CD19 binding agents and uses thereof

1. An isolated antibody or antigen-binding fragment thereof that specifically binds to human CD19, wherein said antibody or said antigen-binding fragment comprises a heavy chain variable domain comprising the amino acid sequence of SEQ ID NO:9 and a light chain variable domain comprising the amino acid sequence of SEQ ID NO: 24, wherein the binding affinity to human CD19 of said antibody or antigen-binding fragment thereof is higher than the binding affinity to human CD19 of an antibody or antigen-binding fragment thereof comprising a heavy chain variable domain comprising the amino acid sequence of SEQ ID NO:9 and a light chain variable domain comprising the amino acid sequence of SEQ ID NO:17.

2. The isolated antibody or antigen-binding fragment of claim 1 , further comprising a human IgG constant region joined to the heavy chain variable region.

3. The isolated antibody or antigen-binding fragment of claim 2 , wherein the isotype of IgG constant region is IgG1, IgG2, or IgG1V1.

4. The isolated antibody or antigen-binding fragment of claim 1 further comprising a light chain constant domain joined to the light chain variable region.

5. The isolated antibody or antigen-binding fragment of claim 4 , wherein the light chain constant domain is a kappa constant domain.

6. The isolated antibody or antigen-binding fragment of claim 1 wherein the antibody or antigen-binding fragment thereof is conjugated to a cytotoxic agent.

7. An antibody-drug conjugate compound or antigen-binding fragment-drug conjugate compound of the following formula:

L-(LU-D) p

or a pharmaceutically acceptable salt or solvate thereof;

wherein:

L is the antibody or antigen-binding fragment of claim 1 ; and

(LU-D) is a Linker unit-Drug unit moiety, wherein:

LU- is a Linker unit, and

-D is a Drug unit having cytostatic or cytotoxic activity against target cells; and

p ranges from 1 to 10.

8. The antibody-drug conjugate compound or antigen-binding fragment-drug conjugate compound of claim 7 wherein the drug unit has the formula D E , O F or D Z :

or a pharmaceutically acceptable salt or solvate form thereof;

wherein, independently at each location:

R 2 is C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;

R 3 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, carbocycle, —C 1 -C 20 alkylene (carbocycle), —C 2 -C 20 alkenylene(carbocycle), —C 2 -C 20 alkynylene(carbocycle), aryl, —C 1 -C 20 alkylene(aryl), —C 2 -C 20 alkenylene(aryl), —C 2 -C 20 alkynylene(aryl), heterocycle, —C 1 -C 20 alkylene(heterocycle), —C 2 -C 20 alkenylene(heterocycle), or —C 2 -C 20 alkynylene(heterocycle);

R 4 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, carbocycle, —C 1 -C 20 alkylene (carbocycle), —C 2 -C 20 alkenylene(carbocycle), —C 2 -C 20 alkynylene(carbocycle), aryl, —C 1 -C 20 alkylene(aryl), —C 2 -C 20 alkenylene(aryl), —C 2 -C 20 alkynylene(aryl), heterocycle, —C 1 -C 20 alkylene(heterocycle), —C 2 -C 20 alkenylene(heterocycle), or —C 2 -C 20 alkynylene(heterocycle);

R 5 is H or C 1 -C 8 alkyl;

or R 4 and R 5 jointly form a carbocyclic ring and have the formula —(CR a R b ) s —wherein R a and R b are independently H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, or carbocycle and s is 2, 3, 4, 5 or 6,

R 6 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;

R 7 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, carbocycle, —C 1 -C 20 alkylene (carbocycle), —C 2 -C 20 alkenylene(carbocycle), —C 2 -C 20 alkynylene(carbocycle), aryl, —C 1 -C 20 alkylene(aryl), —C 2 -C 20 alkenylene(aryl), —C 2 -C 20 alkynylene(aryl), heterocycle, —C 1 -C 20 alkylene(heterocycle), —C 2 -C 20 alkenylene(heterocycle), or —C 2 -C 20 alkynylene(heterocycle);

each R 8 is independently H, OH, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, —O—(C 1 -C 20 alkyl), —O—(C 2 -C 20 alkenyl), —O—(C 1 -C 20 alkynyl), or carbocycle;

R 9 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;

R 24 is aryl, heterocycle, or carbocycle;

R 25 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, carbocycle, —O—(C 1 -C 20 alkyl), —O—(C 2 -C 20 alkenyl), —O—(C 2 -C 20 alkynyl), or OR 18 wherein R 18 is H, a hydroxyl protecting group, or a direct bond where OR 18 represents ═O;

R 26 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl, aryl, heterocycle, or carbocycle;

R 10 is aryl or heterocycle;

Z is O, S, NH, or NR 12 , wherein R 12 is C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;

R 11 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, carbocycle, —C 1 -C 20 alkylene (carbocycle), —C 2 -C 20 alkenylene(carbocycle), —C 2 -C 20 alkynylene(carbocycle), aryl, —C 1 -C 20 alkylene(aryl), —C 2 -C 20 alkenylene(aryl), —C 2 -C 20 alkynylene(aryl), heterocycle, —C 1 -C 20 alkylene(heterocycle), —C 2 -C 20 alkenylene(heterocycle), —C 2 -C 20 alkynylene(heterocycle) —(R 13 O) m —R 14 , or —(R 13 O) m —CH(R 15 ) 2 ;

m is an integer ranging from 0-1000;

R 13 is C 2 -C 20 alkylene, C 2 -C 20 alkenylene, or C 2 -C 20 alkynylene;

R 14 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, or C 2 -C 20 alkynyl;

each occurrence of R 15 is independently H, COOH, —(CH 2 ) n —N(R 16 ) 2 , —(CH 2 ) n —SO 3 H, —(CH 2 ) n —SO 3 —C 1 -C 20 alkyl, —(CH 2 ) n —SO 3 —C 2 -C 20 alkenyl, or —(CH 2 ) n —SO 3 —C 2 -C 20 alkynyl;

each occurrence of R 16 is independently H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl or —(CH 2 ) n —COOH;

n is an integer ranging from 0 to 6;

R 27 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, O—(C 1 -C 20 alkyl), —O—(C 2 -C 20 alkenyl), —O—(C 2 -C 20 alkynyl), halogen, —NO 2 , —COOH, or —C(O)OR 28 wherein R 28 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, aryl, heterocycle, —(CH 2 CH 2 O) r —H, —(CH 2 CH 2 O) r —CH 3 , or —(CH 2 CH 2 O) r —CH 2 CH 2 C(O)OH; wherein r is an integer ranging from 1-10; and

X is —(CR 29 2 ) I —wherein R 29 is H, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl and I is an integer ranging from 0 to 10; wherein said alkyl, alkenyl, alkynyl, alkylene, alkenylene, alkynyklene, aryl, carbocyle, and heterocycle radicals, whether alone or as part of another group, are optionally substituted.

9. An antibody-drug conjugate compound or antigen-binding fragment-drug conjugate compound of the following formula:

or a pharmaceutically acceptable salt or solvate form thereof, wherein mAb is the antibody or antigen-binding fragment of claim 1 and p is from 1 to 8.

10. The antibody-drug conjugate compound or antigen-binding fragment-drug conjugate compound of claim 8 of the following formula:

or a pharmaceutically acceptable salt or solvate form thereof, wherein L is the antibody or antigen-binding fragment of claim 1 and p is from 1 to 8.

11. The antibody-drug conjugate compound or antigen-binding fragment-drug conjugate compound of claim 8 , wherein the drug unit has the formula:

or a pharmaceutically acceptable salt or solvate form thereof.

12. A composition comprising the antibody or antigen-binding fragment of claim 1 , and a pharmaceutically acceptable carrier or excipient.

13. A kit comprising a container containing the antibody-drug conjugate compound or antigen-binding fragment-drug conjugate compound of claim 7 , wherein the antibody-drug conjugate compound is lyophilized, and a second container containing a pharmaceutically acceptable diluent.

14. A method of manufacturing an antibody-drug conjugate compound or antigen-binding fragment-drug conjugate compound comprising conjugating the antibody or antigen-binding fragment of claim 1 to a cytotoxic agent.