Cµ4 region for pairing heavy and light chains in multi-specific antibodies

An antibody, comprising:

• (a) a first chain comprising a first variable region and a first pairing region;
• and
• (b) a second chain comprising a second variable region and a second pairing region;
• wherein the first and second variable regions are heavy and light chain variable regions, or vice versa;
• wherein the first and second chains pair to each other via association of the first and second pairing regions, thereby forming a first binding site that specifically binds a first target epitope;
• wherein the first pairing region is a first IgM Cμ4 region, and the second pairing region is selected from a first kappa light chain constant region and a first CH1 region.

An expression system for producing an antibody in a host cell, the system comprising:

• (a) a first polynucleotide encoding first polypeptide, said first polypeptide comprising a first variable region and a first pairing region;
• (b) a second polynucleotide encoding second polypeptide, said second polypeptide comprising a second variable region and a second pairing region;
• (c) a host cell suitable for expressing the first and second polypeptides following delivery of said first and second polynucleotides into said host cell;
• wherein the first and second variable regions are heavy and light chain variable regions, or vice versa;
• wherein the first and second polypeptides pair to each other via association of the first and second pairing regions, thereby forming a first binding site that specifically binds a first target epitope;
• wherein the first pairing region is a first IgM Cμ4 region, and the second pairing region is selected from a first kappa light chain constant region and a first CH1 region.

A method for producing an antibody in a host cell, the method comprising:

• (a) providing:
• (i) a first polynucleotide encoding a first polypeptide, said first polypeptide comprising a first variable region and a first pairing region;
• (ii) a second polynucleotide encoding a second polypeptide, said second polypeptide comprising a second variable region and a second pairing region;
• wherein
• (A) the first and second variable regions are heavy and light chain variable regions, or vice versa,
• (B) the first and second polypeptides pair to each other via association of the first and second pairing regions, thereby forming a first binding site that specifically binds a first target epitope, and
• (C) the first pairing region is a first IgM Cμ4 region, and the second pairing region is selected from a first kappa light chain constant region and a first CH1 region;
• (iii) a host cell suitable for expressing the first and second polypeptides following delivery of said first and second polynucleotides into said host cell;
• (b) delivering said first and second polynucleotides in said host cell;
• (c) culturing said host cell under conditions for the expression of said first and second polypeptides, thereby producing said antibody.