A compound of formula I, wherein: L 1 represents a direct bond or -[CR 5 R 6]-; X represents a direct bond, -O-, -N(R x)-, -CH 2 - or -S-; A represents an aryl, heteroaryl, cycloalkyl or heterocycloalkyl group, each of which is optionally substituted with one or more Q 1 groups; L 2 represents a direct bond or -C(=O)-; B represents an aryl, heteroaryl, cycloalkyl or heterocycloalkyl group, each of which is optionally substituted with one or more Q 2 groups; L 3 represents -CH 2 - or -CH 2 CH 2 -; R 1 and R 2 independently represent hydrogen, halogen, -OR 7, -NR 8 R 9, C 1-12 alkyl, C 2-12 alkenyl, C 2-12 alkynyl or C 3-12 cycloalkyl (which latter four groups are optionally substituted by one or more E 1 substituents); or R 1 and R 2 together with the carbon atom to which they are bound form C=O, C=C(R 10)R 11 or a C 3-6 cycloalkyl group optionally substituted by one or more E 2 substituents; R 3, R 4, R 5 and R 6 independently represent hydrogen, halogen, C 1-12 alkyl, C 2-12 alkenyl, C 2-12 alkynyl or C 3-6 cycloalkyl (which latter four groups are optionally substituted by one or more E 3 substituents); or any relevant pair of R 3, R 4, R 5 and R 6 form, together with the carbon atom to which they are bound, C=O or a C 3-6 cycloalkyl group optionally substituted by one or more E 4 substituents; R 7, R 8, R 9, R 10 and R 11 independently represent hydrogen or a C 1-6 alkyl group optionally substituted by one or more halo atoms; R x represents hydrogen, C 1-6 alkyl, or C 3-6 cycloalkyl (which latter two groups are optionally substituted by one or more halo atoms); Q 1 and Q 2 independently represent halogen, -CN, -NHCOR 12, C 1-6 alkyl, C 3-6 cycloalkyl, -O-C 1-6 alkyl, aryl or heteroaryl (which latter five groups are optionally substituted by one or more substituents selected from halogen, methyl and halomethyl (e.g. trifluoromethyl)); E 1, E 2, E 3 and E 4 independently represent halogen or a C 1-6 alkyl group optionally substituted by one or more halo atoms; R 12 represents C 1-6 alkyl or phenyl; or a pharmaceutically acceptable salt, ester, amide or solvate thereof. L 1 represents a direct bond or -[CR 5 R 6]-; X represents a direct bond, -O-, -N(R x)-, -CH 2 - or -S-; A represents an aryl, heteroaryl, cycloalkyl or heterocycloalkyl group, each of which is optionally substituted with one or more Q 1 groups; L 2 represents a direct bond or -C(=O)-; B represents an aryl, heteroaryl, cycloalkyl or heterocycloalkyl group, each of which is optionally substituted with one or more Q 2 groups; L 3 represents -CH 2 - or -CH 2 CH 2 -; R 1 and R 2 independently represent hydrogen, halogen, -OR 7, -NR 8 R 9, C 1-12 alkyl, C 2-12 alkenyl, C 2-12 alkynyl or C 3-12 cycloalkyl (which latter four groups are optionally substituted by one or more E 1 substituents); or R 1 and R 2 together with the carbon atom to which they are bound form C=O, C=C(R 10)R 11 or a C 3-6 cycloalkyl group optionally substituted by one or more E 2 substituents; R 3, R 4, R 5 and R 6 independently represent hydrogen, halogen, C 1-12 alkyl, C 2-12 alkenyl, C 2-12 alkynyl or C 3-6 cycloalkyl (which latter four groups are optionally substituted by one or more E 3 substituents); or any relevant pair of R 3, R 4, R 5 and R 6 form, together with the carbon atom to which they are bound, C=O or a C 3-6 cycloalkyl group optionally substituted by one or more E 4 substituents; R 7, R 8, R 9, R 10 and R 11 independently represent hydrogen or a C 1-6 alkyl group optionally substituted by one or more halo atoms; R x represents hydrogen, C 1-6 alkyl, or C 3-6 cycloalkyl (which latter two groups are optionally substituted by one or more halo atoms); Q 1 and Q 2 independently represent halogen, -CN, -NHCOR 12, C 1-6 alkyl, C 3-6 cycloalkyl, -O-C 1-6 alkyl, aryl or heteroaryl (which latter five groups are optionally substituted by one or more substituents selected from halogen, methyl and halomethyl (e.g. trifluoromethyl)); E 1, E 2, E 3 and E 4 independently represent halogen or a C 1-6 alkyl group optionally substituted by one or more halo atoms; R 12 represents C 1-6 alkyl or phenyl; or a pharmaceutically acceptable salt, ester, amide or solvate thereof.