Integrated Multiomics Analysis of Microsatellite Instability-High Colorectal Cancer Identifies a Subtype With Poor Outcome.

Up to 50% of patients with metastatic microsatellite instability-high (MSI-H) colorectal cancer (CRC) are resistant to immunotherapy and experience progression or recurrence after treatment. We integrated the genomic, epigenomic, transcriptomic, and proteomic data for 99 patients in a Chinese MSI-H CRC cohort. Proteomic profiling of primary tumors clearly classified MSI-H tumors into 2 subtypes. We found that the 2 subtypes have different mutational signatures, enriched pathways, gene fusion networks, and clinical outcomes. Notably, NCAM1 could serve as a potential biomarker for checkpoint inhibitor response in MSI-H CRC. Thus, there is an urgent need to stratify the MSI-H group into different subtypes and adopt more targeted therapies to prolong patient survival.