Compounds useful as inhibitors of indoleamine 2,3-dioxygenase

A compound of formula I-A:

• or a pharmaceutically acceptable salt or prodrug thereof, wherein:
• n is 0-4;
• X is halo;
• Z1, Z2, and Z3 are CH or N;
• R1 is independently selected from halo;
• —CN;
• QX;
• or a C1-10aliphatic chain wherein up to four methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —S—, —C(O)—, S(O)—, or —S(O)2—;
• R1 is optionally substituted with 0-5 J1 groups;
• QX is a 3-7 membered monocyclic fully saturated, partially unsaturated, or aromatic ring containing 0-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur;
• J1 is independently selected from halo;
• —CN;
• QY;
• or a C1-6aliphatic chain wherein up to three methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —S—, —C(O)—, S(O)—, or —S(O)2—;
• J1 is optionally substituted with 0-5 J2 groups;
• or
• two occurrences of J1 on the same atom, together with the atom to which they are attached, form a 3-6 membered non-aromatic monocyclic ring;
• the ring formed by two occurrences of J1 on the same atom is optionally substituted with 0-3 J2A groups;
• or
• two occurrences of J1, together with QX, form a bridged ring system;
• QY is independently selected from a 3-7 membered monocyclic fully saturated, partially unsaturated, or aromatic ring containing 0-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur;
• or an 8-12 membered bicyclic fully saturated, partially unsaturated, or aromatic ring containing 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur;
• J2 is independently selected from halo;
• ═O;
• —CN;
• a 3-6 membered aromatic or non-aromatic ring containing 0-3 heteroatoms selected from oxygen, nitrogen, or sulfur;
• or C1-4aliphatic chain wherein up to two methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —S—, —C(O)—, S(O)—, or —S(O)2—;
• J2 is optionally substituted with 0-5 J3 groups;
• or
• two occurrences of J2, together with the atom or atoms to which they are attached, form a 3-6 membered aromatic or non-aromatic monocyclic ring;
• the ring formed by two occurrences of J2 is optionally substituted with 0-3 J3A groups;
• or
• two occurrences of J2, together with QY, form a bridged ring system;
• J2A is independently selected from halo or a C1-4aliphatic chain wherein up to two methylene units of the aliphatic chain are optionally replaced with —O—, —NR—, —S—, —S(O)—, —S(O)2, or —C(O);
• J3 and J3A are independently selected from halo or C1-4alkyl;
• and
• R is independently selected from H or C1-6aliphatic.