A compound of Formula (Ib) or a pharmaceutically acceptable salt thereof: wherein X 2 is N, or CH; X 3 is CR 8; X 4 is C; Y 1 is CH or N; Y 3 is CR 11; R 6 is pyridinyl, pyrazolyl, pyrimidinyl, or furyl, each of which is optionally substituted with one or more -Q 2 -T 2, wherein Q 2 is a bond or C 1 -C 3 alkyl linker each optionally substituted with halo, cyano, hydroxyl or C 1 -C 6 alkoxy, and T 2 is piperazinyl; each R 7 independently is -Q 4 -T 4, in which Q 4 is a bond, C 1 -C 4 alkyl linker, or C 2 -C 4 alkenyl linker, each linker optionally substituted with halo, cyano, hydroxyl or C 1 -C 6 alkoxy, and T 4 is H, halo, cyano, NR g R h, -OR g, -C R g, -C OR g, -C NR g R h, -C NR g OR h, -NR g C R h, -S 2 R g, or R S6, in which each of R g and R h, independently is H or R S7, each of R S6 and R S7, independently is C 1 -C 6 alkyl, C 3 -C 8 cycloalkyl, C 6 -C 10 aryl, 4 to 7-membered heterocycloalkyl, or 5 to 6-membered heteroaryl, and each of R S6 and R S7 is optionally substituted with one or more -Q 5 -T 5, wherein Q 5 is a bond, C, or C 1 -C 3 alkyl linker, and T 5 is H, halo, C 1 -C 6 alkyl, hydroxyl, cyano, C 1 -C 6 alkoxyl, amino, mono-C 1 -C 6 alkylamino, di-C 1 -C 6 alkylamino, C 3 -C 8 cycloalkyl, C 6 -C 10 aryl, 4 to 7-membered heterocycloalkyl, or 5 to 6-membered heteroaryl and T 5 is optionally substituted with one or more substituents selected from the group consisting of halo, C 1 -C 6 alkyl, hydroxyl, cyano, C 1 -C 6 alkoxyl, amino, mono-C 1 -C 6 alkylamino, di-C 1 -C 6 alkylamino, C 3 -C 8 cycloalkyl, C 6 -C 10 aryl, 4 to 7-membered heterocycloalkyl, and 5 to 6-membered heteroaryl except when T 5 is H, halo, hydroxyl, or cyano; or -Q 5 -T 5 is oxo; provided that -Q 4 -T 4 is not H; and each of R 8 and R 11, independently, is H, halo, hydroxyl, COOH, cyano, Rss, ORss, or COORss, in which R S8 is C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, amino, mono-C 1 -C 6 alkylamino, or di-C 1 -C 6 alkylamino, and R S8 is optionally substituted with one or more substituents selected from the group consisting of halo, hydroxyl, COOH, C O-C 1 -C 6 alkyl, cyano, C 1 -C 6 alkoxyl, amino, mono-C 1 -C 6 alkylamino, and di-C 1 -C 6 alkylamino. X 2 is N, or CH; X 3 is CR 8; X 4 is C; Y 1 is CH or N; Y 3 is CR 11; R 6 is pyridinyl, pyrazolyl, pyrimidinyl, or furyl, each of which is optionally substituted with one or more -Q 2 -T 2, wherein Q 2 is a bond or C 1 -C 3 alkyl linker each optionally substituted with halo, cyano, hydroxyl or C 1 -C 6 alkoxy, and T 2 is piperazinyl; each R 7 independently is -Q 4 -T 4, in which Q 4 is a bond, C 1 -C 4 alkyl linker, or C 2 -C 4 alkenyl linker, each linker optionally substituted with halo, cyano, hydroxyl or C 1 -C 6 alkoxy, and T 4 is H, halo, cyano, NR g R h, -OR g, -C R g, -C OR g, -C NR g R h, -C NR g OR h, -NR g C R h, -S 2 R g, or R S6, in which each of R g and R h, independently is H or R S7, each of R S6 and R S7, independently is C 1 -C 6 alkyl, C 3 -C 8 cycloalkyl, C 6 -C 10 aryl, 4 to 7-membered heterocycloalkyl, or 5 to 6-membered heteroaryl, and each of R S6 and R S7 is optionally substituted with one or more -Q 5 -T 5, wherein Q 5 is a bond, C, or C 1 -C 3 alkyl linker, and T 5 is H, halo, C 1 -C 6 alkyl, hydroxyl, cyano, C 1 -C 6 alkoxyl, amino, mono-C 1 -C 6 alkylamino, di-C 1 -C 6 alkylamino, C 3 -C 8 cycloalkyl, C 6 -C 10 aryl, 4 to 7-membered heterocycloalkyl, or 5 to 6-membered heteroaryl and T 5 is optionally substituted with one or more substituents selected from the group consisting of halo, C 1 -C 6 alkyl, hydroxyl, cyano, C 1 -C 6 alkoxyl, amino, mono-C 1 -C 6 alkylamino, di-C 1 -C 6 alkylamino, C 3 -C 8 cycloalkyl, C 6 -C 10 aryl, 4 to 7-membered heterocycloalkyl, and 5 to 6-membered heteroaryl except when T 5 is H, halo, hydroxyl, or cyano; or -Q 5 -T 5 is oxo; provided that -Q 4 -T 4 is not H; and each of R 8 and R 11, independently, is H, halo, hydroxyl, COOH, cyano, Rss, ORss, or COORss, in which R S8 is C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, amino, mono-C 1 -C 6 alkylamino, or di-C 1 -C 6 alkylamino, and R S8 is optionally substituted with one or more substituents selected from the group consisting of halo, hydroxyl, COOH, C O-C 1 -C 6 alkyl, cyano, C 1 -C 6 alkoxyl, amino, mono-C 1 -C 6 alkylamino, and di-C 1 -C 6 alkylamino.