WRN is a gene that cancer cells with a specific defect called microsatellite instability (MSI-H) depend on to survive. This study ranked all cancer types by how strongly MSI-H tumors rely on WRN, finding it is a strong vulnerability especially in colorectal and uterine cancers. Three drugs targeting WRN are now in clinical trials, and the study found that when tumors develop resistance to one drug, they may still respond to another. About 62,000 US cancer patients per year could potentially benefit from these treatments.