluated radiographically according to the modified RECIST1.1 criteria for immunotherapy (iRECIST) and were divided into responsive and non-responsive groups.
In this study, we intend to use metagenomic sequencing to screen the key intestinal microbiota that affect the efficacy of PD-1 inhibitors and predict their possible functional pathways in patients with metastatic colorectal cancer receiving anti-PD-1 immunotherapy. Then, proteomics and metabolomics methods were used to screen differential proteins and metabolites, and the correlation analysis with key intestinal microbiota was carried out, and the efficacy of immunotherapy in patients with mCRC was evaluated. Finally, the above findings were verified in animal models, and then the specific mechanism of intestinal microbiota affecting the efficacy of PD-1 inhibitors was explained by taking the changes in body metabolism and immunity as the starting point.
