Fc polypeptide variants having an increased half-life

Method of increasing the half-life of a polypeptide comprising an Fc fragment, comprising the following steps:

• i) insertion of a mutation A of at least one amino acid selected from amino acids in position 240, 241, 242, 243, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 290, 291, 292, 293, 294, 295, 296, 298, 299, 300, 301, 302, 303, 304 or 305;
• ii) insertion of a mutation B selected from the group consisting of 378V, 378T, 434Y and 434S and insertion of at least one mutation C selected from the group consisting of 226G, 228L, 228R, 230S, 230T, 230L, 241L, 264E, 307P, 315D, 330V, 362R, 378V, 378T, 389T, 389K 434Y and 434S;
• it being understood that:
• the mutations are carried out on the Fc fragment of the polypeptide,
• the mutations A, B and C do not take place on the same amino acid,
• and the amino acid position numbering of the Fc fragment is that of the EU index or equivalent in Kabat.

Method for producing a variant of a parent polypeptide comprising an Fc fragment, the variant having an improved half-life relative to the parent polypeptide, comprising the steps of:

• a) providing a nucleic sequence encoding the parent polypeptide comprising the Fc fragment;
• b) modifying the nucleic sequence provided in a) to obtain a nucleic sequence encoding the variant;
• and
• c) expressing the nucleic sequence obtained in b) in a host cell YB2/0, and recovering the variant,
• wherein step b) comprises:
• i) insertion of a mutation A of at least one amino acid selected from amino acids in position 240, 241, 242, 243, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 290, 291, 292, 293, 294, 295, 296, 298, 299, 300, 301, 302, 303, 304 or 305;
• ii) insertion of a mutation B selected from the group consisting of 378V, 378T, 434Y and 434S and
• iii) insertion of at least one mutation C selected from the group consisting of 226G, 228L, 228R, 230S, 230T, 230L, 241L, 264E, 307P, 315D, 330V, 362R, 378T, 389T, 389K and 434S;
• it being understood that:
• the mutations are carried out on the Fc fragment of the polypeptide,
• the mutations A, B and C do not take place on the same amino acid, and the amino acid position numbering of the Fc fragment is that of the EU index or equivalent in Kabat.

Method for producing a variant of a parent polypeptide comprising an Fc fragment, the variant having an improved half-life relative to the parent polypeptide, comprising the steps of:

• a) providing a nucleic sequence encoding the parent polypeptide comprising the Fc fragment;
• b) modifying the nucleic sequence provided in a) to obtain a nucleic sequence encoding the variant;
• and
• c) expressing the nucleic sequence obtained in b) in a host cell selected from modified transgenic animal cells to produce the polypeptide in the milk, and recovering the variant,
• wherein step b) comprises:
• i) insertion of a mutation A of at least one amino acid selected from amino acids in position 240, 241, 242, 243, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 290, 291, 292, 293, 294, 295, 296, 298, 299, 300, 301, 302, 303, 304 or 305;
• ii) insertion of a mutation B selected from the group consisting of 378V, 378T, 434Y and 434S and iii) insertion of at least one mutation C selected from the group consisting of 226G, 228L, 228R, 230S, 230T, 230L, 241L, 264E, 307P, 315D, 330V, 362R, 378T, 389T, 389K and 434S;
• it being understood that:
• that:
• the mutations are carried out on the Fc fragment of the polypeptide,
• the mutations A, B and C do not take place on the same amino acid, and the amino acid position numbering of the Fc fragment is that of the EU index or equivalent in Kabat.