Interestingly, the combination of DFX with Prexasertib or VE‐822 decreased POLD1 and increased γH2AX (Figure S7G–S7J, Supporting Information), which was used as a bioactivity marker for CHK1 inhibitors.[41] Importantly, 5‐FU, a standard first‐line DNA damaging chemotherapy drug for CRC, also potentiated the growth‐suppressive effect and DDR of DFX on MC38 cells in vitro and in vivo without affecting mouse body weights (Figure 6O–Q). This evidence concerns the gene CHEK1 and colorectal carcinoma.