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Hatamabadi D, Joukar S, Shakeri P, Balalaie S, Yazdani A, Khoramjouy M, Mazidi SM, Kobarfard F, Mosayebnia M, Bozorgchami N, Ahmadi M, Ayyoubzadeh SM, Shahhosseini S. Synthesis and Radiolabeling of Glu-Urea-Lys with 99mTc-Tricarbonyl-Imidazole-Bathophenanthroline Disulfonate Chelation System and Biological Evaluation as Prostate-Specific Membrane Antigen Inhibitor. Cancer Biother Radiopharm 2023; 38:486-496. [PMID: 37578479 DOI: 10.1089/cbr.2023.0024] [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: 08/15/2023] Open
Abstract
Background: The Glu-Urea-Lys (EUK) pharmacophore as prostate-specific membrane antigen (PSMA)-targeted ligand was synthesized, radiolabeled with 99mTc-tricarbonyl-imidazole-BPS chelation system, and biological activities were evaluated. The strategy [2 + 1] ligand is applied for tricarbonyl labeling. (5-imidazole-1-yl)pentanoic acid as a monodentate ligand and bathophenanthroline disulfonate (BPS) as a bidentate ligand formed a chelate system with 99mTc-tricarbonyl. EUK-pentanoic acid-imidazole and EUK were evaluated for PSMA active site using AutoDock 4 software. Materials and Methods: EUK-pentanoic acid-imidazole was synthesized in two steps. BPS was radiolabeled with 99mTc-tricarbonyl at 100°C for 30 min. The purified 99mTc(CO)3(H2O)BPS was used to radiolabel EUK-pentanoic acid-imidazole at 100°C, 30 min. Radiochemical purity, Log P, and stability studies were carried out within 24 h. Affinity of 99mTc(CO)3BPS-imidazole-EUK was performed in the saturation binding studies using LNCaP cells at 37°C for 1 h with a range of 0.001-1000 nM radiolabeled compound range. Internalization studies were performed in LNCaP cells with 1000 nM radiolabeled compound incubated for (0-2) h at 37°C. Biodistribution was studied in normal male Balb/c mice. The artificial intelligence predicts the uptake of radiolabeled compound in tumor. Results: The structures of synthesized compounds were confirmed by mass spectroscopy. Radiochemical purity, Log P, and protein binding were ≥95%, -0.2%, and 23%, respectively. The radiolabeled compound was stable in saline and human plasma within 24 h with radiochemical purity ≥90%. There was no release of 99mTc within 4 h in competition with histidine. The affinity was 82 ± 26.38 nM, and the activity increased inside the cells over time. Biodistribution studies showed radioactivity accumulation in kidneys less than 99mTc-HYNIC-PSMA. There was a moderate accumulation of radioactivity in the liver and intestine. Conclusion: Based on the results, 99mTc(CO)3BPS-imidazole-EUK can potentially be used as an imaging agent for studies at prostate bed and distal areas. The chelate system can be potentially labeled with rhenium for imaging studies (fluorescent or scintigraphy) and therapy.
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Affiliation(s)
- Dara Hatamabadi
- Department of Pharmaceutical Chemistry and Radiopharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Safura Joukar
- Department of Nuclear Pharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Pegah Shakeri
- Peptide Chemistry Research Institute, K. N. Toosi University of Technolology, Tehran, Iran
| | - Saeed Balalaie
- Peptide Chemistry Research Institute, K. N. Toosi University of Technolology, Tehran, Iran
| | - Abdolreza Yazdani
- Department of Pharmaceutical Chemistry and Radiopharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mona Khoramjouy
- Phytochemistry Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Mohammad Mazidi
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
| | - Farzad Kobarfard
- Department of Pharmaceutical Chemistry and Radiopharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mona Mosayebnia
- Department of Pharmaceutical Chemistry and Radiopharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Negar Bozorgchami
- Department of Pharmaceutical Chemistry and Radiopharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahnaz Ahmadi
- Medical Nanotechnology and Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Mohammad Ayyoubzadeh
- Department of Health Information Management, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran
| | - Soraya Shahhosseini
- Department of Pharmaceutical Chemistry and Radiopharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Protein Technology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Brunello S, Salvarese N, Carpanese D, Gobbi C, Melendez-Alafort L, Bolzati C. A Review on the Current State and Future Perspectives of [ 99mTc]Tc-Housed PSMA-i in Prostate Cancer. Molecules 2022; 27:molecules27092617. [PMID: 35565970 PMCID: PMC9099988 DOI: 10.3390/molecules27092617] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/12/2022] [Accepted: 04/12/2022] [Indexed: 02/01/2023] Open
Abstract
Recently, prostate-specific membrane antigen (PSMA) has gained momentum in tumor nuclear molecular imaging as an excellent target for both the diagnosis and therapy of prostate cancer. Since 2008, after years of preclinical research efforts, a plentitude of radiolabeled compounds mainly based on low molecular weight PSMA inhibitors (PSMA-i) have been described for imaging and theranostic applications, and some of them have been transferred to the clinic. Most of these compounds include radiometals (e.g., 68Ga, 64Cu, 177Lu) for positron emission tomography (PET) imaging or endoradiotherapy. Nowadays, although the development of new PET tracers has caused a significant drop in single-photon emission tomography (SPECT) research programs and the development of new technetium-99m (99mTc) tracers is rare, this radionuclide remains the best atom for SPECT imaging owing to its ideal physical decay properties, convenient availability, and rich and versatile coordination chemistry. Indeed, 99mTc still plays a relevant role in diagnostic nuclear medicine, as the number of clinical examinations based on 99mTc outscores that of PET agents and 99mTc-PSMA SPECT/CT may be a cost-effective alternative for 68Ga-PSMA PET/CT. This review aims to give an overview of the specific features of the developed [99mTc]Tc-tagged PSMA agents with particular attention to [99mTc]Tc-PSMA-i. The chemical and pharmacological properties of the latter will be compared and discussed, highlighting the pros and cons with respect to [68Ga]Ga-PSMA11.
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Affiliation(s)
- Sara Brunello
- Institute of Condensed Matter Chemistry and Technologies for Energy ICMATE-CNR, Corso Stati Uniti 4, 35127 Padova, Italy; (S.B.); (N.S.)
| | - Nicola Salvarese
- Institute of Condensed Matter Chemistry and Technologies for Energy ICMATE-CNR, Corso Stati Uniti 4, 35127 Padova, Italy; (S.B.); (N.S.)
| | - Debora Carpanese
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Via Gattamelata 64, 35124 Padova, Italy;
| | - Carolina Gobbi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy;
| | - Laura Melendez-Alafort
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Via Gattamelata 64, 35124 Padova, Italy;
- Correspondence: (L.M.-A.); (C.B.)
| | - Cristina Bolzati
- Institute of Condensed Matter Chemistry and Technologies for Energy ICMATE-CNR, Corso Stati Uniti 4, 35127 Padova, Italy; (S.B.); (N.S.)
- Correspondence: (L.M.-A.); (C.B.)
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Yılmaz B, Şahin S, Ergül N, Çolakoğlu Y, Baytekin HF, Sökmen D, Tuğcu V, Taşçı Aİ, Çermik TF. 99mTc-PSMA targeted robot-assisted radioguided surgery during radical prostatectomy and extended lymph node dissection of prostate cancer patients. Ann Nucl Med 2022; 36:597-609. [DOI: 10.1007/s12149-022-01741-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/28/2022] [Indexed: 11/25/2022]
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Manafi-Farid R, Ranjbar S, Jamshidi Araghi Z, Pilz J, Schweighofer-Zwink G, Pirich C, Beheshti M. Molecular Imaging in Primary Staging of Prostate Cancer Patients: Current Aspects and Future Trends. Cancers (Basel) 2021; 13:5360. [PMID: 34771523 PMCID: PMC8582501 DOI: 10.3390/cancers13215360] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/17/2021] [Accepted: 10/19/2021] [Indexed: 12/19/2022] Open
Abstract
Accurate primary staging is the cornerstone in all malignancies. Different morphological imaging modalities are employed in the evaluation of prostate cancer (PCa). Regardless of all developments in imaging, invasive histopathologic evaluation is still the standard method for the detection and staging of the primary PCa. Magnetic resonance imaging (MRI) and computed tomography (CT) play crucial roles; however, functional imaging provides additional valuable information, and it is gaining ever-growing acceptance in the management of PCa. Targeted imaging with different radiotracers has remarkably evolved in the past two decades. [111In]In-capromab pendetide scintigraphy was a new approach in the management of PCa. Afterwards, positron emission tomography (PET) tracers such as [11C/18F]choline and [11C]acetate were developed. Nevertheless, none found a role in the primary staging. By introduction of the highly sensitive small molecule prostate-specific membrane antigen (PSMA) PET/CT, as well as recent developments in MRI and hybrid PET/MRI systems, non-invasive staging of PCa is being contemplated. Several studies investigated the role of these sophisticated modalities in the primary staging of PCa, showing promising results. Here, we recapitulate the role of targeted functional imaging. We briefly mention the most popular radiotracers, their diagnostic accuracy in the primary staging of PCa, and impact on patient management.
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Affiliation(s)
- Reyhaneh Manafi-Farid
- Research Center for Nuclear Medicine, Tehran University of Medical Sciences, Tehran 1411713135, Iran;
| | - Shaghayegh Ranjbar
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Zahra Jamshidi Araghi
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Julia Pilz
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Gregor Schweighofer-Zwink
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Christian Pirich
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Mohsen Beheshti
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
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Maina T, Thakur M. SPECT Radiochemistry. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00023-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Duatti A. Review on 99mTc radiopharmaceuticals with emphasis on new advancements. Nucl Med Biol 2021; 92:202-216. [PMID: 32475681 DOI: 10.1016/j.nucmedbio.2020.05.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/07/2020] [Accepted: 05/18/2020] [Indexed: 02/06/2023]
Abstract
Rapid imaging acquisition, high spatial resolution and sensitivity, powered by advancements in solid-state detector technology, are significantly changing the perspective of single photon emission tomography (SPECT). In particular, this evolutionary step is fueling a rediscovery of technetium-99m, a still unique radionuclide within the nuclear medicine scenario because of its ideal nuclear properties and easy preparation of its radiopharmaceuticals that does not require a costly infrastructure and complex procedures. Scope of this review is to show that the arsenal of technetium-99m radiopharmaceuticals is already equipped with imaging agents that may complement and integrate the role played by analogous tracers developed for positron emission tomography (PET). These include, in particular, somatostatin (SST) and prostate-specific membrane antigen (PSMA) receptor targeting agents, and a number of peptide-derived radiopharmaceuticals. Additionally, these recent technological developments, combined with new myocardial perfusion tracers having more favorable biodistribution and pharmacokinetic properties as compared to current commercial agents, may also reinvigorate the prevailing position still hold by technetium-99m radiopharmaceuticals in nuclear cardiology.
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Affiliation(s)
- Adriano Duatti
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Ferrara, Italy.
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Spek A, Graser A, Habl G, Muacevic A, Fuerweger C, Seitz M, Haidenberger A. Single‐fraction image‐guided robotic radiosurgery efficiently controls local prostate cancer recurrence after radical prostatectomy. BJUI COMPASS 2020; 1:139-145. [PMID: 35474939 PMCID: PMC8988633 DOI: 10.1002/bco2.32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/25/2020] [Accepted: 06/28/2020] [Indexed: 11/29/2022] Open
Abstract
Purpose To assess the therapeutic potential of single‐fraction robotic stereotactic ablative body radiotherapy (SABR) in patients with locally recurrent prostate cancer (PC) after radical prostatectomy (RP). Materials and methods We included 35 patients with biochemical failure after RP with single‐site local recurrence in the prostate bed diagnosed by PSMA PET/CT. About 20/35 pts had previously received post‐surgical adjuvant radiation therapy. High‐resolution multiparametric magnetic resonance imaging (mpMRI) for exact visualization of tumor tissue was performed at 1.5 (n = 23; Siemens Magnetom Aera) or 3 Tesla (n = 12; Siemens Magnetom VIDA, Siemens Healthineers, Erlangen, Germany). Using the MRI and PET/CT dataset for planning, SABR was carried out after ultrasound‐guided placement of a single gold fiducial marker at the site of tumor recurrence using a CyberKnife M6 unit (Accuray Inc., Sunnyvale, USA). Due to the high diagnostic accuracy of PSMA PET/CT and mpMRI, pre‐SABR biopsy of tumor tissue was not deemed necessary. PSMA PET/CT performed in median 88 days before SABR confirmed the absence of distant metastases. MpMRI was performed at a median of 22 days prior to the intervention. SABR was performed in a single fraction with a dose of 20 (5/35), 21 (27/35) or 22 (3/35) Gy. Follow‐up serum PSA was measured every 3 months thereafter. Results Median patient age was 72 years (57‐80 years) and median time from RP to SABR was 96.8 months (IQR, 69.3‐160.2). Median serum PSA before SABR was 1.38 ng/mL (IQR 0.75‐2.72). At 3 months, median PSA had dropped significantly in 27/35 patients to a median of 0.35 ng/mL (IQR 0.25‐0.68). At 6 months, 30/35 patients showed biochemical response to SABR, while five patients were progressing: three had systemic disease on PSMA PET/CT, while two patients had rising PSA values without a visible correlate on PET/CT. The median follow‐up time was 16 months. Grade 1 genitourinary (GU) toxicity was reported in 3/35 patients (9%) and grade 1 gastrointestinal (GI) toxicity in 2/35 patients (6%), respectively. Conclusion SABR is an efficient new treatment option in the management of single‐site local recurrent PC without the evidence of systemic disease; due to its very low toxicity, it is an alternative to surgical re‐treatment or other focal therapies. It can significantly delay the onset of androgen deprivation therapy (ADT) in biochemical failure after radical prostatectomy.
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Affiliation(s)
- A. Spek
- Department of Urology Ludwig Maximilian University Munich Germany
| | | | - G. Habl
- Department of Radiation Therapy Technical University of Munich Munich Germany
| | - A. Muacevic
- European Cyberknife Center Munich Munich Germany
| | - C. Fuerweger
- European Cyberknife Center Munich Munich Germany
| | - M. Seitz
- Uroclinic Bogenhausen Munich Germany
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Chen J, Wang Z, Zhao J, Zhu S, Sun G, Liu J, Zhang H, Zhang X, Shen P, Shi M, Zeng H. Pelvic lymph node dissection and its extent on survival benefit in prostate cancer patients with a risk of lymph node invasion >5%: a propensity score matching analysis from SEER database. Sci Rep 2019; 9:17985. [PMID: 31784574 PMCID: PMC6884595 DOI: 10.1038/s41598-019-54261-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 10/28/2019] [Indexed: 02/05/2023] Open
Abstract
Pelvic lymph node dissection (PLND) represents the gold standard for nodal staging in PCa and is recommended for patients with a probability of lymph node invasion (LNI) >5%. However, the therapeutic role of PLND and its extent remains a debate. In this study, data of 20,668 patients treated with radical prostatectomy (RP) with and without PLND from SEER database between 2010 and 2015 were retrospectively analyzed. All patients had a risk of LNI >5% according to 2012-Briganti nomogram. Propensity score matching (PSM) was performed to balance baseline characteristics between patients with and without PLND. Kaplan-Meier curves and Cox regression were used to evaluate the impacts of the PLND and its extent on cancer-specific survival (CSS) and overall survival (OS). In overall cohort, patients with PLND were associated with more aggressive clinicopathologic characteristics and had poorer survival compared to those without PLND (5-year CSS rate: 98.4% vs. 99.7%, p < 0.001; 5-year OS rate: 96.3% vs. 97.8%, p < 0.001). In the post-PSM cohort, no significant difference in survival was found between patients with and without PLND (5-year CSS rate: 99.4% vs. 99.7%, p = 0.479; 5-year OS rate: 97.3% vs. 97.8%, p = 0.204). In addition, the extent of PLND had no impact on prognosis (all p > 0.05). Subgroup analyses reported similar negative findings. In conclusion, neither PLND nor its extent was associated with survival in North American patients with a risk of LNI >5%. The cut-off point of 5% probability of LNI might be too low to show benefits in survival in patients underwent PLND.
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Affiliation(s)
- Junru Chen
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Zhipeng Wang
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Jinge Zhao
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Sha Zhu
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Guangxi Sun
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Jiandong Liu
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Haoran Zhang
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xingming Zhang
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Pengfei Shen
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Ming Shi
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Hao Zeng
- Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, 610041, China.
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Carlos Dos Santos J, Beijer B, Bauder-Wüst U, Schäfer M, Leotta K, Eder M, Benešová M, Kleist C, Giesel F, Kratochwil C, Kopka K, Haberkorn U, Mier W. Development of Novel PSMA Ligands for Imaging and Therapy with Copper Isotopes. J Nucl Med 2019; 61:70-79. [PMID: 31541034 DOI: 10.2967/jnumed.119.229054] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/12/2019] [Indexed: 01/05/2023] Open
Abstract
Prostate-specific membrane antigen (PSMA)-binding tracers have been shown to be promising agents for the specific targeting of prostate tumors. On labeling with the short-lived isotopes 18F and 68Ga, excellent molecular imaging performance is achieved. This potential could be further exploited using long-lived isotopes. Because of the favorable half-life of 64Cu, tracers labeled with this PET nuclide could solve logistic problems. Moreover, this isotope provides a theranostic pair with the therapeutic copper isotope 67Cu. Hence, 9 novel tracers that combine dedicated copper chelators with the PSMA-specific urea-based binding motif were developed. Methods: The precursors were obtained by solid-phase synthesis. The purity and molecular weight of the PSMA ligands were confirmed by high-performance liquid chromatography and liquid chromatography-mass spectrometry. The compounds were labeled with 64Cu, with a radiolabeling yield of more than 99%. Competitive cell binding assays and internalization assays were performed with C4-2 cells, a subline of the PSMA-positive cell line LNCaP (human lymph node carcinoma of the prostate). In vitro serum stability, the stability of 64Cu-CA003 in blood, and the in vivo fate of neat 64Cu-chloride or 64Cu-CA003 were determined to prove whether the stability of the radiolabeled compounds is sufficient to ensure no significant loss of copper during the targeting process. For PET imaging and biodistribution studies, a C4-2 tumor-bearing mouse model was used. Results: The radiolabeled 64Cu-PSMA ligands showed high serum stability. All PSMA ligands showed high inhibition potencies, with equilibrium inhibition constants in the low nanomolar range. 64Cu-CA003 and 64Cu-CA005 showed high internalization ratios (34.6% ± 2.8 and 18.6% ± 4.4, respectively). Both the in vitro serum stability determination and the in vivo characterization of the main radiolabeled compounds confirmed that, except for 64Cu-PSMA-617, all compounds showed high serum stability within the observation period of 24 h. Small-animal PET imaging demonstrated high tumor uptake within 20 min. Organ distribution studies confirmed high specific uptake in the tumor, with 30.8 ± 12.6 percentage injected dose (%ID)/g at 1 h after injection. Rapid clearance from the kidneys was observed-a decrease from 67.0 ± 20.9 %ID/g at 1 h after injection to 7.5 ± 8.51 %ID/g at 24 h after injection (in the case of CA003). The performance of CA003, the compound with the best preclinical properties, was assessed in a first patient. In line with its preclinical data, PET imaging resulted in clear visualization of the cancer lesions, with high contrast. Conclusion: The 64Cu-labeled PSMA ligands are promising agents to target PSMA and visualize PSMA-positive tumor lesions as shown in preclinical evaluation by small-animal PET studies, organ distribution, and a patient application. Most importantly, the images obtained at 20 h enabled delineation of unclear lesions, showing that the compounds fulfill the prerequisite for dosimetry in the course of therapy planning with 67Cu. Thus, we suggest clinical use of copper-labeled CA003 for diagnostics and radiotherapy of prostate cancer.
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Affiliation(s)
| | - Barbro Beijer
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Ulrike Bauder-Wüst
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany
| | - Martin Schäfer
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany
| | - Karin Leotta
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Matthias Eder
- Division of Radiopharmaceutical Development, German Cancer Consortium Freiburg, Department of Nuclear Medicine, University of Freiburg, Freiburg, Germany; and
| | - Martina Benešová
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany
| | - Christian Kleist
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Frederik Giesel
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Clemens Kratochwil
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Klaus Kopka
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany
| | - Uwe Haberkorn
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany.,Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany
| | - Walter Mier
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
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