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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, Husser C, Duschmalé MB, Fischer G, Senn C, Koller E, Brink A. Tritium labeling of antisense oligonucleotides via different conjugation agents. AAPS OPEN 2021. [DOI: 10.1186/s41120-021-00040-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractA novel approach to tritium-labeled antisense oligonucleotides (ASO) was established by conjugating N-succinimidyl propionate, as well as maleimide-derivatives, to the 3′-end of ASOs targeting metastasis-associated lung adenocarcinoma transcript 1 (Malat1) containing amino- or sulfhydryl-linkers. In vitro stability and Malat1 RNA reduction studies demonstrated that N-ethylmaleimide (NEM) could be used as a stable tag while maintaining the desired target interaction. The corresponding radioactive label conjugation using [3H]-NEM resulted in tritium-labeled ASOs with a high molar specific activity of up to 17 Ci/mmol. Single-dose in vivo studies in mice were carried out to compare [3H]-ASOs with their unlabeled counterpart ASOs, with and without conjugation to N-acetylgalactosamine (GalNAc), for tissue and plasma concentrations time profiles. Despite the structural modification of the labeled ASOs, in vitro target interaction and in vivo pharmacokinetic behaviors were similar to that of the unlabeled ASOs. In conclusion, this new method provides a powerful technique for fast and safe access to tritium-labeled oligonucleotides, e.g., for pharmacokinetic, mass balance, or autoradiography studies.
Graphical abstract
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