The present disclosure relates to substituted 1,2-dihydro-3h-pyrazolo[4,3-c]quinolin-3-one of Formula-Q as ATR kinase inhibitors. Formula-Q wherein, R is selected from the group consisting of hydrogen and alkyl group wherein, R1, R2, and R3 are independently selected from the group consisting of hydrogen or alkyl, Z is nitrogen at different positions, X is selected from the group consisting of halogen, alkyl, haloalkyl, or cyano, and Y is selected from the group consisting of nitrogen, and oxygen. A process for preparation of compounds of Formula-Q is also disclosed. The pharmaceutical composition of compound of Formula-Q can be used as an ATR kinase inhibitor.
