Described herein are methods of treating a proliferative disorder (e.g., cancer) in a patient by administering a DNA damaging agent and between about 12 and about 48 hours later administering to the subject a compound that inhibits ATR protein kinase. Methods of treating a proliferative disorder (e.g., cancer) in a patient by administering a compound that inhibits ATR protein kinase are also described. Exemplary ATR inhibitors are represented by Formulae A-I and A-II or a pharmaceutically acceptable salt thereof, wherein the variables are as defined herein.
