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Roy T, Pogorilyy E, Kumarananthan CP, Kvitastein UA, Foscato M, Törnroos KW, Adamsen TCH, Le Roux E. Synthesis and stability of the [ 45Ti]Ti-DOTA complex: en route towards aza-macrocyclic 45Ti-based radiopharmaceuticals. Chem Commun (Camb) 2024; 60:7148-7151. [PMID: 38860653 DOI: 10.1039/d4cc01800a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
We report the use of DOTA as a chelator for titanium. The resulting complex is fully characterised and in vitro stability studies reveal its high kinetic inertness against transmetallation and transchelation. The radiolabeling of DOTA with 45Ti, via a guaiacol-based liquid-liquid extraction method, leads to a high radiochemical conversion up to 98%.
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Affiliation(s)
- Tamal Roy
- Department of Chemistry, University of Bergen, Allégaten 41, Bergen, Norway.
| | - Eduard Pogorilyy
- Department of Chemistry, University of Bergen, Allégaten 41, Bergen, Norway.
| | - Chubina P Kumarananthan
- Department of Radiology, Haukeland University Hospital, Centre for Nuclear Medicine and PET, Jonas Lies vei 65, Bergen, Norway
| | - Unni A Kvitastein
- Department of Radiology, Haukeland University Hospital, Centre for Nuclear Medicine and PET, Jonas Lies vei 65, Bergen, Norway
| | - Marco Foscato
- Department of Chemistry, University of Bergen, Allégaten 41, Bergen, Norway.
| | - Karl W Törnroos
- Department of Chemistry, University of Bergen, Allégaten 41, Bergen, Norway.
| | - Tom C H Adamsen
- Department of Chemistry, University of Bergen, Allégaten 41, Bergen, Norway.
- Department of Radiology, Haukeland University Hospital, Centre for Nuclear Medicine and PET, Jonas Lies vei 65, Bergen, Norway
| | - Erwan Le Roux
- Department of Chemistry, University of Bergen, Allégaten 41, Bergen, Norway.
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2
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Koller AJ, Glaser O, DeLuca MC, Motz RN, Amason EK, Carbo-Bague I, Mixdorf JC, Guzei IA, Aluicio-Sarduy E, Śmiłowicz D, Barnhart TE, Ramogida CF, Nolan EM, Engle JW, Boros E. "Off-Label Use" of the Siderophore Enterobactin Enables Targeted Imaging of Cancer with Radioactive Ti (IV). Angew Chem Int Ed Engl 2024; 63:e202319578. [PMID: 38442302 PMCID: PMC11258920 DOI: 10.1002/anie.202319578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/27/2024] [Accepted: 03/04/2024] [Indexed: 03/07/2024]
Abstract
The development of inert, biocompatible chelation methods is required to harness the emerging positron emitting radionuclide 45Ti for radiopharmaceutical applications. Herein, we evaluate the Ti(IV)-coordination chemistry of four catechol-based, hexacoordinate chelators using synthetic, structural, computational, and radiochemical approaches. The siderophore enterobactin (Ent) and its synthetic mimic TREN-CAM readily form mononuclear Ti(IV) species in aqueous solution at neutral pH. Radiolabeling studies reveal that Ent and TREN-CAM form mononuclear complexes with the short-lived, positron-emitting radionuclide 45Ti(IV), and do not transchelate to plasma proteins in vitro and exhibit rapid renal clearance in naïve mice. These features guide efforts to target the 45Ti isotope to prostate cancer tissue through the design, synthesis, and evaluation of Ent-DUPA, a small molecule conjugate composed of a prostate specific membrane antigen (PSMA) targeting peptide and a monofunctionalized Ent scaffold. The [45Ti][Ti(Ent-DUPA)]2- complex forms readily at room temperature. In a tumor xenograft model in mice, selective tumor tissue accumulation (8±5 %, n=5), and low off-target uptake in other organs is observed. Overall, this work demonstrates targeted imaging with 45Ti(IV), provides a foundation for advancing the application of 45Ti in nuclear medicine, and reveals that Ent can be repurposed as a 45Ti-complexing cargo for targeted nuclear imaging applications.
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Affiliation(s)
- Angus J Koller
- Department of Chemistry, Stony Brook University, Stony Brook, New York, 11794, United States
| | - Owen Glaser
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, United States
| | - Molly C DeLuca
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin, 53705, United States
| | - Rachel N Motz
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, United States
| | - Edith K Amason
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, United States
| | - Imma Carbo-Bague
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Jason C Mixdorf
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin, 53705, United States
| | - Ilia A Guzei
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, United States
| | - Eduardo Aluicio-Sarduy
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin, 53705, United States
| | - Dariusz Śmiłowicz
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, United States
| | - Todd E Barnhart
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin, 53705, United States
| | - Caterina F Ramogida
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Elizabeth M Nolan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, United States
| | - Jonathan W Engle
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin, 53705, United States
| | - Eszter Boros
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, United States
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Saini S, Lapi SE. Titanium-45 ( 45Ti) Radiochemistry and Applications in Molecular Imaging. Pharmaceuticals (Basel) 2024; 17:479. [PMID: 38675439 PMCID: PMC11054510 DOI: 10.3390/ph17040479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 04/02/2024] [Accepted: 04/03/2024] [Indexed: 04/28/2024] Open
Abstract
Molecular imaging is an important part of modern medicine which enables the non-invasive identification and characterization of diseases. With the advancement of radiochemistry and scanner technology, nuclear medicine is providing insight into efficient treatment options for individual patients. Titanium-45 (45Ti) is a lesser-explored radionuclide that is garnering increasing interest for the development of positron emission tomography (PET) radiopharmaceuticals. This review discusses aspects of this radionuclide including production, purification, radiochemistry development, and molecular imaging studies.
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Affiliation(s)
- Shefali Saini
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Suzanne E. Lapi
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Saini S, Mullen GED, Blower PJ, Lapi SE. Radiochemistry and In Vivo Imaging of [ 45Ti]Ti-THP-PSMA. Mol Pharm 2024; 21:822-830. [PMID: 38173242 DOI: 10.1021/acs.molpharmaceut.3c00917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Titanium-45 (45Ti) is a radionuclide with excellent physical characteristics for use in positron emission tomography (PET) imaging, including a moderate half-life (3.08 h), decay by positron emission (85%), and a low mean positron energy of 0.439 MeV. However, challenges associated with titanium chemistry have led to the underdevelopment of this radionuclide for incorporation into radiopharmaceuticals. Expanding on our recent studies, which showed promising results for the complexation of 45Ti with the tris hydroxypyridinone (THPMe) chelator, the current work aimed to optimize the chemistry and imaging attributes of [45Ti]Ti-THP-PSMA as a new PET radiopharmaceutical. Methods. Radiolabeling of THP-PSMA was optimized with [45Ti]Ti-citrate at varying pHs and masses of the precursor. The stability of the radiolabeled complex was assessed in mouse serum for up to 6 h. The affinity of [45Ti]Ti-THP-PSMA for prostate-specific membrane antigen (PSMA) was assessed using LNCaP (PSMA +) and PC3 (PSMA -) cell lines. In vivo imaging and biodistribution analysis were performed in tumor-bearing xenograft mouse models to confirm the specificity of the tumor uptake. Results. > 95% of radiolabeling was achieved with a high specific activity of 5.6 MBq/nmol under mild conditions. In vitro cell binding studies showed significant binding of the radiolabeled complex with the PSMA-expressing LNCaP cell line (11.9 ± 1.5%/mg protein-bound activity) compared to that with the nonexpressing PC3 cells (1.9 ± 0.4%/mg protein-bound activity). In vivo imaging and biodistribution studies confirmed specific uptake in LNCaP tumors (1.6 ± 0.27% ID/g) compared to that in PC3 tumors (0.39 ± 0.2% ID/g). Conclusion. This study showed a simple one-step radiolabeling method for 45Ti with THP-PSMA under mild conditions (pH 8 and 37 °C). In vitro cell studies showed promise, but in vivo tumor xenograft studies indicated low tumor uptake. Overall, this study shows the need for more chelators for 45Ti for the development of a PET radiopharmaceutical for cancer imaging.
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Affiliation(s)
- Shefali Saini
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Gregory E D Mullen
- School of Biomedical Engineering and Imaging Sciences, King's College London, London SE1 7EH, U.K
| | - Philip J Blower
- School of Biomedical Engineering and Imaging Sciences, King's College London, London SE1 7EH, U.K
| | - Suzanne E Lapi
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
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Jalilian A, Decristoforo C, Denecke M, Elsinga PH, Hoehr C, Korde A, Lapi SE, Scott PJH. Proceedings of international symposium of trends in radiopharmaceuticals 2023 (ISTR-2023). EJNMMI Radiopharm Chem 2023; 8:39. [PMID: 37950112 PMCID: PMC10638263 DOI: 10.1186/s41181-023-00224-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 10/29/2023] [Indexed: 11/12/2023] Open
Abstract
The International Atomic Energy Agency (IAEA) held the 3rd International Symposium on Trends in Radiopharmaceuticals, (ISTR-2023) at IAEA Headquarters in Vienna, Austria, during the week of 16-21 April 2023. This procedural paper summarizes highlights from symposium presentations, posters, panel discussions and satellite meetings, and provides additional resources that may be useful to researchers working with diagnostic and therapeutic radiopharmaceuticals in the academic, government and industry setting amongst IAEA Member States and beyond. More than 550 participants in person from 88 Member States attended the ISTR-2023. Over 360 abstracts were presented from all over the world by a diverse group of global scientists working with radiopharmaceuticals. Given this group of international radiochemists is unique to ISTR (IAEA funding enabled many to attend), there was an invaluable wealth of knowledge on the global state of the radiopharmaceutical sciences present at the meeting. The intent of this Proceedings paper is to share this snapshot from our international colleagues with the broader radiopharmaceutical sciences community by highlighting presentations from the conference on the following topics: Isotope Production and Radiochemistry, Industrial Insights, Regional Trends, Training and Education, Women in the Radiopharmaceutical Sciences, and Future Perspectives and New Initiatives. The authors of this paper are employees of IAEA, members of the ISTR-2023 Organizing Committee and/or members of the EJNMMI Radiopharmacy and Chemistry Editorial Board who attended ISTR-2023. Overall, ISTR-2023 fostered the successful exchange of scientific ideas around every aspect of the radiopharmaceutical sciences. It was well attended by a diverse mix of radiopharmaceutical scientists from all over the world, and the oral and poster presentations provided a valuable update on the current state-of-the-art of the field amongst IAEA Member States. Presentations as well as networking amongst the attendees resulted in extensive knowledge transfer amongst the various stakeholders representing 88 IAEA Member States. This was considered particularly valuable for attendees from Member States where nuclear medicine and the radiopharmaceutical sciences are still relatively new. Since the goal is for the symposium series to be held every four years; the next one is anticipated to take place in 2027.
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Affiliation(s)
- Amirreza Jalilian
- Division of Physical and Chemical Sciences, International Atomic Energy Agency, Vienna, Austria
| | - Clemens Decristoforo
- Department of Nuclear Medicine, Medical University Innsbruck, Innsbruck, Austria
| | - Melissa Denecke
- Division of Physical and Chemical Sciences, International Atomic Energy Agency, Vienna, Austria
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Aruna Korde
- Division of Physical and Chemical Sciences, International Atomic Energy Agency, Vienna, Austria
| | - Suzanne E Lapi
- Departments of Radiology and Chemistry, O'Neal Comprehensive Cancer Center at UAB, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Peter J H Scott
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA.
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Śmiłowicz D, Eisenberg S, Ahn SH, Koller AJ, Lampkin PP, Boros E. Radiometallation and photo-triggered release of ready-to-inject radiopharmaceuticals from the solid phase. Chem Sci 2023; 14:5038-5050. [PMID: 37206398 PMCID: PMC10189872 DOI: 10.1039/d2sc06977f] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/15/2023] [Indexed: 05/21/2023] Open
Abstract
The efficient, large-scale synthesis of radiometallated radiopharmaceuticals represents an emerging clinical need which, to date, is inherently limited by time consuming, sequential procedures to conduct isotope separation, radiochemical labeling and purification prior to formulation for injection into the patient. In this work, we demonstrate that a solid-phase based, concerted separation and radiosynthesis strategy followed by photochemical release of radiotracer in biocompatible solvents can be employed to prepare ready-to-inject, clinical grade radiopharmaceuticals. Optimization of resin base, resin loading, and radiochemical labeling capacity are demonstrated with 67Ga and 64Cu radioisotopes using a short model peptide sequence and further validated using two peptide-based radiopharmaceuticals with clinical relevance, targeting the gastrin-releasing peptide and the prostate specific membrane antigen. We also demonstrate that the solid-phase approach enables separation of non-radioactive carrier ions Zn2+ and Ni2+ present at 105-fold excess over 67Ga and 64Cu by taking advantage of the superior Ga3+ and Cu2+ binding affinity of the solid-phase appended, chelator-functionalized peptide. Finally, a proof of concept radiolabeling and subsequent preclinical PET-CT study with the clinically employed positron emitter 68Ga successfully exemplifies that Solid Phase Radiometallation Photorelease (SPRP) allows the streamlined preparation of radiometallated radiopharmaceuticals by concerted, selective radiometal ion capture, radiolabeling and photorelease.
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Affiliation(s)
- Dariusz Śmiłowicz
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook NY 11794 USA
| | - Shawn Eisenberg
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook NY 11794 USA
| | - Shin Hye Ahn
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook NY 11794 USA
| | - Angus J Koller
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook NY 11794 USA
| | - Philip P Lampkin
- Department of Chemistry, University of Wisconsin-Madison Madison WI 53705 USA
| | - Eszter Boros
- Department of Chemistry, Stony Brook University 100 Nicolls Road, Stony Brook NY 11794 USA
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Preparation and quality control of a new porphyrin complex labeled with 45Ti for PET imaging. Appl Radiat Isot 2023; 193:110650. [PMID: 36646031 DOI: 10.1016/j.apradiso.2023.110650] [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: 10/14/2022] [Revised: 12/27/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023]
Abstract
This study aims to produce and quality control of a new porphyrin complex labeled with 45Ti for PET imaging, so at the first step, the cross-section of 45Sc(p,n)45Ti was investigated by TALYS-1.6 and the optimal target thickness and theoretical yield were calculated by SRIM code. The purified 45Ti was labeled with the anticancer agent of tetrakis (pentafluorophenyl) porphyrin (TFPP). The radiochemical purity and the percentage of labeling were evaluated by radiation layer chromatography then the division coefficient of [45Ti]-TFPP was calculated. The dual coincidence imaging system was used for imaging 1 and 2 h after injection [45Ti]-TFPP to rats. Immediately after imaging, the mean percent injected dose per gram and specific activity of different tissues including blood, heart, lungs, stomach, liver, bone, kidney, spleen, intestine, muscle, feces, and skin were measured. The yield of 45Ti production was measured 468 MBq/μAh and the labeling rate was observed more than 98%. The highest activity was observed in the liver (%ID/g = 2.27%, 1 h) and spleen (2.2%, 1 h), respectively, because of the high lipophilic of 45Ti-TFPP. SPECT images showed a significant uptake of radiopharmaceuticals in the abdomen. The labeling rate of 45Ti-TFPP was high and this compound has the potential for clinical application in different ways than PSMA, it can be joined with photodynamic therapy (Severin et al., 2015).
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Lengacher R, Marlin A, Śmiłowicz D, Boros E. Medicinal inorganic chemistry - challenges, opportunities and guidelines to develop the next generation of radioactive, photoactivated and active site inhibiting metal-based medicines. Chem Soc Rev 2022; 51:7715-7731. [PMID: 35942718 DOI: 10.1039/d2cs00407k] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Medicinal inorganic chemistry is a burgeoning subfield of medicinal chemistry that focuses on the development of metal-based diagnostic and therapeutic agents. This tutorial review aims to provide an introductory primer, present a timely overview of recent discoveries and identify current challenges and opportunities of the field. Three specific areas of discovery are highlighted herein. The first part focuses on metal-based radiopharmaceuticals for diagnostic and therapeutic purposes and specific design criteria for the development of radiopharmaceuticals that combine fundamental aqueous coordination chemistry with elucidation of pharmacokinetics. The second part describes approaches to photodynamic therapy with metal complexes. Here, photophysical characterization, combined with the challenge of careful control of the chemical behavior and selective biological deposition of transition metals with significant off-target toxicity, is discussed. In the third part, we summarize emerging strategies to modulate enzyme inhibition with coordination chemistry, while also highlighting the utility of the unique properties of metal ions for the characterization of mechanisms of action of these emerging diagnostic and therapeutic agents.
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Affiliation(s)
- Raphael Lengacher
- Department of Chemistry, Stony Brook University, Stony Brook, 11790 New York, USA.
| | - Axia Marlin
- Department of Chemistry, Stony Brook University, Stony Brook, 11790 New York, USA.
| | - Dariusz Śmiłowicz
- Department of Chemistry, Stony Brook University, Stony Brook, 11790 New York, USA.
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, Stony Brook, 11790 New York, USA.
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