Tricyclic heterocyclic compounds as phosphoinositide 3-kinase inhibitors

A compound of formula I:or a pharmaceutically acceptable salt thereof, wherein: W is O, N-H, N-(C1-C10 alkyl) or S; each X is independently CH or N; R1 is a 5 to 7-membered saturated or unsaturated, optionally substituted heterocycle containing at least 1 heteroatom selected from N or O; R2 is LY; each L is a direct bond, C1-C10 alkylene, C2-C10 alkenylene or C2-C10 alkynylene; Y is an optionally substituted fused, bridged or spirocyclic non-aromatic 5-12 membered heterocycle containing up to 4 heteroatoms selected from N or O; and each R3 is independently H, C1-C10 alkyl, halogen, fluoro C1-C10 alkyl, O-C1-C10 alkyl, NH-C1-C10 alkyl, S-C1-C10 alkyl, O-fluoro C1-C10 alkyl, NH-acyl, NH-C(O)-NH-C1-C10 alkyl, C(O)-NH-C1-C10 alkyl, aryl or heteroaryl, are useful as inhibitors of the class IA phosphoinositide 3-kinase enzyme, PI3K-p110δ, and therefore have potential utility in the therapy of cancer, immune and inflammatory diseases.