pH-Dependent Antigen-Binding Protein Constructs for FOLR1 Targeting
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Solution Overview
Problem
Current antibody-drug conjugates have limitations in efficacy, particularly in toxin liberation, target cell killing, and endolysosomal delivery, necessitating enhanced antigen-binding protein constructs that can specifically bind FOLR1 and operate optimally across different pH levels.
Innovation Solution
Development of antigen-binding protein constructs (ABPCs) with antigen-binding domains that have faster dissociation rates or higher dissociation constants at pH 4.0-6.5 compared to pH 7.0-8.0, allowing for increased toxin liberation, target cell killing, and endolysosomal delivery, incorporating histidine substitutions in variable domains and CDRs, and potentially including conjugated toxins or drugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antibody-drug conjugates are used, then they can deliver toxins to target cells, but their efficacy in toxin liberation, target cell killing, and endolysosomal delivery is limited
Solution Approach 1:
The patent modifies the antigen-binding domain through histidine substitutions at specific positions (e.g., positions 24, 27, 29, 31, 32, 33, 34 in the heavy chain variable domain of mirvetuximab). These amino acid substitutions change the pH-sensitive parameters of the antibody, enabling faster dissociation at acidic pH (4.0-6.5) compared to neutral pH (7.0-8.0), thereby enhancing toxin liberation efficiency while maintaining stable binding during circulation
Solution Approach 2:
The invention creates dynamically responsive antibody constructs that change their binding affinity based on pH conditions. The histidine-containing antigen-binding domains exhibit pH-dependent dissociation behavior: stable binding at physiological pH for circulation and targeted delivery, but rapid dissociation at acidic pH within endolysosomes to release the toxin payload, thus dynamically adapting to different cellular environments
2Reliability
If conventional antibody-drug conjugates are used, then they can bind to FOLR1 on target cells, but their endolysosomal delivery and target cell killing are insufficient
Solution Approach 1:
The patent introduces histidine substitutions in the antigen-binding domain that specifically alter the pH-dissociation characteristics. These substitutions enable the antibody to maintain stable binding to FOLR1 at physiological pH during circulation, while rapidly dissociating at the acidic pH of endolysosomes (pH 4.0-6.5) to release the conjugated toxin, thereby significantly improving endolysosomal delivery efficiency
Solution Approach 2:
The invention performs preliminary engineering of the antigen-binding domain by incorporating histidine residues at strategically selected positions before the antibody encounters the target cell. This preliminary modification ensures that the antibody is pre-configured to undergo pH-dependent conformational changes and dissociation upon entering the acidic endolysosomal environment, facilitating efficient toxin release without requiring additional activation steps
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 ABPCs demonstrate enhanced toxin liberation, increased target cell killing, and improved endolysosomal delivery, leading to increased therapeutic efficacy against cancer cells expressing FOLR1, while maintaining minimal reduction in FOLR1 surface levels.
Implementation Method 1
the dissociation rate of the first antigen-binding domain at a pH of about 4.0 to about 6.5 is faster than the dissociation rate at a pH of about 7.0 to about 8.0
Data Source
AI summary
Provided herein are antigen-binding protein constructs capable of specifically binding FOLR1 or an epitope of FOLR1 presented on the surface of a target mammalian cell, wherein said antigen binding is pH-dependent. Provided are also uses of said antigen-binding protein constructs.