Compounds 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 (LQ)mY; and each R3 is independently H, C1-C10 alkyl, aryl or heteroaryl, are surprisingly found to be inhibitors of PI3K-p110δ, and therefore have utility in therapy.