To date, several ATR inhibitors have been developed.733,1262 Ceralasertib (AZD6738) is a selective and potent ATR inhibitor with good solubility, bioavailability, and pharmacokinetic properties.1263 Phase II clinical trials of ceralasertib in patients with osteosarcoma (NCT04417062) and advanced solid tumors (NCT04564027) are undergoing. This evidence concerns the gene ATR and osteosarcoma.