Disclosed is a Chk1 (Checkpoint kinase-1) inhibitor selected from the group consisting of (R)-N-(4-(3-aminopiperidin-1-yl)-5-bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)nicotinamide (R)-N-(4-(3-aminopiperidin-1-yl)-5-bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)isobutyramide (R)-N-(5-bromo-4-(3-(methylamino)piperidin-1-yl)-1H-pyrrolo[2,3-b]pyridin-3-yl)nicotinamide (R)-N-(4-(3-aminopiperidin-1-yl)-5- bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)-5-methylnicotinamide (R)-N-(4-(3-aminopiperidin-1-yl)-5-bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)cyclopropanecarboxamide (R)-N-(4-(3-aminopiperidin-1-yl)-5-bromo-1Hpyrrolo[ 2,3-b]pyridin-3-yl)-3-methyl-butanamide and (R)-N-(4-(3-aminopiperidin-1-yl)-5-bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)-2- cyclopropylacetamide, for administration to a patient with cancer for potentiating a DNA damaging agent, wherein the administration of the CHK1 inhibitor follows the administration of the DNA damaging agent, wherein the CHK1 inhibitor is administered in two doses, the first dose of the CHK1 inhibitor is administered one day after the DNA damaging agent, and the second dose of the CHK1 inhibitor is administered two days after the DNA damaging agent.
