AAZTA-TATE Chelator Single-Step Radiolabeling
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Solution Overview
Problem
Current radiopharmaceutical chelators, such as DOTA, face limitations including slow complex formation rates, harsh reaction conditions, and radioactivity loss during two-step labeling processes, particularly for temperature-sensitive biologically active moieties, necessitating the development of alternative chelators for improved stability and efficiency in nuclear medicine applications.
Innovation Solution
A new conjugate of 6-amino-6-methylperhydro-1,4-diazepinetetraacetic acid (AAZTA) with [Tyr3] octreotate (TATE), a somatostatin receptor agonist, is developed, which forms stable metal complexes suitable for diagnostic and therapeutic applications, allowing for single-step radiolabeling at room temperature with high kinetic inertness and stability, enhancing in vivo properties compared to DOTA-TATE complexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DOTA is used as a chelator for radiometal coordination, then the complex shows high stability and kinetic inertness in vivo, but the complex formation rate is very slow and requires harsh reaction conditions
Solution Approach 1:
The patent modifies the DOTA chelator structure by replacing one acetate arm with an amine function (creating AAZTA), which changes the coordination chemistry parameters and enables faster complex formation at milder conditions while maintaining in vivo stability
Solution Approach 2:
The invention creates a hybrid chelator structure combining features of DOTA (macroyclic backbone) with open-chain amine functionality, achieving properties that balance fast kinetics with high thermodynamic stability
2Temperature
If a two-step radiolabeling process is used for temperature-sensitive biologically active moieties, then the radiometal can be labeled at high temperature, but radioactivity is lost during the subsequent conjugation step
Solution Approach 1:
The patent merges the radiometal labeling and conjugation steps into a single simultaneous reaction, allowing the biologically active moiety to be incorporated during the chelator-metal complexation process without requiring a separate high-temperature step that would degrade temperature-sensitive compounds
Solution Approach 2:
The chelator is pre-modified with the biologically active moiety (creating a bifunctional chelator) before radiometal addition, so that when the radiometal is added, both complexation and conjugation occur together in one step at mild temperatures
3Ease of manufacture
If DOTA is used for radiometal chelation, then the chelator is commercially accessible and well-established, but the reaction conditions are drastic and not suitable for all biologically active moieties
Solution Approach 1:
The patent alters the reaction parameters by using AAZTA which enables complex formation at lower temperatures and milder pH conditions compared to DOTA, making the process compatible with temperature-sensitive biological molecules while maintaining commercial viability
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 AAZTA-TATE conjugate exhibits improved in vivo stability, kinetic inertness, and enhanced tumor uptake, offering superior imaging and therapeutic capabilities for neuroendocrine tumors, with high radiochemical yield and stability in human plasma, overcoming the limitations of existing chelators.
Implementation Method 1
6-amino-6-methylperhydro-1,4-diazepinetetraacetic acid with ([Tyr3] octreotate... forms stable metal complexes... high kinetic inertness and stability
Data Source
AI summary
A chelating compound of formula (I) or a pharmaceutically acceptable salt thereof and its complexes with metals or radioisotopes thereof. The invention further relates to the preparation of such ligand and complexes as well as to their use as diagnostic or therapeutic agents.