An efficient route to human bispecific IgG

Area of Science:

• Biotechnology
• Immunology
• Protein Engineering

Background:

• Bispecific IgG (BsIgG) production is inefficient due to random heavy and light chain pairing.
• Unwanted antibody chain combinations reduce yield and purity of desired BsIgG molecules.

Purpose of the Study:

• To engineer efficient heterodimerization of antibody heavy chains for BsIgG production.
• To circumvent light chain mispairing by utilizing a common light chain for BsIgG.

Main Methods:

• Engineered disulfide bonds and "knobs-into-holes" mutations were introduced into antibody heavy chains to promote heterodimerization.
• A common light chain was employed for both arms of the BsIgG to prevent light chain mispairing.
• Antibodies with common light chains binding to different antigens were selected using an scFv phage library.

Main Results:

• A specific heavy chain variant achieved approximately 95% heterodimerization efficiency.
• The common light chain strategy successfully prevented light chain mispairing.
• A BsIgG targeting HER3 and cMpI was successfully produced and purified using protein A chromatography.
• Engineered heavy chains maintained antibody-dependent cell-mediated cytotoxicity (ADCC) activity.

Conclusions:

• The developed heavy chain engineering strategy significantly enhances BsIgG heterodimerization efficiency.
• Utilizing a common light chain is an effective method to avoid mispairing in BsIgG production.
• This engineered BsIgG platform retains effector functions and enables simultaneous targeting of multiple receptors.