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Suzuki H, Kannaka K, Uehara T. Approaches to Reducing Normal Tissue Radiation from Radiolabeled Antibodies. Pharmaceuticals (Basel) 2024; 17:508. [PMID: 38675468 PMCID: PMC11053530 DOI: 10.3390/ph17040508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/02/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
Radiolabeled antibodies are powerful tools for both imaging and therapy in the field of nuclear medicine. Radiolabeling methods that do not release radionuclides from parent antibodies are essential for radiolabeling antibodies, and practical radiolabeling protocols that provide high in vivo stability have been established for many radionuclides, with a few exceptions. However, several limitations remain, including undesirable side effects on the biodistribution profiles of antibodies. This review summarizes the numerous efforts made to tackle this problem and the recent advances, mainly in preclinical studies. These include pretargeting approaches, engineered antibody fragments and constructs, the secondary injection of clearing agents, and the insertion of metabolizable linkages. Finally, we discuss the potential of these approaches and their prospects for further clinical application.
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Affiliation(s)
- Hiroyuki Suzuki
- Laboratory of Molecular Imaging and Radiotherapy, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan; (K.K.); (T.U.)
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2
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Cheal SM, Chung SK, Vaughn BA, Cheung NKV, Larson SM. Pretargeting: A Path Forward for Radioimmunotherapy. J Nucl Med 2022; 63:1302-1315. [PMID: 36215514 DOI: 10.2967/jnumed.121.262186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/07/2022] [Indexed: 12/19/2022] Open
Abstract
Pretargeted radioimmunodiagnosis and radioimmunotherapy aim to efficiently combine antitumor antibodies and medicinal radioisotopes for high-contrast imaging and high-therapeutic-index (TI) tumor targeting, respectively. As opposed to conventional radioimmunoconjugates, pretargeted approaches separate the tumor-targeting step from the payload step, thereby amplifying tumor uptake while reducing normal-tissue exposure. Alongside contrast and TI, critical parameters include antibody immunogenicity and specificity, availability of radioisotopes, and ease of use in the clinic. Each of the steps can be optimized separately; as modular systems, they can find broad applications irrespective of tumor target, tumor type, or radioisotopes. Although this versatility presents enormous opportunity, pretargeting is complex and presents unique challenges for clinical translation and optimal use in patients. The purpose of this article is to provide a brief historical perspective on the origins and development of pretargeting strategies in nuclear medicine, emphasizing 2 protein delivery systems that have been extensively evaluated (i.e., biotin-streptavidin and hapten-bispecific monoclonal antibodies), as well as radiohaptens and radioisotopes. We also highlight recent innovations, including pretargeting with bioorthogonal chemistry and novel protein vectors (such as self-assembling and disassembling proteins and Affibody molecules). We caution the reader that this is by no means a comprehensive review of the past 3 decades of pretargeted radioimmunodiagnosis and pretargeted radioimmunotherapy. But we do aim to highlight major developmental milestones and to identify benchmarks for success with regard to TI and toxicity in preclinical models and clinically. We believe this approach will lead to the identification of key obstacles to clinical success, revive interest in the utility of radiotheranostics applications, and guide development of the next generation of pretargeted theranostics.
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Affiliation(s)
- Sarah M Cheal
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York;
| | - Sebastian K Chung
- Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Brett A Vaughn
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Nai-Kong V Cheung
- Department of Pediatrics, Memorial Sloan Kettering Cancer Center, New York, New York; and
| | - Steven M Larson
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
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3
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Exner RM, Paisey SJ, Redman JE, Pascu SI. Explorations into Peptide Nucleic Acid Contrast Agents as Emerging Scaffolds for Breakthrough Solutions in Medical Imaging and Diagnosis. ACS OMEGA 2021; 6:28455-28462. [PMID: 34746541 PMCID: PMC8569549 DOI: 10.1021/acsomega.1c03994] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/23/2021] [Indexed: 05/11/2023]
Abstract
Peptide nucleic acids (PNAs, nucleic acid analogues with a peptide backbone rather than a phosphoribosyl backbone) have emerged as promising chemical agents in antigene or antisense therapeutics, as splicing modulators or in gene editing. Their main benefits, compared to DNA or RNA agents, are their biochemical stability and the lack of negative charges throughout the backbone, leading to negligible electrostatic interaction with the strand with which they are hybridizing. As a result, hybridization of PNA strands with DNA or RNA strands leads to higher binding energies and melting temperatures. A lack of natural transporters, however, necessitates the formation of PNA-containing chimeras or the formulation of nanoparticular cell delivery methods. Here, we set out to explore the progress made in using imaging agents based on PNAs in diagnostic applications and highlight selected developments and challenges.
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Affiliation(s)
- Rüdiger M. Exner
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Stephen J. Paisey
- Wales
Research & Diagnostic Positron Emission Tomography Imaging Centre
(PETIC), School of Medicine, Cardiff University,
University Hospital of Wales, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - James E. Redman
- School
of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, United Kingdom
| | - Sofia I. Pascu
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
- Centre
for Sustainable and Circular Technologies, 1 South, University of Bath, Claverton Down, Bath BA2
7AY, United Kingdom
- Centre
for Therapeutic Innovation, 3 West 2.03, University of Bath, Claverton Down, Bath BA2
7AY, United Kingdom
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4
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Addonizio CJ, Gates BD, Webber MJ. Supramolecular "Click Chemistry" for Targeting in the Body. Bioconjug Chem 2021; 32:1935-1946. [PMID: 34415139 DOI: 10.1021/acs.bioconjchem.1c00326] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The fields of precision imaging and drug delivery have revealed a number of tools to improve target specificity and increase efficacy in diagnosing and treating disease. Biological molecules, such as antibodies, continue to be the primary means of assuring active targeting of various payloads. However, molecular-scale recognition motifs have emerged in recent decades to achieve specificity through the design of interacting chemical motifs. In this regard, an assortment of bioorthogonal covalent conjugations offer possibilities for in situ complexation under physiological conditions. Herein, a related concept is discussed that leverages interactions from noncovalent or supramolecular motifs to facilitate in situ recognition and complex formation in the body. Classic supramolecular motifs based on host-guest complexation offer one such means of facilitating recognition. In addition, synthetic bioinspired motifs based on oligonucleotide hybridization and coiled-coil peptide bundles afford other routes to form complexes in situ. The architectures to include recognition of these various motifs for targeting enable both monovalent and multivalent presentation, seeking high affinity or engineered avidity to facilitate conjugation even under dilute conditions of the body. Accordingly, supramolecular "click chemistry" offers a complementary tool in the growing arsenal targeting improved healthcare efficacy.
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Affiliation(s)
- Christopher J Addonizio
- University of Notre Dame, Department of Chemical & Biomolecular Engineering, Notre Dame, Indiana 46556 United States
| | - Brant D Gates
- University of Notre Dame, Department of Chemical & Biomolecular Engineering, Notre Dame, Indiana 46556 United States
| | - Matthew J Webber
- University of Notre Dame, Department of Chemical & Biomolecular Engineering, Notre Dame, Indiana 46556 United States
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5
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Abstract
Affibody molecules are small engineered scaffold proteins suitable for in vivo tumor targeting. Radionuclide molecular imaging using directly radiolabelled affibody molecules provides excellent imaging. However, affibody molecules have a high renal reabsorption, which complicates their use for radionuclide therapy. The high renal reabsorption is a common problem for the use of engineered scaffold proteins for radionuclide therapy. Affibody-based PNA-mediated pretargeting reduces dramatically the absorbed dose to the kidneys and makes affibody-based radionuclide therapy possible. This methodology might, hopefully, solve the problem of high renal reabsorption for radionuclide therapy mediated by other engineered scaffold proteins.
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Evaluation of an antibody-PNA conjugate as a clearing agent for antibody-based PNA-mediated radionuclide pretargeting. Sci Rep 2020; 10:20777. [PMID: 33247180 PMCID: PMC7695838 DOI: 10.1038/s41598-020-77523-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 11/12/2020] [Indexed: 02/06/2023] Open
Abstract
Radionuclide molecular imaging of cancer-specific targets is a promising method to identify patients for targeted antibody therapy. Radiolabeled full-length antibodies however suffer from slow clearance, resulting in high background radiation. To overcome this problem, a pretargeting system based on complementary peptide nucleic acid (PNA) probes has been investigated. The pretargeting relies on sequential injections of primary, PNA-tagged antibody and secondary, radiolabeled PNA probe, which are separated in time, to allow for clearance of non-bound primary agent. We now suggest to include a clearing agent (CA), designed for removal of primary tumor-targeting agent from the blood. The CA is based on the antibody cetuximab, which was conjugated to PNA and lactosaminated by reductive amination to improve hepatic clearance. The CA was evaluated in combination with PNA-labelled trastuzumab, T-ZHP1, for radionuclide HER2 pretargeting. Biodistribution studies in normal mice demonstrated that the CA cleared ca. 7 times more rapidly from blood than unmodified cetuximab. Injection of the CA 6 h post injection of the radiolabeled primary agent [131I]I-T-ZHP1 gave a moderate reduction of the radioactivity concentration in the blood after 1 h from 8.5 ± 1.8 to 6.0 ± 0.4%ID/g. These proof-of-principle results could guide future development of a more efficient CA.
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Site-specific conjugation of recognition tags to trastuzumab for peptide nucleic acid-mediated radionuclide HER2 pretargeting. Biomaterials 2019; 203:73-85. [PMID: 30877838 DOI: 10.1016/j.biomaterials.2019.02.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/01/2019] [Accepted: 02/12/2019] [Indexed: 01/11/2023]
Abstract
Pretargeting is a promising strategy to reach high imaging contrast in a shorter time than by targeting with directly radiolabeled monoclonal antibodies (mAbs). One of problems in pretargeting is a site-specific, reproducible and uniform conjugation of recognition tags to mAbs. To solve this issue we propose a photoconjugation to covalently couple a recognition tag to a mAb via a photoactivatable Z domain. The Z-domain, a 58-amino acid protein derived from the IgG-binding B-domain of Staphylococcus aureus protein A, has a well-characterized binding site in the Fc portion of IgG. We tested the feasibility of this approach using pretargeting based on hybridization between peptide nucleic acids (PNAs). We have used photoconjugation to couple trastuzumab with the PNA-based hybridization probe, HP1. A complementary [57Co]Co-labeled PNA hybridization probe ([57Co]Co-HP2) was used as the secondary targeting probe. In vitro studies demonstrated that trastuzumab-ZHP1 bound specifically to human epidermal growth factor receptor 2 (HER2)-expressing cells with nanomolar affinity. The binding of the secondary [57Co]Co-HP2 probe to trastuzumab-PNA-pretreated cells was in the picomolar affinity range. A two-fold increase in SKOV-3 tumor targeting was achieved when [57Co]Co-HP2 (0.7 nmol) was injected 48 h after injection of trastuzumab-ZHP1 (0.5 nmol) compared with trastuzumab-ZHP1 alone (0.8 ± 0.2 vs. 0.33 ± 0.06 %ID/g). Tumor accumulation of [57Co]Co-HP2 was significantly reduced by pre-saturation with trastuzumab or when no trastuzumab-ZHP1 was preinjected. A tumor-to-blood uptake ratio of 1.5 ± 0.3 was achieved resulting in a clear visualization of HER2-expressing xenografts as confirmed by SPECT imaging. In conclusion, the feasibility of stable site-specific coupling of a PNA-based recognition tag to trastuzumab and successful pretargeting has been demonstrated. This approach can hopefully be used for a broad range of mAbs and recognition tags.
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8
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Liu G. A Revisit to the Pretargeting Concept-A Target Conversion. Front Pharmacol 2018; 9:1476. [PMID: 30618765 PMCID: PMC6304396 DOI: 10.3389/fphar.2018.01476] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 12/03/2018] [Indexed: 01/22/2023] Open
Abstract
Pretargeting is often used as a tumor targeting strategy that provides much higher tumor to non-tumor ratios than direct-targeting using radiolabeled antibody. Due to the multiple injections, pretargeting is investigated less than direct targeting, but the high T/NT ratios have rendered it more useful for therapy. While the progress in using this strategy for tumor therapy has been regularly reviewed in the literature, this review focuses on the nature and quantitative understanding of the pretargeting concept. By doing so, it is the goal of this review to accelerate pretargeting development and translation to the clinic and to prepare the researchers who are not familiar with the pretargeting concept but are interested in applying it. The quantitative understanding is presented in a way understandable to the average researchers in the areas of drug development and clinical translation who have the basic concept of calculus and general chemistry.
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Affiliation(s)
- Guozheng Liu
- Department of Radiology, University of Massachusetts Medical School Worcester, MA, United States
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Stéen EJL, Edem PE, Nørregaard K, Jørgensen JT, Shalgunov V, Kjaer A, Herth MM. Pretargeting in nuclear imaging and radionuclide therapy: Improving efficacy of theranostics and nanomedicines. Biomaterials 2018; 179:209-245. [PMID: 30007471 DOI: 10.1016/j.biomaterials.2018.06.021] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 06/13/2018] [Accepted: 06/14/2018] [Indexed: 01/18/2023]
Abstract
Pretargeted nuclear imaging and radiotherapy have recently attracted increasing attention for diagnosis and treatment of cancer with nanomedicines. This is because it conceptually offers better imaging contrast and therapeutic efficiency while reducing the dose to radiosensitive tissues compared to conventional strategies. In conventional imaging and radiotherapy, a directly radiolabeled nano-sized vector is administered and allowed to accumulate in the tumor, typically on a timescale of several days. In contrast, pretargeting is based on a two-step approach. First, a tumor-accumulating vector carrying a tag is administered followed by injection of a fast clearing radiolabeled agent that rapidly recognizes the tag of the tumor-bound vector in vivo. Therefore, pretargeting circumvents the use of long-lived radionuclides that is a necessity for sufficient tumor accumulation and target-to-background ratios using conventional approaches. In this review, we give an overview of recent advances in pretargeted imaging strategies. We will critically reflect on the advantages and disadvantages of current state-of-the-art conventional imaging approaches and compare them to pretargeted strategies. We will discuss the pretargeted imaging concept and the involved chemistry. Finally, we will discuss the steps forward in respect to clinical translation, and how pretargeted strategies could be applied to improve state-of-the-art radiotherapeutic approaches.
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Affiliation(s)
- E Johanna L Stéen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, DK-2100 Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
| | - Patricia E Edem
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, DK-2100 Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark; Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2100 Copenhagen, Denmark
| | - Kamilla Nørregaard
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark; Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2100 Copenhagen, Denmark
| | - Jesper T Jørgensen
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark; Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2100 Copenhagen, Denmark
| | - Vladimir Shalgunov
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, DK-2100 Copenhagen, Denmark
| | - Andreas Kjaer
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark; Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2100 Copenhagen, Denmark
| | - Matthias M Herth
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, DK-2100 Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.
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Westerlund K, Altai M, Mitran B, Konijnenberg M, Oroujeni M, Atterby C, de Jong M, Orlova A, Mattsson J, Micke P, Karlström AE, Tolmachev V. Radionuclide Therapy of HER2-Expressing Human Xenografts Using Affibody-Based Peptide Nucleic Acid-Mediated Pretargeting: In Vivo Proof of Principle. J Nucl Med 2018; 59:1092-1098. [PMID: 29439013 DOI: 10.2967/jnumed.118.208348] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 01/23/2018] [Indexed: 12/25/2022] Open
Abstract
Affibody molecules are small proteins engineered using a nonantibody scaffold. Radiolabeled Affibody molecules are excellent imaging probes, but their application to radionuclide therapy has been prevented by high renal reabsorption. The aim of this study was to test the hypothesis that Affibody-based peptide nucleic acid (PNA)-mediated pretargeted therapy of human epidermal growth factor receptor 2 (HER2)-expressing cancer extends survival without accompanying renal toxicity. Methods: A HER2-targeting Affibody molecule ligated with an AGTCGTGATGTAGTC PNA hybridization probe (ZHER2:342-SR-HP1) was used as the primary pretargeting agent. A complementary AGTCGTGATGTAGTC PNA conjugated to the chelator DOTA and labeled with the radionuclide 177Lu (177Lu-HP2) was used as the secondary agent. The influence of different factors on pretargeting was investigated. Experimental radionuclide therapy in mice bearing SKOV-3 xenografts was performed in 6 cycles separated by 7 d. Results: Optimal tumor targeting was achieved when 16 MBq/3.5 μg (0.65 nmol) of 177Lu-HP2 was injected 16 h after injection of 100 μg (7.7 nmol) of ZHER2:342-SR-HP1. The calculated absorbed dose to tumors was 1,075 mGy/MBq, whereas the absorbed dose to kidneys was 206 mGy/MBq and the absorbed dose to blood (surrogate of bone marrow) was 4 mGy/MBq. Survival of mice was significantly longer (P < 0.05) in the treatment group (66 d) than in the control groups treated with the same amount of ZHER2:342-SR-HP1 only (37 d), the same amount and activity of 177Lu-HP2 only (32 d), or phosphate-buffered saline (37 d). Conclusion: The studied pretargeting system can deliver an absorbed dose to tumors appreciably exceeding absorbed doses to critical organs, making Affibody-based PNA-mediated pretargeted radionuclide therapy highly attractive.
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Affiliation(s)
- Kristina Westerlund
- Department of Protein Science, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Mohamed Altai
- Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden
| | - Bogdan Mitran
- Division of Molecular Imaging, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden; and
| | - Mark Konijnenberg
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Maryam Oroujeni
- Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden
| | - Christina Atterby
- Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden
| | - Marion de Jong
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Anna Orlova
- Division of Molecular Imaging, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden; and
| | - Johanna Mattsson
- Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden
| | - Patrick Micke
- Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden
| | | | - Vladimir Tolmachev
- Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden
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Altai M, Westerlund K, Velletta J, Mitran B, Honarvar H, Karlström AE. Evaluation of affibody molecule-based PNA-mediated radionuclide pretargeting: Development of an optimized conjugation protocol and 177Lu labeling. Nucl Med Biol 2017; 54:1-9. [PMID: 28810153 DOI: 10.1016/j.nucmedbio.2017.07.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/30/2017] [Accepted: 07/04/2017] [Indexed: 12/20/2022]
Abstract
INTRODUCTION We have previously developed a pretargeting approach for affibody-mediated cancer therapy based on PNA-PNA hybridization. In this article we have further developed this approach by optimizing the production of the primary agent, ZHER2:342-SR-HP1, and labeling the secondary agent, HP2, with the therapeutic radionuclide 177Lu. We also studied the biodistribution profile of 177Lu-HP2 in mice, and evaluated pretargeting with 177Lu-HP2 in vitro and in vivo. METHODS The biodistribution profile of 177Lu-HP2 was evaluated in NMRI mice and compared to the previously studied 111In-HP2. Pretargeting using 177Lu-HP2 was studied in vitro using the HER2-expressing cell lines BT-474 and SKOV-3, and in vivo in mice bearing SKOV-3 xenografts. RESULTS AND CONCLUSION Using an optimized production protocol for ZHER2:342-SR-HP1 the ligation time was reduced from 15h to 30min, and the yield increased from 45% to 70%. 177Lu-labeled HP2 binds specifically in vitro to BT474 and SKOV-3 cells pre-treated with ZHER2:342-SR-HP1. 177Lu-HP2 was shown to have a more rapid blood clearance compared to 111In-HP2 in NMRI mice, and the measured radioactivity in blood was 0.22±0.1 and 0.68±0.07%ID/g for 177Lu- and 111In-HP2, respectively, at 1h p.i. In contrast, no significant difference in kidney uptake was observed (4.47±1.17 and 3.94±0.58%ID/g for 177Lu- and 111In-HP2, respectively, at 1h p.i.). Co-injection with either Gelofusine or lysine significantly reduced the kidney uptake for 177Lu-HP2 (1.0±0.1 and 1.6±0.2, respectively, vs. 2.97±0.87%ID/g in controls at 4h p.i.). 177Lu-HP2 accumulated in SKOV-3 xenografts in BALB/C nu/nu mice when administered after injection of ZHER2:342-SR-HP1. Without pre-injection of ZHER2:342-SR-HP1, the uptake of 177Lu-HP2 was about 90-fold lower in tumor (0.23±0.08 vs. 20.7±3.5%ID/g). The tumor-to-kidney radioactivity accumulation ratio was almost 5-fold higher in the group of mice pre-injected with ZHER2:342-SR-HP1. In conclusion, 177Lu-HP2 was shown to be a promising secondary agent for affibody-mediated tumor pretargeting in vivo.
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Affiliation(s)
- Mohamed Altai
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Kristina Westerlund
- Division of Protein Technology, School of Biotechnology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Justin Velletta
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Bogdan Mitran
- Division of Molecular Imaging, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Hadis Honarvar
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Amelie Eriksson Karlström
- Division of Protein Technology, School of Biotechnology, KTH Royal Institute of Technology, Stockholm, Sweden.
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Chu TW, Kopeček J. Drug-Free Macromolecular Therapeutics--A New Paradigm in Polymeric Nanomedicines. Biomater Sci 2016; 3:908-22. [PMID: 26191406 DOI: 10.1039/c4bm00442f] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This review highlights a unique research area in polymer-based nanomedicine designs. Drug-free macromolecular therapeutics induce apoptosis of malignant cells by the crosslinking of surface non-internalizing receptors. The receptor crosslinking is mediated by the biorecognition of high-fidelity natural binding motifs (such as antiparallel coiled-coil peptides or complementary oligonucleotides) that are grafted to the side chains of polymers or attached to targeting moieties against cell receptors. This approach features the absence of low-molecular-weight cytotoxic compounds. Here, we summarize the rationales, different designs, and advantages of drug-free macromolecular therapeutics. Recent developments of novel therapeutic systems for B-cell lymphomas are discussed, as well as relevant approaches for other diseases. We conclude by pointing out various potential future directions in this exciting new field.
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Affiliation(s)
- Te-Wei Chu
- Department of Pharmaceutics and Pharmaceutical Chemistry/Center for Controlled Chemical Delivery, University of Utah, Salt Lake City, UT 84112, USA
| | - Jindřich Kopeček
- Department of Pharmaceutics and Pharmaceutical Chemistry/Center for Controlled Chemical Delivery, University of Utah, Salt Lake City, UT 84112, USA ; Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
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13
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Leonidova A, Foerster C, Zarschler K, Schubert M, Pietzsch HJ, Steinbach J, Bergmann R, Metzler-Nolte N, Stephan H, Gasser G. In vivo demonstration of an active tumor pretargeting approach with peptide nucleic acid bioconjugates as complementary system. Chem Sci 2015; 6:5601-5616. [PMID: 29861898 PMCID: PMC5949856 DOI: 10.1039/c5sc00951k] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 06/16/2015] [Indexed: 12/15/2022] Open
Abstract
A novel, promising strategy for cancer diagnosis and therapy is the use of a pretargeting approach. For this purpose, the non-natural DNA/RNA analogues Peptide Nucleic Acids (PNAs) are ideal candidates as in vivo recognition units due to their high metabolic stability and lack of unspecific accumulation. In the pretargeting approach, an unlabeled, highly specific antibody-PNA conjugate has sufficient time to target a tumor before administration of a small fast-clearing radiolabeled complementary PNA that hybridizes with the antibody-PNA conjugate at the tumor site. Herein, we report the first successful application of this multistep process using a PNA-modified epidermal growth factor receptor (EGFR) specific antibody (cetuximab) and a complementary 99mTc-labeled PNA. In vivo studies on tumor bearing mice demonstrated a rapid and efficient in vivo hybridization of the radiolabeled PNA with the antibody-PNA conjugate. Decisively, a high specific tumor accumulation was observed with a tumor-to-muscle ratio of >8, resulting in a clear visualization of the tumor by single photon emission computed tomography (SPECT).
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Affiliation(s)
- Anna Leonidova
- Department of Chemistry , University of Zurich , Winterthurerstrasse 190 , CH-8057 Zurich , Switzerland . ; http://www.gassergroup.com ; Tel: +41 44 635 46 30
| | - Christian Foerster
- Helmholtz-Zentrum Dresden - Rossendorf , Institute of Radiopharmaceutical Cancer Research , Bautzner Landstraße 400 , D-01328 Dresden , Germany . ; http://www.hzdr.de/NanoscalicSystems ; Tel: +49 351 260-3091
| | - Kristof Zarschler
- Helmholtz-Zentrum Dresden - Rossendorf , Institute of Radiopharmaceutical Cancer Research , Bautzner Landstraße 400 , D-01328 Dresden , Germany . ; http://www.hzdr.de/NanoscalicSystems ; Tel: +49 351 260-3091
| | - Maik Schubert
- Helmholtz-Zentrum Dresden - Rossendorf , Institute of Radiopharmaceutical Cancer Research , Bautzner Landstraße 400 , D-01328 Dresden , Germany . ; http://www.hzdr.de/NanoscalicSystems ; Tel: +49 351 260-3091
| | - Hans-Jürgen Pietzsch
- Helmholtz-Zentrum Dresden - Rossendorf , Institute of Radiopharmaceutical Cancer Research , Bautzner Landstraße 400 , D-01328 Dresden , Germany . ; http://www.hzdr.de/NanoscalicSystems ; Tel: +49 351 260-3091
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden - Rossendorf , Institute of Radiopharmaceutical Cancer Research , Bautzner Landstraße 400 , D-01328 Dresden , Germany . ; http://www.hzdr.de/NanoscalicSystems ; Tel: +49 351 260-3091
| | - Ralf Bergmann
- Helmholtz-Zentrum Dresden - Rossendorf , Institute of Radiopharmaceutical Cancer Research , Bautzner Landstraße 400 , D-01328 Dresden , Germany . ; http://www.hzdr.de/NanoscalicSystems ; Tel: +49 351 260-3091
| | - Nils Metzler-Nolte
- Lehrstuhl für Anorganische Chemie I - Bioanorganische Chemie , Fakultät für Chemie und Biochemie , Ruhr-Universität Bochum , Universitätsstrasse 150 , D-44801 Bochum , Germany
| | - Holger Stephan
- Helmholtz-Zentrum Dresden - Rossendorf , Institute of Radiopharmaceutical Cancer Research , Bautzner Landstraße 400 , D-01328 Dresden , Germany . ; http://www.hzdr.de/NanoscalicSystems ; Tel: +49 351 260-3091
| | - Gilles Gasser
- Department of Chemistry , University of Zurich , Winterthurerstrasse 190 , CH-8057 Zurich , Switzerland . ; http://www.gassergroup.com ; Tel: +41 44 635 46 30
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14
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Stephan H, Foerster C, Gasser G. Synthesis, characterization, and evaluation of radiometal-containing peptide nucleic acids. Methods Mol Biol 2014; 1050:37-54. [PMID: 24297349 DOI: 10.1007/978-1-62703-553-8_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Peptide nucleic acids (PNAs) have very attractive properties for applications in nuclear medicine. Because PNAs have high selectivity for DNA/RNA recognition, resistance to nuclease/protease degradation, and high thermal and radiolytic stabilities, PNA bioconjugates could transform the areas of diagnostic and therapeutic nuclear medicine. In this book chapter, we report on the current developments towards the preparation of radiometal-containing PNA constructs and summarize the protocols for labeling these probes with (99m)Tc, (111)In, (64)Cu, (90)Y, and (177)Lu.
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Affiliation(s)
- Holger Stephan
- Institute of Radiopharmaceutical Cancer Research, Helmholtz- Zentrum Dresden-Rossendorf, Dresden, Germany
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15
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Sihver W, Pietzsch J, Krause M, Baumann M, Steinbach J, Pietzsch HJ. Radiolabeled Cetuximab Conjugates for EGFR Targeted Cancer Diagnostics and Therapy. Pharmaceuticals (Basel) 2014; 7:311-38. [PMID: 24603603 PMCID: PMC3978494 DOI: 10.3390/ph7030311] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/11/2014] [Accepted: 02/21/2014] [Indexed: 01/09/2023] Open
Abstract
The epidermal growth factor receptor (EGFR) has evolved over years into a main molecular target for the treatment of different cancer entities. In this regard, the anti-EGFR antibody cetuximab has been approved alone or in combination with: (a) chemotherapy for treatment of colorectal and head and neck squamous cell carcinoma and (b) with external radiotherapy for treatment of head and neck squamous cell carcinoma. The conjugation of radionuclides to cetuximab in combination with the specific targeting properties of this antibody might increase its therapeutic efficiency. This review article gives an overview of the preclinical studies that have been performed with radiolabeled cetuximab for imaging and/or treatment of different tumor models. A particularly promising approach seems to be the treatment with therapeutic radionuclide-labeled cetuximab in combination with external radiotherapy. Present data support an important impact of the tumor micromilieu on treatment response that needs to be further validated in patients. Another important challenge is the reduction of nonspecific uptake of the radioactive substance in metabolic organs like liver and radiosensitive organs like bone marrow and kidneys. Overall, the integration of diagnosis, treatment and monitoring as a theranostic approach appears to be a promising strategy for improvement of individualized cancer treatment.
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Affiliation(s)
- Wiebke Sihver
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany.
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany.
| | - Mechthild Krause
- Department of Radiation Oncology and OncoRay, Medical Faculty and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany.
| | - Michael Baumann
- Department of Radiation Oncology and OncoRay, Medical Faculty and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany.
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany.
| | - Hans-Jürgen Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany.
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16
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Zhang Z, Liu Y, Jarreau C, Welch MJ, Taylor JSA. Nucleic Acid-directed Self-assembly of Multifunctional Gold Nanoparticle Imaging Agents. Biomater Sci 2013; 1:1055-1064. [PMID: 24058728 PMCID: PMC3777812 DOI: 10.1039/c3bm60070j] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Gold nanoparticles have attracted much interest as a platform for development of multifunctional imaging and therapeutic agents. Multifunctionalized gold nanoparticles are generally constructed by covalent assembly of a gold core with thiolated ligands. In this study, we have assembled multifunctionalized gold nanoparticles in one step by nucleic acid hybridization of ODN (oligodeoxynucleotide)-derivatized gold nanoparticles with a library of pre-functionalized complementary PNAs (peptide nucleic acids). The PNAs were functionalized by conjugation with DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) for chelating 64Cu for PET imaging, PEG (polyethylene glycol) for conferring stealth properties, and Cy5 for fluorescent imaging. The resulting nanoparticles showed good stability both in vitro and in vivo showing biodistribution behavior in a mouse that would be expected for a PEGylated gold nanoparticle rather than that for the radiolabelled PNA used in its assembly.
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Affiliation(s)
- Ziyan Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Yongjian Liu
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Chad Jarreau
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Michael J. Welch
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - John-Stephen A. Taylor
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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Mallikaratchy P, Gardner J, Nordstrøm LUR, Veomett NJ, McDevitt MR, Heaney ML, Scheinberg DA. A self-assembling short oligonucleotide duplex suitable for pretargeting. Nucleic Acid Ther 2013; 23:289-99. [PMID: 23848521 DOI: 10.1089/nat.2013.0425] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Monoclonal antibodies (mAbs) have naturally evolved as suitable, high affinity and specificity targeting molecules. However, the large size of full-length mAbs yields poor pharmacokinetic properties. A solution to this issue is the use of a multistep administration approach, in which the slower clearing mAb is administered first and allowed to reach the target site selectively, followed by administration of a rapidly clearing small molecule carrier of the cytotoxic or imaging ligand, which bears a cognate receptor for the mAb. Here, we introduce a novel pretargetable RNA based system comprised of locked nucleic acids (LNA) and 2'O-Methyloligoribonucleotides (2'OMe-RNA). The duplex shows fast hybridization, high melting temperatures, excellent affinity, and high nuclease stability in plasma. Using a prototype model system with rituximab conjugated to 2'OMe-RNA (oligo), we demonstrate that LNA-based complementary strand (c-oligo) effectively hybridizes with rituximab-oligo, which is slowly circulating in vivo, despite the high clearance rates of c-oligo.
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Affiliation(s)
- Prabodhika Mallikaratchy
- Molecular Pharmacology and Chemistry Program, Sloan Kettering Institute, New York, New York 10065, USA
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18
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Mier W, Eritja R, Mohammed A, Haberkorn U, Eisenhut M. Synthesis and labeling of peptide nucleic acid oligomers conjugated to octreotate. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.25804401335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Gasser G, Sosniak AM, Metzler-Nolte N. Metal-containing peptide nucleic acid conjugates. Dalton Trans 2011; 40:7061-76. [PMID: 21541385 DOI: 10.1039/c0dt01706j] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Peptide Nucleic Acids (PNAs) are non-natural DNA/RNA analogues with favourable physico-chemical properties and promising applications. Discovered nearly 20 years ago, PNAs have recently re-gained quite a lot of attention. In this Perspective article, we discuss the latest advances on the preparation and utilisation of PNA monomers and oligomers containing metal complexes. These metal- conjugates have found applications in various research fields such as in the sequence-specific detection of nucleic acids, in the hydrolysis of nucleic acids and peptides, as radioactive probes or as modulators of PNA·DNA hybrid stability, and last but not least as probes for molecular and cell biology.
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Affiliation(s)
- Gilles Gasser
- Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
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20
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Quantitative and specific molecular imaging of cancer with labeled engineered monoclonal antibody fragments. Ther Deliv 2011; 2:345-58. [DOI: 10.4155/tde.10.79] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The high target specificity of antibodies and related constructs makes them excellent scaffolds for molecular-imaging probes. Quantitative data on biodistribution and pharmacokinetics can be acquired by radiolabeling these agents. Such studies demonstrate prolonged circulation times and resulting nonspecific accumulation with high background signal using antibody-based agents. Antibody fragments demonstrate more rapid clearance, but lower tumor uptake. Optical labeling of antibodies provides a basis for developing activatable probes that can image antigens with very high specificity, potentially allowing for the simultaneous visualization of multiple targets. While radioimmunoimaging provides valuable whole-body, quantitative information, activatable optical antibody-based agents could generate real-time diagnostic and prognostic information about near-surface lesions at high-spatial and temporal resolution without requiring ionizing radiation.
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21
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Liu G, Dou S, Liu Y, Liang M, Chen L, Cheng D, Greiner D, Rusckowski M, Hnatowich DJ. Unexpected side products in the conjugation of an amine-derivatized morpholino oligomer with p-isothiocyanate benzyl DTPA and their removal. Nucl Med Biol 2010; 38:159-63. [PMID: 21315270 DOI: 10.1016/j.nucmedbio.2010.08.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 08/16/2010] [Accepted: 08/24/2010] [Indexed: 11/28/2022]
Abstract
In connection with pretargeting, an amine-derivatized morpholino phosphorodiamidate oligomer (NH(2)-cMORF) was conjugated conventionally with p-isothiocyanate benzyl-DTPA (p-SCN-Bn-DTPA). However, after (111)In radiolabeling, unexpected label instability was observed. To understand this instability, the NH(2)-cMORF and, as control, the native cMORF without the amine were conjugated in the conventional manner. Surprisingly, the (111)In labeling of the native cMORF conjugate was equally effective as that of the NH(2)-cMORF conjugate (>95%) despite the absence of the amine group. Furthermore, heating the radiolabeled NH(2)-cMORF and native cMORF conjugates resulted in a 35% loss and a complete loss of the label, respectively. Since the (111)In labeled DTPA is known to be stable, the instability in both cases must be due to some unstable association of DTPA to the cMORF, presumably unstable association to some endogenous sites in cMORF. Based on this assumption, a postconjugation-prepurification heating step was introduced, and labeling efficiency and stability were again investigated. By introducing the heating step, the side products were dissociated, and after purification and labeling, the NH(2)-cMORF conjugate provided a stable label and high labeling efficiency with no need for postlabeling purification. The biodistribution of this radiolabeled conjugate in normal mice showed significantly lower backgrounds compared with the labeled unstable native cMORF conjugate. In conclusion, the conventional conjugation procedure to attach the p-SCN-Bn-DTPA to NH(2)-cMORF resulted in side product(s) that were responsible for the (111)In label instability. Adding a postconjugation-prepurification heating step dissociated the side products, improved the label stability and lowered tissue backgrounds in mice.
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Affiliation(s)
- Guozheng Liu
- Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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22
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Gasser G, Jäger K, Zenker M, Bergmann R, Steinbach J, Stephan H, Metzler-Nolte N. Preparation, 99mTc-labeling and biodistribution studies of a PNA oligomer containing a new ligand derivative of 2,2'-dipicolylamine. J Inorg Biochem 2010; 104:1133-40. [PMID: 20674031 DOI: 10.1016/j.jinorgbio.2010.06.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 06/29/2010] [Accepted: 06/30/2010] [Indexed: 11/13/2022]
Abstract
A new azido derivative of 2,2'-dipicolylamine (Dpa), 2-azido-N,N-bis((pyridin-2-yl)methyl)ethanamine, (Dpa-N(3)) was readily prepared from the known 2-(bis(pyridin-2-ylmethyl)amino)ethanol (Dpa-OH). It was demonstrated that Dpa-N(3) could be efficiently labeled with both [Re(CO)(3)(H(2)O)(3)]Br and [(99m)Tc(H(2)O)(3)(CO)(3)](+) to give [Re(CO)(3)(Dpa-N(3))]Br and [(99m)Tc(CO)(3)(Dpa-N(3))](+), respectively. Furthermore, Dpa-N(3) was successfully coupled, on the solid phase, to a Peptide Nucleic Acid (PNA) oligomer (H-4-pentynoic acid-spacer-spacer-tgca-tgca-tgca-Lys-NH(2); spacer= -NH-(CH(2))(2)-O-(CH(2))(2)-O-CH(2)-CO-) using the Cu(I)-catalyzed [2+3] azide/alkyne cycloaddition (Cu-AAC, often referred to as the prototypical "click" reaction) to give the Dpa-PNA oligomer. Subsequent labeling of Dpa-PNA with [(99m)Tc(H(2)O)(3)(CO)(3)](+) afforded [(99m)Tc(CO)(3)(Dpa-PNA)] in radiochemical yields >90%. Partitioning experiments in a 1-octanol/water system were carried out to get more insight on the lipophilicity of [(99m)Tc(CO)(3)(Dpa-N(3))](+) and [(99m)Tc(CO)(3)(Dpa-PNA)]. Both compounds were found rather hydrophilic (log D(o/w) values at pH=7.4 are -0.50: [(99m)Tc(CO)(3)(Dpa-N(3))](+) and -0.85: [(99m)Tc(CO)(3)(Dpa-PNA)]. Biodistribution studies of [(99m)Tc(CO)(3)(Dpa-PNA)] in Wistar rats showed a very fast blood clearance (0.26 ± 0.1 SUV, 1h p.i.) and modest accumulation in the kidneys (5.45 ± 0.45 SUV, 1h p.i.). There was no significant activity in the thyroid and the stomach, demonstrating a high in vivo stability of the (99m)Tc-labeled Dpa-PNA conjugate.
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Affiliation(s)
- Gilles Gasser
- Forschungszentrum Dresden-Rossendorf, Institute of Radiopharmacy, PF 510119, D-01314 Dresden, Germany.
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Frost SHL, Jensen H, Lindegren S. In vitro evaluation of avidin antibody pretargeting using 211At-labeled and biotinylated poly-L-lysine as effector molecule. Cancer 2010; 116:1101-10. [DOI: 10.1002/cncr.24798] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Sosniak AM, Gasser G, Metzler-Nolte N. Thermal melting studies of alkyne- and ferrocene-containing PNA bioconjugates. Org Biomol Chem 2009; 7:4992-5000. [PMID: 19907791 DOI: 10.1039/b913964h] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The preparation of new metal-containing Peptide Nucleic Acids (PNAs) is currently a field of research intensively studied for various purposes, e.g. DNA biosensors. The role played by the metal centre, notably on the stability of the PNA.DNA hybrid, is obviously crucial, but has not yet been fully investigated. In this work, UV-Vis spectroscopic measurements of solutions of DNA.PNA hybrids, whose 11/12-mer PNA oligomers contained either one or two alkyne- (1) or ferrocene-containing (2) PNA monomers, were carried out to determine the effect of these monomers on the thermal stability of the hybrids (PNA: H-Gly-X-gggtc-Y-agctt-X-Lys-NH2 with X = 1 or and Y = 1 or 2 or blank position). Supplementary CD spectroscopic measurements were performed to gain insight into the structures of the PNA.DNA duplexes formed. The effect of both modified monomers was found to depend on their actual positions within the PNA sequences. Insertions at the N- or C-termini of a PNA oligomer did not change the melting temperatures (T(m) values of about 72 degrees C) of the DNA.PNA hybrids significantly. Insertion of monomers 1 or 2 in the middle of a PNA sequence induced a substantial decrease in the T(m) of the hybrids (by about 23 degrees C) when bound to the same DNA oligomer. Interestingly, it was found that the type of modification, namely alkyne or ferrocene, did not significantly influence the T(m) values in these cases. However, the thermal stability of hybrids with the DNA oligomers containing one to four additional thymines and the PNA oligomers containing the ferrocene moiety in its middle, varied significantly with the number of thymines added compared to its alkyne analogues (DeltaT(m) up to -13 degrees C). The presence of the ferrocene moiety induced a significant decrease in thermal stability of the hybrids, probably due to its bulkiness. In order to assess the effect of PNA backbone rigidity on the stability of DNA.PNA hybrids, PNA oligomers with an internal amino acid, propargylglycine (Pgl) or the dipeptide glycine-propargylglycine (Gly-Pgl), were synthesised. It was assumed that the orientation of the alkyne moiety in the Pgl-containing PNA sequence is not identical to an alkyne-containing PNA sequence, as a significantly higher T(m) value (DeltaT(m) = +10 degrees C) was measured. It is anticipated that the alkyne moiety in Pgl is not facing the DNA base and therefore does not disturb as much the neighbouring nucleobases and base-stacking of the complementary DNA, in contrast to the alkyne moiety of 1. Interestingly, no significant differences in the thermal stability of the hybrids was observed between Pgl-containing and dipeptide-containing PNA oligomers, although the former contracts the PNA backbone by three atoms.
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Affiliation(s)
- Anna M Sosniak
- Ruhr-University Bochum, Faculty of Chemistry and Biochemistry, Inorganic Chemistry I-Bioinorganic Chemistry, Universitätsstrasse 150, D-44801, Bochum, Germany
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Abstract
This article provides an overview of a semiempirical pretargeting model now under development. After a brief review of the pretargeting concept, the strategies available, and the complexities of optimizing the dosage and timing, a semiempirical model is described that is not only capable of optimizing dosage and timing but also capable of predicting the results of pretargeting as a function of most pretargeting variables. The model requires knowledge of the pharmacokinetics of both the pretargeting agent (usually an antibody) and the effector, the accessibility of the pretargeting antibody for the effector, and their quantitative relationships in vivo. Several misconceptions that often surround pretargeting are also clarified.
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Affiliation(s)
- Guozheng Liu
- Department of Radiology, Division of Nuclear Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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Synthesis, characterization, and evaluation of a novel 99mTc(CO)3 pyrazolyl conjugate of a peptide nucleic acid sequence. J Biol Inorg Chem 2008; 13:1335-44. [PMID: 18777182 DOI: 10.1007/s00775-008-0419-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 08/15/2008] [Indexed: 10/21/2022]
Abstract
The 16-mer peptide nucleic acid sequence H-A GAT CAT GCC CGG CAT-Lys-NH2 (1), which is complementary to the translation start region of the N-myc oncogene messenger RNA, was synthesized and conjugated to a pyrazolyl diamine bifunctional chelator (pz). The novel conjugate pz-A GAT CAT GCC CGG CAT-Lys-NH2 (2) was labeled with technetium tricarbonyl, yielding quantitatively the complex fac-[99mTc(CO)3(kappa3-pz-A GAT CAT GCC CGG CAT-Lys-NH2)]2+ (4). Complex 4 was obtained with high radiochemical purity and high specific activity, revealing high stability in human serum and in cell culture medium. The identity of 4 was confirmed by comparing its reversed-phase high performance liquid chromatography profile with that of the rhenium analog fac-[Re(CO)3(kappa3-pz-A GAT CAT GCC CGG CAT-Lys-NH2)]2+ (3), prepared by conjugation of fac-[Re(CO)3(3,5-Me2pz(CH2)2N((CH2)3COOH)(CH2)2NH2)]+ to 1, using solid-phase techniques. UV melting experiments of 1 and 3 with the complementary DNA sequence led to the formation of stable duplexes, indicating that the conjugation of 1 to the pyrazolyl chelator and to the metal fragment fac-[M(CO)3]+ did not affect the recognition of the complementary sequence as well as the duplex stability. For a first screening, SH-SY5Y human neuroblastoma cells, which express N-myc, were treated with 4. The results show that 4 internalizes (7% of the activity goes into the cells, after 4 h at 37 degrees C), presenting also a relatively high cellular retention (only 40% of internalized activity is released from the cells after 5 h).
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Chen X, Dou S, Liu G, Liu X, Wang Y, Chen L, Rusckowski M, Hnatowich DJ. Synthesis and in vitro characterization of a dendrimer-MORF conjugate for amplification pretargeting. Bioconjug Chem 2008; 19:1518-25. [PMID: 18646837 DOI: 10.1021/bc8001024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Amplification pretargeting can play an important role in molecular imaging by significantly increasing the accumulation of signal in target tissues. Multiple-step amplification pretargeting offers the potential to greatly improve target localization of effector molecules through the intermediate use of polymers conjugated with multiple copies of complementary oligomers. In this study, PAMAM dendrimer generation 3 (G3) was conjugated with multiple copies of a phosphorodiamidate morpholino (MORF) oligomer. Characterization of the conjugate by native-PAGE and SE-HPLC demonstrated that the conjugation was successful. The average numbers of MORF groups in the G3-MORF conjugate, both attached and accessible to the (99m)Tc labeled complementary MORF (cMORF), were determined. The antitumor antibody CC49 was conjugated with both MORF and cMORF (collectively (c)MORF) at an average of about one group per molecule. Nine of the 32 carboxyl groups of the dendrimer were modified with MORF, of which 90% were accessible in solution to (99m)Tc-cMORF. After purification, the G3-MORF was radiolabeled with tracer (99m)Tc-labeled cMORF (i.e., G3-MORF/(99m)Tc-cMORF) and added to the antibody CC49 previously conjugated with cMORF (i.e., CC49-cMORF/G3-MORF/(99m)Tc-cMORF), the complex demonstrated a single peak on SE-HPLC as evidence of complete hybridization between G3-MORF/(99m)Tc-cMORF and CC49-cMORF. The CC49-(c)MORF were bound to both Protein G and Protein L coated plates, and G3-MORF was added to hybridize with CC49-cMORF before the (99m)Tc-cMORF was added to test amplification pretargeting. In comparison to conventional pretargeting without the G3-MORF, the signal was amplified about 6 and 14 times, respectively, showing that the G3-MORF participated in amplifying the signal. Further amplification studies using the CC49-(c)MORF for LS174T tumor cells in tissue culture also demonstrated clear evidence of signal amplification.
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Affiliation(s)
- Xiangji Chen
- Division of Nuclear Medicine, Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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28
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Schlesinger J, Koezle I, Bergmann R, Tamburini S, Bolzati C, Tisato F, Noll B, Klussmann S, Vonhoff S, Wuest F, Pietzsch HJ, Steinbach J. An 86Y-labeled mirror-image oligonucleotide: influence of Y-DOTA isomers on the biodistribution in rats. Bioconjug Chem 2008; 19:928-39. [PMID: 18345604 DOI: 10.1021/bc700453h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A mirror-image oligonucleotide (L-RNA) was radiolabeled with the positron emitting radionuclide (86)Y (t(1/2) = 14.7 h) via the bifunctional chelator approach. DOTA-modification of the L-RNA (sequence: 5'-aminohexyl UGA CUG ACU GAC-3'; MW 3975) was performed using (S)-p-SCN-Bn-DOTA. (86)Y radiolabeling of the DOTA-L-RNA produced more than one species as evidenced by HPLC radiometric detection. For the identification of the (86)Y-labeled L-RNA, the structural analogue nonradioactive precursor [Y((S)-p-NH2-Bn-DOTA)](-) was synthesized. Two coordination isomers were separated via HPLC adopting the square antiprismatic (SAP) and the twisted square antiprismatic (TSAP) geometry, respectively. Their stereochemical configuration in the solution state was assessed by NMR and circular dichroism spectroscopy. Both [Y((S)-p-NH2-Bn-DOTA)](-) isomers were converted into isothiocyanate derivatives [Y((S)-p-SCN-Bn-DOTA)](-) and conjugated to the L-RNA. The identity of the [(86)Y-DOTA]-L-RNA species was finally established by comparison of the radiometric ((86)Y) and UV-visible chromatographic profiles. Biodistribution studies in Wistar rats showed minor changes in the biodistribution profile of the [(86)Y((S)-p-NH2-Bn-DOTA)](-) complex isomers, while no significant differences were observed for the [(86)Y-DOTA]-L-RNA isomers. High renal excretions were found for the [(86)Y((S)-p-NH 2-Bn-DOTA)](-) complex isomers as well as for the L-RNA isomers.
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Affiliation(s)
- Joern Schlesinger
- Institute of Radiopharmacy, Forschungszentrum Dresden-Rossendorf, Germany
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Liu G, Dou S, Mardirossian G, He J, Zhang S, Liu X, Rusckowski M, Hnatowich DJ. Successful radiotherapy of tumor in pretargeted mice by 188Re-radiolabeled phosphorodiamidate morpholino oligomer, a synthetic DNA analogue. Clin Cancer Res 2006; 12:4958-64. [PMID: 16914585 PMCID: PMC1587615 DOI: 10.1158/1078-0432.ccr-06-0844] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Pretargeting has been attracting increasing attention as a drug delivery approach. We recently proposed Watson-Crick pairing of phosphorodiamidate morpholino oligomers (MORF) for the recognition system in tumor pretargeting. MORF pretargeting involves the initial i.v. injection of a MORF-conjugated antitumor antibody and the subsequent i.v. injection of the radiolabeled complement. Our laboratory has reported on MORF pretargeting for diagnosis using (99m)Tc as radiolabel. We now report on the use of MORF pretargeting for radiotherapy in a mouse tumor model using (188)Re as the therapeutic radiolabel. EXPERIMENTAL DESIGN An initial tracer study was done to estimate radiation dose, and was followed by the radiotherapy study at 400 muCi per mouse with three control groups (untreated, MORF antibody alone, and (188)Re complementary MORF alone). RESULTS Tracer study indicated rapid tumor localization of (188)Re and rapid clearance from normal tissues with a tumor area under the curve (AUC) about four times that of kidney and blood (the normal organs with highest radioactivity). Tumor growth in the study group ceased 1 day after radioactivity injection, whereas tumors continued to grow at the same rate among the three control groups. At sacrifice on day 5, the average net tumor weight in the study group was significantly lower at 0.68 +/- 0.29 g compared with the three control groups (1.24 +/- 0.31 g, 1.25 +/- 0.39 g, and 1.35 +/- 0.41 g; Ps < 0.05), confirming the therapeutic benefit observed by tumor size measurement. CONCLUSIONS MORF pretargeting has now been shown to be a promising approach for tumor radiotherapy as well as diagnosis.
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Affiliation(s)
- Guozheng Liu
- Division of Nuclear Medicine, Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
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He J, Liu C, Vanderheyden JL, Liu G, Dou S, Rusckowski M, Hnatowich DJ. Radiolabelling morpholinos with 188Re tricarbonyl provides improved in vitro and in vivo stability to re-oxidation. Nucl Med Commun 2005; 25:731-6. [PMID: 15208502 DOI: 10.1097/01.mnm.0000130237.91573.34] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND For pretargeting and other nuclear medicine applications, it may eventually be useful to radiolabel phosphodiamidate morpholinos (MORFs) with therapeutic radionuclides such as 188Re. However, by preparing 188Re-MORFs labelled conventionally with MAG3 as chelator, we have observed unacceptable levels of oxidation to perrhenate in vitro and in vivo in mice. OBJECTIVE To improve upon stability, tricarbonyl labelling was considered since tricarbonyl complexes are thought to stabilize metals in low oxidation states. METHODS An amine derivatized 25 mer MORF was conjugated with either NHS-MAG3 or NHS-Hynic. The MAG3 conjugated MORF was radiolabelled conventionally with 188Re while the Hynic conjugated MORF was radiolabelled through its tricarbonyl intermediate. Using a commercial kit modified with additional reducing agent over that required for the preparation of the 99mTc tricarbonyl complex [99mTc(CO)3(H2O)3]+, we demonstrated that the equivalent 188Re tricarbonyl, [188Re(CO)3(H2O)3]+, could be prepared. Simple incubation at elevated temperatures with the Hynic conjugated MORF then provided 188Re-(CO)3-Hynic-MORF. Confirmation was achieved by a shift assay using a complementary MORF conjugated polymer and size exclusion HPLC. To evaluate the relative stability of the tricarbonyl labelled MORF compared to the MAG3 labelled MORF in vitro, the radiolabelled MORFs were incubated in phosphate buffer and the presence of perrhenate measured periodically by strip chromatography. Stability in vivo was evaluated by biodistribution studies in normal mice. RESULTS The overall yields for tricarbonyl intermediates averaged greater than 90% for 99mTc and 60-80% for 188Re. Yields following subsequent labelling to Hynic-MORF were about 60-80% for 99mTc and 15-20% for 188Re. The in vitro stability results in phosphate buffer showed that 188Re-MAG3-MORF was fully oxidized by 48 h while 188Re-(CO)3-Hynic-MORF was less than 20% oxidized at that time. Similarly, the 188Re-(CO)3-Hynic-MORF biodistribution in normal mice showed lower radioactivity level in stomach, intestines and thyroid compared with 188Re-MAG3-MORF. CONCLUSION 188Re-tricarbonyl labelling of Hynic conjugated MORFs may be considerably more stable to oxidation than the MAG3 labelled MORFs and therefore more suitable for radiotherapy trials.
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Affiliation(s)
- Jiang He
- Division of Nuclear Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA
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He J, Liu G, Zhang S, Rusckowski M, Hnatowich DJ. Pharmacokinetics in mice of four oligomer-conjugated polymers for amplification targeting. Cancer Biother Radiopharm 2005; 18:941-7. [PMID: 14969606 DOI: 10.1089/108497803322702905] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
UNLABELLED For use in amplification targeting, an oligomer-conjugated polymer must display adaptable chemistry, minimal steric hindrance, low toxicity, and favorable pharmacokinetics. In particular, the polymer must remain in circulation sufficiently long to permit target localization. OBJECTIVES To evaluate their properties for amplification targeting, the biodistribution in normal mice was determined for four polymers conjugated with multiple copies of a phosphorodiamidate morpholino (MORF) oligomer. METHODS An amine-derivatized 25-mer MORF oligomer was radiolabeled with 99mTc. Three polymers of succinylated polylysine (PL) with initial weight average molecular weights (Mw) of 30, 100, and 200 KDa, and one poly (methyl vinyl ether-alt-maleic acid) (PA) with initial Mw of 45 KDa polymer, were each conjugated with an amine derivatized 25-mer complementary MORF (i.e., cMORF). The average number of attached cMORF groups on each polymer molecule (i.e., gpm) was estimated by a high performance liquid chromatography (HPLC) shift assay after the addition of trace 99mTc-MORF to the unpurified polymer, while the average number of accessible cMORF on each polymer was determined by adding radiolabeled MORF at increasing concentrations to the purified cMORF polymer solution until saturation. After purification, each polymer was radiolabeled by incubation with trace 99mTc-MORF. The biodistribution was then established in normal CD1 mice at a constant dosage of 2-4 micrograms of cMORF. RESULTS The gpm varied from about 12 on 30 KDa PL to 40 on 45 KDa PA. The biodistribution results show that the pharmacokinetics of the radiolabel is a function of both the type of polymer as well as its gpm. Of the four polymers, the 30 KDa PL showed the most favorable pharmacokinetic profile, with the lowest liver accumulation and the highest blood values compared to the remaining three polymers. CONCLUSION The biodistribution of the four polymers showed characteristic differences, with one polymer (30 KDa PL) showing the most favorable properties for amplification targeting.
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Affiliation(s)
- Jiang He
- Division of Nuclear Medicine, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
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Tavitian B. Oligonucleotides as radiopharmaceuticals. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2005:1-34. [PMID: 15524208 DOI: 10.1007/3-540-26809-x_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Affiliation(s)
- B Tavitian
- INSERM ERM 103 Service Hospitalier, Frédéric Joliot CEA Direction des Sciences du Vivant Direction de la Recherche Medicale, Orsay, France.
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Morpholinos and PNAs compared. Int J Pept Res Ther 2005. [DOI: 10.1007/s10989-005-4913-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Affiliation(s)
- Andrew Dodd
- Molecular Genetics and Development Group, School of Biological Sciences, University of Auckland, Auckland 1001, New Zealand
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Liu G, Liu C, Zhang S, He J, Liu N, Gupta S, Rusckowski M, Hnatowich DJ. Investigations of 99mTc morpholino pretargeting in mice. Nucl Med Commun 2003; 24:697-705. [PMID: 12766607 DOI: 10.1097/00006231-200306000-00013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This laboratory is exploring the use of morpholinos (MORFs), synthetic DNA analogues, for nuclear medicine applications, including pretargeting. The anti-CEA antibody MN14 was conjugated with an 18 mer MORF and with diethylenetriaminepentaacetic acid (DTPA) for 111In labelling. In a dual label pretargeting study, tumour-bearing nude mice received different doses of (MN14-DTPA-111In+MN14-MORF) followed, at various times after i.v. injection, by 0.15 microg complementary MORF (cMORF) radiolabelled with 99mTc via MAG(3). Animals were killed 3 h thereafter and tissues were counted for both radionuclides. The 99mTc-cMORF was also administered to tumour bearing mice that, 2 days previously, had received different doses of unlabelled MN14-MORF IgG or, as control, unlabelled Sandoglobulin IgG-MORF (Sandoz-MORF). Tumour uptake was higher at all time points for the labelled antibody itself versus labelled cMORF (8-10 vs 1.3-2.3%ID/g, respectively) in part due to the rapid clearance of cMORF through the kidneys. However, target to non-target ratios were superior for pretargeting at all time points and in all tissue except blood and kidneys. By pretargeting alone, these ratios were highest in all tissues for 15 microg compared to higher MN14-MORF dosages and in all cases were superior to that of the Sandoz-MORF control. The superior target to non-target ratios for pretargeting can be partially explained through calculations based on both radiolabels: after 24 h, only 0-6% of MORF on MN14 was bound by 99mTc-cMORF in liver and spleen suggesting that the antibody is sequestered in these organs and 'invisible' to labelled MORF. Fortunately, this was not the case in tumours in which 50-60% was bound. It is concluded that pretargeting using MORFs provided encouraging results in one mouse model/anti-tumour antibody system. The advantages of pretargeting in this model were evident in the superior target to non-target ratios obtained over conventional imaging.
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Affiliation(s)
- G Liu
- Division of Nuclear Medicine, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655-0243, USA
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36
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PNAs as novel cancer therapeutics. Int J Pept Res Ther 2003. [DOI: 10.1007/s10989-004-4909-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Goldenberg DM, Chang CH, Sharkey RM, Rossi EA, Karacay H, McBride W, Hansen HJ, Chatal JF, Barbet J. Radioimmunotherapy: is avidin-biotin pretargeting the preferred choice among pretargeting methods? Eur J Nucl Med Mol Imaging 2003; 30:777-80. [PMID: 12574971 DOI: 10.1007/s00259-002-1089-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- David M Goldenberg
- Center for Molecular Medicine and Immunology, Garden State Cancer Center, 520 Belleville Avenue, NJ 07109-0023, Belleville, USA.
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39
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40
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Chen Z, Corey DR. Telomerase inhibitors: a new option for chemotherapy. Adv Cancer Res 2003. [DOI: 10.1016/s0065-230x(03)87294-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
Telomerase is expressed in most types of tumors but not in most somatic cells. This observation has led to two hypotheses; (i) telomerase activity is necessary for the proliferation of cancer cells; and (ii) telomerase inhibitors are a powerful strategy for cancer chemotherapy. Testing the latter hypothesis requires the development of potent and selective inhibitors of telomerase and their testing in clinical trials. Assaying the efficacy of telomerase inhibitors will not be simple because telomere erosion will be slow and antiproliferative effects will probably require weeks to become apparent. This review will describe the properties of 2'-O-alkyl oligonucleotide inhibitors of telomerase. Oligonucleotides that block expression of other cancer targets have favorable pharmacokinetic properties and are already in clinical trials. This experience is likely to facilitate clinical trials of anti-telomerase oligomers.
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Affiliation(s)
- David R Corey
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, TX 75390-9041, USA.
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Abstract
Peptide nucleic acids (PNAs) have been around for more than seven years and it was hoped, at their introduction, that they would quickly enter the fields of antisense and antigene technology and drug development. Despite their extremely favorable hybridization and stability properties, as well as the encouraging antisense and antigene activity of PNA in cell-free systems, progress has been slow and experiments on cells in culture and in animals have been lacking. Judging from the very promising results published within the past year, however, there is every reason to believe that both PNA antisense and, possibly, PNA antigene research will strongly pick up momentum again. Specifically, it has been demonstrated that certain peptide-PNA conjugates are taken up very efficiently by, at least some, eukaryotic cells and that antisense down regulation of target genes in nerve cells in culture is attainable using such PNA conjugates. Perhaps even more exciting is that antisense-compatible effects have been reported using PNAs injected into the brain of rats. Finally, it has been shown that the bacterium Escherichia coli is susceptible to antisense gene regulation using PNA.
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Affiliation(s)
- P E Nielsen
- Center for Biomolecular Recognition, Department of Medical Biochemistry and Genetics, The Panum Institute, Copenhagen, Denmark.
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Abstract
Several exciting new developments in the applications of the DNA mimic peptide nucleic acid (PNA) have been published recently. A possible breakthrough may have come in efforts to develop PNA into gene therapeutic drugs. In eukaryotic systems, antisense activity of PNAs (as peptide conjugates) has been reported in nerve cells and even in rats upon injection into the brain, and antisense activity has also been demonstrated in Escherichia coli. PNA hybridization technology has developed rapidly within in situ hybridization, and exciting new methods based on MALDI-TOF detection have also been presented.
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Affiliation(s)
- P E Nielsen
- Center for Biomolecular Recognition Department of Medical Biochemistry and Genetics Biochemical Laboratory B The Panum Institute Blegdamsvej 3c 2200 Copenhagen N Denmark.
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