A compound having the formula (1) wherein: R1 is a group selected from C3-8 cycloalkyl, C1-6 alkyl, C1-6 alkylene-C3-8 cycloalkyl, each of which groups may optionally be substituted with C1-6 alkyl, halogen, haloC1-6 alkyl or OR15, or R1 is heterocyclyl, optionally substituted with C1-6 alkyl, haloC1-6 alkyl or OR15 n is 0, 1, 2, 3 or 4, the alkylene group -(CH2)n- formed thereby being optionally substituted with a group selected from C1-4 alkyl, C3-8 cycloalkyl and arylsulfonyl A is a group selected from -N(R2)CO-, -CON(R2)-, -OC(O)-, -C(O)O-, -CO-, -C(R2)(OR3)-, -C(=N-O-R3)-, - C(=CR2R3)-, -C3-8 cycloalkylene-, -C(R2)(haloC1-6 alkyl)-, C1-4 alkylene and -C(OR3)(haloC1-6 alkyl)- R2 and R3 are each independently selected from H, C1-6 alkyl, and C3-8 cycloalkyl, or, when A is -N(R2)CO- and X is absent, R2 may form, together with the adjacent nitrogen atom and Z, an N-containing heterocyclyl group, which may optionally be substituted X is absent or is C1-4 alkylene or C2-4 alkenylene, each of which may optionally be substituted with one or more C1-4 alkyl groups, OR16, halogen or haloC1-6 alkyl Z is selected from aryl, heteroaryl, C3-8 cycloalkyl, and heterocyclyl, each of which may optionally be substituted by a group selected from -Y-aryl, -Y-heteroaryl, -Y-C3-8 cycloalkyl and -Y-heterocyclyl, or, when X is present, Z may be H, or, when X is absent and A is -C(R2)(OR3)- or -N(R2)CO-, Z may be H, or, when A is -N(R2)CO- and X is absent, Z may form, together with the adjacent nitrogen atom and R2, an N-containing heterocyclyl group which may optionally be substituted, wherein, when A is -CO-, Z is linked to X or A via a carbon atom and wherein, when A is -N(R2)CO- and Z is H, R1 is C3-8 cycloalkyl and Y represents a bond, C1-6 alkylene, CO, NR14, COC2-6 alkenylene, O, SO2 or NHCOC1-6 alkylene wherein said cycloalkyl, aryl, heteroaryl and heterocyclyl groups Z may be optionally substituted by one or more substituents which may be the same or different, and which are se
