Steroids and protein-conjugates thereof

1. A compound of Formula (A):

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof,

wherein:

R 1 and R 2 together form

wherein R 4 is alkyl, aryl, arylalkyl, or an N-containing heterocycloalkyl, wherein the alkyl, aryl, arylalkyl, and N-containing heterocycloalkyl are, independently in each instance, optionally substituted with —NR a R b ;

R 3 is

 wherein R P is halo, t is an integer from 0 to 2;

R 5 is, independently in each instance, —OH, halo, alkyl, or arylalkyl;

R a and R b are, independently in each instance, —H or alkyl

n is an integer from 0-19.

2. The compound of claim 1 , wherein the compound of Formula (A) has the structure of Formula (A 1 ):

wherein R 5A and R 5B are each, independently, halo or a hydrogen atom.

3. The compound of claim 2 , wherein R 4 is aryl, arylalkyl, or alkyl, wherein the aryl, arylalkyl, and alkyl are optionally substituted with —NR a R b .

4. The compound of claim 1 according to Formula (A 2 )

wherein n is an integer from 0 to 4.

5. The compound of claim 1 according to Formula (A 3 ):

wherein n is an integer from 1-4.

6. The compound of claim 1 according to Formula (A 4 ):

wherein R 4 is alkyl.

7. The compound of claim 6 , wherein R 4 is C 1-4 alkyl.

8. The compound of claim 1 according to Formula (A 5 ):

wherein R 4 is alkyl, R P1 is halo or a hydrogen atom, and R P2 is —NR a R b , wherein R a and R b are each, independently, a hydrogen atom or alkyl.

9. The compound of claim 1 according to Formula (A 6 ):

wherein R 4 is alkyl.

10. The compound of claim 1 according to Formula 1000:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof,

wherein:

R 1 and R 2 together form

R 3 is

 wherein R P is halo, t is an integer from 0 to 2;

R 4 is selected from the group consisting of alkyl, aryl, arylalkyl, -alkylene-NR a R b , —X-arylene-Y—NR a R b , and N-containing heterocycloalkyl; wherein X is absent or —CH 2 —; wherein Y is absent;

R 5 is, independently in each instance, selected from a substituent in the group consisting of —OH, halo, and alkyl; n is an integer from 0-17; and each R 5 is positioned on any ring atom;

R a and R b are, independently in each instance, selected from the group consisting of —H and alkyl.

11. The compound of claim 10 according to Formula 1110, 1120, 1130, or 1140:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

12. The compound of claim 11 wherein

R 4 is n-propyl.

13. The compound of claim 11 according to formula 1120.

14. The compound of claim 11 wherein R 4 is H 2 NCH 2 CH 2 — or

15. The compound of claim 11 wherein

R 4 is alkyl, aryl, or arylalkyl.

16. The compound of claim 15 wherein R 3 is

17. The compound of claim 15 , wherein R 4 is n-propyl.

18. The compound of claim 1 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

19. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

20. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

21. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

22. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

23. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

24. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

25. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

26. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

27. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

28. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

29. The compound of claim 20 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

30. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

31. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

32. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.

33. The compound of claim 18 , wherein the compound is:

or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof.