Glycosylation engineering of antibodies for improving antibody-dependent cellular cytotoxicity

1. A glycoengineered, recombinant antibody comprising an immunoglobulin G (IgG) Fc region containing N-linked oligosaccharides, wherein said antibody is isolated from a glycoengineered Chinese Hamster Ovary (CHO) host cell that has altered glycosyltransferase expression and has been engineered to have an increased proportion of nonfucosylated oligosaccharides in the Fc region compared to a corresponding antibody produced by the same host cell without altered glycosyltransferase expression, and wherein said antibody has increased Fc-mediated cellular cytotoxicity and/or Fc receptor binding affinity as a result of said increased proportion of nonfucosylated oligosaccharides.

2. A glycoengineered, recombinant antibody according to claim 1 , wherein the predominant N-linked oligosaccharide in the Fc region is nonfucosylated.

3. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody is a chimeric antibody.

4. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody is a humanized antibody.

5. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody is an antibody fragment that contains a Fc region.

6. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody is a fusion protein that includes a Fc region of an immunoglobulin.

7. A glycoengineered, recombinant antibody according to claim 1 , wherein the Fc region comprises N-linked oligosaccharides, and wherein the predominant N-linked oligosaccharide in the Fc region is not a high-mannose structure.

8. A glycoengineered, recombinant antibody according to claim 1 , wherein said Fc region containing N-linked oligosaccharides further comprises an increased proportion of GlcNAc residues compared to the corresponding antibody produced by the same host cell without altered glycosyltransferase expression.

9. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody is produced by a mammalian host cell that has been genetically manipulated to have altered activity of at least one glycoprotein-modifying glycosyltransferase.

10. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody is a therapeutic antibody.

11. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody selectively binds to an antigen expressed by cancer cells.

12. A glycoengineered, recombinant antibody according to claim 10 , wherein said antibody is a monoclonal antibody.

13. A glycoengineered recombinant antibody according to claim 10 , wherein said antibody is a selected from the group consisting of: an anti-CD20 antibody, an anti-human neuroblastoma antibody, an anti-human renal cell carcinoma antibody, an anti-HER2 antibody, an anti-human colon, lung, and breast carcinoma antibody, an anti-human 17-1A antigen antibody, a humanized anti-human colorectal tumor antibody, an anti-human melanoma antibody, and an anti-human squamous-cell carcinoma antibody.

14. A glycoengineered, recombinant antibody according to claim 1 , wherein the Fc region comprises N-linked oligosaccharides, and wherein the majority of the N-linked oligosaccharides in the Fc region of said antibody are bisected and/or nonfucosylated.

15. A glycoengineered, recombinant antibody according to claim 1 , wherein said antibody is produced by a process comprising:

(a) providing a Chinese Hamster Ovary (CHO) host cell comprising at least one nucleic acid encoding a recombinant antibody;

(b) genetically manipulating said host cell to alter the activity in said host cell of at least one glycoprotein-modifying glycosyltransferase;

(c) culturing said host cell under conditions which permit expression of the glycoengineered, recombinant antibody; and

(d) isolating said glycoengineered, recombinant antibody.

16. A glycoengineered, recombinant antibody according to claim 9 , wherein said antibody is a therapeutic monoclonal antibody having a human Fc region and that selectively binds an antigen expressed by cancer cells, and wherein the majority of oligosaccharides in the Fc region of said antibody are nonfucosylated.

17. A glycoengineered, recombinant antibody according to claim 9 , wherein said altered activity comprises altered expression of at least one glycoprotein-modifying glycosyltransferase.

18. A glycoengineered, recombinant antibody according to claim 15 , wherein said altered activity comprises altered expression of at least one glycoprotein-modifying glycosyltransferase.

19. A glycoengineered, recombinant antibody according to claim 16 , wherein at least 45% of the oligosaccharides in the Fc region are complex structures.

20. A glycoengineered, recombinant antibody according to claim 16 , wherein said glycoengineered, recombinant antibody exhibits at least an 80% increase in maximal ADCC activity compared to the same antibody produced by the same host cell under identical culture and purification conditions, but which has not been glycoengineered.

21. A glycoengineered, recombinant antibody according to claim 9 , wherein said at least one glycoprotein-modifying glycosyltransferase is GnTIII or ManII.

22. A glycoengineered, recombinant antibody according to claim 1 , wherein said IgG Fc region containing N-linked oligosaccharides comprises an entire IgG Fc region.

23. A glycoengineered, recombinant antibody according to claim 1 , wherein said IgG Fc region containing N-linked oligosaccharides comprises an IgG fragment.

24. A glycoengineered, recombinant antibody according to claim 23 , wherein said IgG fragment comprises a CH2 domain.