Although the efficacy of ATM inhibitors such as KU-55933, KU-60019, KU-59403, CP-466722, AZ31, AZ32, AZD0156, and AZD1390 has been demonstrated in different tumor types showing different responses to RT in preclinical studies (28, 66–68), systematic and comprehensive testing is lagging in CRC (7). Here, ATM is linked to colorectal carcinoma.