Polypeptide variants
A variant of a polypeptide comprising a human IgG Fc region is described, which variant comprises an amino acid substitution at one or more of amino acid positions 270, 322, 326,327, 329, 331, 333 or 334 of the human IgG Fc region. Such variants display altered effector function. For example, C1q binding and/or complement dependent cytotoxicity (CDC) activity may be altered in the variant polypeptide. The application also discloses a variant of a parent polypeptide comprising a human IgG Fc region, which variant has a better binding affinity for human C1q than the parent polypeptide.
1. A variant of an antibody or immunoadhesin comprising a human IgG Fc region, which variant comprises an amino acid substitution at amino acid position 270 or 329, or at two or more of amino acid positions 270, 322, 329 and 331 of the human IgG Fc region, where the numbering of the residues in the IgG Fc region is that of the EU index as in Kabat.
2. The variant of claim 1 having Pro329 of the human IgG Fc region substituted with another amino acid.
3. The variant of claim 1 having Asp270 of the human IgG Fc region substituted with another amino acid.
4. The variant of claim 1 wherein the variant is an antibody.
5. The variant of claim 1 wherein the human IgG Fc region is a human IgG1 Fc region.
6. The variant of claim 1 which does not activate complement.
7. The variant of claim 6 wherein the human IgG Fc region binds an FcR.
8. The variant of claim 7 which binds FcγRI, FcγRII, FcγRIII and FcRn.
9. A composition comprising the variant of claim 1 and a physiologically acceptable carrier.
10. The variant of claim 4 wherein the antibody binds vascular endothelial growth factor (VEGF).
11. A variant of an antibody comprising a human IgG1 Fc region, which variant comprises an amino acid substitution at amino acid position 270 of the human IgG1 Fc region, where the numbering of the residues in the IgG Fc region is that of the EU index as in Kabat.
12. An antibody variant that binds vascular endothelial growth factor (VEGF) and comprises a human IgG1 Fc region, wherein the human IgG1 Fc region comprises an amino acid substitution at position 270, where the numbering of the residues in the IgG Fc region is that of the EU index as in Kabat.
13. The antibody of claim 12 wherein the amino acid residue at position 270 is substituted with alanine, valine, or lysine.
14. A composition comprising the antibody of claim 12 and a pharmaceutically acceptable carrier.
15. The composition of claim 14 which is sterile.