Engineered IgG Hinge Cysteine Conjugation for ADC DAR Control
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Solution Overview
Problem
Existing antibody-drug conjugates (ADCs) face challenges such as suboptimal therapeutic index, higher clearance rates, narrower therapeutic windows, and poor stability due to their complex heterogeneity and reliance on non-specific conjugation methods.
Innovation Solution
The development of ADCs with engineered IgG hinge regions that contain a predetermined number of cysteine residues, allowing for site-specific cysteine-based conjugation to achieve a homogeneous product with a tailored drug-to-antibody ratio (DAR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If random conjugation to primary amines on lysine side chains is used, then the conjugation process is simple, but the product heterogeneity increases and manufacturing precision decreases
Solution Approach 1:
The invention extracts and utilizes the naturally occurring cysteine residues in the IgG hinge region as specific conjugation sites, removing the need for random lysine conjugation. This provides predetermined, site-specific attachment points that enable precise DAR control while maintaining a relatively simple conjugation process using thiol-reactive linkers.
Solution Approach 2:
The invention applies local quality by concentrating all conjugation activity at the hinge region cysteine residues, which are strategically positioned away from the antigen-binding and Fc effector functions. This localized approach ensures uniform DAR across the antibody population while preserving biological activity.
2Manufacturing precision
If enzyme-mediated conjugation to specific peptide tags is used, then manufacturing precision improves, but device complexity and ease of manufacture worsen due to additional manufacturing steps
Solution Approach 1:
The invention employs the antibody's own hinge region cysteine residues as the conjugation sites, eliminating the need for external enzymes or additional peptide tags. The thiol-reactive linkers directly conjugate to these endogenous cysteines, providing precise DAR control without requiring enzyme production, purification, or removal steps.
3Manufacturing precision
If sortase conjugation with peptide tags is used, then manufacturing precision improves, but ease of manufacture worsens due to immunogenicity concerns
Solution Approach 1:
The invention removes the need for exogenous peptide tags and bacterial enzymes by utilizing the naturally occurring cysteine residues in the human IgG hinge region. This eliminates potential immunogenicity concerns associated with non-human sequences while maintaining precise site-specific conjugation.
4Productivity
If first-generation ADCs with heterogenic structures are produced, then productivity is high, but reliability and stability worsen due to complex heterogeneity
Solution Approach 1:
The invention achieves homogeneity by directing all drug conjugation to the identical hinge region cysteine residues across the antibody population. This produces a uniform ADC structure with defined DAR values (primarily DAR 4), eliminating the complex heterogeneity of first-generation ADCs while maintaining efficient production through straightforward thiol-maleimide chemistry.
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
This approach enables the production of ADCs with preserved or elevated stability, cell binding, internalization, antibody-dependent cellular cytotoxicity (ADCC), and complement-dependent cytotoxicity (CDC), while reducing immunogenicity and avoiding CMC challenges associated with free cysteines.
Implementation Method 1
the engineered IgG hinge region is heterologous to the Fc region and/or is mutated to provide a predetermined number of cysteine residues
Implementation Method 2
conjugated to the antibody of interest, wherein the linker-payload comprises a thiol-reactive group
Data Source
Figure 1~1C
Figure 2
Figure 2
AI summary
The present invention provides an antibody-drug conjugate (ADC), wherein the antibody is conjugated to the drug by cysteine-based site-specific conjugation, wherein the antibody comprises a first polypeptide comprising an immunoglobulin fragment crystallisable (Fc) region, at least one variable domain N-terminal of the Fc region and an engineered IgG hinge region between the Fc region and the at least one variable domain, and wherein the engineered IgG hinge region is heterologous to the Fc region and/or is mutated to provide a predetermined number of cysteine residues.