Heterodimeric IgG1 pI Engineering for Homodimer Purification
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Solution Overview
Problem
Existing methods for producing heterodimeric antibodies result in significant production of undesirable homodimers, necessitating complex purification steps, and there is a need to extend the serum half-life of antibodies by altering the constant domains without affecting antigen binding affinity or immunogenicity.
Innovation Solution
Engineer heterodimeric antibodies with variant heavy and light chain constant regions that have isoelectric points at least 0.5 logs apart, allowing for purification by ion exchange chromatography and incorporating specific amino acid substitutions to reduce pI and enhance serum half-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to produce heterodimeric antibodies, then production is straightforward, but significant amounts of undesirable homodimers are generated requiring complex purification steps
Solution Approach 1:
The patent introduces asymmetric modifications to the constant domains of heavy and light chains, creating local differences in isoelectric point (pI) properties. Specifically, the heavy chain constant domain is engineered with a pI of approximately 6.0-7.0 while the light chain constant domain maintains a different pI, enabling the heterodimer to have a distinct overall pI from homodimer variants. This local quality difference allows selective purification based on charge properties without affecting the antigen-binding variable regions.
Solution Approach 2:
The invention systematically alters the isoelectric point parameter of the antibody constant domains through amino acid substitutions. By modifying basic residues (lysine, arginine, histidine) to acidic residues (aspartic acid, glutamic acid) or neutral residues in the constant domains, the patent creates a measurable pI difference between heterodimer and homodimer species. This parameter change enables separation via ion exchange chromatography or isoelectric focusing, simplifying purification while increasing heterodimer yield.
2Duration of action of moving object
If the serum half-life of antibodies is extended by altering constant domains, then pharmacokinetic properties improve, but antigen binding affinity or immunogenicity may be affected
Solution Approach 1:
The patent divides the antibody into functional segments: the variable domains (VH and VL) that are responsible for antigen binding are kept unchanged to preserve binding affinity, while the constant domains (CH1, CH2, CH3) are separately engineered to modify pharmacokinetic properties. This segmentation allows independent optimization of binding function and serum half-life without cross-interference. The asymmetric pI modification is applied specifically to constant domains, leaving the antigen-binding regions intact.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates high-yield purification of heterodimers and extends serum half-life of antibodies by reducing immunogenicity and improving pharmacokinetic properties.
Implementation Method 1
purification by ion exchange chromatography
Data Source
AI summary
The invention relates generally to compositions and methods for purifying the desired species from a mixture of desired heterodimer and contaminating homodimer immunoglobulin variants by modifying the isoelectric point(s) of the individual chains.