Cyclic dinucleotides as anticancer agents

A compound of the formula

• wherein
• each X is independently O or S;
• X1, X2, X3 and X4 are each independently O or NH;
• R1 and R2 are independently
• with the proviso that one of R1 and R2 must be
• Z1 is N or CRa;
• Z2 is NRb;
• Ra is H, halogen, C1-6 alkyl substituted with 0-6 R5, C3-6 cycloalkyl substituted with 0-6 R5, CN, NO2, OH, ORa1, SR1, —C(O)NRa1Ra1, —COORa1, —OC(O)Ra1, —OC(O)NRa1Ra1, —NRa1Ra1, —NRa1 C(O)Ra1,—NRa1COORa1, —NRa1C(O)NRa1Ra1, —NRa1S(O)2Ra1, —NRa1S(O)2NRa1Ra1, —S(O)Ra1, —S(O)NRa1Ra1, —S(O)2Ra1 or S(O)2NRa1Ra1;
• Rb is H, C1-6 alkyl substituted with 0-6 R5, C3-6 cycloalkyl substituted with 0-6 R5, —C(O)Ra1, —C(O)NRa1Ra1, —S(O)2Ra1 or S(O)2NRa1Ra1;
• Ra1 is H or C1-3 alkyl;
• R3 and R4 are independently H, CH3, halogen, NH2 or OH;
• R3a and R4a are independently H, CH3, halogen, NH2 or OH;
• or
• R3 and R3a or R4 and R4a may independently be taken together to form a 3-4 membered carbocycle;
• or
• R3 and R3a or R4 and R4a may independently be taken together to form a C═CH2 substituent;
• R5 is H, halogen, C1-3 alkyl, CN, NO2, OH, OR, SRa1, —C(O)NRa1Ra1, —COORa1, —OC(O)Ra1, —OC(O)NRa1Ra1, —NRa1Ra1, —NRa1 C(O)Ra1, —NRa1COORa1, —NRa1C(O)NRa1Ra1, —NRa1S(O)2Ra1, —NRa1S(O)2NRa1Ra1, —S(O)Ra1, —S(O)NRa1Ra1, —S(O)2Ra1 or S(O)2NRa1Ra1;
• R5a is H or C1-3 alkyl;
• R6 is H, halogen, C1-3 alkyl, CN, NO2, OH, ORa1, SRa1, —C(O)NRa1Ra1, —COORa1, —OC(O)Ra1, —OC(O)NRa1Ra1, —NRa1Ra1, —NRa1 C(O)Ra1, —NRa1COORa1, —NRa1C(O)NRa1Ra1, —NRa1S(O)2Ra1, —NRa1S(O)2NRa1Ra1, —S(O)Ra1, —S(O)NRa1Ra1, —S(O)2Ra1 or S(O)2NRa1Ra1;
• R8 is H, halogen, C1-3 alkyl, CN, NO2, OH, ORa1, SRa1, —C(O)NRa1Ra1, —COORa1, —OC(O)Ra1, —OC(O)NRa1Ra1, —NRa1, —NRa1 C(O)Ra1, —NRa1COORa1, —NRa1C(O)NRa1Ra1, —NRa1S(O)2Ra1, —NRa1S(O)2NRa1Ra1, —S(O)Ra1, —S(O)NRa1Ra1, —S(O)2Ra1 or S(O)2NRa1Ra1;
• or a pharmaceutically acceptable salt, tautomer or stereoisomer thereof.