Steroids and protein-conjugates thereof

1. A conjugate compound comprising an antibody or antigen binding fragment thereof conjugated to a compound of Formula (A):

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

wherein:

R 1 and R 2 are, independently, —H, alkyl, alkyl-C(O)—O—, —OH, or halo; or

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 —NR a R b ;

R 5 is, independently in each instance, —OH, halo, alkyl, or arylalkyl and each R 5 is positioned on any ring atom;

R a and R b are, independently in each instance, —H, alkyl, or optionally substituted aryl; or

R a and R b cyclize to form cycloheteroalkyl with three to six ring atoms, including one hetero atom, which is the N to which they are attached; and

hetero atom, which is the N to which they are attached; and

n is an integer from 0-19; and

the antibody or antigen binding fragment thereof is covalently bonded to R 3 .

2. A conjugate compound according to Formula 1200:

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

wherein:

R 1 and R 2 are, independently, selected from the group consisting of —H, —OH, alkyl, —O—C(O)-alkyl, and halo; or

R 1 and R 2 together form

either (a) or (b):

(a) R 3 is —NR a R b ; and

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

or

(b) R 3 is —NR a R b ; and

R 4 is alkyl;

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 0-16; 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; or R a and R b cyclize to form cycloheteroalkyl with three to six ring atoms, including one hetero atom, which is the N to which they are attached;

BA is an antibody or antigen binding fragment thereof;

each L is an optional linker;

BA or L is covalently bonded to R 3 ; and

x is an integer from 1 to 30.

3. The conjugate compound of claim 2 according to Formula 1210, 1220, 1230, or 1240:

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

wherein R 3 is covalently bonded to L or BA.

4. The conjugate compound of claim 1 selected from the group consisting of:

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

wherein each L is an optional linker;

each BA is an antibody or antigen binding fragment thereof; and

each x is an integer from 1 to 30.

5. The conjugate compound of claim 1 selected from the group consisting of:

wherein x is an integer from 1 to 30;

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

6. The conjugate compound of claim 1 wherein the compound of Formula (A) is

7. The conjugate compound of claim 1 wherein the compound of Formula (A) is

8. The conjugate compound of claim 1 , wherein the compound of Formula (A) is

9. The conjugate compound of claim 1 , wherein the compound of Formula (A) is a compound of the formula: