A compound selected from compounds of Formula A, and pharmaceutically acceptable salts, solvates, and hydrates thereof: wherein: n is 1 or 2; each of R 6, R 7, and R 8 is independently selected from hydrogen and C 1 -C 6 alkyl; R 9 is hydrogen or C 1 -C 6 alkyl; X 2 is N or CR 2; X 3 is N or CR 3; X 4 is N or CR 4; wherein each of R 1, R 2, R 3, and R 4 is independently selected from: a) hydrogen; b) C 1 -C 6 alkyl optionally substituted with one or more groups each independently selected from: C 6 -C 10 aryl optionally substituted with halogen; C 1 -C 6 alkoxy optionally substituted with 3- to 8-membered heterocycloalkyl; C 3 -C 8 cycloalkyl; OH; CN; 3- to 8-membered heterocycloalkyl; 5- to 10-membered heteroaryl; and halogen; c) C 2 -C 6 alkenyl; d) C 3 -C 8 cycloalkyl; e) 5- to 10-membered heteroaryl optionally substituted with halogen; f) C 6 -C 10 aryl optionally substituted with one or more groups each independently selected from halogen, C 1 -C 6 alkoxy optionally substituted with halogen, and C 1 -C 6 alkyl optionally substituted with halogen, wherein the C 6 -C 10 aryl is optionally fused to a heterocyclic ring; g) CONHC 1 -C 6 alkyl optionally substituted with halogen; h) NH R 5, wherein R 5 is selected from C 1 -C 6 alkoxy, C 1 -C 6 alkyl optionally substituted with C 6 -C 10 aryl, C 6 -C 10 aryl optionally substituted with halogen, 3- to 8-membered heterocycloalkyl, and C 3 -C 8 cycloalkyl; i) halogen; and j) C 1 -C 6 alkylthio; wherein at least one but not more than two of X 2, X 3 and X 4 are N, and either (i) only one of X 2, X 3 and X 4 is N and at least one of R 1, R 2, R 3, and R 4 is hydrogen; or (ii) only X 2 and X 4 are N. n is 1 or 2; each of R 6, R 7, and R 8 is independently selected from hydrogen and C 1 -C 6 alkyl; R 9 is hydrogen or C 1 -C 6 alkyl; X 2 is N or CR 2; X 3 is N or CR 3; X 4 is N or CR 4; wherein each of R 1, R 2, R 3, and R 4 is independently selected from: a) hydrogen; b) C 1 -C 6 alkyl optionally substituted with one or more groups each independently selected from: C 6 -C 10 aryl optionally substituted with halogen; C 1 -C 6 alkoxy optionally substituted with 3- to 8-membered heterocycloalkyl; C 3 -C 8 cycloalkyl; OH; CN; 3- to 8-membered heterocycloalkyl; 5- to 10-membered heteroaryl; and halogen; c) C 2 -C 6 alkenyl; d) C 3 -C 8 cycloalkyl; e) 5- to 10-membered heteroaryl optionally substituted with halogen; f) C 6 -C 10 aryl optionally substituted with one or more groups each independently selected from halogen, C 1 -C 6 alkoxy optionally substituted with halogen, and C 1 -C 6 alkyl optionally substituted with halogen, wherein the C 6 -C 10 aryl is optionally fused to a heterocyclic ring; g) CONHC 1 -C 6 alkyl optionally substituted with halogen; h) NH R 5, wherein R 5 is selected from C 1 -C 6 alkoxy, C 1 -C 6 alkyl optionally substituted with C 6 -C 10 aryl, C 6 -C 10 aryl optionally substituted with halogen, 3- to 8-membered heterocycloalkyl, and C 3 -C 8 cycloalkyl; i) halogen; and j) C 1 -C 6 alkylthio; wherein at least one but not more than two of X 2, X 3 and X 4 are N, and either (i) only one of X 2, X 3 and X 4 is N and at least one of R 1, R 2, R 3, and R 4 is hydrogen; or (ii) only X 2 and X 4 are N. a) hydrogen; b) C 1 -C 6 alkyl optionally substituted with one or more groups each independently selected from: C 6 -C 10 aryl optionally substituted with halogen; C 1 -C 6 alkoxy optionally substituted with 3- to 8-membered heterocycloalkyl; C 3 -C 8 cycloalkyl; OH; CN; 3- to 8-membered heterocycloalkyl; 5- to 10-membered heteroaryl; and halogen; C 6 -C 10 aryl optionally substituted with halogen; C 1 -C 6 alkoxy optionally substituted with 3- to 8-membered heterocycloalkyl; C 3 -C 8 cycloalkyl; OH; CN; 3- to 8-membered heterocycloalkyl; 5- to 10-membered heteroaryl; and halogen; c) C 2 -C 6 alkenyl; d) C 3 -C 8 cycloalkyl; e) 5- to 10-membered heteroaryl optionally substituted with halogen; f) C 6 -C 10 aryl optionally substituted with one or more groups each independently selected from halogen, C 1 -C 6 alkoxy optionally substituted with halogen, and C 1 -C 6 alkyl optionally substituted with halogen, wherein the C 6 -C 10 aryl is optionally fused to a heterocyclic ring; g) CONHC 1 -C 6 alkyl optionally substituted with halogen; h) NH R 5, wherein R 5 is selected from C 1 -C 6 alkoxy, C 1 -C 6 alkyl optionally substituted with C 6 -C 10 aryl, C 6 -C 10 aryl optionally substituted with halogen, 3- to 8-membered heterocycloalkyl, and C 3 -C 8 cycloalkyl; i) halogen; and j) C 1 -C 6 alkylthio; wherein at least one but not more than two of X 2, X 3 and X 4 are N, and either (i) only one of X 2, X 3 and X 4 is N and at least one of R 1, R 2, R 3, and R 4 is hydrogen; or (ii) only X 2 and X 4 are N. wherein at least one but not more than two of X 2, X 3 and X 4 are N, and either (i) only one of X 2, X 3 and X 4 is N and at least one of R 1, R 2, R 3, and R 4 is hydrogen; or (ii) only X 2 and X 4 are N. (i) only one of X 2, X 3 and X 4 is N and at least one of R 1, R 2, R 3, and R 4 is hydrogen; or (ii) only X 2 and X 4 are N.