There are provided according to the invention novel compounds of formula (I) or a pharmaceutically acceptable salt thereof: wherein: X represents a nitrogen atom; Y represents —C(H2)—, (—C(H2)—)2, —S(O2)— or —C(═O)—; Z represents —C(H2)—, —S(O2)—, —N(Rz)—, or an oxygen or sulphur atom; A represents hydrogen or —CH2OH; Rz represents hydrogen, C1-6 alkyl, C1-6 alkoxy, —COR7 or —SO2R7; R1 represents halogen, C1-6 alkyl, C1-6 alkoxy, ═O, haloC1-6 alkyl, haloC1-6 alkoxy, hydroxyl or —CH2OH; m represents an integer from 0 to 3; R2 represents halogen, ═O, C1-6 alkyl (optionally substituted by one or more hydroxyl groups), —COOR7, —CONR7R8, C1-6 alkoxy, haloC1-6 alkyl, haloC1-6 alkoxy or C1-6alkylOC1-6alkyl; n represents an integer from 0 to 3; p and q independently represent an integer from 0 to 2; R3 represents an -aryl, -heteroaryl, -heterocyclyl, -aryl-aryl, -aryl-heteroaryl, -aryl-heterocyclyl, -heteroaryl-aryl, -heteroaryl-heteroaryl, -heteroaryl-heterocyclyl, -heterocyclyl-aryl, -heterocyclyl-heteroaryl or -heterocyclyl-heterocyclyl group, all of which may be optionally substituted by one or more (e.g. 1, 2 or 3) halogen, C1-6 alkyl (optionally substituted by one or more hydroxyl groups), C3-8 cycloalkyl, C1-6 alkoxy, hydroxyl, haloC1-6 alkyl, haloC1-6 alkoxy, cyano, —S—C1-6 alkyl, —SO—C1-6 alkyl, —SO2—C1-6 alkyl, —COR7, —CONR7R8, —NR7R8, —NR7COC1-6 alkyl, —NR7SO2—C1-6 alkyl, C1-6 alkyl-NR7R8, —OCONR7R8, —NR7CO2R8 or —SO2NR7R8 groups; R4 and R5 independently represent C1-6 alkyl, or R4 and R5 together with the carbon atom to which they are attached may together form a C3-8 cycloalkyl group; R6 represents halogen, C1-6 alkyl, C3-8 cycloalkyl, C1-6 alkoxy, haloC1-6 alkyl or haloC1-6 alkoxy; s represents an integer from 0 to 4; R7 and R8 independently represent hydrogen, C1-6 alkyl or C3-8 cycloalkyl; or solvates thereof.