Tricyclic heterocycles as bet protein inhibitors

1. A compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein:

X is N;

Y is CR 5 ;

L is C 1-6 alkylene, optionally substituted by 1, 2, or 3 substituents independently selected from F, Cl, OH, C 1-4 alkoxy, CF 3 , and CN;

Cy is C 6-10 aryl, C 3-10 cycloalkyl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, each of which is optionally substituted by 1, 2, or 3 R Cy ;

R 1 is H, C 1-6 alkyl, cyclopropyl, cyclobutyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, or C 1-6 hydroxyalkyl;

R 2 and R 3 are each independently selected from H, halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, CN, NO 2 , OR a , SR a , C(O)R b , C(O)NR c R d , C(O)OR a , OC(O)R b , OC(O)NR c R d , NR c R d , NR c C(O)R b , NR c C(O)OR a , NR c C(O)NR c R d , C(═NR e )R b , C(═NR e )NR c R d , NR c C(═NR e )NR c R d , NR c S(O)R b , NR c S(O) 2 R b , NR c S(O) 2 NR c R d , S(O)R b , S(O)NR c R d , S(O) 2 R b , and S(O) 2 NR c R d ; wherein said C 1-6 alkyl, C 2-6 alkenyl, and C 2-6 alkynyl are each optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from halo, CN, NO 2 , OR a , SR a , C(O)R b , C(O)NR c R d , C(O)OR a , OC(O)R b , OC(O)NR c R d , C(═NR e )NR c R d , NR c C(═NR e )NR c R d , NR c R d , NR c C(O)R b , NR c C(O)OR a , NR c C(O)NR c R d , NR c S(O)R b , NR c S(O) 2 R b , NR c S(O) 2 NR c R d , S(O)R b , S(O)NR c R d , S(O) 2 R b , and S(O) 2 NR c R d ;

R 5 is H, halo, C 1-4 alkyl, C 2-4 alkenyl, C 1-4 haloalkyl, OR a2 , C(O)R b2 , C(O)NR c2 R d2 , C(O)OR a2 , NR c2 R d2 , NR c2 C(O)R b2 , NR c2 C(O)OR a2 , NR c2 C(O)NR c2 R d2 , NR c2 S(O)R b2 , NR c2 S(O) 2 R b2 , NR c2 S(O) 2 NR c2 R d2 , S(O)R b2 , S(O)NR c2 R d2 , S(O) 2 R b2 , or S(O) 2 NR c2 R d2 ;

each R Cy is independently selected from halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, C 6-10 aryl, C 3-10 cycloalkyl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 6-10 aryl-C 1-4 alkyl, C 3-10 cycloalkyl-C 1-4 alkyl, (5-10 membered heteroaryl)-C 1-4 alkyl, (4-10 membered heterocycloalkyl)-C 1-4 alkyl, CN, NO 2 , OR a3 , SR a3 , C(O)R b3 , C(O)NR c3 R d3 , C(O)OR a3 , OC(O)R b3 , OC(O)NR c3 R d3 , NR c3 R d3 , NR c3 C(O)R b3 , NR c3 C(O)OR a3 , NR c3 C(O)NR c3 R d3 , C(═NR e3 )R b3 , C(═NR e3 )NR c3 R d3 , NR c3 C(═NR e3 )NR c3 R d3 , NR c3 S(O)R b3 , NR c3 S(O) 2 R b3 , NR c3 S(O) 2 NR c3 R d3 , S(O)R b3 , S(O)NR c3 R d3 , S(O) 2 R b3 , and S(O) 2 NR c3 R d3 ; wherein said C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 6-10 aryl, C 3-10 cycloalkyl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 6-10 aryl-C 1-4 alkyl, C 3-10 cycloalkyl-C 1-4 alkyl, (5-10 membered heteroaryl)-C 1-4 alkyl, and (4-10 membered heterocycloalkyl)-C 1-4 alkyl are each optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, CN, NO 2 , OR a3 , SR a3 , C(O)R b3 , C(O)NR c3 R d3 , C(O)OR a3 , OC(O)R b3 , OC(O)NR c3 R d3 , C(═NR e3 )NR c3 R d3 , NR c3 C(═NR e3 )NR c3 R d3 , NR c3 R d3 , NR c3 C(O)R b3 , NR c3 C(O)OR a3 , NR c3 C(O)NR c3 R d3 , NR c3 S(O)R b3 , NR c4 S(O) 2 R b3 , NR c3 S(O) 2 NR c3 R d3 , S(O)R b3 , S(O)NR c3 R d3 , S(O) 2 R b3 , and S(O) 2 NR c3 R d3 ;

each Cy 1 is independently selected from C 6-10 aryl, C 3-10 cycloalkyl, 5-10 membered heteroaryl, and 4-10 membered heterocycloalkyl, each of which is optionally substituted by 1, 2, 3, 4, or 5 substituents independently selected from halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, CN, NO 2 , OR a5 , SR a5 , C(O)R b5 , C(O)NR c5 R d5 , C(O)OR a5 , OC(O)R b5 , OC(O)NR c5 R d5 , NR c5 R d5 , NR c5 C(O)R b5 , NR c5 C(O)OR a5 , NR c5 C(O)NR c5 R d5 , C(═NR e5 )R b5 , C(═NR e5 )NR c5 R d5 , NR c5 C(═NR e5 )NR c5 R d5 , NR c5 S(O)R b5 , NR c5 S(O) 2 R b5 , NR c5 S(O) 2 NR c5 R d5 , S(O)R b5 , S(O)NR c5 R d5 , S(O) 2 R b5 , and S(O) 2 NR c5 R d5 ; wherein said C 1-6 alkyl, C 2-6 alkenyl, and C 2-6 alkynyl are each optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from halo, C 1-6 haloalkyl, CN, NO 2 , OR a5 , SR a5 , C(O)R b5 , C(O)NR c5 R d5 , C(O)OR a5 , OC(O)R b5 , OC(O)NR c5 R d5 , C(═NR e5 )NR c5 R d5 , NR c5 C(═NR e5 )NR c5 R d5 , NR c5 R d5 , NR c5 C(O)R b5 , NR c5 C(O)OR a5 , NR c5 C(O)NR c5 R d5 , NR c5 S(O)R b5 , NR c5 S(O) 2 R b5 , NR c5 S(O) 2 NR c5 R d5 , S(O)R b5 , S(O)NR c5 R d5 , S(O) 2 R b5 , and S(O) 2 NR c5 R d5 ;

each R a , R b , R c , R d , R a2 , R b2 , R c2 , R d2 , R a3 , R b3 , R c3 , R d3 , R c4 , —R a5 , R b5 , R c5 , and R d5 is independently selected from H, C 1-6 alkyl, C 1-4 haloalkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 6-10 aryl, C 3-10 cycloalkyl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 6-10 aryl-C 1-6 alkyl, C 3-10 cycloalky-C 1-6 alkyl, (5-10 membered heteroaryl)-C 1-6 alkyl, and (4-10 membered heterocycloalkyl)-C 1-6 alkyl, wherein said C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 6-10 aryl, C 3-10 cycloalkyl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 6-10 aryl-C 1-6 alkyl, C 3-10 cycloalky-C 1-6 alkyl, (5-10 membered heteroaryl)-C 1-6 alkyl, and (4-10 membered heterocycloalkyl)-C 1-6 alkyl is optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from C 1-4 alkyl, C 1-4 haloalkyl, halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 ;

or any R c and R d together with the N atom to which they are attached form a 4-, 5-, 6-, or 7-membered heterocycloalkyl group optionally substituted with 1, 2, or 3 substituents independently selected from C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, 5-6 membered heteroaryl, C 1-6 haloalkyl, halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 , wherein said C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, and 5-6 membered heteroaryl are optionally substituted by 1, 2, or 3 substituents independently selected from halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 ;

or any R c2 and R d2 together with the N atom to which they are attached form a 4-, 5-, 6-, or 7-membered heterocycloalkyl group optionally substituted with 1, 2, or 3 substituents independently selected from C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, 5-6 membered heteroaryl, C 1-6 haloalkyl, halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 , C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 , wherein said C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, and 5-6 membered heteroaryl are optionally substituted by 1, 2, or 3 substituents independently selected from halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 ;

or any R c3 and R d3 together with the N atom to which they are attached form a 4-, 5-, 6-, or 7-membered heterocycloalkyl group optionally substituted with 1, 2, or 3 substituents independently selected from C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, 5-6 membered heteroaryl, C 1-6 haloalkyl, halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 , C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 , wherein said C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, and 5-6 membered heteroaryl are optionally substituted by 1, 2, or 3 substituents independently selected from halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 ;

or any R c5 and R d5 together with the N atom to which they are attached form a 4-, 5-, 6-, or 7-membered heterocycloalkyl group optionally substituted with 1, 2, or 3 substituents independently selected from C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, 5-6 membered heteroaryl, C 1-6 haloalkyl, halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 , C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 , wherein said C 1-6 alkyl, C 3-7 cycloalkyl, 4-7 membered heterocycloalkyl, C 6-10 aryl, and 5-6 membered heteroaryl are optionally substituted by 1, 2, or 3 substituents independently selected from halo, CN, OR a6 , SR a6 , C(O)R b6 , C(O)NR c6 R d6 , C(O)OR a6 , OC(O)R b6 , OC(O)NR c6 R d6 , NR c6 R d6 , NR c6 C(O)R b6 , NR c6 C(O)NR c6 R d6 , NR c6 C(O)OR a6 , C(═NR e6 )NR c6 R d6 , NR c6 C(═NR e6 )NR c6 R d6 , S(O)R b6 , S(O)NR c6 R d6 , S(O) 2 R b6 , NR c6 S(O) 2 R b6 , NR c6 S(O) 2 NR c6 R d6 , and S(O) 2 NR c6 R d6 ;

each R e , R e1 , R w3 , and R e5 is independently selected from H, C 1-4 alkyl, CN, OR a6 , SR b6 , S(O) 2 R b6 , C(O)R b6 , S(O) 2 NR c6 R d6 , and C(O)NR c6 R d6 ,

each R a6 , R b6 , R c6 , and R d6 is independently selected from H, C 1-4 alkyl, C 1-4 haloalkyl, C 2-4 alkenyl, and C 2-4 alkynyl, wherein said C 1-4 alkyl, C 2-4 alkenyl, and C 2-4 alkynyl, is optionally substituted with 1, 2, or 3 substituents independently selected from OH, CN, amino, halo, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, C 1-4 alkylamino, di(C 1-4 alkyl)amino, C 1-4 haloalkyl, and C 1-4 haloalkoxy;

or any R c6 and R d6 together with the N atom to which they are attached form a 4-, 5-, 6-, or 7-membered heterocycloalkyl group optionally substituted with 1, 2, or 3 substituents independently selected from OH, CN, amino, halo, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio, C 1-4 alkylamino, di(C 1-4 alkyl)amino, C 1-4 haloalkyl, and C 1-4 haloalkoxy; and

each R e6 is independently selected from H, C 1-4 alkyl, and CN.

2. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein L is CH 2 , —CH(CH 2 OH)—, or —CH((CH 2 ) 3 CH 3 )—.

3. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein L is CH 2 .

4. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein Cy is C 6-10 aryl, C 3-10 cycloalkyl, or 5-10 membered heteroaryl, each of which is optionally substituted by 1, 2, or 3 R Cy .

5. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein Cy is phenyl, cyclopentyl, quinolinyl, or pyridyl, each of which is optionally substituted by 1, 2, or 3 R Cy .

6. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein Cy is phenyl or pyridyl, each of which is optionally substituted by 1, 2, or 3 R Cy .

7. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein Cy is phenyl optionally substituted by 1, 2, or 3 R Cy .

8. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein each R Cy is independently selected from halo, C 1-6 alkyl, C 1-4 haloalkyl, (4-10 membered heterocycloalkyl)-C 1-4 alkyl, CN, OR a3 , C(O)NR c3 R d3 , NR c3 C(O)R b3 , and NR c3 C(O)NR c3 R d3 wherein said C 1-6 alkyl and (4-10 membered heterocycloalkyl)-C 1-4 alkyl are each optionally substituted with 1, 2, or 3 substituents independently selected from halo, C 1-6 alkyl, OR a3 , and NR c3 R d3 .

9. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein each R Cy is independently selected from halo, C 1-6 alkyl, (4-10 membered heterocycloalkyl)-C 1-4 alkyl, CN, OR a3 , C(O)NR c3 R d3 , NR c3 C(O)R b3 , and NR c3 C(O)NR c3 R d3 wherein said C 1-6 alkyl and (4-10 membered heterocycloalkyl)-C 1-4 alkyl are each optionally substituted with 1, 2, or 3 substituents independently selected from C 1-6 alkyl, OR a3 , and NR c3 R d3 .

10. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein each R Cy is independently selected from fluoro, chloro, methyl, cyano, hydroxy, methoxy, aminocarbonyl, methylcarbonylamino, methylaminocarbonyl, ethylaminocarbonyl, azetidinylmethyl, pyrrolidinylmethyl, piperidinylmethyl, piperazinylmethyl, morpholinomethyl, ureido, and ethylureido, wherein said methyl, azetidinylmethyl, pyrrolidinylmethyl, piperidinylmethyl, piperazinylmethyl, and morpholinomethyl are each optionally substituted with 1, 2, or 3 substituents independently selected from fluoro, methyl, hydroxy, methoxy, methylamino, ethylamino, dimethylamino, hydroxycyclobutylamino, hydroxyethyl(methyl)amino, and hydroxyethylamino.

11. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is H or C 1-6 alkyl.

12. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is C 1-6 alkyl.

13. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is methyl.

14. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 2 and R 3 are both H.

15. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 3 is H.

16. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 2 is H, OR a , NR c R d , NR c C(O)R b , NR c C(O)OR a , NR c C(O)NR c R d , or NR c S(O) 2 R b .

17. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 2 is H, —OH, —NHC(═O)OCH 3 , —NHC(═O)CH 3 —, NHC(═O)CH 2 CH 3 , —NHC(═O)CH 2 CH 2 CH 3 , —NHC(═O)CH(CH 3 ) 2 , —NHS(═O) 2 CH 3 , —OCH 3 , —NHCH 3 , —NHCH 2 CH 3 , —NHCH(CH 3 ) 2 , —NHCH 2 CH 2 CH 3 , —NH-(phenyl), —NH-(imidazolyl), —NH-(pyridyl), —NHCH 2 CH 2 NH 2 , —NHCH 2 CH 2 CH 2 NH 2 , —NHC(═O)NH 2 , —NHC(═O)NH(CH 3 ), —NHC(═O)N(CH 3 ) 2 , —NHC(═O)NHCH(CH 3 ) 2 , —NHC(═O)NHCH 2 CH 3 , —NHC(═O)O-(t-butyl), —NH-(hydroxycyclobutyl), —NHCH 2 CH 2 N(CH 3 ) 2 , —NHCH 2 CH 2 CH 2 N(CH 3 ) 2 , —NH-(t-butyloxycarbonylazetidinyl), —NH-(t-butyloxycarbonylazetidinylmethyl), —NH-(t-butyloxycarbonylpiperidinylmethyl), —NH-(cyclobutylmethyl), —NH-(cyclohexyl), —NH-(cyclopropylmethyl), —NH-(8-azabicyclo[3,2,1]octan-3-yl), —NH-(dimethylpiperidinyl), —NH-(methylpiperidinyl), —NH-(piperidinyl), —NH-(methylpiperidinyl), —NH-(dimethylaminocyclohexyl), —NH-(methylaminocyclohexyl), —NH-(aminocyclohexyl), —NH-(acetylpiperidinyl), —NH-(cyanocyclohexyl), —NH-(t-butyloxycarbonylpiperidinyl), —NH-(2-propylpiperidinyl), —NH-(ethylpiperidinyl), —NH-(methylsulfonylpiperidinyl), —NHCH 2 CH 2 OH, —NHCH 2 CH 2 OCH 3 , —NH-(morpholinoethyl), —NH-(benzimidazolyl), —NH-(benzoxazolyl), —NH-(methylpyrazolyl), —NH-(pyrimidinyl), —NH-(pyrazolyl), —NH-(pyrrolidinyl), —NH-(methylpyrrolidinyl), —NH-(t-butyloxycarbonylpyrrolidinyl), —NH-(tetrahydrofuranyl), or —NH-(tetrahydropyranyl).

18. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 5 is H.

19. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having Formula IIc:

20. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having Formula III:

21. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having Formula IVc:

22. The compound of claim 1 , wherein the compound is

6-benzyl-1-methyl-6H-pyrazolo[3,4-e][1,2,4]triazolo[4,3-a]pyridine, or a pharmaceutically acceptable salt thereof.

23. A pharmaceutical composition comprising a compound of claim 1 , or a pharmaceutically acceptable salt thereof, and at least one pharmaceutically acceptable carrier.

24. A method of inhibiting a BET protein comprising contacting a compound of claim 1 , or a pharmaceutically acceptable salt thereof, with said BET protein.