CXCR4 Ligand Linkers Balancing Affinity and Functional Utility
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Solution Overview
Problem
Existing CXCR4 ligands face challenges in maintaining high affinity towards the human CXCR4 receptor while allowing linkage of a broad variety of functional groups for diagnostic or therapeutic applications, often resulting in significant affinity losses with structural modifications.
Innovation Solution
Development of novel CXCR4 receptor ligands with a specific linker structure that allows attachment of various functional moieties, preserving or enhancing CXCR4 affinity, and featuring a cyclopeptide group and a linker with a substituent carrying a positive charge under physiological conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If structural modifications are made to allow linkage of functional groups for diagnostic or therapeutic applications, then versatility and adaptability are improved, but CXCR4 affinity deteriorates with significant affinity losses
Solution Approach 1:
The ligand is divided into distinct functional modules: a core CXCR4-binding motif (cyclopeptide with specific amino acid sequence) and separate functional group moieties (diagnostic labels, therapeutic agents). These modules are connected through linkers that minimize interference with the binding motif, allowing functional versatility while preserving high CXCR4 affinity through the segregated design of binding and functional elements.
Solution Approach 2:
Linker molecules serve as intermediaries connecting the CXCR4-binding motif to various functional groups (diagnostic labels, therapeutic agents). These linkers are specifically designed with appropriate length, flexibility, and chemical properties to bridge the binding motif and functional moieties while minimizing steric hindrance and electrostatic interference, thus maintaining high affinity binding to CXCR4 despite the presence of diverse functional attachments.
2Adaptability or versatility
If functional groups are attached to the ligand structure, then diagnostic and therapeutic utility are improved, but the ligand structure becomes more complex
Solution Approach 1:
A universal modular platform is established with a standardized core CXCR4-binding motif and standardized linker architecture. This universal core can accommodate multiple different functional groups (various diagnostic labels, different therapeutic agents) attached through the standardized linker interface, enabling one core structure to serve multiple diagnostic and therapeutic applications without redesigning the entire ligand each time.
Solution Approach 2:
Different regions of the ligand are assigned specific functional qualities: the core cyclopeptide region is optimized for high-affinity CXCR4 binding with specific amino acid properties, while the linker region provides flexibility and spacing, and the terminal functional groups provide diagnostic or therapeutic functions. This local optimization of different regions allows the overall molecule to achieve multiple functions without excessive complexity in any single region.
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 novel ligands achieve high CXCR4 affinity with minimal impact from functional groups, enabling versatile applications in medical imaging and therapeutic interventions such as preclinical and clinical imaging, and endoradiotherapy.
Implementation Method 1
The compounds are capable of binding to the seven transmembrane G-protein coupled chemokine receptor subtype (CXCR4) with high affinity
Data Source
AI summary
The invention provides a CXCR4 receptor ligand compound of formula (I) or a salt thereof:wherein:a is 0 or 1; b is 0 or 1; c is 0 or 1, and d is 0 or 1, with the proviso that at least one of c and d is 1; e is an integer of 1 to 4;RCP is a binding motif which allows the compound to bind to the CXCR4 receptor;RL1 is H or alkyl;RL2 is substituted alkyl, which substituted alkyl is substituted with at least one group selected from —NH2 and —NH—C(═X)—NH2 with X being selected from NH and O;RL3 is —CH2—NH2 or —CH2-(1H-imidazol-4-yl);RL4 is —NH2;X1 is a coupling group;RS is a divalent spacer group; andRA is a functional group comprising a moiety with diagnostic or therapeutic utility.The compounds of the invention are suitable for use in the treatment, prevention, and/or diagnosis of a disease or disorder which can be treated or prevented by blocking the CXCR4 receptor, or which is associated with an increased or aberrant expression of the CXCR4 receptor.