GRPR Radiopharmaceutical Peptide Modifications for Faster Tissue Washout
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Solution Overview
Problem
Current radiopharmaceuticals for cancer treatment, particularly those targeting the Gastrin-Releasing Peptide Receptor (GRPR), suffer from poor pharmacokinetic properties such as slow washout from non-tumor tissues and metabolic instability, leading to potential side effects and limited therapeutic efficacy.
Innovation Solution
Development of compounds with modified dipeptides, where the C-terminal tryptophan is replaced by a specific α-amino acid to enhance the stability of the peptide bond in serum, combined with a moiety capable of generating therapeutically effective radiation, such as 68Ga or 177Lu, to improve tumor uptake and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If GRPR antagonists are used for cancer imaging and therapy, then tumor accumulation is achieved, but washout from non-tumor tissues is slow leading to poor pharmacokinetics
Solution Approach 1:
The patent modifies the peptide structure by replacing specific amino acids (e.g., Trp at position 8 with α-amino acid variants, modifications at positions 7, 9, 11) to alter the pharmacokinetic parameters of GRPR antagonists. These structural parameter changes result in faster renal clearance while maintaining tumor uptake, thereby improving the tumor-to-background ratio and overall pharmacokinetic profile.
2Reliability
If Bombesin analogs are used to target GRPR, then subnanomolar affinity is achieved, but metabolic stability is poor limiting tumor accumulation
Solution Approach 1:
The patent creates composite peptide structures by combining the GRPR-targeting Bombesin analog core with stabilizing modifications including D-amino acid replacements, N-methylated amino acids, and cyclic constraints. These composite structures maintain the subnanomolar affinity for GRPR while significantly improving metabolic stability and resistance to proteolytic degradation.
3Stability of the object's composition
If more stable GRPR derivatives are used, then metabolic stability is improved, but washout from pancreas is slower potentially causing pancreatitis
Solution Approach 1:
The patent applies localized modifications at specific positions within the peptide sequence (e.g., position 8 Trp replacement, position 7 Gln/His modifications, position 9 Ala variants) to achieve metabolic stability in circulation while maintaining rapid renal clearance. The local structural changes at these specific positions differentiate the pharmacokinetic behavior in different tissues, providing stability where needed while enabling fast clearance from the pancreas.
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 modified compounds exhibit enhanced pharmacokinetic properties with increased tumor accumulation, faster clearance from non-tumor tissues, and improved therapeutic outcomes, reducing side effects and enhancing diagnostic precision.
Implementation Method 1
diagnosis and therapy of cancers by nuclear medicine based on radioactive tracers which accumulate fast and almost exclusively at the tumor site
Implementation Method 2
a moiety capable of generating therapeutically effective radiation, such as 68Ga or 177Lu
Data Source
AI summary
The present invention relates to a compound binding to an endogenous receptor, said compound comprising (i) an oligopeptide comprising a dipeptide with Trp being the C-terminal amino acid of said dipeptide, wherein said Trp is replaced with an α-amino acid Xaa2, whereby the stability in serum or plasma of the peptide bond connecting Xaa2 to the N-terminally adjacent amino acid is increased as compared to the peptide bond connecting Trp to the N-terminally adjacent amino acid in an otherwise identical compound; and (ii) a moiety capable of generating therapeutically effective radiation, said moiety being covalently bound to said oligopeptide.