ART0380 (IACS-030380) is a potent and selective, orally bioavailable inhibitor of ATR kinase, with an IC50 of 51.7 nM effectively inhibiting the enzyme activity of the ATR-ATRIP complex. It functions as an ATP-competitive inhibitor, binding to the ATP pocket of ATR, where ATP would typically bind. It interacts with the hinge through its morpholine oxygen and occupies the ribose pocket with a sulfoximine group. It also exhibits antitumor activity.