Preparation of maytansinoid antibody conjugates by a one-step process

1. A process for preparing a cell-binding agent-maytansinoid conjugate comprising the step of:

(a) contacting a cell-binding agent with a maytansinoid to form a first mixture comprising the cell-binding agent and the maytansinoid, then contacting the first mixture with a bifunctional crosslinking reagent comprising a cleavable linker, in a solution having a pH of about 4 to about 9 to provide a second mixture comprising (i) the cell-binding agent-maytansinoid conjugate, wherein the cell-binding agent is chemically coupled through the cleavable linker to the maytansinoid, (ii) free maytansinoid, and (iii) reaction by-products, wherein the maytansinoid is N2′-deacetyl-N2′-(3-mercapto-1-oxopropyl)-maytansine (DM1) or N2′-deacetyl-N2′(4-methyl-4-mercapto-1-oxopentyl)-maytansine (DM4).

2. The process of claim 1 , wherein the process further comprises the step of:

(b) purifying the second mixture comprising the cell-binding agent-maytansinoid conjugate to provide a purified cell-binding agent-maytansinoid conjugate.

3. The process of claim 2 , wherein the second mixture is purified by subjecting the mixture to tangential flow filtration, selective precipitation, adsorptive filtration, adsorptive chromatography, non-absorptive chromatography, or a combination thereof, to purify the cell-binding agent-maytansinoid conjugate from the free maytansinoid and reaction by-products.

4. The process of claim 3 , wherein the second mixture is purified by subjecting the mixture to tangential flow filtration.

5. The process of claim 1 , wherein the contacting in step (a) is effected by providing the cell-binding agent in a reaction vessel, adding the maytansinoid to the reaction vessel to form the first mixture comprising the cell-binding agent and the maytansinoid, and then adding the bifunctional crosslinking reagent to the first mixture.

6. The process of claim 2 , further comprising holding the second mixture between steps (a) (b) to release the unstably bound linkers from the cell-binding agent.

7. The process of claim 6 , wherein the second mixture is held for about 20 hours at a temperature of about 2° C. to about 8° C.

8. The process of claim 2 , further comprising quenching the second mixture between steps (a) (b) to quench any unreacted maytansinoid and/or unreacted bifunctional crosslinking reagent.

9. The process of claim 8 , wherein the mixture is quenched by contacting the second mixture with a quenching reagent that reacts with the free maytansinoid.

10. The process of claim 9 , wherein the quenching reagent is selected from 4-maleimidobutyric acid, 3-maleimidopropionic acid, N-ethylmaleimide, iodoacetamide, and iodoacetamidopropionic acid.

11. The process of claim 1 , wherein the contacting in step (a) occurs in a solution having a pH of about 7 to about 9.

12. The process of claim 1 , wherein the contacting in step (a) occurs at a temperature of about 16° C. to about 24° C.

13. The process of claim 1 , wherein the contacting in step (a) occurs at a temperature of about 0° C. to about 15° C.

14. The process of claim 1 , wherein the cell-binding agent is an antibody.

15. The process of claim 14 , wherein the antibody is a monoclonal antibody.

16. The process of claim 15 , wherein the antibody is a humanized monoclonal antibody.

17. The process of claim 1 , wherein the maytansinoid is N 2′ -deacetyl-N 2′ -(3-mercapto-1-oxopropyl)-maytansine (DM1).

18. The process of claim 1 , wherein the maytansinoid is N 2′ -deacetyl-N 2′ -(4-methyl-4-mercapto-1-oxopentyl)-maytansine (DM4).

19. The process of claim 1 , wherein the cell-binding agent is chemically coupled to the maytansinoid via chemical bonds selected from disulfide bonds, acid labile bonds, photolabile bonds, peptidase labile bonds, thioether bonds, and esterase labile bonds.

20. The process of claim 1 , wherein the bifunctional crosslinking reagent comprises an N-succinimidyl ester moiety or an N-sulfosuccinimidyl ester moiety.

21. The process of claim 20 , wherein the bifunctional crosslinking reagent is selected from SPDP, SPP, SPDB, and sulfo-SPDB.

22. The process of claim 1 , wherein the solution in step (a) comprises sucrose.

23. The process of claim 1 , wherein the solution in step (a) comprises a buffering agent selected from a citrate buffer, an acetate buffer, a succinate buffer, and a phosphate buffer.

24. The process of claim 1 , wherein the solution in step (a) comprises a buffering agent selected from HEPPSO (N-(2-hydroxyethyl)piperazine-N′-(2-hydroxypropanesulfonic acid)), POP SO (piperazine-1,4-bis-(2-hydroxy-propane-sulfonic acid) dihydrate), HEPES (4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid), HEPPS (EPPS) (4-(2-hydroxyethyl)piperazine-1-propanesulfonic acid), TES (N-[tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid), and a combination thereof.

25. The process of claim 14 , wherein the antibody binds an antigen selected from EpCAM, GD3, FLT3, PSMA, PSCA, MUC1, MUC16, STEAP, CEA, TENB2, EphA receptor, EphB receptor, folate receptor, FOLR1, mesothelin, crypto, alphavbeta6, integrins, VEGF, VEGFR, EGFR, transferrin receptor, IRTA1, IRTA2, IRTA3, IRTA4, IRTA5, CD2, CD3, CD4, CD5, CD6, CD8, CD11, CD14, CD19, CD20, CD21, CD22, CD25, CD26, CD28, CD30, CD33, CD36, CD37, CD38, CD40, CD44, CD52, CD55, CD56, CD59, CD70, CD79, CD80, CD81, CD103, CD105, CD134, CD137, CD138, and CD152.

26. The process of claim 14 , wherein the antibody is an immunoglobulin fragment.

27. The process of claim 26 , wherein the immunoglobulin fragment is selected from Fab, Fab′, F(ab′)2, dsFv, sFv, minibody, diabody, tribody, and tetrabody.

28. The process of claim 14 , wherein the antibody is an immunoglobulin chimera.