Inhibitors of indoleamine 2,3-dioxygenase

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof wherein,
• R1 is selected from the group consisting of:
• R11 is H, halogen, (1-2C)alkyl or (1-2C)alkoxy, all alkyl and alkoxy groups optionally being substituted with one or more halogen;
• R12 is halogen, (1-2C)alkyl (2-3C)alkenyl, (2-3C)alkynyl, (1-2C)alkoxy, (3-8C)cycloalkyl, cyano or nitro all alkyl, alkoxy and cycloalkyl groups optionally being substituted with one or more halogen;
• R13 is H, halogen, (1-2C)alkyl or (1-2C)alkoxy, all alkyl and alkoxy groups optionally being substituted with one or more halogen;
• R14 is H, halogen, (1-2C)alkyl or (1-2C)alkoxy, all alkyl and alkoxy groups optionally being substituted with one or more halogen;
• R15 is H, halogen, (1-2C)alkyl or (1-2C)alkoxy, all alkyl and alkoxy groups optionally being substituted with one or more halogen;
• R2 is selected from the group consisting of:
• a) hydrogen,
• b) (1-6C)alkyl,
• wherein (1-6C)alkyl optionally can be substituted,
• R3 is selected from the group consisting of:
• a) (6-10C)aryl,
• b) (1-9C)heteroaryl,
• c) (3-8C)cycloalkyl,
• d) (2-7C)heterocycloalkyl,
• e) (1-6C)alkyl,
• f) (1-6)alkylamino,
• g) (3-6C)cycloalkylamino
• h) (6-10C)arylamino,
• i) (1-9C)heteroarylamino,
• j) (2-7C)heterocycloalkylamino,
• wherein all groups optionally can be substituted,
• R4 is selected from the group consisting of:
• a) hydrogen,
• b) (1-6C)alkyl,
• wherein (1-6C)alkyl optionally can be substituted,
• R5 is selected from the group consisting of:
• a) hydrogen,
• b) (1-6C)alkyl,
• wherein (1-6C)alkyl optionally can be substituted,
• A is selected from CH(Ra), C(O), S(O) or SO2,
• Ra is selected from the group consisting of:
• a) hydrogen,
• b) (1-6C)alkyl,
• wherein (1-6C)alkyl optionally can be substituted with fluorine or hydroxyl.