Inhibitors of RET

1. A compound having the formula (A):

or a pharmaceutically acceptable salt thereof, wherein:

ring A is an aryl or heteroaryl ring;

each of X 1 and X 2 is independently selected from N and C(R 6 );

each of Y 1 and Y 2 is independently selected from —CH 2 — and —O—, wherein no more than one of Y 1 or Y 2 is —O—;

each R 1 and each R 7 is independently selected from selected from C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 alkoxy, halo, C 1 -C 6 heteroalkyl, cycloalkyl, aryl, heteroaryl, aryloxy, aralkyl, heterocyclyl, heterocyclylalkyl, nitro, cyano, —C(O)R, —OC(O)R, —C(O)OR, -(C 1 -C 6 alkylene)-C(O)R, —SR, —S(O) 2 R, —S(O) 2 —N(R)(R), -(C 1 -C 6 alkylene)-S(O) 2 R, -(C 1 -C 6 alkylene)-S(O) 2 —N(R)(R), —N(R)(R), —C(O)—N(R)(R), —N(R)—C(O)R, —N(R)—C(O)OR, —(C 1 -C 6 alkylene)-N(R)—C(O)R, —N(R)S(O) 2 R, and —P(O)(R)(R), wherein each of alkyl, alkenyl, alkynyl, alkoxy, heteroalkyl, cycloalkyl, aryl, heteroaryl, aryloxy, aralkyl, heterocyclyl, and heterocyclylalkyl is independently substituted with 0-5 occurrences of R a , or two R 1 or two R 7 are taken together with the carbon atoms to which they are attached form a cycloalkyl or heterocyclyl ring independently substituted with 0-5 occurrences of R b ;

each of R 2 , R 3a , R 3b , R 4 , R 8a , and R 8b is independently selected from hydrogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, halo, hydroxyl, C 1 -C 6 heteroalkyl, and —N(R)(R), wherein each alkyl, alkoxy, and heteroalkyl is independently substituted with 0-5 occurrences of R a ;

each of R 5 and R 9 is independently selected from hydrogen, C 1 -C 6 alkyl, and C 1 -C 6 heteroalkyl, wherein each alkyl and heteroalkyl is independently substituted with 0-5 occurrences of R a ;

each R 6 is independently selected from hydrogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, halo, C 1 -C 6 heteroalkyl, and —N(R)(R), wherein each alkyl, alkoxy, and heteroalkyl is independently substituted with 0-5 occurrences of R a ;

each R is independently selected from hydrogen, hydroxyl, halo, thiol, C 1 -C 6 alkyl, C 1 -C 6 thioalkyl, C 1 -C 6 alkoxy, C 1 -C 6 heteroalkyl, cycloalkyl, cycloalkylalkyl, heteroarylalkyl, heterocyclyl, and heterocyclylalkyl, wherein each alkyl, thioalkyl, alkoxy, heteroalkyl, cycloalkyl, cycloalkylalkyl, heteroarylalkyl, heterocyclyl, and heterocyclylalkyl is independently substituted with 0-5 occurrences of R a , or 2 R together with the atom(s) to which they are attached form a cycloalkyl or heterocyclyl ring independently substituted with 0-5 occurrences of R b ;

each R a and each R b is independently selected from C 1 -C 6 alkyl, halo, hydroxyl, C 1 -C 6 heteroalkyl, C 1 -C 6 alkoxy, cycloalkyl, heterocyclyl, and cyano, wherein each alkyl, heteroalkyl, alkoxy, cycloalkyl, and heterocyclyl is independently substituted with 0-5 occurrences of R′;

each R′ is independently selected from C 1 -C 6 alkyl, C 1 -C 6 heteroalkyl, halo, hydroxyl, cycloalkyl, and cyano, or 2 R′ together with the atom(s) to which they are attached form a cycloalkyl or heterocyclyl ring;

represents a single or double bond;

m is 0, 1, or 2;

n is 0, 1, 2, or 3; and

each o is 0 when is a double bond; and

each o is 1 when is a single bond.

2. The compound of claim 1 having the formula (I):

or a pharmaceutically acceptable salt thereof, wherein;

represents a single or double bond.

3. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein:

m is 1;

R 1 is located at the 5-position; and

R 1 is C 1 -C 4 alkyl optionally substituted with 0-3 occurrences of R a .

4. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein R 2 is selected from hydrogen, hydroxyl, halo, and C 1 -C 4 alkoxy.

5. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein each of R 3a , R 3b , R 8a , and R 8b is independently selected from hydrogen and C 1 -C 4 alkyl optionally substituted with 0-3 occurrences of R a .

6. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein at least one pair of R 3a and R 3b or R 8a and R 8b is simultaneously hydrogen.

7. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein R 4 is selected from hydrogen, C 1 -C 4 alkyl, and C 1 -C 4 alkoxy, wherein each alkyl portion of R 4 is optionally substituted with 0-3 occurrences of R a .

8. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein R 5 is hydrogen or C 1 -C 4 alkyl optionally substituted with 0-3 occurrences of R a .

9. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein each R 6 is independently selected from hydrogen, halo, and C 1 -C 4 alkyl optionally substituted with 0-3 occurrences of R a .

10. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein ring A is a 6-membered monocyclic heteroaryl comprising at least one nitrogen ring atom.

11. The compound of claim 10 or a pharmaceutically acceptable salt thereof, wherein ring A is selected from

12. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein:

n is 1; and

R 7 is pyrazol-1-yl optionally substituted with 0-3 occurrences of R a .

13. The compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein R 9 is hydrogen.

14. A compound having the formula (II):

or a pharmaceutically acceptable salt thereof, wherein:

X 1 is selected from N, CH, and C(halo);

X 2 is selected from N and CH;

X 3 is selected from N and CH;

R 12 is selected from hydrogen, hydroxyl, halo, and O—C 1 -C 4 alkyl;

each of R 13a , R 13b , R 18a , and R 18b is independently selected from hydrogen and C 1 -C 4 alkyl;

R 14 is selected from hydrogen, C 1 -C 4 alkyl and O—C 1 -C 4 alkyl;

R 15 is selected from hydrogen and C 1 -C 4 alkyl;

R 16 is selected from hydrogen and C 1 -C 4 alkyl;

R 17b is selected from hydrogen and halo; and

each of R 17a and R 17c is independently selected from hydrogen and C 1 -C 4 alkyl.

15. The compound of claim 14 or a pharmaceutically acceptable salt thereof, wherein:

X 1 is selected from N, CH, and C(Cl);

R 12 is selected from hydrogen, hydroxyl, fluoro, and —O—CH 3 ;

each of R 13a , R 13b , R 18a , and R 18b is independently selected from hydrogen, methyl, and ethyl, wherein at least one pair of R 13a and R 13b or R 18a and R 18b is simultaneously hydrogen;

R 14 is selected from hydrogen, —CH 3 , —CH 2 CH 3 , —OCH 3 , and —OCH 2 CH 3 ;

R 15 is selected from hydrogen and —CH 3 ;

R 16 is selected from hydrogen and —CH 3 ;

R 17b is selected from hydrogen, chloro, and fluoro;

R 17a and R 17c are simultaneously hydrogen or —CH 3 , wherein when R 17a and R 17c are simultaneously —CH 3 , R 17b is hydrogen.

16. A pharmaceutical composition comprising:

a compound of claim 1 or a pharmaceutically acceptable salt thereof; and

a pharmaceutically acceptable carrier.

17. A method for treating a subject suffering from non-small cell lung cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof.

18. A method for treating a subject suffering from papillary thyroid cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof.

19. A method for treating a subject suffering from medullary thyroid cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof.

20. A method for treating a subject suffering from colorectal cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof.

21. A method for treating a subject suffering from multiple endocrine neoplasia, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof.

22. A compound selected from:

TABLE 1

Exemplary Compounds of the Invention.

Compound

Structure

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

and pharmaceutically acceptable salts thereof.

23. A compound selected from:

and pharmaceutically acceptable salts thereof.

24. A pharmaceutical composition comprising:

a compound of claim 23 or a pharmaceutically acceptable salt thereof; and

a pharmaceutically acceptable carrier.

25. A method for treating a subject suffering from non-small cell lung cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 23 or a pharmaceutically acceptable salt thereof.

26. A method for treating a subject suffering from papillary thyroid cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 23 or a pharmaceutically acceptable salt thereof.

27. A method for treating a subject suffering from medullary thyroid cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 23 or a pharmaceutically acceptable salt thereof.

28. A method for treating a subject suffering from colorectal cancer, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 23 or a pharmaceutically acceptable salt thereof.

29. A method for treating a subject suffering from multiple endocrine neoplasia, the method comprising administering to the subject a therapeutically effective amount of a compound of claim 23 or a pharmaceutically acceptable salt thereof.

30. A compound