Thiol-Reactive ADC Linkers for Stable Targeted Drug Release
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Solution Overview
Problem
Current antibody-drug conjugates (ADCs) face challenges with narrow therapeutic windows and unpredictable dose-limiting toxicities due to off-target effects, necessitating improved linker-payload chemistry for targeted delivery and reduced off-target toxicity.
Innovation Solution
Development of linkers with thiol-reactive groups, such as substituted acrylic and propiolic groups, for conjugating cytotoxic agents to cell-binding molecules, allowing for multiple drug attachments and precise control over drug ratios and sites, enhancing targeted delivery and reducing off-target exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemotherapy is used, then cytotoxic agents can kill malignant cells, but they cannot discriminate between normal and malignant cells causing off-target toxicity and narrow therapeutic windows
Solution Approach 1:
The conjugate is segmented into distinct functional modules: a cell-binding molecule (antibody or ligand) for targeted recognition, a linker for stable circulation and controlled delivery, and a cytotoxic payload for cell killing. This segmentation allows the cytotoxic agent to be delivered specifically to target cells while remaining inert during circulation, resolving the contradiction between efficacy and off-target toxicity.
Solution Approach 2:
The linker acts as an intermediary component that bridges the cell-binding molecule and the cytotoxic payload. It remains stable during circulation to prevent premature drug release and off-target effects, then enables controlled drug release at the target site through specific cleavage mechanisms (enzymatic, pH-dependent, or reducing conditions), thus resolving the contradiction between stable delivery and targeted activation.
2Reliability
If multiple drugs are conjugated to cell-binding molecules, then efficacy is enhanced through dual targeting strategies, but control over drug ratios and sites becomes more difficult
Solution Approach 1:
The patent employs site-specific conjugation strategies where the linker is attached to specific residues or structures on the cell-binding molecule (such as engineered cysteines, N-terminal residues, or glycan sites). This local quality approach ensures that multiple drugs are conjugated at defined locations with controlled stoichiometry, achieving both enhanced efficacy through multi-drug delivery and manufacturing precision through homogeneous conjugate populations.
Solution Approach 2:
The patent utilizes changes in chemical parameters (pH, reducing conditions, enzymatic activity) to control the conjugation process and drug release. By adjusting these parameters, the conjugation reaction can be controlled to achieve desired drug-to-antibody ratios (DAR), and the linker can be designed to release drugs at specific sites under controlled conditions, resolving the contradiction between multi-drug efficacy and conjugation precision.
3Object-affected harmful factors
If the linker is stable in circulation, then off-target exposure is reduced, but the linker must still release the cytotoxic agent efficiently in target cells
Solution Approach 1:
The linker is designed with dynamic properties that allow it to transition from a stable state during circulation to an activated state at the target site. The linker remains stable under physiological conditions in blood but undergoes specific changes (cleavage by intracellular enzymes, pH-dependent opening, or reduction by intracellular thiols) upon entering the target cell, enabling efficient drug release only where needed and resolving the contradiction between stability and release efficiency.
Solution Approach 2:
The linker exploits changes in biochemical parameters between the circulation environment and the intracellular environment. For example, the intracellular reducing environment (high glutathione concentration), specific pH conditions in endosomes/lysosomes, or presence of cleavage-specific enzymes trigger linker activation and drug release. This parameter-based control ensures stable circulation while enabling reliable target-specific drug release.
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
The proposed linkers enable prolonged circulation half-life, increased efficacy through dual targeting strategies, and minimized off-target toxicity, leading to improved batch-to-batch consistency and enhanced therapeutic outcomes.
Implementation Method 1
linkers having a group of propiolyl, substituted acryl (acryloyl), or disubstituted propanoyl, used for the conjugation of compounds, in particular, cytotoxic agents to a cell-binding molecule
Data Source
AI summary
The present invention relates to linkers having a group of propiolyl, substituted acryl (acryloyl), or disubstituted propanoyl, and using such linkers for the conjugation of compounds, in particular, cytotoxic agents to a cell-binding molecule.