Since irinotecan is approved for the treatment of colon cancer, and rabusertib (a CHEK1-selective inhibitor) has an acceptable safety profile in phase 1 trials26, our data indicate that this combination—with appropriate consideration of potential toxicity—could be particularly effective for patients with MSS or KRAS–TP53 double-mutant colon cancer. This evidence concerns the gene CHEK1 and malignant colon neoplasm.