A compound of formula: or a salt or solvate thereof, wherein: each of A 1 is independently selected from the group consisting of nitrogen and CH; and each of A 2 and A 3 is independently selected from the group consisting of nitrogen, CH, and C(R 6); wherein each A 1 is CH and each of A 2 and A 3 is independently selected from CH and C(R 6), provided that only one of A 2 and A 3 is C(R 6); or exactly one of A 2 and A 3 is C(R 6) and no less than one and no more than two of A 1, A 2, and A 3 are nitrogen; R 1, R 2, and R 3 are each independently selected from the group consisting of hydrogen, halogen, -CN, -ORb, and -C 1-4 alkyl, wherein said -C 1-4 alkyl group is optionally substituted by 1, 2 or 3 independently selected halogen atoms, with the proviso that at least one R 1, R 2, and R 3 is other than hydrogen; R 6 is -β-NH-R 7; B is -CO- or -SO 2 -; each R 4 is independent selected from the group consisting of halogen, -C 1-4 alkyl, -C 1-4 alkoxy, -CN and hydroxy; n has a value selected from 0, 1 or 2; R 5 is hydrogen or -C 1-4 alkyl; R 7 is selected from the group consisting of -C 1-4 alkyl, -C 3-10 cycloalkyl, -C 1-4 alkyl-C 3-10 cycloalkyl, -C 6-10 aryl, -C 1-4 alkyl-C 6-10 aryl, (5- to 10-membered)-C 1-9 heteroaryl, -C 1-4 alkyl-(5- to 10-membered)-C 1-9 heteroaryl, (5- to 10-membered)-C 1-9 heterocyclyl, and -C 1-4 alkyl-(5- to 10-membered)-C 1-9 heterocyclyl; said alkyl, cycloalkyl, alkylcycloalkyl, aryl, alkylaryl, heteroaryl, alkylheteroaryl, heterocyclyl, and alkylheterocyclyl groups optionally being substituted with 1, 2, or 3 groups independently selected from the group consisting of halogen, hydroxy, -CN, -ORb, -SRb, -N(Rb) 2, -C 1-4 alkyl optionally substituted with 1, 2, or 3 halogen atoms, optionally substituted C 6-10 aryl, optionally substituted (5- to 10-membered)-C 1-9 heteroaryl, and (5- to 10-membered)-C 1-9 heterocyclyl; said cycloalkyl, alkylcycloalkyl, aryl, alkylaryl, heteroaryl, alkylheteroaryl, heterocyclyl, and alkylheterocyclyl is optionally fused to a further (second) ring, and each Rb is independently hydrogen, -C 1-4 alkyl, or -C 3-10 cycloalkyl, (5- to 10-membered)-C 1-9 heterocyclyl; said alkyl, cycloalkyl or heterocyclyl groups optionally being substituted by 1, 2 or 3 fluorine atoms. each of A 1 is independently selected from the group consisting of nitrogen and CH; and each of A 2 and A 3 is independently selected from the group consisting of nitrogen, CH, and C(R 6); wherein each A 1 is CH and each of A 2 and A 3 is independently selected from CH and C(R 6), provided that only one of A 2 and A 3 is C(R 6); or exactly one of A 2 and A 3 is C(R 6) and no less than one and no more than two of A 1, A 2, and A 3 are nitrogen; each A 1 is CH and each of A 2 and A 3 is independently selected from CH and C(R 6), provided that only one of A 2 and A 3 is C(R 6); or exactly one of A 2 and A 3 is C(R 6) and no less than one and no more than two of A 1, A 2, and A 3 are nitrogen; R 1, R 2, and R 3 are each independently selected from the group consisting of hydrogen, halogen, -CN, -ORb, and -C 1-4 alkyl, wherein said -C 1-4 alkyl group is optionally substituted by 1, 2 or 3 independently selected halogen atoms, with the proviso that at least one R 1, R 2, and R 3 is other than hydrogen; R 6 is -β-NH-R 7; B is -CO- or -SO 2 -; each R 4 is independent selected from the group consisting of halogen, -C 1-4 alkyl, -C 1-4 alkoxy, -CN and hydroxy; n has a value selected from 0, 1 or 2; R 5 is hydrogen or -C 1-4 alkyl; R 7 is selected from the group consisting of -C 1-4 alkyl, -C 3-10 cycloalkyl, -C 1-4 alkyl-C 3-10 cycloalkyl, -C 6-10 aryl, -C 1-4 alkyl-C 6-10 aryl, (5- to 10-membered)-C 1-9 heteroaryl, -C 1-4 alkyl-(5- to 10-membered)-C 1-9 heteroaryl, (5- to 10-membered)-C 1-9 heterocyclyl, and -C 1-4 alkyl-(5- to 10-membered)-C 1-9 heterocyclyl; said alkyl, cycloalkyl, alkylcycloalkyl, aryl, alkylaryl, heteroaryl, alkylheteroaryl, heterocyclyl, and alkylheterocyclyl groups optionally being substituted with 1, 2, or 3 groups independently selected from the group consisting of halogen, hydroxy, -CN, -ORb, -SRb, -N(Rb) 2, -C 1-4 alkyl optionally substituted with 1, 2, or 3 halogen atoms, optionally substituted C 6-10 aryl, optionally substituted (5- to 10-membered)-C 1-9 heteroaryl, and (5- to 10-membered)-C 1-9 heterocyclyl; said cycloalkyl, alkylcycloalkyl, aryl, alkylaryl, heteroaryl, alkylheteroaryl, heterocyclyl, and alkylheterocyclyl is optionally fused to a further (second) ring, and each Rb is independently hydrogen, -C 1-4 alkyl, or -C 3-10 cycloalkyl, (5- to 10-membered)-C 1-9 heterocyclyl; said alkyl, cycloalkyl or heterocyclyl groups optionally being substituted by 1, 2 or 3 fluorine atoms.