Activatable Antibody Cleavable Linker Reduces Off-Target Toxicity
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Solution Overview
Problem
Existing activatable antibodies face challenges such as immune responses, reduced efficacy due to incomplete masking peptide release, strong antigen-antibody interactions, and toxicity to normal tissues, limiting their effectiveness in targeting tumors while minimizing off-target effects.
Innovation Solution
Design of activatable antibodies with a cleavable linker that prevents antigen binding until cleaved by tumor-associated proteases, allowing for enhanced binding affinity to tumor-specific antigens and reduced binding to normal tissues, thereby improving therapeutic index and drug tolerability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a masking moiety is used to block the antigen binding site, then off-target toxicity is reduced, but the masking moiety competes with the target for binding to the target binding moiety, reducing efficacy
Solution Approach 1:
The patent removes the masking moiety entirely from the antibody structure. Instead of using a separate masking component that competes for binding, the design relies on the cleavable linker itself to control antibody activation, eliminating the competition between masking moiety and target antigen.
Solution Approach 2:
The antibody is segmented into variable regions (VH and VL) connected by a cleavable linker. This segmentation allows the antibody to be inactive in circulation (when linker is intact) and become active only after linker cleavage at the tumor site, achieving both reduced off-target toxicity and maintained binding efficacy.
2Object-affected harmful factors
If a masking moiety is used to prevent binding to normal tissues, then normal tissue targeting is reduced, but incomplete release of the masking peptide reduces therapeutic efficacy
Solution Approach 1:
The patent extracts and removes the masking moiety from the system entirely. The cleavable linker directly connects the variable regions without any intermediate masking component, ensuring complete and clean activation of the antibody at the target site without residual masking peptides that could reduce efficacy.
Solution Approach 2:
The cleavable linker serves as the intermediary mechanism between the inactive pro-antibody form in circulation and the active antibody form at the tumor site. This intermediary is designed to be cleaved specifically by tumor-associated proteases, enabling reliable activation without masking moiety interference.
3Reliability
If a cleavable linker is used to activate the antibody at the tumor site, then binding affinity to tumor targets is enhanced, but the linker may be cleaved prematurely leading to off-target effects
Solution Approach 1:
The cleavable linker is designed with specific protease recognition sequences that are selectively cleaved by tumor-associated proteases (such as MMPs or cathepsins) present in the tumor microenvironment. This local quality ensures activation occurs specifically at the tumor site rather than systemically, enhancing binding affinity where needed while minimizing off-target cleavage.
4Reliability
If the antibody is designed to bind strongly to the target antigen, then therapeutic efficacy is improved, but toxicity to normal tissues expressing the same antigen increases
Solution Approach 1:
The antibody is administered in an inactive pro-antibody form that cannot bind to the target antigen. The cleavable linker prevents binding activity during circulation through normal tissues. Only after reaching the tumor site and being cleaved by tumor-associated proteases does the antibody become active and bind strongly to the target, achieving high therapeutic efficacy without toxicity to normal tissues.
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 antibodies exhibit significantly increased binding affinity to tumor targets post-cleavage, reducing off-target toxicities and enhancing therapeutic efficacy while maintaining long half-life and stability, thus improving cancer treatment outcomes.
Implementation Method 1
wherein the cleavable linker prevents or reduces the first light chain and the first heavy chain from forming a first antigen binding site against a first antigen; and wherein cleavage of the cleavable linker releases the first heavy chain
Data Source
AI summary
The present invention includes proteins, nucleic acids and methods of making and using an activatable antibody (aAb) comprising, in order, the following structure: a first light chain comprising: a first variable light region; a cleavable linker; a first heavy chain comprising: a first variable heavy region; wherein the cleavable linker prevents or reduces the first light chain and the first heavy chain from forming a first antigen binding site against a first antigen; and wherein cleavage of the cleavable linker releases the first heavy chain to allow formation of the first antigen binding site to bind a first antigen.