1
|
Song L, Nguyen V, Xie J, Jia S, Chang CJ, Uchio E, Zi X. ATPase Copper Transporting Beta (ATP7B) Is a Novel Target for Improving the Therapeutic Efficacy of Docetaxel by Disulfiram/Copper in Human Prostate Cancer. Mol Cancer Ther 2024; 23:854-863. [PMID: 38417139 PMCID: PMC11150099 DOI: 10.1158/1535-7163.mct-23-0876] [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: 12/10/2023] [Revised: 01/31/2024] [Accepted: 02/23/2024] [Indexed: 03/01/2024]
Abstract
Docetaxel has been the standard first-line chemotherapy for lethal metastatic prostate cancer (mPCa) since 2004, but resistance to docetaxel treatment is common. The molecular mechanisms of docetaxel resistance remain largely unknown and could be amenable to interventions that mitigate resistance. We have recently discovered that several docetaxel-resistant mPCa cell lines exhibit lower uptake of cellular copper and uniquely express higher levels of a copper exporter protein ATP7B. Knockdown of ATP7B by silencing RNAs (siRNA) sensitized docetaxel-resistant mPCa cells to the growth-inhibitory and apoptotic effects of docetaxel. Importantly, deletions of ATP7B in human mPCa tissues predict significantly better survival of patients after their first chemotherapy than those with wild-type ATP7B (P = 0.0006). In addition, disulfiram (DSF), an FDA-approved drug for the treatment of alcohol dependence, in combination with copper, significantly enhanced the in vivo antitumor effects of docetaxel in a docetaxel-resistant xenograft tumor model. Our analyses also revealed that DSF and copper engaged with ATP7B to decrease protein levels of COMM domain-containing protein 1 (COMMD1), S-phase kinase-associated protein 2 (Skp2), and clusterin and markedly increase protein expression of cyclin-dependent kinase inhibitor 1 (p21/WAF1). Taken together, our results indicate a copper-dependent nutrient vulnerability through ATP7B exporter in docetaxel-resistant prostate cancer for improving the therapeutic efficacy of docetaxel.
Collapse
Affiliation(s)
- Liankun Song
- Department of Urology, University of California, Irvine, Orange, CA 92868, USA
| | - Vyvyan Nguyen
- Department of Urology, University of California, Irvine, Orange, CA 92868, USA
| | - Jun Xie
- Department of Urology, University of California, Irvine, Orange, CA 92868, USA
| | - Shang Jia
- Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 USA
| | - Christopher J. Chang
- Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 USA
| | - Edward Uchio
- Department of Urology, University of California, Irvine, Orange, CA 92868, USA
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Orange, CA 92868, USA
| | - Xiaolin Zi
- Department of Urology, University of California, Irvine, Orange, CA 92868, USA
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Orange, CA 92868, USA
- Veterans Affairs Long Beach Healthcare System, Long Beach, CA 90822, USA
| |
Collapse
|
2
|
Svedjehed J, Kutyreff CJ, Engle JW, Gagnon K. Automated, cassette-based isolation and formulation of high-purity [ 61Cu]CuCl 2 from solid Ni targets. EJNMMI Radiopharm Chem 2020; 5:21. [PMID: 33151400 PMCID: PMC7644601 DOI: 10.1186/s41181-020-00108-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/19/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND A need for improved, cassette-based automation of 61Cu separation from irradiated Ni targets was identified given the growing interest in theranostics, and generally lengthy separation chemistries for 64Cu/64Ni, upon which 61Cu chemistry is often based. METHODS A method for separating 61Cu from irradiated natNi targets was therefore developed, with provision for target recycling. Following deuteron irradiation, electroplated natNi targets were remotely transferred from the cyclotron and dissolved in acid. The dissolved target solution was then transferred to an automated FASTlab chemistry module, where sequential TBP and TK201 (Triskem) resins isolated the [61Cu]CuCl2, removed Ni, Co, and Fe, and concentrated the product into a formulation suitable for anticipated radiolabelling reactions. RESULTS 61Cu saturation yields of 190 ± 33 MBq/μA from energetically thick natNi targets were measured. The average, decay-corrected, activity-based dissolution efficiency was 97.5 ± 1.4% with an average radiochemical yield of 90.4 ± 3.2% (N = 5). The isolated activity was collected approximately 65 min post end of bombardment in ~ 2 mL of 0.06 M HCl (HCl concentration was verified by titration). Quality control of the isolated [61Cu]CuCl2 (N = 5) measured 58Co content of (8.3 ± 0.6) × 10- 5% vs. 61Cu by activity, Ni separation factors ≥ (2.2 ± 1.8) × 106, EoB molar activities 85 ± 23 GBq/μmol and NOTA-based EoB apparent molar activities of 31 ± 8 MBq/nmol and 201 MBq/nmol for the 30 min and 3.3 h (N = 1) irradiations, respectively. CONCLUSION High purity 61Cu was produced with the developed automated method using a single-use, cassette-based approach. It was also applicable for 64Cu, as demonstrated with a single proof-of-concept 64Ni target production run.
Collapse
Affiliation(s)
- Johan Svedjehed
- Cyclotrons and TRACERcenter, GE Healthcare, GEMS PET Systems AB, Uppsala, Sweden
| | - Christopher J Kutyreff
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Jonathan W Engle
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.,Department of Radiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Katherine Gagnon
- Cyclotrons and TRACERcenter, GE Healthcare, GEMS PET Systems AB, Uppsala, Sweden.
| |
Collapse
|
3
|
Lepage ML, Kuo H, Roxin Á, Huh S, Zhang Z, Kandasamy R, Merkens H, Kumlin JO, Limoges A, Zeisler SK, Lin K, Bénard F, Perrin DM. Toward18F‐Labeled Theranostics: A Single Agent that Can Be Labeled with18F,64Cu, or177Lu. Chembiochem 2020; 21:943-947. [DOI: 10.1002/cbic.201900632] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Indexed: 12/21/2022]
Affiliation(s)
- Mathieu L. Lepage
- Chemistry DepartmentUniversity of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| | | | - Áron Roxin
- Chemistry DepartmentUniversity of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
- BC Cancer 675 W 10th Avenue Vancouver BC V5Z 1L3 Canada
- Department of RadiologyUniversity of British Columbia 2775 Laurel Street Vancouver BC V5Z 1M9 Canada
| | - Sungjoon Huh
- Chemistry DepartmentUniversity of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| | - Zhengxing Zhang
- BC Cancer 675 W 10th Avenue Vancouver BC V5Z 1L3 Canada
- Department of RadiologyUniversity of British Columbia 2775 Laurel Street Vancouver BC V5Z 1M9 Canada
| | - Rajaguru Kandasamy
- Chemistry DepartmentUniversity of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| | - Helen Merkens
- BC Cancer 675 W 10th Avenue Vancouver BC V5Z 1L3 Canada
- Department of RadiologyUniversity of British Columbia 2775 Laurel Street Vancouver BC V5Z 1M9 Canada
| | | | - Alan Limoges
- TRIUMF 4004 Wesbrook Mall Vancouver BC V6T 2A3 Canada
| | | | - Kuo‐Shyan Lin
- BC Cancer 675 W 10th Avenue Vancouver BC V5Z 1L3 Canada
| | - François Bénard
- BC Cancer 675 W 10th Avenue Vancouver BC V5Z 1L3 Canada
- Department of RadiologyUniversity of British Columbia 2775 Laurel Street Vancouver BC V5Z 1M9 Canada
| | - David M. Perrin
- Chemistry DepartmentUniversity of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| |
Collapse
|
4
|
Calabria F, Pichler R, Leporace M, Wolfsgruber J, Coscarelli P, Dunzinger A, Schillaci O, Cascini GL, Bagnato A. 68Ga/64Cu PSMA Bio-Distribution in Prostate Cancer Patients: Potential Pitfalls for Different Tracers. Curr Radiopharm 2020; 12:238-246. [PMID: 31113354 DOI: 10.2174/1874471012666190515090755] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 03/20/2019] [Accepted: 04/04/2019] [Indexed: 01/02/2023]
Abstract
BACKGROUND 68Ga-PSMA is a widely useful PET/CT tracer for prostate cancer imaging. Being a transmembrane protein acting as a glutamate carboxypeptidase enzyme, PSMA is highly expressed in prostate cancer cells. PSMA can also be labeled with 64Cu, offering a longer half-life and different resolution imaging. Several studies documented bio-distribution and pitfalls of 68Ga-PSMA as well as of 64Cu- PSMA. No data are reported on differences between these two variants of PSMA. Our aim was to evaluate physiological distribution of these two tracers and to analyze false positive cases. METHODS We examined tracer bio-distribution in prostate cancer patients with negative 68Ga-PSMA PET/CT (n=20) and negative 64Ga-PSMA PET/CT (n=10). A diagnostic pitfall for each tracer was documented. RESULT Bio-distribution of both tracers was similar, with some differences due to renal excretion of 68Ga- PSMA and biliary excretion of 64Cu-PSMA. 68Ga-PSMA uptake was observed in sarcoidosis while 64Cu- PSMA uptake was recorded in pneumonitis. DISCUSSION Both tracers may present similar bio-distribution in the human body, with similar uptake in exocrine glands and high intestinal uptake. Similarly to other tracers, false positive cases cannot be excluded in clinical practice. CONCLUSION The knowledge of difference in bio-distribution between two tracers may help in interpretation of PET data. Diagnostic pitfalls can be documented, due to the possibility of PSMA uptake in inflammation. Our results are preliminary to future studies comparing diagnostic accuracies of 68Ga-PSMA and 64Cu-PSMA.
Collapse
Affiliation(s)
- Ferdinando Calabria
- Department of Nuclear Medicine and Theranostics, National Public Hospital "Mariano Santo", 87100, Cosenza, Italy
| | - Robert Pichler
- Institute of Nuclear Medicine, Kepler University Hospital, Neuromed Campus, Wagner-Jauregg Weg 15, A-4021 Linz, Austria
| | - Mario Leporace
- Department of Nuclear Medicine and Theranostics, National Public Hospital "Mariano Santo", 87100, Cosenza, Italy
| | | | | | - Andreas Dunzinger
- Institute of Nuclear Medicine, Kepler University Hospital, Neuromed Campus, Wagner-Jauregg Weg 15, A-4021 Linz, Austria
| | - Orazio Schillaci
- Department of Biomedicine and Prevention, University "Tor Vergata", 00133, Rome, Italy.,IRCCS INM Neuromed, 86077, Pozzilli (IS), Italy
| | - Giuseppe Lucio Cascini
- Department of Diagnostic Imaging, Nuclear Medicine Unit, Magna Graecia University, Catanzaro, Italy
| | - Antonio Bagnato
- Department of Nuclear Medicine and Theranostics, National Public Hospital "Mariano Santo", 87100, Cosenza, Italy
| |
Collapse
|
5
|
Jokar N, Assadi M, Yordanova A, Ahmadzadehfar H. Bench-to-Bedside Theranostics in Nuclear Medicine. Curr Pharm Des 2020; 26:3804-3811. [PMID: 32067609 DOI: 10.2174/1381612826666200218104313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 12/11/2019] [Indexed: 11/22/2022]
Abstract
The optimum selection of the appropriate radiolabelled probe for the right target and the right patient is the foundation of theranostics in personalised medicine. In nuclear medicine, this process is realised through the appropriate choice of radiopharmaceuticals based on molecular biomarkers regarding molecular imaging. Theranostics is developing a strategy that can be used to implement accepted tools for individual molecular targeting, including diagnostics, and advances in genomic molecular knowledge, which has led to identifying theranostics biomaterials that have the potency to diagnose and treat malignancies. Today, numerous studies have reported on the discovery and execution of these radiotracers in personalised medicine. In this review, we presented our point of view of the most important theranostics agents that can be used to treat several types of malignancies. Molecular targeted radionuclide treatment methods based on theranostics are excellent paradigms of the relationship between molecular imaging and therapy that has been used to provide individualised or personalised patient care. Toward that end, a precise planned prospective examination of theranostics must be done to compare this approach to more standard therapies.
Collapse
Affiliation(s)
- Narges Jokar
- The Persian Gulf Nuclear Medicine Research Center, Department of Molecular Imaging and Radionuclide Therapy (MIRT), Bushehr Medical University Hospital, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
| | - Majid Assadi
- The Persian Gulf Nuclear Medicine Research Center, Department of Molecular Imaging and Radionuclide Therapy (MIRT), Bushehr Medical University Hospital, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
| | - Anna Yordanova
- Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany
| | | |
Collapse
|
6
|
van der Meulen NP, Hasler R, Blanc A, Farkas R, Benešová M, Talip Z, Müller C, Schibli R. Implementation of a new separation method to produce qualitatively improved 64
Cu. J Labelled Comp Radiopharm 2019; 62:460-470. [DOI: 10.1002/jlcr.3730] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 03/06/2019] [Accepted: 03/20/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Nicholas P. van der Meulen
- Laboratory of Radiochemistry; Paul Scherrer Institute; Villigen-PSI Switzerland
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
| | - Roger Hasler
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
| | - Alain Blanc
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
| | - Renata Farkas
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
| | - Martina Benešová
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
- Department of Chemistry and Applied Biosciences; ETH Zurich; Zurich Switzerland
| | - Zeynep Talip
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
| | - Cristina Müller
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
- Department of Chemistry and Applied Biosciences; ETH Zurich; Zurich Switzerland
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ; Paul Scherrer Institute; Villigen-PSI Switzerland
- Department of Chemistry and Applied Biosciences; ETH Zurich; Zurich Switzerland
| |
Collapse
|
7
|
The emerging role of copper-64 radiopharmaceuticals as cancer theranostics. Drug Discov Today 2018; 23:1489-1501. [DOI: 10.1016/j.drudis.2018.04.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 03/02/2018] [Accepted: 04/03/2018] [Indexed: 12/12/2022]
|
8
|
Dam JH, Olsen BB, Baun C, Høilund-Carlsen PF, Thisgaard H. A PSMA Ligand Labeled with Cobalt-55 for PET Imaging of Prostate Cancer. Mol Imaging Biol 2018; 19:915-922. [PMID: 28924629 DOI: 10.1007/s11307-017-1121-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE Prostate-specific membrane antigen (PSMA) comprises a recognized target for molecular imaging of prostate cancer. As such, radiolabeled PSMA inhibitors are of great value for diagnosis and staging of this disease. Herein, we disclose the preclinical characterization of [55Co]PSMA-617 for positron emission tomography (PET)/x-ray computed tomography (CT) imaging of prostate cancer lesions. PROCEDURES By the application of microwave heating, PSMA-617 in acetate buffer (0.4 M, pH 4.4) was labeled with the radioisotopes cobalt-55/57. The extents of internalization and dissociation constants (K D) were determined against 2-(phosphonomethyl)-pentanedioic acid in two PSMA-positive cell lines, LNCaP, and PC3-PIP, with [57Co]PSMA-617 as a surrogate for [55Co]PSMA-617 (T½ 17.5 h, β max 1.5 MeV, Iβ 76 %). The biodistribution in LNCaP xenograft mice was investigated using [57Co]PSMA-617 and [55Co]PSMA-617 was employed for PET/CT imaging at 1, 4, and 24 h and compared to PET/CT scans using [68Ga]PSMA-617. RESULTS The radiolabeling with cobalt-55/57 was performed in yields greater than 99.5 and 99.8 % and radiochemical purities of 99.7 and 98.9 %, respectively. The molar-specific activities were 18.2 MBq/nmol and 3.3 MBq/nmol. The cellular K D were determined to be 4.7 nM for LNCaP and 9.8 nM for PC3-PIP, correspondingly. Internalization of 76 and 71 % of the cell-associated radioactivity was found for LNCaP and PC3-PIP cells after incubation up to 240 min, respectively. In regard to the biodistribution in LNCaP xenograft mice, [57Co]PSMA-617 displayed a high and relatively constant uptake in the tumor (12.9 %IA/g at 1 h to 10.5 %IA/g at 24 h) with an initial but transient high uptake in the kidneys, adrenals, and spleen. Tumor-to-background ratios improved over time as normal tissue cleared of the radioligand (tumor-to-blood: 26, 258, and 3013; tumor-to-kidney: 0.11, 0.28, and 4.3 at 1, 4, and 24 h). PET/CT imaging with [55Co]PSMA-617 in xenograft mice confirmed the high tumor uptake and fast clearance of normal tissues over time and was found superior to imaging with [68Ga]PSMA-617. CONCLUSION Radiolabeling of PSMA-617 was achieved in excellent yields and radiochemical purities. Favorable in vitro data comprising low K D values and high extent of internalization was determined for two PSMA-positive cell lines. In xenograft mice, high tumor accumulation and excellent tumor-to-normal tissues ratios were established by biodistribution experiments and PET/CT imaging and, hence, confirm the potential of [55Co]PSMA-617 for delayed clinical imaging of prostate cancer.
Collapse
Affiliation(s)
- Johan Hygum Dam
- Department of Nuclear Medicine, Odense University Hospital, Kløvervænget 47, 5000, Odense, Denmark.
| | - Birgitte Brinkmann Olsen
- Department of Nuclear Medicine, Odense University Hospital, Kløvervænget 47, 5000, Odense, Denmark
| | - Christina Baun
- Department of Nuclear Medicine, Odense University Hospital, Kløvervænget 47, 5000, Odense, Denmark
| | - Poul Flemming Høilund-Carlsen
- Department of Nuclear Medicine, Odense University Hospital, Kløvervænget 47, 5000, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Helge Thisgaard
- Department of Nuclear Medicine, Odense University Hospital, Kløvervænget 47, 5000, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| |
Collapse
|
9
|
Vaidyanathan G, Kang CM, McDougald D, Minn I, Brummet M, Pomper MG, Zalutsky MR. Brush border enzyme-cleavable linkers: Evaluation for reducing renal uptake of radiolabeled prostate-specific membrane antigen inhibitors. Nucl Med Biol 2018; 62-63:18-30. [PMID: 29803076 DOI: 10.1016/j.nucmedbio.2018.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/01/2018] [Accepted: 05/02/2018] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Radiolabeled, low-molecular-weight prostate-specific membrane antigen (PSMA) inhibitors based on the Glu-ureido pharmacophore show promise for the detection and treatment of castration-resistant prostate cancer; however, high renal retention of activity, related in part to overexpression of PSMA in kidneys can be problematic. The goal of the current study was to investigate the use of brush border enzyme-cleavable linkers as a strategy for reducing kidney activity levels from radiolabeled PSMA inhibitors. METHODS PSMA-769 (6), a derivative of the prototypical PSMA inhibitor (((S)‑1‑carboxy‑5‑(4‑iodobenzamido)pentyl)carbamoyl)glutamate (12) modified to contain a Gly-Tyr linker, and its protected tin precursor (11) were synthesized starting from the basic pharmacophore molecule Lys-urea-Glu. An analogue of 6 containing d‑tyrosine in lieu of l‑tyrosine (PSMA-769-d-tyrosine) and the corresponding tin precursor (d-11) also were synthesized. Both radioiodinated and 211At-labeled 6 were synthesized by radiohalogenation of 11 and deprotection in situ. Similarly, radioiodinated d-6 was synthesized from d-11. Paired label biodistribution of [125I]12 and [131I]6 was performed in normal mice and in SCID mice bearing both PC3 PIP (PSMA+) and PC3 flu (PSMA-) subcutaneous prostate carcinoma xenografts. The biodistribution of [131I]6 and [211At]6 was also evaluated in this tumor model. Biodistribution of the two radioiodinated diastereomers of 6 was evaluated in normal mice and urine samples were analyzed for the presence of 4‑iodohippuric acid. RESULTS Compounds [131I]6 and [211At]6 were synthesized from 11 in overall radiochemical yields of 32.5 ± 0.1% (n = 4) and 22% (n = 1), respectively; radiochemical purity was >95%. In normal mice, renal uptake of [131I]6 was 1.4-, 2.8- and 161-fold lower than that seen for co-injected [125I]12 at 1 h, 4 h and 21 h, respectively. In tumor-bearing mice, kidney uptake of [131I]6 was similar to that for [125I]12 (P > 0.05) at 1 h and 4 h but was 6- to 7-fold lower at 21 h; however, [131I]6 uptake in PC3 PIP tumors was also lower than that seen for [125I]12 at 21 h (12.6 ± 3.4%ID/g vs. 36.8 ± 12.4%ID/g). Uptake of [211At]PSMA-769 in PC3 PIP tumors was slightly higher than that seen for [131I]PSMA-769 at 4 h (9.6 ± 1.6%ID/g versus 7.8 ± 1.6%ID/g; P = 0.002); its uptake in a number of normal tissues also was higher. In normal mice, kidney uptake of [125I]PSMA-769 at 4 h was about 73% of that seen for [131I]PSMA-769-d-tyrosine. Activity in the urine of mice receiving [125I]PSMA-769 contained mainly 4‑[125I]iodohippuric acid while unmetabolized intact molecule was present in the case of [125I]PSMA-769-d-tyrosine. CONCLUSION Use of this brush border enzyme-cleavable linker reduced kidney uptake and resulted in improved tumor:kidney uptake ratios. Although further structural improvements are needed, this linker approach might be useful as a component in strategies for reducing renal uptake of radiolabeled PSMA inhibitors.
Collapse
Affiliation(s)
| | - Choong Mo Kang
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Darryl McDougald
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Il Minn
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21231, USA
| | - Mary Brummet
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21231, USA
| | - Martin G Pomper
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21231, USA
| | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| |
Collapse
|