Subsequently, we assessed the impact of ARN‐3236 on radiotherapy efficacy in a CRC xenograft model. ARN‐3236 addition increased the tumor inhibition ratio of IR from 69.27% (CON + IR) to 90.41% (ARN + IR), and the combination treatment exhibited a markedly synergistic effect (Q = 1.35),26, 27 although ARN‐3236 alone at administrated dose did not show significant efficacy at the indicated dose (Figure 6E). IHC analysis also revealed that ARN‐3236 resulted in reduced staining of KI67 and increased staining of γH2AX (Figure S7D). Here, MKI67 is linked to colorectal carcinoma.