A compound of formula or, or pharmaceutically acceptable salts thereof, wherein X is selected from i) N, and ii) CR 18; Y is selected from i) N, and ii) CH; Z is selected from i) N, and ii) CH; R 1 is selected from i) C 1-6 -alkyl, ii) H, iii) halo-C 1-6 -alkyl, iv) C 1-6 -alkoxy, v) halo-C 1-6 -alkoxy, vi) hydroxy-C 1-6 -alkyl, vii) C 3-8 -cycloalkyl, and viii) halogen; R 2 is selected from i) H, ii) C 1-6 -alkyl, and iii) halogen; R 3 is selected from i) heteroaryl optionally substituted with R 6, R 7 and R 8, ii) amino substituted on the nitrogen atom by one or two substituents independently selected from R 4 and R 5 iii) heterocycloalkyl optionally substituted with R 9, R 10 and R 11, iv) aryl substituted with R 6, R 7 and R 8, v) halo-C 1-6 -alkoxy, vi) hydroxy-C 1-6 -alkyl, and vii) halo-C 1-6 -alkyl; R 4 is selected from i) H, and ii) C 1-6 -alkyl; R 5 is selected form i) H, and ii) C 1-6 -alkyl; R 6, R 7 and R 8 are independently selected from i) C 1-6 -alkyl, ii) hydroxy-C 1-6 -alkyl, iii) C 1-6 -alkoxy, iv) halogen, v) halo-C 1-6 -alkyl, vi) C 3-8 -cycloalkyl, and vii) cyano; R 9, R 10 and R 11 are independently selected from i) C 1-6 -alkyl, ii) C 1-6 -alkoxy, iii) C 1-6 -alkoxycarbonyl, iv) C 3-8 -cycloalkoxy, v) C 3-8 -cycloalkyl, vi) C 3-8 -cycloalkyl-C 1-6 -alkoxy, vii) halo-C 1-6 -alkyl, viii) C 1-6 -alkoxy C 1-6 -alkyl, ix) C 3-8 -cycloalkylcarbonyl, x) halo-C 1-6 -alkoxy, xi) cyano, xii) halogen, xiii) heteroaryl optionally substituted with R 12, R 13 and R 14, xiv) heteroaryloxy optionally substituted with R 12, R 13 and R 14, xv) hydroxy, xvi) hydroxy-C 1-6 -alkyl, and xvii) oxo; R 12, R 13 and R 14 are independently selected from i) halo-C 1-6 -alkyl, ii) C 1-6 -alkyl, iii) C 1-6 -alkoxy, and iv) halogen; R 18 is selected from i) H, and ii) halogen. X is selected from i) N, and ii) CR 18; i) N, and ii) CR 18; Y is selected from i) N, and ii) CH; i) N, and ii) CH; Z is selected from i) N, and ii) CH; i) N, and ii) CH; R 1 is selected from i) C 1-6 -alkyl, ii) H, iii) halo-C 1-6 -alkyl, iv) C 1-6 -alkoxy, v) halo-C 1-6 -alkoxy, vi) hydroxy-C 1-6 -alkyl, vii) C 3-8 -cycloalkyl, and viii) halogen; i) C 1-6 -alkyl, ii) H, iii) halo-C 1-6 -alkyl, iv) C 1-6 -alkoxy, v) halo-C 1-6 -alkoxy, vi) hydroxy-C 1-6 -alkyl, vii) C 3-8 -cycloalkyl, and viii) halogen; R 2 is selected from i) H, ii) C 1-6 -alkyl, and iii) halogen; i) H, ii) C 1-6 -alkyl, and iii) halogen; R 3 is selected from i) heteroaryl optionally substituted with R 6, R 7 and R 8, ii) amino substituted on the nitrogen atom by one or two substituents independently selected from R 4 and R 5 iii) heterocycloalkyl optionally substituted with R 9, R 10 and R 11, iv) aryl substituted with R 6, R 7 and R 8, v) halo-C 1-6 -alkoxy, vi) hydroxy-C 1-6 -alkyl, and vii) halo-C 1-6 -alkyl; i) heteroaryl optionally substituted with R 6, R 7 and R 8, ii) amino substituted on the nitrogen atom by one or two substituents independently selected from R 4 and R 5 iii) heterocycloalkyl optionally substituted with R 9, R 10 and R 11, iv) aryl substituted with R 6, R 7 and R 8, v) halo-C 1-6 -alkoxy, vi) hydroxy-C 1-6 -alkyl, and vii) halo-C 1-6 -alkyl; R 4 is selected from i) H, and ii) C 1-6 -alkyl; i) H, and ii) C 1-6 -alkyl; R 5 is selected form i) H, and ii) C 1-6 -alkyl; i) H, and ii) C 1-6 -alkyl; R 6, R 7 and R 8 are independently selected from i) C 1-6 -alkyl, ii) hydroxy-C 1-6 -alkyl, iii) C 1-6 -alkoxy, iv) halogen, v) halo-C 1-6 -alkyl, vi) C 3-8 -cycloalkyl, and vii) cyano; i) C 1-6 -alkyl, ii) hydroxy-C 1-6 -alkyl, iii) C 1-6 -alkoxy, iv) halogen, v) halo-C 1-6 -alkyl, vi) C 3-8 -cycloalkyl, and vii) cyano; R 9, R 10 and R 11 are independently selected from i) C 1-6 -alkyl, ii) C 1-6 -alkoxy, iii) C 1-6 -alkoxycarbonyl, iv) C 3-8 -cycloalkoxy, v) C 3-8 -cycloalkyl, vi) C 3-8 -cycloalkyl-C 1-6 -alkoxy, vii) halo-C 1-6 -alkyl, viii) C 1-6 -alkoxy C 1-6 -alkyl, ix) C 3-8 -cycloalkylcarbonyl, x) halo-C 1-6 -alkoxy, xi) cyano, xii) halogen, xiii) heteroaryl optionally substituted with R 12, R 13 and R 14, xiv) heteroaryloxy optionally substituted with R 12, R 13 and R 14, xv) hydroxy, xvi) hydroxy-C 1-6 -alkyl, and xvii) oxo; i) C 1-6 -alkyl, ii) C 1-6 -alkoxy, iii) C 1-6 -alkoxycarbonyl, iv) C 3-8 -cycloalkoxy, v) C 3-8 -cycloalkyl, vi) C 3-8 -cycloalkyl-C 1-6 -alkoxy, vii) halo-C 1-6 -alkyl, viii) C 1-6 -alkoxy C 1-6 -alkyl, ix) C 3-8 -cycloalkylcarbonyl, x) halo-C 1-6 -alkoxy, xi) cyano, xii) halogen, xiii) heteroaryl optionally substituted with R 12, R 13 and R 14, xiv) heteroaryloxy optionally substituted with R 12, R 13 and R 14, xv) hydroxy, xvi) hydroxy-C 1-6 -alkyl, and xvii) oxo; R 12, R 13 and R 14 are independently selected from i) halo-C 1-6 -alkyl, ii) C 1-6 -alkyl, iii) C 1-6 -alkoxy, and iv) halogen; i) halo-C 1-6 -alkyl, ii) C 1-6 -alkyl, iii) C 1-6 -alkoxy, and iv) halogen; R 18 is selected from i) H, and ii) halogen. i) H, and ii) halogen.