PSMA Radiopharmaceutical Complexes With Stable Actinium-225 Chelation
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Solution Overview
Problem
Current radiopharmaceuticals for targeted radiotherapy, particularly those using alpha-emitting radionuclides like 211At, 213Bi, and 225Ac, suffer from instability and reduced selectivity due to dissociation of the radionuclide from the chelating macrocycle, leading to increased toxicity and reduced efficacy in treating hyperproliferative diseases such as cancer, especially prostate cancer.
Innovation Solution
Development of tissue-targeting compounds comprising a monoclonal antibody or its antigen-binding fragment with high binding affinity for prostate-specific membrane antigen (PSMA), complexed with actinium-225 (225Ac), which are stable at room temperature and have low chelator-to-antigen ratios, ensuring high selectivity and efficacy by minimizing non-targeted tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If macrocyclic complexes of radionuclides (e.g., DOTA) are used in targeted radiotherapy, then the radionuclide can be delivered to target tissue, but the complexes lack stability leading to dissociation of the radionuclide from the chelating macrocycle, which results in reduced selectivity and activity to the targeted tissue and increased toxicity to non-targeted tissue
Solution Approach 1:
The patent changes the chemical parameters of the chelating agent by using macropa (N,N'-bis[(6-carboxy-2-pyridil)methyl]-4,13-diaza-18-crown-6) instead of conventional chelators like DOTA. This parameter change in the chelating moiety results in significantly improved stability of the actinium-225 complex, preventing dissociation and subsequent toxicity to non-targeted tissues while maintaining effective targeting.
2Power
If alpha-emitting radionuclides are used for targeted therapy, then more potent cell killing is achieved, but stringent demands are imposed on the biological targeting and control of radionuclide distribution to avoid unacceptable side effects
Solution Approach 1:
The patent creates a composite structure consisting of the monoclonal antibody (targeting component) conjugated to the macropa chelator (stabilizing component) complexed with actinium-225 (therapeutic component). This composite radiopharmaceutical combines the high cell-killing potency of alpha-emitting radionuclides with improved stability and controlled distribution, reducing the complexity of control requirements while maintaining therapeutic efficacy.
3Manufacturing precision
If high chelator-to-antigen ratio is used in radiolabeling, then quantitative labeling can be achieved, but the resulting compounds have reduced selectivity and increased toxicity due to radionuclide dissociation
Solution Approach 1:
The patent changes the chelating parameter by using macropa, which has superior chelating properties compared to conventional agents. This allows achieving quantitative labeling at lower chelator-to-antigen ratios, thereby maintaining high labeling efficiency while preventing radionuclide dissociation and preserving selectivity for targeted tissue binding.
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 compounds demonstrate improved stability, selectivity, and efficacy, with enhanced tumor targeting and reduced liver accumulation, allowing for more effective cancer treatment with fewer side effects and increased therapeutic outcomes compared to existing agents.
Implementation Method 1
comprising a monoclonal antibody or an antigen-binding fragment thereof having binding affinity for the prostate-specific membrane antigen (PSMA)
Implementation Method 2
wherein the chelating moiety is complexed with actinium-225 (225Ac)
Implementation Method 3
there has, however, been some interest in the use of alpha-emitting radionuclides in therapy because of their potential for more potent cell killing
Data Source
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AI summary
The present invention relates to tissue-targeting compounds. In particular, the present invention relates to tissue-targeting compounds comprising a monoclonal antibody or an antigen-binding fragment thereof having binding affinity for the prostate-specific membrane antigen (PSMA). Further, the present invention relates to combinations, preferably pharmaceutical combinations comprising a tissue-targeting compound of formula (I) and a further pharmaceutical agent. Said combinations are useful in therapy, preferably in treating hyperproliferative diseases such as cancer.