A compound represented by the following structural formula: or a pharmaceutically acceptable salt thereof, wherein: the thiazole ring is optionally substituted with F or Cl; Cy is (C 3 -C 7)cycloalkyl, bridged (C 6 -C 12) cycloalkyl, or a 4-10 membered heterocyclic ring, each of which is optionally substituted with one or more groups selected from the group consisting of halogen, OH, (C 1 -C 4)alkyl, and (C 1 -C 4)alkoxy; when X 5 is connected with a nitrogen ring atom of Cy, X 5 is absent; when X 5 is connected with a carbon ring atom of Cy, X 5 is NR a or O; X 6 is NR a or O; R 1 is (C 1 -C 5)alkyl optionally substituted with OH; R 3 is (C 1 -C 5)alkyl, -CH 2 -phenyl, (C 3 -C 7)cycloalkyl, -CH 2 -(C 3 -C 7)cycloalkyl, -CH 2 -monocyclic 3-7 membered heterocyclic ring, or monocyclic 3-7 membered heterocyclic ring, wherein the (C 1 -C 5)alkyl, (C 3 -C 7)cycloalkyl, phenyl or monocyclic 3-7 membered heterocyclic ring represented by R 3 or in the group represented by R 3 is optionally substituted with one or more groups selected from the group consisting of halogen, OH, (C 1 -C 4)alkyl, halomethyl, halomethoxy, CN, and (C 1 -C 4)alkoxy; R 2 is -NR a C O(C 1 -C 4)alkyl, -NR a C NR a (C 1 -C 4)alkyl, -NR a C O(C 2 -C 4)alkenyl, -NR a C NR a (C 2 -C 4)alkenyl, -NR a C O-(C 3 -C 6)cycloalkyl, -NR a C NR a -(C 3 -C 7)cycloalkyl, -NR a C O-phenyl, -NR a C NR a -phenyl, -NR a C O-monocyclic 3-7 membered heterocyclic ring, -NR a C NR a -monocyclic 3-7 membered heterocyclic ring, -NR a C O-monocyclic 5-6 membered heteroaromatic ring, or -NR a C NR a -monocyclic 5-6 membered heteroaromatic ring, wherein the (C 1 -C 4)alkyl and the (C 2 -C 4)alkenyl in the group represented by R 2 are each optionally and independently substituted with one or more groups selected from the group consisting of halogen, N 3, OR a, NR a R a, (C 3 -C 6)cycloalkyl, phenyl, a monocyclic 3-7 membered heterocyclic ring, and a monocyclic 5-6 membered heteroaromatic ring; wherein the (C 3 -C 7)cycloalkyl in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of halogen, CH 3, =O, OR a, and NR a R a; wherein the phenyl in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of halogen, CH 3, halomethyl, halomethoxy, CN, OR a, and N 3; wherein the heterocyclic ring in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of =O, halogen, OR a, CH 3, halomethyl, and halomethoxy; wherein the heteroaromatic ring in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of halogen, CN, CH 3, halomethyl, halomethoxy, OR a, and NR a R a; and each R a is independently H or CH 3. the thiazole ring is optionally substituted with F or Cl; Cy is (C 3 -C 7)cycloalkyl, bridged (C 6 -C 12) cycloalkyl, or a 4-10 membered heterocyclic ring, each of which is optionally substituted with one or more groups selected from the group consisting of halogen, OH, (C 1 -C 4)alkyl, and (C 1 -C 4)alkoxy; when X 5 is connected with a nitrogen ring atom of Cy, X 5 is absent; when X 5 is connected with a carbon ring atom of Cy, X 5 is NR a or O; X 6 is NR a or O; R 1 is (C 1 -C 5)alkyl optionally substituted with OH; R 3 is (C 1 -C 5)alkyl, -CH 2 -phenyl, (C 3 -C 7)cycloalkyl, -CH 2 -(C 3 -C 7)cycloalkyl, -CH 2 -monocyclic 3-7 membered heterocyclic ring, or monocyclic 3-7 membered heterocyclic ring, wherein the (C 1 -C 5)alkyl, (C 3 -C 7)cycloalkyl, phenyl or monocyclic 3-7 membered heterocyclic ring represented by R 3 or in the group represented by R 3 is optionally substituted with one or more groups selected from the group consisting of halogen, OH, (C 1 -C 4)alkyl, halomethyl, halomethoxy, CN, and (C 1 -C 4)alkoxy; R 2 is -NR a C O(C 1 -C 4)alkyl, -NR a C NR a (C 1 -C 4)alkyl, -NR a C O(C 2 -C 4)alkenyl, -NR a C NR a (C 2 -C 4)alkenyl, -NR a C O-(C 3 -C 6)cycloalkyl, -NR a C NR a -(C 3 -C 7)cycloalkyl, -NR a C O-phenyl, -NR a C NR a -phenyl, -NR a C O-monocyclic 3-7 membered heterocyclic ring, -NR a C NR a -monocyclic 3-7 membered heterocyclic ring, -NR a C O-monocyclic 5-6 membered heteroaromatic ring, or -NR a C NR a -monocyclic 5-6 membered heteroaromatic ring, wherein the (C 1 -C 4)alkyl and the (C 2 -C 4)alkenyl in the group represented by R 2 are each optionally and independently substituted with one or more groups selected from the group consisting of halogen, N 3, OR a, NR a R a, (C 3 -C 6)cycloalkyl, phenyl, a monocyclic 3-7 membered heterocyclic ring, and a monocyclic 5-6 membered heteroaromatic ring; wherein the (C 3 -C 7)cycloalkyl in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of halogen, CH 3, =O, OR a, and NR a R a; wherein the phenyl in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of halogen, CH 3, halomethyl, halomethoxy, CN, OR a, and N 3; wherein the heterocyclic ring in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of =O, halogen, OR a, CH 3, halomethyl, and halomethoxy; wherein the heteroaromatic ring in the group represented by R 2 is optionally substituted with one or more groups selected from the group consisting of halogen, CN, CH 3, halomethyl, halomethoxy, OR a, and NR a R a; and each R a is independently H or CH 3.