Beta-Eliminative Linkers That Suppress Aza-Michael Addition
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Solution Overview
Problem
Existing β-eliminative linkers in drug conjugates suffer from undesired aza-Michael addition reactions, leading to linker residues that can react with physiological nucleophiles, compromising the stability and control of drug release.
Innovation Solution
Incorporating a geminally-substituted carbon adjacent to the leaving oxygen in the linker structure, which significantly suppresses nucleophile addition and lowers the equilibrium constant, thereby reducing unwanted side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional linkers are used in antibody conjugation, then the conjugation process is simple, but the stability and pharmacokinetic properties of the conjugate are insufficient
Solution Approach 1:
The linker is divided into distinct functional modules: a stable core structure (e.g., PEG backbone), a site-specific attachment point for the antibody (e.g., engineered cysteine or lysine), and a payload attachment site. This segmentation allows each module to be optimized independently for stability while maintaining a relatively simple overall conjugation process.
Solution Approach 2:
The patent introduces engineered amino acid residues (intermediaries) in the antibody that specifically recognize and bind to the linker structure. This intermediary mechanism enables stable conjugation without requiring complex crosslinking chemistry, as the engineered residues mediate the attachment through their inherent chemical properties.
2Ease of manufacture
If conventional linkers are used in antibody conjugation, then the manufacturing process is straightforward, but the pharmacokinetic properties and in vivo stability are inadequate
Solution Approach 1:
The patent modifies the chemical parameters of the linker by incorporating PEG chains of specific lengths and compositions, adjusting the hydrophilicity, molecular weight, and flexibility parameters to optimize both manufacturability and in vivo stability. These parameter changes allow the linker to resist proteolysis while maintaining solubility and ease of conjugation.
Solution Approach 2:
The linker employs composite structures combining PEG (polyethylene glycol) with amino acid sequences and optional charged groups. This composite design integrates the biocompatibility and stability of PEG with the specific binding capabilities of amino acids, creating a linker that is both easy to manufacture and highly stable in vivo.
3Productivity
If non-specific conjugation methods are used, then the process is simple and fast, but the heterogeneity and batch-to-batch variability increase
Solution Approach 1:
The patent introduces specific amino acid residues at defined positions in the antibody (local modifications) that have enhanced nucleophilicity or binding affinity for the linker. This local quality enhancement allows rapid conjugation to occur at specific sites rather than throughout the entire antibody, maintaining productivity while achieving homogeneous products with reduced batch-to-batch variability.
Data Source
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AI summary
Provided are β-eliminative linkers suitable for the conjugation of small molecule, peptide, and protein and compounds comprising the linkers.