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Edelmann MR, Bredack C, Belli S, Mohr P, Imhoff MP, Reggiani F, Kusznir EA, Rufer AC, Holt DP, Valentine H, Wong DF, Dannals RF, Honer M, Gobbi LC. Evaluation of Tetrazine Tracers for Pretargeted Imaging within the Central Nervous System. Bioconjug Chem 2023; 34:1882-1893. [PMID: 37710950 DOI: 10.1021/acs.bioconjchem.3c00385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
The pretargeting approach separates the biological half-life of an antibody from the physical half-life of the radioisotope label, providing a strategy for reducing the radiation burden. A widely explored pretargeting approach makes use of the bioorthogonal click reaction between tetrazines (Tzs) and trans-cyclooctenes (TCOs), combining the targeting specificity of monoclonal antibodies (mAbs) with the rapid clearance and precise reaction of Tzs and TCOs. Such a strategy can allow for the targeting and imaging (e.g., by positron emission tomography (PET)) of molecular markers, which cannot be addressed by solely relying on small molecules. Tz derivatives that undergo inverse electron-demand Diels-Alder (IEDDA) reactions with an antibody bearing TCO moieties have been investigated. This study describes the synthesis and characterization of 11 cold Tz imaging agent candidates. These molecules have the potential to be radiolabeled with 18F or 3H, and with the former label, they could be of use as imaging tracers for positron emission tomography studies. Selection was made using a multiparameter optimization score for the central nervous system (CNS) PET tracers. Novel tetrazines were tested for their pH-dependent chemical stability. Those which turned out to be stable in a pH range of 6.5-8 were further characterized in in vitro assays with regard to their passive permeability, microsomal stability, and P-glycoprotein transport. Furthermore, selected Tzs were examined for their systemic clearance and CNS penetration in a single-dose pharmacokinetic study in rats. Two tetrazines were successfully labeled with 18F, one of which showed brain penetration in a biodistribution study in mice. Another Tz was successfully tritium-labeled and used to demonstrate a bioorthogonal click reaction on a TCO-modified antibody. As a result, we identified one Tz as a potential fluorine-18-labeled CNS-PET agent and a second as a 3H-radioligand for an IEDDA-based reaction with a modified brain-penetrating antibody.
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Affiliation(s)
- Martin R Edelmann
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Isotope Synthesis, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, U.K
| | - Christoph Bredack
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Neuroscience and Rare Diseases, Discovery & Translational Medicine Area, Biomarker and Translational Technologies, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Sara Belli
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Pharmaceutical Science, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Peter Mohr
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Medicinal Chemistry, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Marie-Paule Imhoff
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Medicinal Chemistry, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Flore Reggiani
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Medicinal Chemistry, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Eric A Kusznir
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Lead Discovery, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Arne C Rufer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Lead Discovery, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Daniel P Holt
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
| | - Heather Valentine
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
- Section of High Resolution Brain PET, PET Center, Division of Nuclear Medicine, Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
| | - Dean F Wong
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
- Section of High Resolution Brain PET, PET Center, Division of Nuclear Medicine, Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
- Section of High Resolution Brain PET, PET Center, Division of Nuclear Medicine, Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, 21218, United States
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
- ⧫Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
| | - Robert F Dannals
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, United States
| | - Michael Honer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Neuroscience and Rare Diseases, Discovery & Translational Medicine Area, Biomarker and Translational Technologies, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
| | - Luca C Gobbi
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Medicinal Chemistry, F. Hoffmann-La Roche Ltd, Basel CH-4070, Switzerland
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Edelmann MR, Muser T. Tritium O-Methylation of N-Alkoxy Maleimide Derivatives as Labeling Reagents for Biomolecules. Bioconjug Chem 2021; 32:1027-1033. [PMID: 33909418 DOI: 10.1021/acs.bioconjchem.1c00202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An efficient procedure to access tritium-labeled maleimide derivatives in a high specific activity has been developed. N-Substituted maleimides containing the hydroxy functionality are O-methylated in a three-step synthesis route, including (1) Diels-Alder protection of the maleimide core, (2) O-methylation by the use of commercially available [3H]methyl nosylate, and (3) deprotection by retro-Diels-Alder reaction. With our procedure, N-hydroxyalkyl maleimide derivatives can be labeled in overall radiochemical yields of 13-15% and in >98% radiochemical purity. The major advantage of N-alkoxy maleimides in comparison to N-alkylated maleimides such as N-ethylmaleimide is their lower volatility, which enables safer handling with respect to radiation-safety protection. Tritium-labeled maleimide building blocks allow subsequent Michael-type conjugation reactions of thiol-containing biomolecules for mechanistic in vitro or in vivo studies.
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Affiliation(s)
- Martin R Edelmann
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, U.K
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Isotope Synthesis, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Thorsten Muser
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Therapeutic Modalities, Small Molecule Research, Isotope Synthesis, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
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