Polyazamacrocyclic Picaga Scaffolds for Stable Sc-18F PSMA Theranostics
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Solution Overview
Problem
Existing methods for radiolabeling picaga with lutetium at room temperature are unsuccessful, and there is a need for improved chelation methods to enhance the apparent molar activities of radiopharmaceuticals for clinical scale production, as well as the lack of a suitable therapeutic isotope pair for fluorine-18 in diagnostic cancer imaging.
Innovation Solution
Development of novel picaga analogs that form stable Sc-18F ternary complexes under mild, aqueous conditions, enabling high radiochemical yield and specific activity, and the use of these analogs in conjunction with targeting vectors for prostate-specific membrane antigen (PSMA) to create theranostic pairs for imaging and therapy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If picaga is used for radiolabeling with Sc isotopes at room temperature, then radiolabeling is successful with good kinetic inertness, but apparent molar activities need improvement for clinical scale production
Solution Approach 1:
The patent modifies the chemical structure of picaga by introducing fluorine atoms at specific positions (Y1 and Y2 substituents) to create picaga analogs with enhanced chelation properties. This structural parameter change enables improved apparent molar activities while preserving the kinetic inertness and radiolabeling success at room temperature.
Solution Approach 2:
The patent creates Sc-18F ternary complexes where scandium is coordinated by the picaga analog ligand and fluorine-18. This composite coordination complex combines the kinetic stability of the macrocyclic chelator with the diagnostic utility of fluorine-18, achieving both reliability and improved productivity for clinical production.
2Adaptability or versatility
If picaga is used for therapeutic radiometals like 177Lu, then therapeutic application is possible, but radiolabeling at room temperature has been unsuccessful
Solution Approach 1:
The patent introduces fluorine substituents at Y1 and Y2 positions of picaga to modify the electronic and steric properties of the chelator. This parameter change enhances the chelation strength and kinetics, enabling successful radiolabeling with therapeutic radiometals like 177Lu at room temperature while maintaining versatility across different radiometal isotopes.
Solution Approach 2:
The picaga analog chelator is designed to be universally applicable to multiple radiometals including both diagnostic (44Sc, 18F) and therapeutic (47Sc, 177Lu) isotopes. The modified structure maintains kinetic inertness and chelation efficiency across different metal ions, achieving ease of manufacture for various theranostic applications.
3Measurement precision
If fluorine-18 is used for diagnostic imaging, then PET imaging capability is achieved, but there is no suitable therapeutic isotopologue for theranostic pairing
Solution Approach 1:
The patent uses the picaga analog chelator as an intermediary that can bind both fluorine-18 (for PET imaging) and scandium isotopes (for therapy). This intermediary chelator enables the creation of matched theranostic pairs by serving as a common platform for both diagnostic and therapeutic isotopes, resolving the mismatch problem between F-18 and radiometal-based therapies.
Solution Approach 2:
The patent creates Sc-18F ternary complexes where the scandium center coordinates both the picaga analog ligand and fluorine-18. This composite structure integrates the imaging capabilities of fluorine-18 with the therapeutic potential of scandium isotopes, achieving chemically matched theranostic pairs with excellent potential for clinical translation.
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 Sc-18F ternary complexes demonstrate excellent in vivo stability and PET image quality, providing a chemically matched theranostic pair for clinical translation, with improved tumor targeting and therapeutic efficacy.
Implementation Method 1
the preparation of novel Picaga analogs with the purpose of enabling improved chelation methods. These analogs along with the chelation methods can be used to prepare conjugates with improved properties
Implementation Method 2
44Scandium is an ideal short-lived radioisotope with a half-life well matched to the typical pharmacokinetics of small molecules, peptides and small biologics and with ideal emission properties (t1/2=3.97 h, Emean β+=632 keV) for PET imaging
Data Source
AI summary
The present invention provides a compound having the structure:and methods of using the compound in targeted PET and SPECT imaging.