ATRi including berzosertib (also known as M6620, VX-970) and gartisertib (M4344, VX-803) produced by Merck KGaA (Darmstadt, Germany), ceralasertib (AZD6738) by AstraZeneca (Cambridge, UK), elimusertib (BAY1895344) by Bayer (Leverkusen, Germany), camonsertib (RP-3500) by Repare Therapeutics Inc. (St-Laurent, QC, Canada), and ART0380 by Artios Pharma (Cambridge, UK), have demonstrated high anti-cancer activity, especially in cancers with high RS level and increased ATR-CHK1 dependency, oncogenic Ras activation, CCNE1 or MYC amplification [99]. This evidence concerns the gene CHEK1 and cancer.