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Böhnke N, Indrevoll B, Hammer S, Papple A, Kristian A, Briem H, Celik A, Mumberg D, Cuthbertson A, Zitzmann-Kolbe S. Mono- and multimeric PSMA-targeting small molecule- thorium-227 conjugates for optimized efficacy and biodistribution in preclinical models. Eur J Nucl Med Mol Imaging 2024; 51:669-680. [PMID: 37882848 PMCID: PMC10796422 DOI: 10.1007/s00259-023-06474-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 10/15/2023] [Indexed: 10/27/2023]
Abstract
PURPOSE PSMA (prostate-specific membrane antigen) is highly expressed on prostate cancer (PrCa) cells and extensively used as a homing target for PrCa treatment. Most prominently, PSMA-targeting conjugate PSMA-617, carrying a DOTA chelator and labeled with therapeutic radionuclides like beta-emitting lutetium-177 or alpha-emitting actinium-225, has shown clinical activity in PrCa patients. We sought to develop PSMA-targeting small molecule (SMOL) conjugates that show high uptake in PSMA-expressing tumors and fast clearance, and can easily be labeled with the alpha emitter thorium-227 (half-life 18.7 days). METHODS A novel linker motif with improved competition against 3H-PSMA-617 on PSMA-expressing LNCaP cells was identified. A 2,3-hydroxypyridinone chelator modified with carboxyl groups (carboxy-HOPO) with increased hydrophilicity and robust labeling with thorium-227 was developed and allowed the synthesis of mono-, di-, tri-, and tetrameric conjugates. The resulting monomeric and multimeric PSMA SMOL-TTCs (targeted thorium conjugate) were evaluated for cellular binding, internalization, and antiproliferative activity. The in vivo antitumor efficacy of the PSMA SMOL-TTCs was determined in ST1273 and KUCaP-1 PrCa models in mice, and their biodistribution was assessed in cynomolgus monkeys, minipigs, and mice. RESULTS The monomeric and multimeric PSMA SMOL conjugates were readily labeled with thorium-227 at room temperature and possessed high stability and good binding, internalization, and antiproliferative activity in vitro. In vivo, the monomeric, dimeric, and trimeric PSMA SMOL-TTCs showed fast clearance, potent antitumor efficacy, and high uptake and retention in prostate tumors in mice. No major uptake or retention in other organs was observed beyond kidneys. Low uptake of free thorium-227 into bone confirmed high complex stability in vivo. Salivary gland uptake remained inconclusive as mini pigs were devalidated as a relevant model and imaging controls failed in cynomolgus monkeys. CONCLUSION Monomeric and multimeric PSMA SMOL-TTCs show high tumor uptake and fast clearance in preclinical models and warrant further therapeutic exploration.
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Affiliation(s)
- Niels Böhnke
- Pharmaceuticals, Bayer AG, 13342, Berlin, Germany
| | | | | | | | | | - Hans Briem
- Pharmaceuticals, Bayer AG, 13342, Berlin, Germany
| | - Arif Celik
- Pharmaceuticals, Bayer AG, 13342, Berlin, Germany
| | - Dominik Mumberg
- Pharmaceuticals, Bayer AG, 13342, Berlin, Germany
- Adcendo ApS, Copenhagen, Denmark
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Benabdallah N, Scheve W, Dunn N, Silvestros D, Schelker P, Abou D, Jammalamadaka U, Laforest R, Li Z, Liu J, Ballard DH, Maughan NM, Gay H, Baumann BC, Hobbs RF, Rogers B, Iravani A, Jha AK, Dehdashti F, Thorek DLJ. Practical considerations for quantitative clinical SPECT/CT imaging of alpha particle emitting radioisotopes. Theranostics 2021; 11:9721-9737. [PMID: 34815780 PMCID: PMC8581409 DOI: 10.7150/thno.63860] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 09/15/2021] [Indexed: 02/05/2023] Open
Abstract
Rationale: Alpha particle emitting radiopharmaceuticals are generating considerable interest for the treatment of disseminated metastatic disease. Molecular imaging of the distribution of these agents is critical to safely and effectively maximize the clinical potential of this emerging drug class. The present studies aim to investigate the feasibility and limitations of quantitative SPECT for 223Ra, 225Ac and 227Th. Methods: Three state-of-the-art SPECT/CT systems were investigated: the GE Discovery NM/CT 670, the GE Optima NM/CT 640, and the Siemens Symbia T6. A series of phantoms, including the NEMA IEC Body phantom, were used to compare and calibrate each camera. Additionally, anthropomorphic physical tumor and vertebrae phantoms were developed and imaged to evaluate the quantitative imaging protocol. Results: This work describes and validates a methodology to calibrate each clinical system. The efficiency of each gamma camera was analyzed and compared. Using the calibration factors obtained with the NEMA phantom, we were able to quantify the activity in 3D-printed tissue phantoms with an error of 2.1%, 3.5% and 11.8% for 223Ra, 225Ac, and 227Th, respectively. Conclusion: The present study validates that quantitative SPECT/CT imaging of 223Ra, 225Ac, and 227Th is achievable but that careful considerations for camera configuration are required. These results will aid in future implementation of SPECT-based patient studies and will help to identify the limiting factors for accurate image-based quantification with alpha particle emitting radionuclides.
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Affiliation(s)
- Nadia Benabdallah
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
- Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri
| | | | | | | | | | - Diane Abou
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
- Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri
| | - Uday Jammalamadaka
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Richard Laforest
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Zekun Li
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Jonathan Liu
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - David H. Ballard
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Nichole M. Maughan
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri
| | - Hiram Gay
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri
| | - Brian C. Baumann
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri
| | - Robert F. Hobbs
- Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Buck Rogers
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri
| | - Amir Iravani
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Abhinav K. Jha
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
- Oncologic Imaging Program, Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri
| | - Farrokh Dehdashti
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
- Oncologic Imaging Program, Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri
| | - Daniel L. J. Thorek
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri
- Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri
- Oncologic Imaging Program, Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri
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Hatcher-Lamarre JL, Sanders VA, Rahman M, Cutler CS, Francesconi LC. Alpha emitting nuclides for targeted therapy. Nucl Med Biol 2021; 92:228-240. [PMID: 33558017 PMCID: PMC8363053 DOI: 10.1016/j.nucmedbio.2020.08.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/25/2020] [Accepted: 08/26/2020] [Indexed: 02/07/2023]
Abstract
Targeted alpha therapy (TAT) is an area of research with rapidly increasing importance as the emitted alpha particle has a significant effect on inducing cytotoxic effects on tumor cells while mitigating dose to normal tissues. Two significant isotopes of interest within the area of TAT are thorium-227 and actinium-225 due to their nuclear characteristics. Both isotopes have physical half-lives suitable for coordination with larger biomolecules, and additionally actinium-225 has potential to serve as an in vivo generator. In this review, the authors will discuss the production, purification, labeling reactions, and biological studies of actinium-225 and thorium-227 complexes and clinical studies.
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Affiliation(s)
| | - Vanessa A Sanders
- Collider Accelerator Department, Brookhaven National Laboratory, USA
| | - Mohammed Rahman
- Chemistry Department, Hunter College of the City University of New York, USA
| | - Cathy S Cutler
- Collider Accelerator Department, Brookhaven National Laboratory, USA
| | - Lynn C Francesconi
- Chemistry Department, Hunter College of the City University of New York, USA; Chemistry Department, Graduate Center of the City University of New York, USA.
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Murray I, Rojas B, Gear J, Callister R, Cleton A, Flux GD. Quantitative Dual-Isotope Planar Imaging of Thorium-227 and Radium-223 Using Defined Energy Windows. Cancer Biother Radiopharm 2020; 35:530-539. [PMID: 32429699 PMCID: PMC7475104 DOI: 10.1089/cbr.2019.3554] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Introduction: Thorium-227 is an alpha-emitting radioisotope with potential therapeutic applications in targeted alpha therapy. Thorium-227 decays to Radium-223, which may have an independent biodistribution to that of the parent Thorium-227 radiopharmaceutical. Quantitative in vivo imaging with sodium iodide (NaI) detectors is challenging due to cross-talk between neighboring γ-photopeaks as well as scattered γ-photons. The aim of this work was to validate the use of a spectral analysis technique to estimate the activity of each isotope within a region of interest applied to a pair of conjugate view planar acquisitions, acquired at multiple energy windows. Methods: Energy spectra per unit activity arising from unscattered Thorium-227 photons and Radium-223 photons as well as from scattered photons were modeled. These spectra were scaled until the combination of these component spectra resulted in the closest match to the measured data in four energy windows. Results: Measured estimates of activity followed the known decay curves in phantoms representative of a human torso. The mean errors in estimating Thorium-227 and Radium-223 were 5.1% (range −8.0% to 40.0%) and 3.4% (range −50.0% to 48.7%), respectively. The differences between the integrals of the theoretical and estimated time activity curve were <10% for both Thorium-227 and Radium-223. Conclusion: γ-camera quantification of Thorium-227 and Radium-223 can be achieved by using multiple energy window acquisitions.
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Affiliation(s)
- Iain Murray
- Physics Department, Royal Marsden NHS Hospital, Sutton, United Kingdom
| | - Bruno Rojas
- Physics Department, Royal Marsden NHS Hospital, Sutton, United Kingdom
| | - Jonathan Gear
- Physics Department, Royal Marsden NHS Hospital, Sutton, United Kingdom
| | - Ruby Callister
- Physics Department, Royal Marsden NHS Hospital, Sutton, United Kingdom
| | | | - Glenn D Flux
- Physics Department, Royal Marsden NHS Hospital, Sutton, United Kingdom
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Baranowska-Kortylewicz J, Sharp JG, McGuire TR, Joshi S, Coulter DW. Alpha-Particle Therapy for Multifocal Osteosarcoma: A Hypothesis. Cancer Biother Radiopharm 2020; 35:418-424. [PMID: 32073902 DOI: 10.1089/cbr.2019.3112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Osteosarcoma (OST) is the most common bone tumor in children and adolescents with a second peak of incidence in elderly adults usually diagnosed as secondary tumors in Paget's disease or irradiated bone. Subjects with metastatic disease or whose disease relapses after the initial therapy have a poor prognosis. Moreover, multifocal OST contains tumor-initiating cells that are resistant to chemotherapy. The use of aggressive therapies in an attempt to eradicate these cells can have long-term negative consequences in these vulnerable patient populations. 227Th-labeled molecular probes based on ligands to OST-associated receptors such as IGF-1R (insulin-like growth factor receptor 1), HER2 (human epidermal growth factor receptor 2), and PSMA (prostate-specific membrane antigen) are expected to detect and treat osseous and nonosseous sites of multifocal OST. Published reports indicate that 227Th has limited myelotoxicity, can be stably chelated to its carriers and, as it decays at targeted sites, 227Th produces 223Ra that is subsequently incorporated into the areas of increased osteoblastic activity, that is, osseous metastatic lesions. Linear energy transfer of α particles emitted by 227Th and its daughter 223Ra is within the range of the optimum relative biological effectiveness. The radiotoxicity of α particles is virtually independent of the phase in the cell cycle, oxygenation, and the dose rate. For these reasons, even resistant OST cells remain susceptible to killing by high-energy α particles, which can also kill adjacent quiescent OST cells or cells with low expression of targeted receptors. Systemic side effects are minimized by the limited range of these intense radiations. Quantitative single-photon emission computed tomography of 227Th and 223Ra is feasible. Additionally, the availability of radionuclide pairs, for example, 89Zr for positron emission tomography and 227Th for therapy, establish a strong basis for the theranostic use of 227Th in the individualized treatment of multifocal OST.
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Affiliation(s)
- Janina Baranowska-Kortylewicz
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - John G Sharp
- Department of Genetics Cell Biology & Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Timothy R McGuire
- Department of Pharmacy Practice and Science, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Shantharam Joshi
- Department of Genetics Cell Biology & Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Don W Coulter
- Division of Hematology/Oncology, Department of Pediatrics, University of Nebraska Medical Center, Omaha, Nebraska, USA
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Wickstroem K, Karlsson J, Ellingsen C, Cruciani V, Kristian A, Hagemann UB, Bjerke RM, Ryan OB, Linden L, Mumberg D, Brands M, Cuthbertson A. Synergistic Effect of a HER2 Targeted Thorium-227 Conjugate in Combination with Olaparib in a BRCA2 Deficient Xenograft Model. Pharmaceuticals (Basel) 2019; 12:ph12040155. [PMID: 31618864 PMCID: PMC6958469 DOI: 10.3390/ph12040155] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/11/2019] [Accepted: 10/12/2019] [Indexed: 01/07/2023] Open
Abstract
Targeted thorium-227 conjugates (TTCs) represent a novel class of therapeutic radiopharmaceuticals for the treatment of cancer. TTCs consist of the alpha particle emitter thorium-227 complexed to a 3,2-hydroxypyridinone chelator conjugated to a tumor-targeting monoclonal antibody. The high energy and short range of the alpha particles induce potent and selective anti-tumor activity driven by the induction of DNA damage in the target cell. Methods: The efficacy of human epidermal growth factor receptor 2 (HER2)-TTC was tested in combination in vitro and in vivo with the poly ADP ribose polymerase (PARP) inhibitor (PARPi), olaparib, in the human colorectal adenocarcinoma isogenic cell line pair DLD-1 and the knockout variant DLD-1 BRCA2 -/- Results: The in vitro combination effects were determined to be synergistic in DLD-1 BRCA2 -/- and additive in DLD-1 parental cell lines. Similarly, the in vivo efficacy of the combination was determined to be synergistic only in the DLD-1 BRCA2 -/- xenograft model, with statistically significant tumor growth inhibition at a single TTC dose of 120 kBq/kg body weight (bw) and 50 mg/kg bw olaparib (daily, i.p. for 4 weeks), demonstrating comparable tumor growth inhibition to a single TTC dose of 600 kBq/kg bw. Conclusions: This study supports the further investigation of DNA damage response inhibitors in combination with TTCs as a new strategy for the effective treatment of mutation-associated cancers.
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Affiliation(s)
| | - Jenny Karlsson
- Thorium Conjugate Research, Bayer AS, Oslo 0283, Norway.
| | | | | | | | - Urs B Hagemann
- Bayer AG, Pharmaceuticals Division, Berlin 13353, Germany.
| | - Roger M Bjerke
- Thorium Conjugate Research, Bayer AS, Oslo 0283, Norway.
| | - Olav B Ryan
- Thorium Conjugate Research, Bayer AS, Oslo 0283, Norway.
| | - Lars Linden
- Bayer AG, Pharmaceuticals Division, Wuppertal 42113, Germany.
| | | | - Michael Brands
- Bayer AG, Pharmaceuticals Division, Berlin 13353, Germany.
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