Self-Stabilizing Linker Units in Drug Conjugates
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Solution Overview
Problem
Ligand Drug Conjugates (LDCs) face issues with premature loss of drug linker moieties due to retro-Michael addition, leading to reduced effectiveness and off-target effects, and the stereochemistry of acyclic Basic Units can impact release kinetics and manufacturing heterogeneity.
Innovation Solution
The development of Ligand Drug Conjugate compositions with self-stabilizing Linker Units, specifically incorporating a cyclic Basic Unit that undergoes hydrolysis to form succinic acid amides, which are resistant to retro-Michael addition, and the use of targeting agents like antibodies that selectively bind to abnormal cells to enhance therapeutic efficacy while minimizing side effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an electrophilic maleimide moiety is used in the Linker Unit to react with thiol functional groups of targeting agents, then the conjugation kinetics are fast and specific, but the thio-substituted product is subject to slow elimination and retro-Michael addition, leading to loss of drug linker moiety
Solution Approach 1:
The Linker Unit is divided into two functional segments: an electrophilic maleimide moiety for rapid conjugation with thiol groups, and a basic substituent component that stabilizes the thio-substituted product. This segmentation allows each segment to perform its specific function - the maleimide provides fast kinetics while the basic substituent prevents retro-Michael addition, resolving the contradiction between speed and reliability.
Solution Approach 2:
The basic substituent component acts as an intermediary that mediates between the maleimide-thiol reaction and the stability issue. It provides a stabilizing interaction with the thio-substituted product, preventing elimination and retro-Michael addition without interfering with the initial conjugation kinetics. This intermediary element resolves the contradiction by adding stability without sacrificing reaction speed.
2Reliability
If an acyclic Basic Unit is used to stabilize the Linker Unit against retro-Michael addition, then the drug linker moiety stability improves, but loss of stereochemical integrity occurs and manufacturing heterogeneity increases
Solution Approach 1:
The invention changes the structural parameter of the Basic Unit from acyclic to cyclic form. This parameter change has two effects: it maintains the stabilizing function against retro-Michael addition while simultaneously improving stereochemical integrity. The cyclic structure is more rigid and maintains its configuration better during synthesis and storage, reducing manufacturing heterogeneity while preserving the stability benefit.
Solution Approach 2:
The Linker Unit is designed as a composite structure combining the electrophilic maleimide moiety with a cyclic Basic Unit. This composite design integrates both the rapid conjugation capability and the stability function, while the cyclic Basic Unit specifically addresses the stereochemical integrity issue by providing a more rigid, configurationally stable structure compared to acyclic alternatives.
3Reliability
If the Linker Unit is designed for rapid hydrolysis to ring-opened forms, then resistance to retro-Michael addition improves, but the complexity of the linker structure increases
Solution Approach 1:
The Linker Unit is designed to be self-stabilizing through its own inherent structure. The basic substituent component (particularly the cyclic Basic Unit) provides intrinsic stability against retro-Michael addition without requiring external stabilization mechanisms or complex multi-component systems. The structure serves its own stabilization function, reducing overall system complexity while maintaining high reliability.
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 self-stabilizing Linker Units in LDCs improve the stability and controlled release of biologically active compounds, reducing unwanted side effects and enhancing the therapeutic effect by maintaining stereochemical integrity and heterogeneity, thereby improving the targeting specificity and efficacy of the conjugates.
Implementation Method 1
an electrophilic maleimide moiety in a Linker Unit of a Drug Linker compound... has proven to be very useful due to its high degree of specificity for reacting with thiol functional groups (eqn. 1) of a targeting agent. For example, a cysteine residue that is native to or introduced into an antibody and is solvent accessible typically exhibits very fast kinetics for conjugate addition (Michael addition) of its thiol functional group to the maleimide moiety.
Implementation Method 2
the thio-substituted product of the reaction between the electrophilic maleimide moiety and a sulfur atom of a free thiol functional group of an antibody is subject to slow elimination, thus reversing the above reaction. When this type of reversible reaction occurs in a purified preparation of an ADC, or other LDC prepared in similar manner, the reaction may be undetectable because the maleimide and thiol functional groups, which are regenerated through the elimination process, can simply react again, thus reforming, to some extent, the intact Conjugate.
Implementation Method 3
the acyclic Basic Unit is placed on a carbon atom of an alkylene moiety attached to imide nitrogen of a maleimide moiety in a Drug Linker compound so that once conjugate addition by a thiol functional group of a targeting agent to the maleimide moiety occurs to provide a Ligand Drug Conjugate, the resultant thio-substituted succinimide ring system undergoes sufficiently rapid hydrolysis to a ring-opened form(s).
Data Source
AI summary
Compounds and compositions are disclosed in which a Drug Unit is linked to a targeting Ligand Unit through a self-stabilizing Linker Unit from which a drug compound or active drug moiety is released at the targeted site of action. Methods for treating diseases characterized by the targeted abnormal cells, such as cancer or an autoimmune disease using the compounds and compositions of the invention are also disclosed.