Pyrimidopyrimidinones useful as Wee-1 kinase inhibitors

A compound of Formula (I):

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is a phenyl ring substituted with alkyl and/or halogen;
• R2 and R3 are independently selected from the group consisting of a hydrogen atom, a deuterium atom, an optionally substituted alkyl group, an optionally substituted cycloalkyl group, an optionally substituted alkoxy group, an optionally substituted amino group, an optionally substituted aryl group and an optionally substituted heteroaryl group;
• or R2, R3 and the carbon atom to which they are both attached, as taken together, form an optionally substituted cycloalkyl group or an optionally substituted heterocyclyl group;
• R4 is a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aryl group or an optionally substituted heteroaryl group;
• or R4 and R2 or R3 and the ring atoms to which they are attached, as taken together, form an optionally substituted heterocyclyl group;
• and
• R5 is an optionally substituted phenyl ring or a heterocyclic bicyclic ring, wherein the heterocyclic bicyclic ring comprises a phenyl ring that is bound to the amino group.