Capped Antibody Cysteines for Homogeneous ADC Conjugation
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Solution Overview
Problem
The production of antibody-drug conjugates (ADCs) faces challenges due to the formation of disulfide bonds between unpaired cysteine residues in mammalian cells, leading to heterogeneous mixtures and the need for complex reduction and reoxidation steps, which can disrupt protein folding and stability.
Innovation Solution
Engineered antibodies with specific capping entities, such as nitrobenzoate-capped antibodies, allow for selective reduction and direct conjugation without inter-chain disulfide reduction-reoxidation steps, using agents like tris(3-sulfonatophenyl) phosphine, and the use of chemical handles like aldehydes and azides for additional conjugation chemistry, enabling the production of fully uncapped antibodies in low cysteine media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If unpaired cysteine residues form disulfide bonds in mammalian cells, then antibody stability is improved, but manufacturing precision deteriorates due to heterogeneous mixtures
Solution Approach 1:
The patent applies preliminary action by pre-capping unpaired cysteine residues with non-disulfide forming groups (such as maleimide or other thiol-reactive groups) before the antibody is secreted from mammalian cells. This prevents the formation of heterogeneous disulfide bonds in vivo, ensuring that the antibody remains in a defined, homogeneous state ready for controlled site-specific conjugation later in the manufacturing process.
2Productivity
If reduction and reoxidation steps are used to conjugate drugs to cysteine residues, then conjugation efficiency is improved, but protein stability deteriorates due to disulfide shuffling
Solution Approach 1:
The patent extracts the problematic reduction-reoxidation step from the conjugation process by using site-specific cysteine residues that are already in the reduced thiol state (either engineered as such or reduced selectively without affecting interchain disulfides). This allows direct conjugation to occur without requiring global reduction and reoxidation, thereby eliminating disulfide shuffling and maintaining protein stability while achieving efficient drug attachment.
3Reliability
If complex reduction and reoxidation steps are implemented, then conjugation completeness is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-preparing the antibody with accessible, site-specific cysteine residues in the reduced thiol state before conjugation. This eliminates the need for complex in-process reduction and reoxidation steps, simplifying the overall workflow while ensuring complete and controlled drug attachment at the predetermined sites.
4Adaptability or versatility
If unpaired cysteine residues are left uncapped, then conjugation sites are available, but manufacturing precision deteriorates due to random disulfide formation
Solution Approach 1:
The patent applies local quality by engineering specific cysteine residues at predetermined locations on the antibody (such as in the Fc region) to serve as dedicated conjugation sites. These localised cysteine residues are kept in a reactive thiol state while other cysteines form stable disulfides, ensuring that drug conjugation occurs only at the intended sites with high precision and controlled drug-to-antibody ratios.
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 simplifies the drug conjugation process, maintains antibody integrity, and improves the therapeutic index by avoiding disulfide shuffling and protein instability, resulting in more homogeneous and stable ADCs.
Implementation Method 1
ADCs formed by the selective reduction of the capped antibodies' cysteine residues which avoids the reduction of inter-chain disulfides
Implementation Method 2
the formation of disulfide bonds between unpaired cysteine residues in mammalian cells
Data Source
AI summary
An antibody production process in mammalian cells in which engineered unpaired cysteine residues are post-translationally modified and capped with particular chemical entities, which capped antibodies are well suited to further site-specific conjugation steps to form antibody-drug conjugates (ADCs) or protein drug conjugates; ADCs produced using these capped antibodies including in particular ADCs formed by the selective reduction of the capped antibodies' cysteine residues, and ADCs formed using chemical handles such as aldehyde/azide/alkyne biorthogonal groups, which permit additional drug conjugation chemistry; and uncapped antibodies produced by cells in low cysteine, cysteine and glutathione media, and ADCs produced via direct conjugation to these uncapped antibodies.