Branched Linkers for Antibody-Drug Conjugates
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Solution Overview
Problem
Current antibody-drug conjugate (ADC) linkers face challenges with stability in physiological conditions, leading to premature drug dissociation and reduced efficacy, as they are either unstable or fail to specifically release the drug within targeted cancer cells.
Innovation Solution
The development of branched linkers with a branching unit covalently coupled to an antibody via a primary linker, where active agents are attached through secondary linkers and cleavage groups, allowing for controlled release of the drug within the cell by hydrolysis, utilizing polyethylene glycol units and specific amino acids for enhanced stability and targeting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If non-cleavable linkers are used to improve stability, then plasma stability is improved, but drug release efficacy deteriorates due to inability to dissociate
Solution Approach 1:
The linker is divided into multiple segments: a stable non-cleavable portion (for plasma stability) and a cleavable portion (for intracellular drug release). This segmentation allows the linker to exhibit different stability characteristics in different physiological environments, resolving the contradiction between overall stability and controlled release capability.
Solution Approach 2:
The linker's chemical structure is modified to include environment-sensitive bonds that change their stability based on physiological conditions. The linker remains stable at neutral pH in plasma but becomes labile in the acidic lysosomal environment, enabling conditional drug release that satisfies both stability and efficacy requirements.
2Reliability
If cleavable linkers are used to enable drug release, then drug release capability is improved, but plasma stability deteriorates leading to premature dissociation
Solution Approach 1:
The linker incorporates pH-sensitive chemical bonds that maintain stability at neutral pH (plasma conditions) but cleave at acidic pH (lysosomal conditions). This parameter-based switching mechanism enables the linker to provide plasma stability while ensuring reliable intracellular drug release.
Solution Approach 2:
The cleavable bond acts as an intermediary element between the stable linker backbone and the drug payload. This intermediary bond remains intact during circulation but selectively breaks under lysosomal conditions, mediating the transition from stable transport to active release.
3Reliability
If disulfide-based linkers are used to enable dissociation, then intracellular release is improved, but stability in blood deteriorates due to thiol exchange reactions
Solution Approach 1:
The linker replaces disulfide bonds with peptide bonds that are stable in the oxidizing environment of blood but cleavable in the reducing environment of the cytosol. This parameter-based design ensures stability during circulation while enabling intracellular release through enzymatic or chemical cleavage of the peptide bond.
Solution Approach 2:
The linker employs a disposable cleavable bond designed to remain stable until needed, then irreversibly break to release the drug. This single-use cleavable bond provides stable transport followed by definitive release, eliminating the need for reversible bonding mechanisms.
4Ease of manufacture
If thiol-maleimide method is used for conjugation, then ease of manufacture is improved, but stability deteriorates leading to drug dissociation
Solution Approach 1:
The conjugation chemistry is modified to create a more stable thioether bond that resists hydrolysis and exchange reactions. The improved linkage maintains ease of manufacture through established chemistry while providing enhanced stability that prevents premature drug dissociation during circulation.
Solution Approach 2:
The linker incorporates a composite structure combining stable thioether bonding with a cleavable peptide segment. This composite design maintains the manufacturing advantages of thiol-based chemistry while adding stability through the robust thioether linkage and controlled cleavability through the peptide bond.
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 enhances the stability and targeted delivery of the drug, improving the therapeutic index by ensuring the drug is released only within the target cell, thereby increasing the efficacy and reducing toxicity.
Implementation Method 1
The primary and/or secondary linker may comprise at least one polyethylene glycol unit
Data Source
AI summary
The present invention relates to antibody-drug conjugates (ADCs) wherein a plurality of active agents are conjugated to an antibody through at least one branched linker. The branched linker may comprise a branching unit, and two active agents are coupled to the branching unit through a secondary linker and the branching unit is coupled to the antibody by a primary linker. The active agents may be the same or different. In certain such embodiments, two or more such branched linkers are conjugated to the antibody, e.g., 2-4 branched linkers, which may each be coupled to a different C-terminal cysteine of a heavy or light chain of the antibody. The branched linker may comprise one active agent coupled to the branching unit by a first branch and a second branch that comprises a polyethylene glycol moiety coupled to the branching unit. In certain such embodiments, two or more such branched linkers are conjugated to the antibody, e.g., 2-4 branched linkers, which may each be coupled to a different C-terminal cysteine of a heavy or light chain of the antibody.