Site-Specific Antibody Conjugation via Cycloaddition
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Solution Overview
Problem
Current antibody-drug conjugates (ADCs) face challenges in achieving a controlled and specific drug-antibody ratio (DAR) of 1, leading to inefficiencies in targeted drug delivery and increased off-target toxicities due to random conjugation methods, which result in heterogeneous drug loading and reduced therapeutic index.
Innovation Solution
A method to convert full-length antibodies into stable site-specific ADCs with a single drug load (DAR1) using cycloaddition conjugation reactions, involving glycan trimming and cyclooctyne-based click chemistry, allowing for precise attachment of payloads without prior antibody reengineering, thereby avoiding effector function abrogation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If random conjugation methods are used to attach payloads to antibodies, then the conjugation process is simple and fast, but the drug-antibody ratio is uncontrolled and heterogeneous, leading to reduced therapeutic index and increased off-target toxicities
Solution Approach 1:
The patent introduces non-natural amino acids (such as p-azidophenylalanine or p-acetamidophenylalanine) at specific positions in the antibody sequence before conjugation. These pre-installed functional groups serve as predetermined attachment sites that enable controlled site-specific conjugation, resolving the contradiction by preparing the antibody in advance with built-in conjugation handles that ensure both speed and precision.
Solution Approach 2:
The patent modifies specific local regions of the antibody by incorporating non-natural amino acids at defined positions (e.g., in the CDR regions or Fc region). This localized modification approach allows controlled attachment of payloads at specific sites while leaving the rest of the antibody structure unchanged, achieving both controlled DAR and maintained antibody function.
2Manufacturing precision
If site-specific conjugation methods are used to achieve controlled drug-antibody ratio, then the therapeutic index is improved, but the antibody requires prior reengineering and the process becomes more complex
Solution Approach 1:
The patent uses non-natural amino acids as surrogate handles that copy the functionality of traditional conjugation sites (like cysteine or lysine residues) but with the advantage of being site-specific and controllable. These synthetic amino acid copies enable precise conjugation without requiring complex antibody engineering, simplifying the overall process while maintaining controlled DAR.
Solution Approach 2:
The patent changes the chemical parameters of the antibody by incorporating non-natural amino acids with specific functional groups (azide, acetamido, etc.) at defined positions. This parameter change approach allows controlled conjugation chemistry to occur at specific sites, achieving precise DAR control without complex structural reengineering of the antibody framework.
3Ease of manufacture
If traditional conjugation methods are used, then the process is easier to implement, but off-target toxicities increase due to heterogeneous drug loading
Solution Approach 1:
The patent segments the antibody structure by introducing distinct non-natural amino acid handles at specific locations (such as different CDRs or Fc regions). This segmentation allows controlled attachment of exactly one payload per antibody at a predetermined site, eliminating the heterogeneous mixture of 0-8 drugs per antibody that causes off-target toxicities in traditional methods.
4Reliability
If high drug-antibody ratio is achieved to increase therapeutic potency, then the efficacy against target cells is improved, but off-target toxicities and immunogenicity increase
Solution Approach 1:
The patent pre-installs non-natural amino acid handles at optimal positions that maximize therapeutic efficacy while minimizing off-target effects. By controlling the exact location and number of payload attachments (typically DAR=1 or DAR=2), the method achieves high therapeutic potency without the immunogenicity and off-target toxicities associated with high DAR achieved through random conjugation methods.
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 enables homogeneous and stable ADCs with improved therapeutic index and reduced off-target toxicities by ensuring a consistent single drug load, enhancing the precision and efficacy of targeted drug delivery.
Implementation Method 1
attachment of a bivalent cyclooctyne-based click chemistry reagent, allowing for precise attachment of payloads
Data Source
AI summary
The present invention provides antibody-payload conjugates having a payload-to-antibody ratio of 1. The antibody-payload conjugate having structure (1): wherein:a, b and c are each independently 0 or 1;L1, L2 and L3 are linkers;D is a payload;BM is a branching moiety;Z are connecting groups obtainable by a cycloaddition reaction.The invention further provides a method for preparing the antibody-payload conjugate according to the invention, an intermediate compound in that preparation method, and medical uses of the antibody-payload conjugate according to the invention.