Cyclic Octapeptide Ligands for Selective AlphaVbeta8 Integrin Targeting
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Solution Overview
Problem
Current therapies lack highly active and selective small molecule ligands for the αvβ8 integrin, which is up-regulated in various diseases, including cancer and fibrosis, and existing antibodies are costly and prone to side effects.
Innovation Solution
Development of low molecular weight 8-mer cyclic peptides with a specific amino acid sequence, such as Cyclo-(Arg-Gly-Asp-X1-X2-X3-X4-X5), that exhibit sub-nanomolar binding affinity for αvβ8 integrin with minimal binding to other RGD-recognizing integrins, allowing for selective targeting and potential therapeutic applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antibodies are used to target αvβ8 integrin, then high binding affinity can be achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent creates simplified peptide copies (cyclic octapeptides with RGD motif) that replicate the high binding affinity function of full-length antibodies against αvβ8 integrin. These peptide mimics capture the essential binding capability while eliminating the manufacturing complexity of producing complete antibody molecules.
Solution Approach 2:
The invention extracts and isolates the critical binding domain from the complex antibody structure. By identifying and utilizing only the essential amino acid sequence (cyclic octapeptide containing RGD motif) responsible for integrin binding, the patent removes unnecessary portions of the antibody molecule, thereby simplifying manufacturing while preserving therapeutic function.
2Measurement precision
If antibodies are used for imaging purposes, then target detection is achieved, but undesired binding to serum albumin occurs
Solution Approach 1:
The patent modifies the binding interface by using cyclic octapeptides with specific local amino acid sequences (particularly the RGD motif combined with cyclic constraints) that provide high specificity for αvβ8 integrin. This localized optimization of binding properties eliminates off-target interactions with serum albumin while maintaining strong target detection capability.
3Adaptability or versatility
If existing ligands are used for multiple integrin subtypes, then broader therapeutic coverage is achieved, but selectivity for αvβ8 integrin is reduced
Solution Approach 1:
Instead of designing ligands that bind multiple integrin subtypes (broad coverage approach), the patent inverts the strategy by creating ligands with highly restricted specificity for αvβ8 integrin alone. This inversion prioritizes selectivity over versatility, using cyclic octapeptide structures that are tailored to recognize unique features of αvβ8 integrin while deliberately avoiding cross-reactivity with other integrin subtypes.
Data Source
AI summary
Disclosed are compounds represented by the following general formula (I): Cyclo-(Arg-Gly-Asp-X1-X2-X3-X4-X5) (I) wherein the variables groups X1 to X5 have the following meanings X1: Leu, Ile, Nle, Val, Tyr, Phe; X2: D-amino acid such as D-Pro, N-Me-D-Phe; X3: Pro, N-Me-amino acid such as N-Me-Lys, N-Me-Lys(Ac); Pro-Rx3, N-Me-Lys-Rx4; X4: Gly, Ala, Ser, Thr; X5: Leu, Ala, Tyr, His, Ile, Nle, Val, Phe wherein Pro-Rx3 represents a proline residue that carries at the C-3, C-4 or C-5 carbon atom and preferably the C-4 carbon atom a functional group selected from –NH2, -OH, -NH-Ac, -NH-hexyne, and wherein Lys-Rx4 represents a lysine residue, wherein the ω-amino nitrogen atom carries a group of the formula –L4-R4, wherein L4 is selected from the group consisting of covalent bond, -C(O)-, and -C(O)-O-,..., and wherein R4 is selected from the group consisting of –(CH2)n-C≡CH with n = 0, 1, 2, 3, 4, 5, 6, 7 or 8, or wherein the sub-sequence -X2-X3- represents a β-turn mimetic diffeωωring from the meanings above, or pharmaceutically acceptable salts, esters, solvates, polymorphs or modified forms thereof represented by the following general formula (II): (X0)n1L(X8)n2 wherein X0 represents the compound of the general formula (I) as specified above (excluding one hydrogen atom to allow bonding to the linker), L represents a linker, X8 represents the effector moiety and wherein n1 and n2 are each independently selected from the range of 1 to 5, preferably such that each of n1 and n2 represents 1, wherein n1+n2 represents the number of valencies of the linker and is preferably in the range of from 2 to 6, more preferably 2-5, with the proviso that each of n1 and n2 is at least 1, as well as uses therefore in therapy and imaging.