Parg inhibitory compounds

A compound of formula (I):

• or a pharmaceutically acceptable salt thereof, wherein
• X1, and X5 are each independently selected from N and CH,
• X4 is selected from N and C—R2, wherein R2 is selected from hydrogen, C1-2 alkyl, C2 alkenyl, C2 alkynyl, C1-2 haloalkyl, cyclopropyl, cyclobutyl, oxetanyl, halogen, —SO2(C1-2 alkyl), —SO(NH)(C1-2 alkyl), —SO(NC1-2 alkyl)(C1-2 alkyl), —CONH(C1-2 alkyl), O(C1-2 alkyl), —NH2, —NH(C1-2 alkyl) and —N(C1-2 alkyl)(C1-2 alkyl);
• R is selected from
• and
• R1 is selected from the group consisting of fluoro, cyano, formyl, (C1-2)alkyl, (C2)alkenyl, (C2)alkynyl, (C1-2)haloalkyl, —(C1-2 alkylene)-OH and —(C1-2 alkylene)-O—(C1-2 alkyl).