A Biomarker Exploratory Study of Dual Blockade of PD1/PDL1 and CTLA4 and Anti-angiogenic Therapy

This study is a single-center prospective exploratory research. Patients with MSS metastatic colorectal cancer and MSI solid tumors resistant to PD-1/PD-L1 antibody monotherapy who are treated with dual PD1/PDL1 and CTLA4 blockade combined with anti-angiogenic therapy in the Department of Gastrointestinal Oncology of Peking University Cancer Hospital will be enrolled. Their clinical-pathological features and specimens will be collected at baseline, at each tumor assessment point, and at disease progression. This study aims to identify clinical characteristics and biomarkers associated with the therapeutic effects through multi-omics approaches, and to investigate MR image characteristics during treatment. Samples include tissue, blood, urine and stool, and multi-omics approaches include single-cell sequencing, spatial transcriptome sequencing, macro transcriptome sequencing, whole exome sequencing, microproteomics, immunohistochemistry, and multiplex fluorescence immunohistochemistry.