Antigen-binding molecule and combination

A method for producing a second antigen-binding molecule, comprising the steps of:

• (d) culturing an antibody-producing cell obtained from a screening method comprising steps (a) to (c):
• (a) immunizing a mammal with an antigen/antigen-binding molecule complex comprising an antigen and an antigen-binding molecule, and obtaining a first group of antibody-producing cells which produce monoclonal antibodies that bind to the complex;
• (b) selecting from the first group of antibody-producing cells, a second group of cells which produces monoclonal antibodies whose binding activity to either or both of the antigen not in the form of the complex and the antigen-binding molecule not in the form of the complex is lower than their binding to the complex in at least one assay selected from surface plasmon resonance (SPR), biolayer interference (BLI), and enzyme-linked immunosorbent assay (ELISA);
• and
• (c) selecting from the second group of cells, a cell which produces monoclonal antibodies that enhance the binding activity of the first antigen-binding molecule to the antigen in at least one assay selected from SPR, BLI, and ELISA;
• (e) obtaining a culture supernatant or a cell homogenate from the antibody-producing-cell culture;
• and
• (f) purifying the second antigen-binding molecule from the culture supernatant or the cell homogenate.

A method for producing a second antigen-binding molecule, comprising the steps of:

• (d) culturing a cell expressing the second antigen-binding molecule encoded by the DNA in a cell selected from a screening method comprising the following steps (a) to (c):
• (a) screening an antigen binding molecule display library for cells that display an antigen binding molecule that binds an antigen/antigen-binding molecule complex comprising a first antigen and a first antigen-binding molecule and obtaining a first group of cells that display antigen binding molecules that bind to the complex;
• (b) selecting from the first group of cells, a second group of cells that display an antigen binding molecule for which binding activity to either or both of the first antigen not in the form of the complex and the first antigen-binding molecule not in the form of the complex is lower than their binding to the complex in at least one assay selected from SPR, BLI, and ELISA;
• and
• (c) selecting from the second group of cells, a cell that displays a second antigen binding molecule that enhances the binding activity of the first antigen-binding molecule to the first antigen in at least one assay selected from SPR, BLI, and ELISA, and optionally engineering a host cell to express the second antigen-binding molecule;
• (e) obtaining a culture supernatant or a cell homogenate from the antibody-producing-cell culture;
• and
• (f) purifying the second antigen-binding molecule from the culture supernatant or the cell homogenate.