Arginase inhibitors and methods of use

A compound of formula IA:

• or a stereoisomer, lactone prodrug, or pharmaceutically-acceptable salt thereof, wherein:
• said dashed line represents an optional double bond;
• Z is
• X1 is —(CH2)—;
• X2 is —(CH2)—;
• X3 is —(CH2)—;
• X4 is —(CH2)—;
• R1 is ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hydroxy(C1-C4)alkyl, (C2-C4)alkenyl, (C6-C10)aryl(C1-C4)alkyl, (C4-C10)heteroaryl(C1-C4)alkyl, (C2-C10)heterocycloalkyl(C1-C4)alkyl, (C6-C10)aryloxy(C1-C4)alkyl, (C4-C10)heteroaryloxy(C1-C4)alkyl, —Rx—C(═O)—Ry, —Rx—O—Rz, —Rx—O—Rx—NR3R5, —Rx—NR3R5 or (C1-C4)alkyl-B—(OH)2;
• each Rx is independently (C1-C4)alkylenyl;
• Ry is (C1-C4)alkyl, hydroxyl, (C1-C6)alkoxy or (C6-C10)aryl;
• Rz is (C1-C4)alkyl;
• R3 is H;
• R4 is (C1-C4)alkyl or H;
• and
• R5 is —C(═O)—(C1-C4)alkyl, —C(═O)—(C6-C10)aryl, —SO2—(C6-C10)aryl, —C(═O)NR3R4 or —C(═O)—NR4(C6-C10)aryl.