Substituted sulfoximine compounds as indoleamine 2,3-dioxygenase (IDO) inhibitors

1. A compound of formula (I), or a pharmaceutically acceptable salt thereof:

wherein:

m is 0, 1, 2, 3, 4 or 5;

p is 0, 1, 2, 3, 4 or 5;

each occurrence of W is independently selected from (a) CR a R b —, (b) —NR a —, (c) —C(O)— and (d) —O—(CR a R b ) r —; wherein r is 1, 2 or 3; each occurrence of R a and R b is independently selected from the group consisting of (a) hydrogen, (b) halogen and (c) C 1-6 alkyl, optionally substituted with 1 to 3 halogens;

X is selected from —NR c —, —S— and —O—; R c is selected from (a) hydrogen and (b) C 1-6 alkyl;

“ ” is an optional double bond; provided that when “ ” is a double bond, then the W attached to the double bond is ═CR d — and one R 2 on the adjacent carbon is absent;

each occurrence of R 1 is independently selected from the group consisting of (a) hydrogen, (b) halogen, (c) —CN, (d) C 1-6 alkyl, optionally substituted with 1 to 3 halogens, (e) C 3-6 cycloalkyl, (f) OCHF 2 , (g) OCF 3 , (h) SCF 3 , and (i) SF 5 ;

each occurrence of R 2 is independently selected from the group consisting of (a) hydrogen, (b) halogen, (c) —OH and (d) C 1-6 alkyl, optionally substituted with 1 to 3 halogens;

or two R 2 groups together with the carbon to which they are attached form a C 3-6 cycloakyl or a 4-, 5-, or 6-membered heterocycle;

or R 2 and R 5 together with the carbon and sulfur atoms to which they are attached form a 4-, 5- or 6-membered heterocycle;

or R 2 and R a of W together with the carbon and/or nitrogen atoms to which they are attached form (a) a 4-, 5- or 6-membered carbocycle, (b) a 7-8 membered spiro bicyclic carbocyclyl, (c) a 7-8 membered spiro bicyclic heterocycle, (d) a 5-6 membered bridged bicyclic carbocyclyl, or (e) a 4-, 5- or 6-membered heterocycle;

R 4 is selected from the group consisting of (a) hydrogen and (b) C 1-6 alkyl;

R 5 is selected from the group consisting of (a) C 1-6 alkyl optionally substituted with —OH, (b) C 3-6 cycloalkyl, (c) aryl and (d) 4-, 5- or 6-membered heterocycle; and

R 6 is selected from the group consisting of (a) hydrogen, (b) —CN, (c) —C(O)—NH 2 , (d) C 1-6 alkyl optionally substituted with —OH and (e) —O—C 1-6 alkyl.

2. The compound of claim 1 , or a pharmaceutically acceptable salt thereof,

wherein m is 0, 1, 2 or 3; p is 0, 1 or 2;

“ ” is a single bond;

X is selected from —NH—, —S— and —O—;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

each occurrence of R 2 is independently selected from (a) hydrogen (b) —OH and (c) C 1-4 alkyl;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl;

R 5 is selected from (a) C 1-4 alkyl optionally substituted with —OH and (b) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) C 1-4 alkyl, (c) —CN and (d) —C(O)—NH 2 .

3. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ia):

wherein: m is 1, 2, 3 or 4;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

each occurrence of R 2 is independently selected from (a) hydrogen (b) —OH and (c) C 1-4 alkyl;

R 5 is C 4 alkyl optionally substituted with —OH; and

R 6 is selected from (a) hydrogen, (b) C 1-4 alkyl, (c) —CN and (d) —C(O)—NH 2 .

4. The compound of claim 3 , or a pharmaceutically acceptable salt thereof,

wherein:

m is 2, 3 or 4;

each occurrence of R 1 is independently selected from (a) hydrogen, (b) Cl and (c) F;

each occurrence of R 2 is independently selected from (a) hydrogen, (b) —OH, (c) methyl, (d) ethyl and (e) propyl;

R 5 is selected from (a) methyl, (b) ethyl and (c) propyl; and

R 6 is selected from (a) hydrogen, (b) methyl, (c) ethyl, (d) —CN and (e) —C(O)—NH 2 .

5. The compound of claim 3 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ib):

wherein: m is 2, 3 or 4;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) F;

each occurrence of R 2 is independently selected from (a) hydrogen, (b) —OH and (c) methyl;

R 5 is selected from (a) methyl, (b) ethyl and (c) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) methyl, (c) —CN and (d) —C(O)—NH 2 .

6. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ic):

wherein: p is 0, 1 or 2; q is 0, 1 or 2; r is 1 or 2;

W is —CR a R b —;

X is selected from —NH—, —S— and —O—;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

each occurrence of R 2 is independently selected from (a) hydrogen, (b) —OH and (c) C 1-4 alkyl;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl; and

R 6 is selected from (a) hydrogen, (b) —CN and (c) C 1-4 alkyl.

7. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Id):

wherein: p is 0, 1 or 2; r is 1 or 2;

W is —CR a R b —;

X is selected from —NH—, —S— and —O—;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

each occurrence of R 2 is independently selected from (a) hydrogen, (b) —OH and (c) C 1-4 alkyl;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl; and

R 6 is selected from (a) hydrogen, (b) —CN and (c) C 1-4 alkyl.

8. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ie):

wherein: q is 0, 1 or 2; r is 1 or 2; t is 1 or 2;

W is selected from the group consisting of CR b and N;

each occurrence of R a and R b is independently selected from the group consisting of (a) hydrogen and (b) C 1-4 alkyl;

each of R 2 is independently selected from (a) hydrogen (b) —OH and (c) C 1-4 alkyl;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl;

R 5 is selected from (a) C 1-4 alkyl optionally substituted with —OH and (b) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) —CN and (c) C 1-4 alkyl.

9. The compound of claim 8 , or a pharmaceutically acceptable salt thereof,

wherein: q is 0 or 1; r is 2; t is 2;

W is N;

R 4 is hydrogen;

R 5 is selected from (a) methyl, (b) ethyl and (c) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) —CN, (c) methyl and (d) ethyl.

10. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (If):

wherein: q is 0, 1, or 2; r is 0 or 1;

W is selected from the group consisting of —CR a R b — and —NR a —;

X is selected from —NH—, —S— and —O—;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

each occurrence of R 2 is independently selected from (a) hydrogen and (b) C 1-4 alkyl;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl;

R 5 is selected from (a) C 1-4 alkyl optionally substituted with —OH and (b) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) —CN, (c) methyl and (d) ethyl.

11. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ig):

where m is 0, 1, 2 or 3; n is 1 or 2; p is 1, 2, 3 or 4;

X is selected from —NH—, —S— and —O—;

W is selected from the group consisting of —CR a R b —, —NR a —, and —C(O)—;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl;

R 5 is C 1-4 alkyl; and

R 6 is selected from (a) hydrogen, (b) C 1-4 alkyl, (c) —CN and —C(O)—NH 2 .

12. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ih):

wherein: q is 1 or 2; r is 1, 2 or 3;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl;

R 5 is selected from (a) C 1-4 alkyl optionally substituted with —OH and (b) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) —CN and (c) C 1-4 alkyl.

13. The compound of claim 12 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ii):

wherein:

each occurrence of R 1 is independently selected from (a) hydrogen (b) Cl and (c) F;

R 5 is selected from (a) methyl, (b) ethyl, (c) propyl; and (d) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) —CN, (c) methyl, (d) ethyl, (e) propyl.

14. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ij):

wherein: m is 1, 2 or 3; r is 1, 2 or 3;

each occurrence of R 1 is independently selected from (a) hydrogen and (b) halogen;

R 5 is selected from (a) C 1-4 alkyl optionally substituted with —OH and (b) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) C 1-4 alkyl, (c) —CN and —C(O)—NH 2 .

15. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the compound has formula (Ik):

wherein: q is 0, 1 or 2; r is 1 or 2; t is 1 or 2; u is 1, 2 or 3;

W is selected from the group consisting of —CR a R b — and —NR a —;

each occurrence of R a and R b is independently selected from the group consisting of (a) hydrogen and (b) C 1-4 alkyl;

each of R 2 is independently selected from (a) hydrogen (b) —OH and (c) C 1-4 alkyl;

R 4 is selected from (a) hydrogen and (b) C 1-4 alkyl;

R 5 is selected from (a) C 1-4 alkyl optionally substituted with —OH and (b) C 3-6 cycloalkyl; and

R 6 is selected from (a) hydrogen, (b) —CN and (c) C 1-4 alkyl.

16. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, selected from the group consisting of:

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-((S)—S-methylsulfonimidoyl)ethyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-((R)—S-methylsulfonimidoyl)ethyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(((1R,3s)-1-imino-1-oxido-1λ 6 -thietan-3-yl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(((1S,3r)-1-imino-1-oxido-1λ 6 -thietan-3-yl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((((1R,3s)-1-imino-1-oxido-1λ 6 -thietan-3-yl)methyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((((1S,3r)-1-imino-1-oxido-1λ 6 -thietan-3-yl)methyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-((R)-2-hydroxyethylsulfonimidoyl)ethyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-((S)-2-hydroxyethylsulfonimidoyl)ethyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-hydroxy-3-(S-methylsulfonimidoyl)propyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl)-N′-hydroxy-4-((1-(S-methylsulfonimidoyl)piperidin-4-yl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-(methylsulfonoamidimidamido)ethyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

2-((4-(N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxycarbamimidoyl)-1,2,5-oxadiazol-3-yl)amino)-N-(2-(S-methylsulfonimidoyl)ethyl)acetamide,

2-((4-(N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxycarbamimidoyl)-1,2,5-oxadiazol-3-yl)amino)-N-(2-((R)—S-methylsulfonimidoyl)ethyl)acetamide,

2-((4-(N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxycarbamimidoyl)-1,2,5-oxadiazol-3-yl)amino)-N-(2-((S)—S-methylsulfonimidoyl)ethyl)acetamide,

4-(((E)-2-(N-cyano-S-methylsulfonimidoyl)vinyl)amino)-N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide,

4-((2-(N-carbamoyl-S-methylsulfonimidoyl)ethyl)amino)-N—((S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl)-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide,

4-((2-(N-cyano-S-methylsulfonimidoyl)ethyl)amino)-N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl)-N′-hydroxy-4-((1-((R)—S-methylsulfonimidoyl)piperidin-4-yl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl)-N′-hydroxy-4-((1-((S)—S-methylsulfonimidoyl)piperidin-4-yl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((1-((S)—S-methylsulfonimidoyl)azetidin-3-yl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((1-((R)—S-methylsulfonimidoyl)azetidin-3-yl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((((2R)-1-imino-1-oxido-1λ 6 -thietan-2-yl)methyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((((2S)-1-imino-1-oxido-1λ 6 -thietan-2-yl)methyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((3-((R)—S-methylsulfonimidoyl)propyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((3-((S)—S-methylsulfonimidoyl)propyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(((2R)-2-hydroxy-3-((S)—S-methylsulfonimidoyl)propyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(((2R)-2-hydroxy-3-((R)—S-methylsulfonimidoyl)propyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(((2S)-2-hydroxy-3-((S)—S-methylsulfonimidoyl)propyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(((2S)-2-hydroxy-3-((R)—S-methylsulfonimidoyl)propyl)amino)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(3-((R)—S-methylsulfonimidoyl)propoxy)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(3-((S)—S-methylsulfonimidoyl) propoxy)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(4-((R)—S-methylsulfonimidoyl)butoxy)-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-(4-((S)—S-methylsulfonimidoyl)butoxy)-1,2,5-oxadiazole-3-carboximidamide,

4-{[2-(N,S-dimethylsulfonimidoyl)ethyl]amino}-N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({[3-hydroxy-1-(S-methylsulfonimidoyl)azetidin-3-yl]methyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[4-(S-methylsulfonimidoyl)butyl]amino}-1,2,5-oxadiazole-3-carboximidamide,

N-[2-(N,S-dimethylsulfonimidoyl)ethyl]-N˜2˜-(4-{N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxycarbamimidoyl}-1,2,5-oxadiazol-3-yl)glycinamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[1-(S-methylsulfonimidoyl)azetidin-3-yl]oxy}-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[1-(S-methylsulfonimidoyl)pyrrolidin-3-yl]amino}-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({2-[2-(S-methylsulfonimidoyl)ethoxy]ethyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({1-[(S-methylsulfonimidoyl)acetyl]azetidin-3-yl}oxy)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{2-[(S-methylsulfonimidoyl)amino]ethoxy}-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({4-[(S-methylsulfonimidoyl)amino]butyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({2-[methyl(S-methylsulfonimidoyl)amino]ethyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({2-hydroxy-3-[(S-methylsulfonimidoyl)amino]propyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({2-[N-(2-hydroxyethyl)-S-methylsulfonimidoyl]ethyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({[(2S)-4-(S-methylsulfonimidoyl)morpholin-2-yl]methyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({cis-3-[(S-methylsulfonimidoyl)amino]cyclobutyl}oxy)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({[(2R)-4-(S-methylsulfonimidoyl)morpholin-2-yl]methyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

4-{[3-(S-aminosulfonimidoyl)propyl]amino}-N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide,

4-({2-[(N,S-dimethylsulfonimidoyl)amino]ethyl}amino)-N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide,

4-{[2-(S-cyclopropylsulfonimidoyl)ethyl]amino}-N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({[1-(S-methylsulfonimidoyl)azetidin-3-yl]methyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[trans-3-(S-methylsulfonimidoyl)cyclobutyl]amino}-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[6-(S-methylsulfonimidoyl)spiro[3.3]heptan-2-yl]amino}-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[2-(S-methylsulfonimidoyl)-2-azaspiro[3.3]heptan-6-yl]amino}-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[2-hydroxy-4-(S-methylsulfonimidoyl)butyl]amino}-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({3-[(S-methylsulfonimidoyl)methyl]bicyclo[1.1.1]pentan-1-yl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-4-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-({2-[S-(2-hydroxypropyl)sulfonimidoyl]ethyl}amino)-1,2,5-oxadiazole-3-carboximidamide,

N-[(7S)-5-fluorobicyclo[4.2.0]octa-1,3,5-trien-7-yl]-N′-hydroxy-4-{[2-(S-methylsulfonimidoyl)ethyl]amino}-1,2,5-oxadiazole-3-carboximidamide,

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-(N-methoxy-S-methylsulfonimidoyl)ethyl)amino)-1,2,5-oxadiazole-3-carboximidamide, and

N—((S)-4-fluorobicyclo[4.2.0]octa-1(6),2,4-trien-7-yl)-N′-hydroxy-4-((2-(N-methoxy-R-methylsulfonimidoyl)ethyl)amino)-1,2,5-oxadiazole-3-carboximidamide.

17. A composition which comprises an inert carrier and a compound of claim 1 or a pharmaceutically acceptable salt thereof.

18. A method for treating an IDO-associated disease or disorder in a mammalian subject which comprises administering to the subject an effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof,

wherein the IDO-associated disease or disorder is a cancer selected from colon cancer, breast cancer, prostate cancer, lung cancer, brain cancer, ovarian cancer, head and neck cancer and melanoma.

19. A method for treating an IDO-associated disease or disorder in a mammalian subject which comprises administering to the subject an effective amount of a compound of claim 1 , or a pharmaceutically acceptable salt thereof, in combination with another anti-cancer agent;

wherein the IDO-associated disease or disorder is a cancer selected from colon cancer, breast cancer, prostate cancer, lung cancer, brain cancer, ovarian cancer, head and neck cancer and melanoma.

20. The method of claim 19 , wherein the IDO-associated disease or disorder is a cancer selected from breast cancer, lung cancer, head and neck cancer and melanoma.