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Zhang H, Qi L, Cai Y, Gao X. Gastrin-releasing peptide receptor (GRPR) as a novel biomarker and therapeutic target in prostate cancer. Ann Med 2024; 56:2320301. [PMID: 38442298 PMCID: PMC10916925 DOI: 10.1080/07853890.2024.2320301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 02/13/2024] [Indexed: 03/07/2024] Open
Abstract
Aim: This comprehensive review aims to explore the potential applications of Gastrin-releasing peptide receptor (GRPR) in the diagnosis and treatment of prostate cancer. Additionally, the study investigates the role of GRPR in prognostic assessment for individuals afflicted with prostate cancer.Methods: The review encompasses a thorough examination of existing literature and research studies related to the upregulation of GRPR in various tumor types, with a specific focus on prostate. The review also evaluates the utility of GRPR as a molecular target in prostate cancer research, comparing its significance to the well-established Prostate-specific membrane antigen (PSMA). The integration of radionuclide-targeted therapy with GRPR antagonists is explored as an innovative therapeutic approach for individuals with prostate cancer.Results: Research findings suggest that GRPR serves as a promising molecular target for visualizing low-grade prostate cancer. Furthermore, it is demonstrated to complement the detection of lesions that may be negative for PSMA. The integration of radionuclide-targeted therapy with GRPR antagonists presents a novel therapeutic paradigm, offering potential benefits for individuals undergoing treatment for prostate cancer.Conclusions: In conclusion, this review highlights the emerging role of GRPR in prostate cancer diagnosis and treatment. Moreover, the integration of radionuclide-targeted therapy with GRPR antagonists introduces an innovative therapeutic approach that holds promise for improving outcomes in individuals dealing with prostate cancer. The potential prognostic value of GRPR in assessing the disease's progression adds another dimension to its clinical significance in the realm of urology.
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Affiliation(s)
- Honghu Zhang
- Department of Urology, Disorders of Prostate Cancer Multidisciplinary Team, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha City, P. R. China
| | - Lin Qi
- Department of Urology, Disorders of Prostate Cancer Multidisciplinary Team, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha City, P. R. China
| | - Yi Cai
- Department of Urology, Disorders of Prostate Cancer Multidisciplinary Team, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha City, P. R. China
| | - Xiaomei Gao
- Department of Pathology, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha City, P. R. China
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2
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Taunk NK, Escorcia FE, Lewis JS, Bodei L. Radiopharmaceuticals for Cancer Diagnosis and Therapy: New Targets, New Therapies-Alpha-Emitters, Novel Targets. Cancer J 2024; 30:218-223. [PMID: 38753757 PMCID: PMC11232930 DOI: 10.1097/ppo.0000000000000720] [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] [Indexed: 05/18/2024]
Abstract
ABSTRACT Radiopharmaceutical therapy has emerged as a promising approach for the treatment of various cancers. The exploration of novel targets such as tumor-specific antigens, overexpressed receptors, and intracellular biomolecules using antibodies, peptides, or small molecules has expanded the scope of radiopharmaceutical therapy, enabling precise and effective cancer treatment for an increasing number of tumor types. Alpha emitters, characterized by their high linear energy transfer and short path length, offer unique advantages in targeted therapy due to their potent cytotoxicity against cancer cells while sparing healthy tissues. This article reviews recent advancements in identifying novel targets for radiopharmaceutical therapy and applications in utilizing α-emitters for targeted treatment.
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Affiliation(s)
- Neil K. Taunk
- Department of Radiation Oncology and Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Freddy E. Escorcia
- Molecular Imaging Branch, Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Jason S. Lewis
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Lisa Bodei
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY
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Kanellopoulos P, Mattsson A, Abouzayed A, Obeid K, Nock BA, Tolmachev V, Maina T, Orlova A. Preclinical evaluation of new GRPR-antagonists with improved metabolic stability for radiotheranostic use in oncology. EJNMMI Radiopharm Chem 2024; 9:13. [PMID: 38366299 PMCID: PMC10873254 DOI: 10.1186/s41181-024-00242-6] [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: 12/15/2023] [Accepted: 02/05/2024] [Indexed: 02/18/2024] Open
Abstract
BACKGROUND The gastrin-releasing peptide receptor (GRPR) has been extensively studied as a biomolecular target for peptide-based radiotheranostics. However, the lack of metabolic stability and the rapid clearance of peptide radioligands, including radiolabeled GRPR-antagonists, often impede clinical application. Aiming at circumventing these drawbacks, we have designed three new GRPR-antagonist radioligands using [99mTc]Tc-DB15 ([99mTc]Tc-N4-AMA-DIG-DPhe-Gln-Trp-Ala-Val-Sar-His-Leu-NHEt; AMA: p-aminomethylaniline; DIG: diglycolate) as a motif, due to its high GRPR-affinity and stability to neprilysin (NEP). The new analogues carry the DOTAGA-chelator (1,4,7,10-tetraazacyclododecane-1-glutaric acid-4,7,10-triacetic acid) through different linkers at the N-terminus to allow for labeling with the theranostic radionuclide pair In-111/Lu-177. After labeling with In-111 the following radioligands were evaluated: (i) [111In]In-AU-SAR-M1 ([111In]In-DOTAGA-AMA-DIG-DPhe-Gln-Trp-Ala-Val-Sar-His-Leu-NHEt), (ii) [111In]In-AU-SAR-M2 ([111In]In-[DOTAGA-Arg]AU-SAR-M1) and (iii) [111In]In-AU-SAR-M3 ([111In]In-[DOTAGA-DArg]AU-SAR-M1). RESULTS These radioligands were compared in a series of in vitro assays using prostate adenocarcinoma PC-3 cells and in murine models. They all displayed high and GRPR-specific uptake in PC-3 cells. Analysis of mice blood collected 5 min post-injection (pi) revealed similar or even higher metabolic stability of the new radioligands compared with [99mTc]Tc-DB15. The stability could be further increased when the mice were treated with Entresto® to in situ induce NEP-inhibition. In PC-3 xenograft-bearing mice, [111In]In-AU-SAR-M1 displayed the most favourable biodistribution profile, combining a good tumor retention with the highest tumor-to-organ ratios, with the kidneys as the dose-limiting organ. CONCLUSIONS These findings strongly point at AU-SAR-M1 as a promising radiotherapeutic candidate when labeled with Lu-177, or other medically appealing therapeutic radiometals, especially when combined with in situ NEP-inhibition. To this goal further investigations are currently pursued.
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Affiliation(s)
- Panagiotis Kanellopoulos
- Department of Medicinal Chemistry, Uppsala University, 75183, Uppsala, Sweden
- Molecular Radiopharmacy, INRaSTES, NCSR "Demokritos", 15341, Athens, Greece
| | - Adam Mattsson
- Department of Medicinal Chemistry, Uppsala University, 75183, Uppsala, Sweden
| | - Ayman Abouzayed
- Department of Medicinal Chemistry, Uppsala University, 75183, Uppsala, Sweden
| | - Karim Obeid
- Department of Medicinal Chemistry, Uppsala University, 75183, Uppsala, Sweden
| | - Berthold A Nock
- Molecular Radiopharmacy, INRaSTES, NCSR "Demokritos", 15341, Athens, Greece
| | - Vladimir Tolmachev
- Department of Immunology, Genetics and Pathology, Uppsala University, 75183, Uppsala, Sweden
| | - Theodosia Maina
- Molecular Radiopharmacy, INRaSTES, NCSR "Demokritos", 15341, Athens, Greece
| | - Anna Orlova
- Department of Medicinal Chemistry, Uppsala University, 75183, Uppsala, Sweden.
- Science for Life Laboratory, Uppsala University, 75237, Uppsala, Sweden.
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4
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Verhoeven M, Haeck J, de Blois E, Orlandi F, Barbato D, Tedesco M, Konijnenberg M, Dalm SU. The Balance Between the Therapeutic Efficacy and Safety of [ 177Lu]Lu-NeoB in a Preclinical Prostate Cancer Model. Mol Imaging Biol 2024; 26:114-123. [PMID: 37640941 PMCID: PMC10828073 DOI: 10.1007/s11307-023-01851-4] [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: 05/16/2023] [Revised: 08/11/2023] [Accepted: 08/11/2023] [Indexed: 08/31/2023]
Abstract
PURPOSE Radiolabeled NeoB is a promising gastrin-releasing peptide receptor (GRPR)-targeting radiopharmaceutical for theranostics of GRPR-expressing malignancies, e.g., prostate cancer (PCa). The aim of this study was to evaluate the effect of different doses of [177Lu]Lu-NeoB on the balance between therapeutic efficacy and safety in a preclinical PCa model. PROCEDURES To determine the efficacy of [177Lu]Lu-NeoB, PC-3 xenografted mice received 3 sham injections (control group) or 3 injections of 30 MBq/300 pmol, 40 MBq/400 pmol, or 60 MBq/600 pmol [177Lu]Lu-NeoB (groups 1, 2, and 3, respectively) 1 week apart. To quantify tumor uptake, single-photon emission computed tomography/computed tomography (SPECT/CT) imaging was performed 4 h after the first, second, and third injection on a separate group of animals. For safety evaluations, pancreatic and renal tissues of non-tumor-bearing mice treated with the abovementioned [177Lu]Lu-NeoB doses were evaluated 12 and 24 weeks post-treatment. RESULTS Treatment of PC-3 tumors with all three studied [177Lu]Lu-NeoB doses was effective. Median survival times were significantly (p < 0.0001) improved for treatment groups 1, 2, and 3 versus the control group (82 days, 89 days, 99 days versus 19 days, respectively). However, no significant differences were observed between treatment groups. Quantification of SPECT/CT images showed minimal differences in the average absolute radioactivity uptake, especially after the third injection. Histopathological analysis revealed no clear signs of treatment-related pancreatic toxicity. For the kidneys, atrophy and fibrosis were observed for one animal from group 1 and a chronic inflammatory response was observed for both animals from group 3 at 24 weeks post-treatment. CONCLUSIONS Treatment with [177Lu]Lu-NeoB is effective in a preclinical PCa model. Adjusting the administered dose could positively impact the risk-benefit balance as a higher dose might not lead to an increased therapeutic effect, but it may lead to an increase in toxicological effects in healthy organs such as the kidneys.
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Affiliation(s)
- Marjolein Verhoeven
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, 3015 GD, Rotterdam, The Netherlands
| | - Joost Haeck
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, 3015 GD, Rotterdam, The Netherlands
| | - Erik de Blois
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, 3015 GD, Rotterdam, The Netherlands
| | - Francesca Orlandi
- Advanced Accelerator Applications, a Novartis Company, 10010, Colleretto Giacosa, Italy
| | - Donato Barbato
- Advanced Accelerator Applications, a Novartis Company, 10010, Colleretto Giacosa, Italy
| | - Mattia Tedesco
- Advanced Accelerator Applications, a Novartis Company, 10010, Colleretto Giacosa, Italy
| | - Mark Konijnenberg
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, 3015 GD, Rotterdam, The Netherlands
| | - Simone U Dalm
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, 3015 GD, Rotterdam, The Netherlands.
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Alati S, Singh R, Pomper MG, Rowe SP, Banerjee SR. Preclinical Development in Radiopharmaceutical Therapy for Prostate Cancer. Semin Nucl Med 2023; 53:663-686. [PMID: 37468417 DOI: 10.1053/j.semnuclmed.2023.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 06/19/2023] [Accepted: 06/21/2023] [Indexed: 07/21/2023]
Abstract
Prostate cancer is a leading cause of cancer death in men worldwide. Among the various treatment options, radiopharmaceutical therapy has shown notable success in metastatic, castration-resistant disease. Radiopharmaceutical therapy is a systemic approach that delivers cytotoxic radiation doses precisely to the malignant tumors and/or tumor microenvironment. Therapeutic radiopharmaceuticals are composed of a therapeutic radionuclide and a high-affinity, tumor-targeting carrier molecule. Therapeutic radionuclides used in preclinical prostate cancer studies are primarily α-, β--, or Auger-electron-emitting radiometals or radiohalogens. Monoclonal antibodies, antibody-derived fragments, peptides, and small molecules are frequently used as tumor-targeting molecules. Over the years, several important membrane-associated proteases and receptors have been identified, validated, and subsequently used for preclinical radiotherapeutic development for prostate cancer. Prostate-specific membrane antigen (PSMA) is the most well-studied prostate cancer-associated protease in preclinical literature. PSMA-targeting radiotherapeutic agents are being investigated using high-affinity antibody- and small-molecule-based agents for safety and efficacy. Early generations of such agents were developed simply by replacing radionuclides of the imaging agents with therapeutic ones. Later, extensive structure-activity relationship studies were conducted to address the safety and efficacy issues obtained from initial patient data. Recent regulatory approval of the 177Lu-labeled low-molecular-weight agent, 177Lu-PSMA-617, is a significant accomplishment. Current preclinical experiments are focused on the structural modification of 177Lu-PSMA-617 and relevant investigational agents to increase tumor targeting and reduce off-target binding and toxicity in healthy organs. While lutetium-177 (177Lu) remains the most widely used radionuclide, radiolabeled analogs with iodine-131 (128I), yttrium-90 (89Y), copper-67 (67Cu), and terbium-161 (161Tb) have been evaluated as potential alternatives in recent years. In addition, agents carrying the α-particle-emitting radiohalogen, astatine-211 (211At), or radiometals, actinium-225 (225Ac), lead-212 (212Pb), radium-223 (223Ra), and thorium-227 (227Th), have been increasingly investigated in preclinical research. Besides PSMA-based radiotherapeutics, other prominent prostate cancer-related proteases, for example, human kallikrein peptidases (HK2 and HK3), have been explored using monoclonal-antibody-(mAb)-based targeting platforms. Several promising mAbs targeting receptors overexpressed on the different stages of prostate cancer have also been developed for radiopharmaceutical therapy, for example, Delta-like ligand 3 (DLL-3), CD46, and CUB domain-containing protein 1 (CDCP1). Progress is also being made using peptide-based targeting platforms for the gastrin-releasing peptide receptor (GRPR), a well-established membrane-associated receptor expressed in localized and metastatic prostate cancers. Furthermore, mechanism-driven combination therapies appear to be a burgeoning area in the context of preclinical prostate cancer radiotherapeutics. Here, we review the current developments related to the preclinical radiopharmaceutical therapy of prostate cancer. These are summarized in two major topics: (1) therapeutic radionuclides and (2) tumor-targeting approaches using monoclonal antibodies, small molecules, and peptides.
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Affiliation(s)
- Suresh Alati
- Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD; Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD
| | - Rajan Singh
- Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD; Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD
| | - Martin G Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD; Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD
| | - Steven P Rowe
- Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD; Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD
| | - Sangeeta Ray Banerjee
- Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD; Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD.
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Grzmil M, Wiesmann F, Schibli R, Behe M. Targeting mTORC1 Activity to Improve Efficacy of Radioligand Therapy in Cancer. Cancers (Basel) 2022; 15:cancers15010017. [PMID: 36612012 PMCID: PMC9817840 DOI: 10.3390/cancers15010017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/06/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Radioligand therapy (RLT) represents an effective strategy to treat malignancy by cancer-selective delivery of radioactivity following systemic application. Despite recent therapeutic successes, cancer radioresistance and insufficient delivery of the radioactive ligands, as well as cytotoxicity to healthy organs, significantly impairs clinical efficacy. To improve disease management while minimizing toxicity, in recent years, the combination of RLT with molecular targeted therapies against cancer signaling networks showed encouraging outcomes. Characterization of the key deregulated oncogenic signaling pathways revealed their convergence to activate the mammalian target of rapamycin (mTOR), in which signaling plays an essential role in the regulation of cancer growth and survival. Therapeutic interference with hyperactivated mTOR pathways was extensively studied and led to the development of mTOR inhibitors for clinical applications. In this review, we outline the regulation and oncogenic role of mTOR signaling, as well as recapitulate and discuss mTOR complex 1 (mTORC1) inhibition to improve the efficacy of RLT in cancer.
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Affiliation(s)
- Michal Grzmil
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, 5232 Villigen, Switzerland
- Correspondence:
| | - Fabius Wiesmann
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, 5232 Villigen, Switzerland
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Martin Behe
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, 5232 Villigen, Switzerland
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7
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A Treatment Paradigm Shift: Targeted Radionuclide Therapies for Metastatic Castrate Resistant Prostate Cancer. Cancers (Basel) 2022; 14:cancers14174276. [PMID: 36077820 PMCID: PMC9454920 DOI: 10.3390/cancers14174276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Metastatic prostate cancer has traditionally been treated with a combination of hormonal and chemotherapy regimens. With the recent FDA approval of targeted radionuclide therapeutics, there is now a new class of therapy that is routinely available to patients and clinicians. This review explores the most commonly studied therapeutic radiopharmaceuticals and their appropriate use and contraindications. Additionally, we detail how these therapeutic radiopharmaceuticals can fit into the common medical oncology practice and future directions of this field of medicine. Abstract The recent approval of 177Lu PSMA-617 (Pluvicto®) by the United States Food and Drug Administration (FDA) is the culmination of decades of work in advancing the field of targeted radionuclide therapy for metastatic prostate cancer. 177Lu PSMA-617, along with the bone specific radiotherapeutic agent, 223RaCl2 (Xofigo®), are now commonly used in routine clinical care as a tertiary line of therapy for men with metastatic castrate resistant prostate cancer and for osseus metastatic disease respectively. While these radiopharmaceuticals are changing how metastatic prostate cancer is classified and treated, there is relatively little guidance to the practitioner and patient as to how best utilize these therapies, especially in conjunction with other more well-established regimens including hormonal, immunologic, and chemotherapeutic agents. This review article will go into detail about the mechanism and effectiveness of these radiopharmaceuticals and less well-known classes of targeted radionuclide radiopharmaceuticals including alpha emitting prostate specific membrane antigen (PSMA)-, gastrin-releasing peptide receptor (GRPR)-, and somatostatin targeted radionuclide therapeutics. Additionally, a thorough discussion of the clinical approach of these agents is included and required futures studies.
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8
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Synthesis and in vitro proof-of-concept studies on bispecific iron oxide magnetic nanoparticles targeting PSMA and GRP receptors for PET/MR imaging of prostate cancer. Int J Pharm 2022; 624:122008. [PMID: 35820513 DOI: 10.1016/j.ijpharm.2022.122008] [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: 11/27/2021] [Revised: 06/08/2022] [Accepted: 07/05/2022] [Indexed: 11/20/2022]
Abstract
Prostate cancer (PCa) is the most common malignancy worldwide in men. This is a proof-of-concept study describing the development of 68Ga-magnetic iron oxide nanoparticles (mNP) targeting prostate specific membrane antigen (PSMA) and gastrin releasing peptide (GRPR) receptors as potential tools for diagnosis of PCa with PET/MRI. Two pharmacophores targeting PSMA, 1, and GRPR, 2, were coupled to mNPs carrying -SH (mNP-S1/2) or -NH2 (mNP-N1/2) groups. The mNP-S1/2 and mNP-N1/2 were characterized for their size, zeta potential, structure, and efficiency of functionalization using dynamic light scattering (DLS), FT-IR and RP-HPLC. A direct 68Ga-labelling procedure was followed, where 68Ga-mNP-N1/2 proved superior to 68Ga-mNP-S1/2 regarding radiolabelling efficiency, and thus were further evaluated in vitro. Toxicity studies in PCa cells (LNCaP, PC-3) showed low toxicity, and minimal hemolysis of red blood cells. In vitro assays in cells expressing PSMA (LNCaP), and GRPR (PC-3), showed specific time-dependent binding (40 min to plateau), high avidity (PC-3: Kd = 28.27 nM, LNCaP: Kd = 11.49 nM) and high internalization rates for 68Ga-mNP-N1/2 in both cell lines.
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9
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Copper-67-Labeled Bombesin Peptide for Targeted Radionuclide Therapy of Prostate Cancer. Pharmaceuticals (Basel) 2022; 15:ph15060728. [PMID: 35745647 PMCID: PMC9229378 DOI: 10.3390/ph15060728] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/01/2022] [Accepted: 06/02/2022] [Indexed: 01/03/2023] Open
Abstract
The gastrin-releasing peptide receptor (GRPR) is a promising molecular target for imaging and therapy of prostate cancer using bombesin peptides that bind to the receptor with high affinity. Targeted copper theranostics (TCTs) using copper radionuclides, 64Cu for imaging and 67Cu for therapy, offer significant advantages in the development of next-generation theranostics. [64Cu]Cu-SAR-BBN is in clinical development for PET imaging of GRPR-expressing cancers. This study explores the therapeutic efficacy of [67Cu]Cu-SAR-BBN in a pre-clinical mouse model. The peptide was radiolabeled with 67Cu, and specific binding of the radiolabeled peptide towards GRPR-positive PC-3 prostate cancer cells was confirmed with 52.2 ± 1.4% total bound compared to 5.8 ± 0.1% with blocking. A therapy study with [67Cu]Cu-SAR-BBN was conducted in mice bearing PC-3 tumors by injecting 24 MBq doses a total of six times. Tumor growth was inhibited by 93.3% compared to the control group on day 19, and median survival increased from 34.5 days for the control group to greater than 54 days for the treatment group. The ease and stability of the radiochemistry, favorable biodistribution, and the positive tumor inhibition demonstrate the suitability of this copper-based theranostic agent for clinical assessment in the treatment of cancers expressing GRPR.
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10
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Kurth J, Potratz M, Heuschkel M, Krause BJ, Schwarzenböck SM. GRPr Theranostics: Current Status of Imaging and Therapy using GRPr Targeting Radiopharmaceuticals. Nuklearmedizin 2022; 61:247-261. [PMID: 35668669 DOI: 10.1055/a-1759-4189] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Addressing molecular targets, that are overexpressed by various tumor entities, using radiolabeled molecules for a combined diagnostic and therapeutic (theranostic) approach is of increasing interest in oncology. The gastrin-releasing peptide receptor (GRPr), which is part of the bombesin family, has shown to be overexpressed in a variety of tumors, therefore, serving as a promising target for those theranostic applications. A large amount of differently radiolabeled bombesin derivatives addressing the GRPr have been evaluated in the preclinical as well as clinical setting showing fast blood clearance and urinary excretion with selective GRPr-binding. Most of the available studies on GRPr-targeted imaging and therapy have evaluated the theranostic approach in prostate and breast cancer applying bombesin derivatives tagged with the predominantly used theranostic pair of 68Ga/177Lu which is the focus of this review.
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Affiliation(s)
- Jens Kurth
- Department of Nuclear Medicine, Rostock University Medical Center, Rostock, Germany
| | - Madlin Potratz
- Department of Nuclear Medicine, Rostock University Medical Center, Rostock, Germany
| | - Martin Heuschkel
- Department of Nuclear Medicine, Rostock University Medical Center, Rostock, Germany
| | - Bernd J Krause
- Department of Nuclear Medicine, Rostock University Medical Center, Rostock, Germany
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11
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Kirchenwitz M, Stahnke S, Prettin S, Borowiak M, Menke L, Sieben C, Birchmeier C, Rottner K, Stradal TEB, Steffen A. SMER28 Attenuates PI3K/mTOR Signaling by Direct Inhibition of PI3K p110 Delta. Cells 2022; 11:1648. [PMID: 35626685 PMCID: PMC9140127 DOI: 10.3390/cells11101648] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/03/2022] [Accepted: 05/12/2022] [Indexed: 02/06/2023] Open
Abstract
SMER28 (Small molecule enhancer of Rapamycin 28) is an autophagy-inducing compound functioning by a hitherto unknown mechanism. Here, we confirm its autophagy-inducing effect by assessing classical autophagy-related parameters. Interestingly, we also discovered several additional effects of SMER28, including growth retardation and reduced G1 to S phase progression. Most strikingly, SMER28 treatment led to a complete arrest of receptor tyrosine kinase signaling, and, consequently, growth factor-induced cell scattering and dorsal ruffle formation. This coincided with a dramatic reduction in phosphorylation patterns of PI3K downstream effectors. Consistently, SMER28 directly inhibited PI3Kδ and to a lesser extent p110γ. The biological relevance of our observations was underscored by SMER28 interfering with InlB-mediated host cell entry of Listeria monocytogenes, which requires signaling through the prominent receptor tyrosine kinase c-Met. This effect was signaling-specific, since entry of unrelated, gram-negative Salmonella Typhimurium was not inhibited. Lastly, in B cell lymphoma cells, which predominantly depend on tonic signaling through PI3Kδ, apoptosis upon SMER28 treatment is profound in comparison to non-hematopoietic cells. This indicates SMER28 as a possible drug candidate for the treatment of diseases that derive from aberrant PI3Kδ activity.
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Affiliation(s)
- Marco Kirchenwitz
- Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (M.K.); (S.S.); (S.P.); (K.R.)
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Stephanie Stahnke
- Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (M.K.); (S.S.); (S.P.); (K.R.)
| | - Silvia Prettin
- Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (M.K.); (S.S.); (S.P.); (K.R.)
| | - Malgorzata Borowiak
- Developmental Biology/Signal Transduction, Max Delbrueck Center for Molecular Medicine, 13125 Berlin, Germany; (M.B.); (C.B.)
| | - Laura Menke
- Nanoscale Infection Biology Group, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (L.M.); (C.S.)
| | - Christian Sieben
- Nanoscale Infection Biology Group, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (L.M.); (C.S.)
| | - Carmen Birchmeier
- Developmental Biology/Signal Transduction, Max Delbrueck Center for Molecular Medicine, 13125 Berlin, Germany; (M.B.); (C.B.)
| | - Klemens Rottner
- Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (M.K.); (S.S.); (S.P.); (K.R.)
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Theresia E. B. Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (M.K.); (S.S.); (S.P.); (K.R.)
| | - Anika Steffen
- Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; (M.K.); (S.S.); (S.P.); (K.R.)
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Ma L, Grant C, Gallazzi F, Watkinson LD, Carmack TL, Embree MF, Smith CJ, Medvedev D, Cutler CS, Li Y, Wilbur DS, Hennkens HM, Jurisson SS. Development and biodistribution studies of 77As-labeled trithiol RM2 bioconjugates for prostate cancer: Comparison of [77As]As-trithiol-Ser-Ser-RM2 vs. [77As]As-trithiol-Glu-Ser-RM2. Nucl Med Biol 2022; 108-109:61-69. [DOI: 10.1016/j.nucmedbio.2022.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 02/26/2022] [Accepted: 03/11/2022] [Indexed: 02/07/2023]
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Liolios C, Patsis C, Lambrinidis G, Tzortzini E, Roscher M, Bauder-Wüst U, Kolocouris A, Kopka K. Investigation of Tumor Cells and Receptor-Ligand Simulation Models for the Development of PET Imaging Probes Targeting PSMA and GRPR and a Possible Crosstalk between the Two Receptors. Mol Pharm 2022; 19:2231-2247. [PMID: 35467350 DOI: 10.1021/acs.molpharmaceut.2c00070] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Prostate-specific membrane antigen (PSMA) and gastrin-releasing peptide receptor (GRPR) have both been used in nuclear medicine as targets for molecular imaging and therapy of prostate (PCa) and breast cancer (BCa). Three bioconjugate probes, the PSMA specific: [68Ga]Ga-1, ((HBED-CC)-Ahx-Lys-NH-CO-NH Glu or PSMA-11), the GRPR specific: [68Ga]Ga-2, ((HBED-CC)-4-amino-1-carboxymethyl piperidine-[D-Phe6, Sta13]BN(6-14), a bombesin (BN) analogue), and 3 (the BN analogue: 4-amino-1-carboxymethyl piperidine-[(R)-Phe6, Sta13]BN(6-14) connected with the fluorescent dye, BDP-FL), were synthesized and tested in vitro with PCa and BCa cell lines, more specifically, with PCa cells, PC-3 and LNCaP, with BCa cells, T47D, MDA-MB-231, and with the in-house created PSMA-overexpressing PC-3(PSMA), T47D(PSMA), and MDA-MB-231(PSMA). In addition, biomolecular simulations were conducted on the association of 1 and 2 with PSMA and GRPR. The PSMA overexpression resulted in an increase of cell-bound radioligand [68Ga]Ga-1 (PSMA) for PCa and BCa cells and also of [68Ga]Ga-2 (GRPR), especially in those cell lines already expressing GRPR. The results were confirmed by fluorescence-activated cell sorting with a PE-labeled PSMA-specific antibody and the fluorescence tracer 3. The docking calculations and molecular dynamics simulations showed how 1 enters the PSMA funnel region and how pharmacophore Glu-urea-Lys interacts with the arginine patch, the S1', and S1 subpockets by forming hydrogen and van der Waals bonds. The chelating moiety of 1, that is, HBED-CC, forms additional stabilizing hydrogen bonding and van der Waals interactions in the arene-binding site. Ligand 2 is diving into the GRPR transmembrane (TM) helical cavity, thereby forming hydrogen bonds through its amidated end, water-mediated hydrogen bonds, and π-π interactions. Our results provide valuable information regarding the molecular mechanisms involved in the interactions of 1 and 2 with PSMA and GRPR, which might be useful for the diagnostic imaging and therapy of PCa and BCa.
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Affiliation(s)
- Christos Liolios
- Division of Radiopharmaceutical Chemistry, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,Radiochemical Studies Laboratory, INRASTES, N.C.S.R. "Demokritos", Agia Paraskevi Attikis, 15310 Athens, Greece.,Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens (NKUA), Panepistimioupolis-Zografou, 15771 Athens, Greece
| | - Christos Patsis
- Division of Cell Plasticity and Epigenetic Remodelling, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,Department of Translational Oncology, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - George Lambrinidis
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens (NKUA), Panepistimioupolis-Zografou, 15771 Athens, Greece
| | - Efpraxia Tzortzini
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens (NKUA), Panepistimioupolis-Zografou, 15771 Athens, Greece
| | - Mareike Roscher
- Division of Radiopharmaceutical Chemistry, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Ulrike Bauder-Wüst
- Division of Radiopharmaceutical Chemistry, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Antonios Kolocouris
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens (NKUA), Panepistimioupolis-Zografou, 15771 Athens, Greece
| | - Klaus Kopka
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, Technical University Dresden, Lebensmittelchemie Chemiegebäude, Raum 413 Bergstr. 66, 01069 Dresden, Germany
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Safety of [ 177Lu]Lu-NeoB treatment: a preclinical study characterizing absorbed dose and acute, early, and late organ toxicity. Eur J Nucl Med Mol Imaging 2022; 49:4440-4451. [PMID: 35951084 PMCID: PMC9605926 DOI: 10.1007/s00259-022-05926-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/25/2022] [Indexed: 12/24/2022]
Abstract
Purpose The radiolabeled gastrin-releasing peptide receptor (GRPR)-targeting antagonist NeoB is a promising radioligand for imaging and therapy of GRPR-expressing malignancies. In the current study, we aimed to discover the target organs of toxicity and the radiotoxic effects to these organs, when repeated dosages of [177Lu]Lu-NeoB are administered to healthy female and male mice. Methods Animals received either 3 injections, with a 7-day interval, of vehicle (control group 1), 1200 pmol [175Lu]Lu-NeoB (control group 2) or 40 MBq/400 pmol, 80 MBq/800 pmol, and 120 MBq/1200 pmol [177Lu]Lu-NeoB (treatment groups 1, 2, and 3, respectively). At week 5, 19, and 43 after the first injection acute, early, and late organ toxicity, respectively, was determined. For this, histopathological and blood analyses were performed. To correlate the observed toxicity to absorbed dose, we also performed extensive biodistribution and dosimetry studies. Results The biodistribution study showed the highest absorbed doses in GRPR-expressing pancreas, the liver, and the kidneys (the main organs of excretion). Both control groups and almost all animals of treatment group 1 did not show any treatment-related toxicological effects. Despite the high absorbed doses, no clear microscopic signs of toxicity were found in the pancreas and the liver. Histological analysis indicated kidney damage in the form of hydronephrosis and nephropathy in treatment groups 2 and 3 that were sacrificed at the early and late time point. In the same groups, increased blood urea nitrogen levels were found. Conclusion In general, repeated administration of [177Lu]Lu-NeoB was tolerated. The most significant radiotoxic effects were found in the kidneys, similar to other clinically applied radioligands. The results of this study underline the potential of [177Lu]Lu-NeoB as a promising option for clinical therapy. Supplementary Information The online version contains supplementary material available at 10.1007/s00259-022-05926-2.
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Maina T, Nock BA. Peptide radiopharmaceuticals for targeted diagnosis & therapy of human tumors. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00078-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Grzmil M, Imobersteg S, Blanc A, Frank S, Schibli R, Béhé MP. Therapeutic Response of CCKBR-Positive Tumors to Combinatory Treatment with Everolimus and the Radiolabeled Minigastrin Analogue [177Lu]Lu-PP-F11N. Pharmaceutics 2021; 13:pharmaceutics13122156. [PMID: 34959437 PMCID: PMC8708304 DOI: 10.3390/pharmaceutics13122156] [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: 11/19/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 12/28/2022] Open
Abstract
The inhibition of the mammalian target of rapamycin complex 1 (mTORC1) by everolimus (RAD001) was recently shown to enhance the tumor uptake of radiolabeled minigastrin. In this paper, we investigate if this finding can improve the in vivo therapeutic response to [177Lu]Lu-PP-F11N treatment. The N-terminal DOTA-conjugated gastrin analogue PP-F11N (DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Nle-Asp-Phe) was used to evaluate treatment efficacy in the human A431/CCKBR xenograft nude mouse model in combination with RAD001. Both RAD001 and [177Lu]Lu-PP-F11N single treatments as well as their combination inhibited tumor growth and increased survival. In concomitantly treated mice, the average tumor size and median survival time were significantly reduced and extended, respectively, as compared to the monotherapies. The histological analysis of kidney and stomach dissected after treatment with RAD001 and [177Lu]Lu-PP-F11N did not indicate significant adverse effects. In conclusion, our study data demonstrate the potential of mTORC1 inhibition to substantially improve the therapeutic efficacy of radiolabeled minigastrin analogues in CCKBR-positive cancers.
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Affiliation(s)
- Michal Grzmil
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen, Switzerland; (S.I.); (A.B.); (R.S.); (M.P.B.)
- Correspondence: ; Tel.: +41-56-310-28-57
| | - Stefan Imobersteg
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen, Switzerland; (S.I.); (A.B.); (R.S.); (M.P.B.)
| | - Alain Blanc
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen, Switzerland; (S.I.); (A.B.); (R.S.); (M.P.B.)
| | - Stephan Frank
- Division of Neuropathology, Institute of Pathology, University of Basel, 4031 Basel, Switzerland;
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen, Switzerland; (S.I.); (A.B.); (R.S.); (M.P.B.)
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Martin P. Béhé
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen, Switzerland; (S.I.); (A.B.); (R.S.); (M.P.B.)
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Mansi R, Nock BA, Dalm SU, Busstra MB, van Weerden WM, Maina T. Radiolabeled Bombesin Analogs. Cancers (Basel) 2021; 13:cancers13225766. [PMID: 34830920 PMCID: PMC8616220 DOI: 10.3390/cancers13225766] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/13/2021] [Accepted: 11/15/2021] [Indexed: 12/16/2022] Open
Abstract
Simple Summary Recent medical advancements have strived for a personalized medicine approach to patients, aimed at optimizing therapy outcomes with minimum toxicity. In this respect, nuclear medicine methodologies have been playing increasingly important roles. For example, the overexpression of peptide receptors, such as the gastrin-releasing peptide receptor (GRPR), on tumor cells as opposed to their lack of expression in healthy surrounding tissues can be elegantly exploited with the aid of “smart” peptide carriers, such as the analogs of the amphibian 14-peptide bombesin (BBN). These molecules can bring clinically attractive radionuclides to malignant lesions in prostate, breast, and other human cancers, sparing healthy tissues. Depending upon the radionuclide in question, diagnostic imaging with single-photon emission computed tomography (SPECT) or positron emission tomography (PET) has been pursued, identifying patients who are eligible for peptide radionuclide receptor therapy (PRRT) in an integrated “theranostic” approach. In the present review, we (i) discuss the major steps taken in the development of anti-GRPR theranostic radioligands, with a focus on those selected for clinical testing; (ii) comment on the present status in this field of research; and (iii) reflect on the current limitations as well as on new opportunities for their broader and more successful clinical applications. Abstract The gastrin-releasing peptide receptor (GRPR) is expressed in high numbers in a variety of human tumors, including the frequently occurring prostate and breast cancers, and therefore provides the rationale for directing diagnostic or therapeutic radionuclides on cancer lesions after administration of anti-GRPR peptide analogs. This concept has been initially explored with analogs of the frog 14-peptide bombesin, suitably modified at the N-terminus with a number of radiometal chelates. Radiotracers that were selected for clinical testing revealed inherent problems associated with these GRPR agonists, related to low metabolic stability, unfavorable abdominal accumulation, and adverse effects. A shift toward GRPR antagonists soon followed, with safer analogs becoming available, whereby, metabolic stability and background clearance issues were gradually improved. Clinical testing of three main major antagonist types led to promising outcomes, but at the same time brought to light several limitations of this concept, partly related to the variation of GRPR expression levels across cancer types, stages, previous treatments, and other factors. Currently, these parameters are being rigorously addressed by cell biologists, chemists, nuclear medicine physicians, and other discipline practitioners in a common effort to make available more effective and safe state-of-the-art molecular tools to combat GRPR-positive tumors. In the present review, we present the background, current status, and future perspectives of this endeavor.
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Affiliation(s)
- Rosalba Mansi
- Division of Radiopharmaceutical Chemistry, Clinic of Radiology and Nuclear Medicine University Hospital Basel, 4031 Basel, Switzerland;
| | - Berthold A. Nock
- Molecular Radiopharmacy, INRaSTES, NCSR “Demokritos”, 15310 Athens, Greece;
| | - Simone U. Dalm
- Erasmus Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (S.U.D.); (M.B.B.); (W.M.v.W.)
| | - Martijn B. Busstra
- Erasmus Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (S.U.D.); (M.B.B.); (W.M.v.W.)
| | - Wytske M. van Weerden
- Erasmus Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (S.U.D.); (M.B.B.); (W.M.v.W.)
| | - Theodosia Maina
- Molecular Radiopharmacy, INRaSTES, NCSR “Demokritos”, 15310 Athens, Greece;
- Correspondence: ; Tel.: +30-650-3908/3891
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Mardanshahi A, Gharibkandi NA, Vaseghi S, Abedi SM, Molavipordanjani S. The PI3K/AKT/mTOR signaling pathway inhibitors enhance radiosensitivity in cancer cell lines. Mol Biol Rep 2021; 48:1-14. [PMID: 34357550 DOI: 10.1007/s11033-021-06607-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 07/29/2021] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Radiotherapy is one of the most common types of cancer treatment modalities. Radiation can affect both cancer and normal tissues, which limits the whole delivered dose. It is well documented that radiation activates phosphatidylinositol 3-kinase (PI3K) and AKT signaling pathway; hence, the inhibition of this pathway enhances the radiosensitivity of tumor cells. The mammalian target of rapamycin (mTOR) is a regulator that is involved in autophagy, cell growth, proliferation, and survival. CONCLUSION The inhibition of mTOR as a downstream mediator of the PI3K/AKT signaling pathway represents a vital option for more effective cancer treatments. The combination of PI3K/AKT/mTOR inhibitors with radiation can increase the radiosensitivity of malignant cells to radiation by autophagy activation. Therefore, this review aims to discuss the impact of such inhibitors on the cell response to radiation.
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Affiliation(s)
- Alireza Mardanshahi
- Department of Radiology and Nuclear Medicine, Faculty of Medicine, Cardiovascular Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Nasrin Abbasi Gharibkandi
- Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Samaneh Vaseghi
- Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Seyed Mohammad Abedi
- Department of Radiology and Nuclear Medicine, Faculty of Medicine, Cardiovascular Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Sajjad Molavipordanjani
- Department of Radiology and Nuclear Medicine, Faculty of Medicine, Cardiovascular Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
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In Vivo Biodistribution and Efficacy Evaluation of NeoB, a Radiotracer Targeted to GRPR, in Mice Bearing Gastrointestinal Stromal Tumor. Cancers (Basel) 2021; 13:cancers13051051. [PMID: 33801382 PMCID: PMC7958597 DOI: 10.3390/cancers13051051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 12/11/2022] Open
Abstract
Simple Summary NeoB is undergoing evaluation as a novel theragnostic agent—that is, that it can be employed either for the diagnosis of tumor expressing gastrin-releasing peptide receptor (GRPR) using nuclear imaging, or for the therapy of such GRPR positive tumors using internal radiotherapy. The switch from diagnosis to therapy simply rely on the choice of the radioisotope that is coupled to NeoB. The aim of our study was to investigate—for the first time—the potency of NeoB for tumor therapy once labeled with the beta- emitter Lu-177. This study has been conducted in mice bearing human Gastrointestinal Stromal Tumors (GIST). [177Lu]Lu-NeoB was found to accumulate in the tumor, with only minimal retention in off-target organs. Consequently, mice treated with therapeutic doses of [177Lu]Lu-NeoB (37MBq/week for three weeks) exhibited tumor regression and therefore long term survival in comparison to the control untreated mice. Abstract NeoB is a radiotracer targeting the gastrin-releasing peptide receptor (GRPR), a G-protein–coupled receptor expressed in various cancers. The aim of the present study was to evaluate the biodistribution and efficacy of this new therapeutic agent in Gastrointestinal Stromal Tumors (GIST). Eighty-two SCID mice bearing GIST-882 tumors were employed. [177Lu]Lu-NeoB biodistribution was evaluated up to seven days by organ sampling (200 pmol/0.8 MBq, i.v.). For efficacy evaluation, mice received either saline, 400 pmol or 800 pmol of [177Lu]Lu-NeoB (37MBq, 1/w, 3 w, i.v.). SPECT/CT imaging was performed at 24 h, and tumor volume was determined up to 100 days. Elevated and specific [177Lu]Lu-NeoB uptake was found in the GIST tumor, as demonstrated by in vivo competition (19.1 ± 3.9 %ID/g vs. 0.3 ± 0.1 %ID/g at 4h). [177Lu]Lu-NeoB tumor retention (half-life of 40.2 h) resulted in elevated tumor-to-background ratios. Tumor volumes were significantly reduced in both treated groups (p < 0.01), even leading to complete tumor regression at the 400 pmol dose. [177Lu]Lu-NeoB exhibited excellent pharmacokinetics with elevated and prolonged tumor uptake and low uptake in non-target organs such as pancreas. The potential of this new theragnostic agent in different indications, including GIST, is under evaluation in the FIH [177Lu]Lu-NeoB clinical trial.
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Bandari RP, Carmack TL, Malhotra A, Watkinson L, Fergason Cantrell EA, Lewis MR, Smith CJ. Development of Heterobivalent Theranostic Probes Having High Affinity/Selectivity for the GRPR/PSMA. J Med Chem 2021; 64:2151-2166. [PMID: 33534560 DOI: 10.1021/acs.jmedchem.0c01785] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this study, we describe the development of heterobivalent [DUPA-6-Ahx-([111In]In-DO3A)-8-Aoc-BBN ANT] and [DUPA-6-Ahx-([177Lu]Lu-DO3A)-8-Aoc-BBN ANT] radiotracers that display very high selectivity/specificity for gastrin-releasing peptide receptor (GRPR)-/prostate-specific membrane antigen (PSMA)-expressing cells. These studies include metallation, purification, characterization, and in vitro and in vivo evaluation of the new small-molecule-/peptide-based radiopharmaceuticals having utility for imaging and potentially therapy. Competitive displacement binding assays using PC-3 cells and LNCaP cell membranes showed high binding affinity for the GRPR or the PSMA. Biodistribution studies showed favorable excretion pharmacokinetics with high tumor uptake in PC-3 or PC-3 prostatic inhibin peptide (PIP) tumor-bearing mice. For example, tumor accumulation at the 1 h time point ranged from (4.74 ± 0.90) to (7.51 ± 2.61)%ID/g. Micro-single-photon emission computed tomography (microSPECT) molecular imaging investigations showed very high uptake in tumors with minimal accumulation of tracers in the surrounding collateral tissues in xenografted mice at 4 h postintravenous injection. In conclusion, [DUPA-6-Ahx-([111In]In-DO3A)-8-Aoc-BBN ANT] and [DUPA-6-Ahx-([177Lu]Lu-DO3A)-8-Aoc-BBN ANT] tracers displayed favorable pharmacokinetic and excretion profiles with high uptake and retention in tumors.
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Affiliation(s)
- Rajendra P Bandari
- Research Division, Harry S. Truman Memorial Veterans' Hospital, Research Service Room A005, 800 Hospital Drive, Columbia, Missouri 65201, United States.,Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri 65211, United States
| | - Terry L Carmack
- Research Division, Harry S. Truman Memorial Veterans' Hospital, Research Service Room A005, 800 Hospital Drive, Columbia, Missouri 65201, United States.,University of Missouri Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States
| | - Anil Malhotra
- Research Division, Harry S. Truman Memorial Veterans' Hospital, Research Service Room A005, 800 Hospital Drive, Columbia, Missouri 65201, United States
| | - Lisa Watkinson
- Research Division, Harry S. Truman Memorial Veterans' Hospital, Research Service Room A005, 800 Hospital Drive, Columbia, Missouri 65201, United States.,University of Missouri Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States
| | - Emily A Fergason Cantrell
- Research Division, Harry S. Truman Memorial Veterans' Hospital, Research Service Room A005, 800 Hospital Drive, Columbia, Missouri 65201, United States.,University of Missouri Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States
| | - Michael R Lewis
- Department of Veterinary Medicine and Surgery, University of Missouri College of Veterinary Medicine, Columbia, Missouri 65211, United States
| | - Charles J Smith
- Research Division, Harry S. Truman Memorial Veterans' Hospital, Research Service Room A005, 800 Hospital Drive, Columbia, Missouri 65201, United States.,Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri 65211, United States.,University of Missouri Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States
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Makris G, Bandari RP, Kuchuk M, Jurisson SS, Smith CJ, Hennkens HM. Development and Preclinical Evaluation of 99mTc- and 186Re-Labeled NOTA and NODAGA Bioconjugates Demonstrating Matched Pair Targeting of GRPR-Expressing Tumors. Mol Imaging Biol 2021; 23:52-61. [PMID: 32886303 DOI: 10.1007/s11307-020-01537-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/10/2020] [Accepted: 08/26/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE The goal of this work was to develop hydrophilic gastrin-releasing peptide receptor (GRPR)-targeting complexes of the general formula fac-[M(CO)3(L)]+ [M = natRe, 99mTc, 186Re; L: NOTA for 1, NODAGA for 2] conjugated to a powerful GRPR peptide antagonist (DPhe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) via a 6-aminohexanoic acid linker. PROCEDURES Metallated-peptides were prepared employing the [M(OH2)3(CO)3]+ [M = Re, 99mTc, 186Re] precursors. Re-1/2 complexes were characterized with HR-MS. IC50 studies were performed for peptides 1/2 and their respective Re-1/2 complexes in a binding assay utilizing GRPR-expressing human PC-3 prostate cancer cells and [125I]I-Tyr4-BBN as the competing ligand. The 99mTc/186Re-complexes were identified by HPLC co-injection with their Re-analogues. All tracers were challenged in vitro at 37 °C against cysteine/histidine (phosphate-buffered saline 10 mM, pH 7.4) and rat serum. Biodistribution and micro-SPECT/CT imaging of [99mTc]Tc-1/2 and [186Re]Re-2 were performed in PC-3 tumor-bearing ICR SCID mice. RESULTS High in vitro receptor affinity (IC50 2-3 nM) was demonstrated for all compounds. The 99mTc/186Re-tracers were found to be hydrophilic (log D7.4 ≤ - 1.35) and highly stable. Biodistribution in PC-3 xenografted mice revealed good tumor uptake (%ID/g at 1 h: 4.3 ± 0.7 for [99mTc]Tc-1, 8.3 ± 0.9 for [99mTc]Tc-2 and 4.2 ± 0.8 for [186Re]Re-2) with moderate retention over 24 h. Rapid renal clearance was observed for [99mTc]Tc-2 and [186Re]Re-2 (> 84 % at 4 h), indicating favorable pharmacokinetics. Micro-SPECT/CT images for the 99mTc-tracers clearly visualized PC-3 tumors in agreement with the biodistribution data and with superior imaging properties found for [99mTc]Tc-2. CONCLUSIONS [99mTc]Tc-2 shows promise for further development as a GRPR-imaging agent. [186Re]Re-2 demonstrated very similar in vivo behavior to [99mTc]Tc-2, and further studies are therefore justified to explore the theranostic potential of our approach for targeting of GRPR-positive cancers.
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Affiliation(s)
- George Makris
- Research Reactor Center, University of Missouri, Columbia, MO, 65211, USA
| | - Rajendra P Bandari
- Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, 65201, USA
| | - Marina Kuchuk
- Research Reactor Center, University of Missouri, Columbia, MO, 65211, USA
| | - Silvia S Jurisson
- Department of Chemistry, University of Missouri, Columbia, MO, 65211, USA
| | - Charles J Smith
- Research Reactor Center, University of Missouri, Columbia, MO, 65211, USA
- Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, 65201, USA
- Department of Radiology, University of Missouri School of Medicine, Columbia, MO, 65212, USA
| | - Heather M Hennkens
- Research Reactor Center, University of Missouri, Columbia, MO, 65211, USA.
- Department of Chemistry, University of Missouri, Columbia, MO, 65211, USA.
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22
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Makris G, Shegani A, Kankanamalage PHA, Kuchuk M, Bandari RP, Smith CJ, Hennkens HM. Preclinical Evaluation of Novel 64Cu-Labeled Gastrin-Releasing Peptide Receptor Bioconjugates for PET Imaging of Prostate Cancer. Bioconjug Chem 2021; 32:1290-1297. [PMID: 33434428 DOI: 10.1021/acs.bioconjchem.0c00656] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report herein the preclinical evaluation of new [64Cu]Cu-gastrin-releasing peptide receptor (GRPR)-targeting tracers, employing the potent peptide antagonist DPhe-Gln-Trp-Ala-VaI-Gly-His-Sta-Leu-NH2 conjugated to NOTA (in 1) or NODAGA (in 2) chelators via a 6-aminohexanoic acid linker. The Cu-1/2 metalated peptides were synthesized by reacting 1/2 with CuCl2 and were characterized by LC-ESI-MS and HR-ESI-MS. Cu-1/2 exhibited high GRPR-binding affinities with IC50 values <3 nM, as measured in a competition assay using the GRPR-expressing human PC-3 prostate cancer cell line and [125I]I-Tyr4-BBN as the competing ligand. Tracers [64Cu]Cu-1/2 were prepared in quantitative radiochemical yield (by radio-HPLC), and their identities were confirmed by coelution with their Cu-1/2 standards via comparative HPLC studies. Lipophilicity was measured in 1-octanol/PBS (pH 7.4), and the negative log D7.4 values (≤-1) confirmed the anticipated hydrophilic character for [64Cu]Cu-1/2. Both tracers demonstrated excellent in vitro stability, with ≥98% remaining intact through 24 h at physiological conditions (PBS, pH 7.4, 37 °C). Biodistribution in PC-3 tumor-bearing mice demonstrated good tumor uptake (%ID/g at 4 h: 4.34 ± 0.71 for [64Cu]Cu-1, 3.92 ± 1.03 for [64Cu]Cu-2) and rapid renal clearance (≥87% ID at 4 h). Tumor uptake was receptor-mediated, as verified by parallel GRPR-blocking studies. Small-animal PET/CT imaging studies validated the biodistribution data. These preclinical data support that the [64Cu]Cu-1/2 tracers show promise for further development as diagnostic PET imaging agents of GRPR-expressing tumors.
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Affiliation(s)
- George Makris
- Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States
| | - Antonio Shegani
- Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States.,Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, National Centre for Scientific Research "Demokritos", 15310 Athens, Greece
| | | | - Marina Kuchuk
- Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States
| | - Rajendra P Bandari
- Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, Missouri 65201, United States
| | - Charles J Smith
- Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States.,Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, Missouri 65201, United States.,Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri 65212, United States
| | - Heather M Hennkens
- Research Reactor Center, University of Missouri, Columbia, Missouri 65211, United States.,Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
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Hofstetter M, Moon ES, D'Angelo F, Geissbühler L, Alberts I, Afshar-Oromieh A, Rösch F, Rominger A, Gourni E. Effect of the versatile bifunctional chelator AAZTA 5 on the radiometal labelling properties and the in vitro performance of a gastrin releasing peptide receptor antagonist. EJNMMI Radiopharm Chem 2020; 5:29. [PMID: 33258012 PMCID: PMC7704979 DOI: 10.1186/s41181-020-00115-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/23/2020] [Indexed: 12/24/2022] Open
Abstract
Background Gastrin Releasing Peptide receptor (GRPr)-based radioligands have shown great promise for diagnostic imaging of GRPr-positive cancers, such as prostate and breast. The present study aims at developing and evaluating a versatile GRPr-based probe for both PET/SPECT imaging as well as intraoperative and therapeutic applications. The influence of the versatile chelator AAZTA5 on the radiometal labelling properties and the in vitro performance of the generated radiotracers were thoroughly investigated. The GRPr-based antagonist D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 was functionalized with the chelator 6-[Bis (carboxymethyl)amino]-1,4-bis (carboyxmethyl)-6-methyl-1,4-diazepane (AAZTA5) through the spacer 4-amino-1-carboxymethyl-piperidine (Pip) to obtain AAZTA5-Pip-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (LF1). LF1 was radiolabelled with gallium-68 (PET), indium-111 (SPECT, intraoperative applications) and lutetium-177 (therapy, SPECT). In vitro evaluation included stability studies, determination of lipophilicity, protein-binding studies, determination of Kd and Bmax as well as internalization studies using the epithelial human prostate cancer cell line PC3. In vitro monotherapy as well as combination therapy studies were further performed to assess its applicability as a theranostic compound. Results LF1 was labelled with gallium-68, indium-111 and lutetium-177 within 5 min at room temperature (RT). The apparent molar activities (Am) were ranging between 50 and 60 GBq/μmol for the 68Ga-labelled LF1, 10–20 GBq/μmol for the 111In- and 177Lu-labelled LF1. The radiotracers were stable for a period of 4 h post labeling exhibiting a hydrophilic profile with an average of a LogDoctanol/PBS of − 3, while the bound activity to the human serum protein was approximately 10%. 68/natGa-LF1, 177/natLu-LF1 and 111/natIn-LF1 exhibited high affinity for the PC3 cells, with Kd values of 16.3 ± 2.4 nM, 10.3 ± 2.73 nM and 5.2 ± 1.9 nM, respectively, and the required concentration of the radiotracers to saturate the receptors (Bmax) was between 0.5 and 0.8 nM which corresponds to approximately 4 × 105 receptors per cell. Low specific internalization rate was found in cell culture, while the total specific cell surface bound uptake always exceeded the internalized activity. In vitro therapy studies showed that inhibition of PC3 cells growth is somewhat more efficient when combination of 177Lu-labelled LF1 with rapamycin is applied compared to 177Lu-laballed LF1 alone. Conclusion Encouraged by these promising in vitro data, preclinical evaluation of the LF1 precursor are planned in tumour models in vivo.
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Affiliation(s)
- Michael Hofstetter
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, Freiburgstr. 18, 3010, Bern, Switzerland
| | - Euy Sung Moon
- Department of Chemistry - TRIGA site, Johannes Gutenberg - University Mainz, Mainz, Germany
| | - Fabio D'Angelo
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, Freiburgstr. 18, 3010, Bern, Switzerland
| | - Lucien Geissbühler
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, Freiburgstr. 18, 3010, Bern, Switzerland
| | - Ian Alberts
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, Freiburgstr. 18, 3010, Bern, Switzerland
| | - Ali Afshar-Oromieh
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, Freiburgstr. 18, 3010, Bern, Switzerland
| | - Frank Rösch
- Department of Chemistry - TRIGA site, Johannes Gutenberg - University Mainz, Mainz, Germany
| | - Axel Rominger
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, Freiburgstr. 18, 3010, Bern, Switzerland
| | - Eleni Gourni
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, Freiburgstr. 18, 3010, Bern, Switzerland.
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Abouzayed A, Tano H, Nagy Á, Rinne SS, Wadeea F, Kumar S, Westerlund K, Tolmachev V, Eriksson Karlström A, Orlova A. Preclinical Evaluation of the GRPR-Targeting Antagonist RM26 Conjugated to the Albumin-Binding Domain for GRPR-Targeting Therapy of Cancer. Pharmaceutics 2020; 12:E977. [PMID: 33081166 PMCID: PMC7594083 DOI: 10.3390/pharmaceutics12100977] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/12/2020] [Accepted: 10/14/2020] [Indexed: 01/02/2023] Open
Abstract
The targeting of gastrin-releasing peptide receptors (GRPR) was recently proposed for targeted therapy, e.g., radiotherapy. Multiple and frequent injections of peptide-based therapeutic agents would be required due to rapid blood clearance. By conjugation of the GRPR antagonist RM26 (D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) to an ABD (albumin-binding domain), we aimed to extend the blood circulation of peptides. The synthesized conjugate DOTA-ABD-RM26 was labelled with indium-111 and evaluated in vitro and in vivo. The labelled conjugate was stable in PBS and retained specificity and its antagonistic function against GRPR. The half-maximal inhibitory concentration (IC50) of natIn-DOTA-ABD-RM26 in the presence of human serum albumin was 49 ± 5 nM. [111In]In-DOTA-ABD-RM26 had a significantly longer residence time in blood and in tumors (without a significant decrease of up to 144 h pi) than the parental RM26 peptide. We conclude that the ABD-RM26 conjugate can be used for GRPR-targeted therapy and delivery of cytotoxic drugs. However, the undesirable elevated activity uptake in kidneys abolishes its use for radionuclide therapy. This proof-of-principle study justified further optimization of the molecular design of the ABD-RM26 conjugate.
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Affiliation(s)
- Ayman Abouzayed
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
| | - Hanna Tano
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Ábel Nagy
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Sara S. Rinne
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
| | - Fadya Wadeea
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
| | - Sharmishtaa Kumar
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Kristina Westerlund
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Vladimir Tolmachev
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85 Uppsala, Sweden;
- Research Centrum for Oncotheranostics, Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University, Tomsk 634050, Russia
| | - Amelie Eriksson Karlström
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Anna Orlova
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
- Research Centrum for Oncotheranostics, Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University, Tomsk 634050, Russia
- Science for Life Laboratory, Uppsala University, 751 05 Uppsala, Sweden
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25
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Internal Radiation Therapy. Recent Results Cancer Res 2020. [PMID: 32594411 DOI: 10.1007/978-3-030-42618-7_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/08/2023]
Abstract
Targeted therapies are applied to increase the efficiency of antitumor treatment by simultaneously decreasing side effects. This can be achieved using carrier molecules which specifically bind to target structures or areas with remodeling activity. These carrier molecules may be coupled to chemotherapeutic drugs or to radioactive isotopes. In most cases, these carrier molecules are antibodies against tumor antigens, peptides, or small molecules which are binders for overexpressed receptors on tumor cells. The paradigm of endoradiotherapy is exemplified by the peptidic tracer DOTATOC which binds to somatostatin receptors and recently also small molecule inhibitors with high affinity for the prostate-specific membrane antigen.
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Philippou Y, Sjoberg H, Lamb AD, Camilleri P, Bryant RJ. Harnessing the potential of multimodal radiotherapy in prostate cancer. Nat Rev Urol 2020; 17:321-338. [PMID: 32358562 DOI: 10.1038/s41585-020-0310-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2020] [Indexed: 12/11/2022]
Abstract
Radiotherapy in combination with androgen deprivation therapy (ADT) is a standard treatment option for men with localized and locally advanced prostate cancer. However, emerging clinical evidence suggests that radiotherapy can be incorporated into multimodality therapy regimens beyond ADT, in combinations that include chemotherapy, radiosensitizing agents, immunotherapy and surgery for the treatment of men with localized and locally advanced prostate cancer, and those with oligometastatic disease, in whom the low metastatic burden in particular might be treatable with these combinations. This multimodal approach is increasingly recognized as offering considerable clinical benefit, such as increased antitumour effects and improved survival. Thus, radiotherapy is becoming a key component of multimodal therapy for many stages of prostate cancer, particularly oligometastatic disease.
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Affiliation(s)
- Yiannis Philippou
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Headington, Oxford, UK
- Nuffield Department of Surgical Sciences, University of Oxford, Headington, Oxford, UK
| | - Hanna Sjoberg
- Nuffield Department of Surgical Sciences, University of Oxford, Headington, Oxford, UK
| | - Alastair D Lamb
- Nuffield Department of Surgical Sciences, University of Oxford, Headington, Oxford, UK
| | - Philip Camilleri
- Oxford Department of Clinical Oncology, Churchill Hospital Cancer Centre, Oxford University Hospitals NHS Foundation Trust, Headington, Oxford, UK
| | - Richard J Bryant
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Headington, Oxford, UK.
- Nuffield Department of Surgical Sciences, University of Oxford, Headington, Oxford, UK.
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Wanigasooriya K, Tyler R, Barros-Silva JD, Sinha Y, Ismail T, Beggs AD. Radiosensitising Cancer Using Phosphatidylinositol-3-Kinase (PI3K), Protein Kinase B (AKT) or Mammalian Target of Rapamycin (mTOR) Inhibitors. Cancers (Basel) 2020; 12:E1278. [PMID: 32443649 PMCID: PMC7281073 DOI: 10.3390/cancers12051278] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/08/2020] [Accepted: 05/12/2020] [Indexed: 02/07/2023] Open
Abstract
Radiotherapy is routinely used as a neoadjuvant, adjuvant or palliative treatment in various cancers. There is significant variation in clinical response to radiotherapy with or without traditional chemotherapy. Patients with a good response to radiotherapy demonstrate better clinical outcomes universally across different cancers. The PI3K/AKT/mTOR pathway upregulation has been linked to radiotherapy resistance. We reviewed the current literature exploring the role of inhibiting targets along this pathway, in enhancing radiotherapy response. We identified several studies using in vitro cancer cell lines, in vivo tumour xenografts and a few Phase I/II clinical trials. Most of the current evidence in this area comes from glioblastoma multiforme, non-small cell lung cancer, head and neck cancer, colorectal cancer, and prostate cancer. The biological basis for radiosensitivity following pathway inhibition was through inhibited DNA double strand break repair, inhibited cell proliferation, enhanced apoptosis and autophagy as well as tumour microenvironment changes. Dual PI3K/mTOR inhibition consistently demonstrated radiosensitisation of all types of cancer cells. Single pathway component inhibitors and other inhibitor combinations yielded variable outcomes especially within early clinical trials. There is ample evidence from preclinical studies to suggest that direct pharmacological inhibition of the PI3K/AKT/mTOR pathway components can radiosensitise different types of cancer cells. We recommend that future in vitro and in vivo research in this field should focus on dual PI3K/mTOR inhibitors. Early clinical trials are needed to assess the feasibility and efficacy of these dual inhibitors in combination with radiotherapy in brain, lung, head and neck, breast, prostate and rectal cancer patients.
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Affiliation(s)
- Kasun Wanigasooriya
- College of Medical and Dental Sciences, Institute of Cancer and Genomic Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (J.D.B.-S.); (Y.S.); (A.D.B.)
- The New Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Edgbaston, Birmingham B15 2TH, UK; (R.T.); (T.I.)
| | - Robert Tyler
- The New Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Edgbaston, Birmingham B15 2TH, UK; (R.T.); (T.I.)
| | - Joao D. Barros-Silva
- College of Medical and Dental Sciences, Institute of Cancer and Genomic Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (J.D.B.-S.); (Y.S.); (A.D.B.)
| | - Yashashwi Sinha
- College of Medical and Dental Sciences, Institute of Cancer and Genomic Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (J.D.B.-S.); (Y.S.); (A.D.B.)
- The New Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Edgbaston, Birmingham B15 2TH, UK; (R.T.); (T.I.)
| | - Tariq Ismail
- The New Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Edgbaston, Birmingham B15 2TH, UK; (R.T.); (T.I.)
| | - Andrew D. Beggs
- College of Medical and Dental Sciences, Institute of Cancer and Genomic Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (J.D.B.-S.); (Y.S.); (A.D.B.)
- The New Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Edgbaston, Birmingham B15 2TH, UK; (R.T.); (T.I.)
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Michalski K, Stoykow C, Bronsert P, Juhasz-Böss I, Meyer PT, Ruf J, Erbes T, Asberger J. Association between gastrin-releasing peptide receptor expression as assessed with [ 68Ga]Ga-RM2 PET/CT and histopathological tumor regression after neoadjuvant chemotherapy in primary breast cancer. Nucl Med Biol 2020; 86-87:37-43. [PMID: 32473549 DOI: 10.1016/j.nucmedbio.2020.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 05/05/2020] [Accepted: 05/08/2020] [Indexed: 12/24/2022]
Abstract
INTRODUCTION The gastrin-releasing peptide receptor is overexpressed in breast cancer (BC) tissue and can be visualized by positron emission tomography (PET) using the GRPR antagonist [68Ga]Ga-RM2. This study assessed tumor binding of RM2 before and after neoadjuvant chemotherapy (NAC) in primary BC with reference to residual tumor size in the resected specimen. MATERIALS AND METHODS In this retrospective study, five female patients with biopsy-confirmed estrogen receptor (ER)-positive primary BC (one with bilateral tumors) underwent [68Ga]Ga-RM2 PET/CT before and after NAC. PET/CT was acquired 1 h after injection of 143-224 MBq [68Ga]Ga-RM2. Time from pre-NAC PET to beginning of NAC was 23 ± 4.9 days, from end of NAC to post-NAC PET 18.7 ± 6.3 days, and from post-NAC PET to surgery 9.5 ± 10.8 days. In vivo tumor uptake of [68Ga]Ga-RM2 was assessed before and after NAC and correlated with histopathological response. RESULTS All tumors (6/6) showed strongly increased [68Ga]Ga-RM2 uptake compared to normal breast tissue on pre-NAC PET (mean SUVmax 13.2 ± 7.3; mean SUVpeak 9.4 ± 4.4). [68Ga]Ga-RM2 uptake was significantly reduced on post-NAC PET in all primary tumors (mean SUVmax 2.3 ± 0.8, -79 ± 11%; p = 0.0125; mean SUVpeak 1.6 ± 0.4, -79 ± 10%; p = 0.0096). Residual tumor size in resected specimens correlated well with SUVmax (r = 0.91, p = 0.0057) and SUVpeak (r = 0.88, p = 0.0196) on [68Ga]Ga-RM2 PET/CT after NAC. CONCLUSION AND IMPLICATIONS FOR PATIENT CARE In this pilot study, residual uptake of [68Ga]Ga-RM2 in ER-positive primary BC correlated well with residual vital tumor size after NAC. This suggests that [68Ga]Ga-RM2 PET/CT merits further investigation for response assessment to NAC in patients with ER-positive BC.
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Affiliation(s)
- Kerstin Michalski
- Department of Nuclear Medicine, University Medical Center Freiburg, Germany.
| | - Christian Stoykow
- Department of Nuclear Medicine, University Medical Center Freiburg, Germany
| | - Peter Bronsert
- Department for Surgical Pathology, University Medical Center Freiburg, Germany; German Cancer Consortium (DKTK), Freiburg, Germany; Tumorbank, Comprehensive Cancer Center Freiburg, University Medical Center Freiburg, Germany
| | - Ingolf Juhasz-Böss
- Department of Obstetrics and Gynecology, University Medical Center Freiburg, Germany
| | - Philipp T Meyer
- Department of Nuclear Medicine, University Medical Center Freiburg, Germany; German Cancer Consortium (DKTK), Freiburg, Germany
| | - Juri Ruf
- Department of Nuclear Medicine, University Medical Center Freiburg, Germany
| | - Thalia Erbes
- Department of Obstetrics and Gynecology, University Medical Center Freiburg, Germany
| | - Jasmin Asberger
- Department of Obstetrics and Gynecology, University Medical Center Freiburg, Germany
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Ermert J, Benešová M, Hugenberg V, Gupta V, Spahn I, Pietzsch HJ, Liolios C, Kopka K. Radiopharmaceutical Sciences. Clin Nucl Med 2020. [DOI: 10.1007/978-3-030-39457-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Oroujeni M, Abouzayed A, Lundmark F, Mitran B, Orlova A, Tolmachev V, Rosenström U. Evaluation of Tumor-Targeting Properties of an Antagonistic Bombesin Analogue RM26 Conjugated with a Non-Residualizing Radioiodine Label Comparison with a Radiometal-Labelled Counterpart. Pharmaceutics 2019; 11:pharmaceutics11080380. [PMID: 31382362 PMCID: PMC6724035 DOI: 10.3390/pharmaceutics11080380] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/16/2019] [Accepted: 07/24/2019] [Indexed: 12/24/2022] Open
Abstract
Radiolabelled antagonistic bombesin analogues are successfully used for targeting of gastrin-releasing peptide receptors (GRPR) that are overexpressed in prostate cancer. Internalization of antagonistic bombesin analogues is slow. We hypothesized that the use of a non-residualizing radioiodine label might not affect the tumour uptake but would reduce the retention in normal organs, where radiopharmaceutical would be internalized. To test this hypothesis, tyrosine was conjugated via diethylene glycol linker to N-terminus of an antagonistic bombesin analogue RM26 to form Tyr-PEG2-RM26. [111In]In-DOTA-PEG2-RM26 was used as a control with a residualizing label. Tyr-PEG2-RM26 was labelled with 125I with 95% radiochemical purity and retained binding specificity to GRPR. The IC50 values for Tyr-PEG2-RM26 and DOTA-PEG2-RM26 were 1.7 ± 0.3 nM and 3.3 ± 0.5 nM, respectively. The cellular processing of [125I]I-Tyr-PEG2-RM26 by PC-3 cells showed unusually fast internalization. Biodistribution showed that uptake in pancreas and tumour was GRPR-specific for both radioconjugates. Blood clearance of [125I]I-Tyr-PEG2-RM26 was appreciably slower and activity accumulation in all organs was significantly higher than for [111In]In-DOTA-PEG2-RM26. Tumor uptake of [111In]In-DOTA-PEG2-RM26 was significantly higher than for [125I]I-Tyr-PEG2-RM26, resulting in higher tumour-to-organ ratio for [111In]In-DOTA-PEG2-RM26 at studied time points. Incorporation of amino acids with hydrophilic side-chains next to tyrosine might overcome the problems associated with the use of tyrosine as a prosthetic group for radioiodination.
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Affiliation(s)
- Maryam Oroujeni
- Department of Immunology, Genetics and Pathology, Uppsala University, SE-751 85 Uppsala, Sweden
| | - Ayman Abouzayed
- Department of Medicinal Chemistry, Uppsala University, SE-751 23 Uppsala, Sweden
| | - Fanny Lundmark
- Department of Medicinal Chemistry, Uppsala University, SE-751 23 Uppsala, Sweden
| | - Bogdan Mitran
- Department of Medicinal Chemistry, Uppsala University, SE-751 23 Uppsala, Sweden
| | - Anna Orlova
- Department of Medicinal Chemistry, Uppsala University, SE-751 23 Uppsala, Sweden
- Science for Life Laboratory, Uppsala University, SE-750 03 Uppsala, Sweden
| | - Vladimir Tolmachev
- Department of Immunology, Genetics and Pathology, Uppsala University, SE-751 85 Uppsala, Sweden.
| | - Ulrika Rosenström
- Department of Medicinal Chemistry, Uppsala University, SE-751 23 Uppsala, Sweden
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Mitran B, Rinne SS, Konijnenberg MW, Maina T, Nock BA, Altai M, Vorobyeva A, Larhed M, Tolmachev V, de Jong M, Rosenström U, Orlova A. Trastuzumab cotreatment improves survival of mice with PC-3 prostate cancer xenografts treated with the GRPR antagonist 177 Lu-DOTAGA-PEG 2 -RM26. Int J Cancer 2019; 145:3347-3358. [PMID: 31077356 PMCID: PMC6852655 DOI: 10.1002/ijc.32401] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 04/19/2019] [Accepted: 05/02/2019] [Indexed: 12/24/2022]
Abstract
Gastrin‐releasing peptide receptors (GRPRs) are overexpressed in prostate cancer and are suitable for targeted radionuclide therapy (TRT). We optimized the bombesin‐derived GRPR‐antagonist PEG2‐RM26 for labeling with 177Lu and further determined the effect of treatment with 177Lu‐labeled peptide alone or in combination with the anti‐HER2 antibody trastuzumab in a murine model. The PEG2‐RM26 analog was coupled to NOTA, NODAGA, DOTA and DOTAGA chelators. The peptide‐chelator conjugates were labeled with 177Lu and characterized in vitro and in vivo. A preclinical therapeutic study was performed in PC‐3 xenografted mice. Mice were treated with intravenous injections (6 cycles) of (A) PBS, (B) DOTAGA‐PEG2‐RM26, (C) 177Lu‐DOTAGA‐PEG2‐RM26, (D) trastuzumab or (E) 177Lu‐DOTAGA‐PEG2‐RM26 in combination with trastuzumab. 177Lu‐DOTAGA‐PEG2‐RM26 demonstrated quantitative labeling yield at high molar activity (450 GBq/μmol), high in vivo stability (5 min pi >98% of radioligand remained when coinjected with phosphoramidon), high affinity to GRPR (KD = 0.4 ± 0.2 nM), and favorable biodistribution (1 hr pi tumor uptake was higher than in healthy tissues, including the kidneys). Therapy with 177Lu‐DOTAGA‐PEG2‐RM26 induced a significant inhibition of tumor growth. The median survival for control groups was significantly shorter than for treated groups (Group C 66 days, Group E 74 days). Trastuzumab together with radionuclide therapy significantly improved survival. No treatment‐related toxicity was observed. In conclusion, based on in vitro and in vivo characterization of the four 177Lu‐labeled PEG2‐RM26 analogs, we concluded that 177Lu‐DOTAGA‐PEG2‐RM26 was the most promising analog for TRT. Radiotherapy using 177Lu‐DOTAGA‐PEG2‐RM26 effectively inhibited tumor growth in vivo in a murine prostate cancer model. Anti‐HER2 therapy additionally improved survival. What's new? Targeted radionuclide therapy (TRT) using radiolabeled peptides seeking gastrin‐releasing peptide receptors (GRPRs) in tumors is a promising approach to treat disseminated prostate cancer. The possibility to improve the therapeutic index via combination therapies also warrants further investigation. Here, the authors developed and characterized a promising GRPR‐targeting radioligand and demonstrated its therapeutic efficacy in prostate cancer xenografts. Moreover, this study using the anti‐HER2 antibody trastuzumab presents the first in vivo proof‐of‐principle that the effects of anti‐GRPR radiotherapy can be amplified by co‐administration of anti‐HER2 treatment leading to prolonged survival.
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Affiliation(s)
- Bogdan Mitran
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Sara S Rinne
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Mark W Konijnenberg
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece
| | - Berthold A Nock
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece
| | - Mohamed Altai
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Anzhelika Vorobyeva
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Mats Larhed
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden.,Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Vladimir Tolmachev
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Marion de Jong
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Ulrika Rosenström
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Anna Orlova
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden.,Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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Bakker IL, van Tiel ST, Haeck J, Doeswijk GN, de Blois E, Segbers M, Maina T, Nock BA, de Jong M, Dalm SU. In Vivo Stabilized SB3, an Attractive GRPR Antagonist, for Pre- and Intra-Operative Imaging for Prostate Cancer. Mol Imaging Biol 2019; 20:973-983. [PMID: 29556947 PMCID: PMC6244536 DOI: 10.1007/s11307-018-1185-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Purpose The gastrin-releasing peptide receptor (GRPR), overexpressed on various tumor types, is an attractive target for receptor-mediated imaging and therapy. Another interesting approach would be the use of GRPR radioligands for pre-operative imaging and subsequent radio-guided surgery, with the goal to improve surgical outcome. GRPR radioligands were successfully implemented in clinical studies, especially Sarabesin 3 (SB3) is an appealing GRPR antagonist with high receptor affinity. Gallium-68 labeled SB3 has good in vivo stability, after labeling with Indium-111; however, the molecule shows poor in vivo stability, which negatively impacts tumor-targeting capacity. A novel approach to increase in vivo stability of radiopeptides is by co-administration of the neutral endopeptidase (NEP) inhibitor, phosphoramidon (PA). We studied in vivo stability and biodistribution of [111In]SB3 without/with (−/+) PA in mice. Furthermore, SPECT/MRI on a novel, state-of-the-art platform was performed. Procedures GRPR affinity of SB3 was determined on PC295 xenograft sections using [125I]Tyr4-bombesin with tracer only or with increasing concentrations of SB3. For in vivo stability, mice were injected with 200/2000 pmol [111In]SB3 −/+ 300 μg PA. Blood was collected and analyzed. Biodistribution and SPECT/MRI studies were performed at 1, 4, and 24 h postinjection (p.i.) of 2.5 MBq/200 pmol or 25 MBq/200 pmol [111In]SB3 −/+ 300 μg PA in PC-3-xenografted mice. Results SB3 showed high affinity for GRPR (IC50 3.5 nM). Co-administration of PA resulted in twice higher intact peptide in vivo vs [111In]SB3 alone. Biodistribution studies at 1, 4, and 24 h p.i. show higher tumor uptake values with PA co-administration (19.7 ± 3.5 vs 10.2 ± 1.5, 17.6 ± 5.1 vs 8.3 ± 1.1, 6.5 ± 3.3 vs 3.1 ± 1.9 % ID/g tissue (P < 0.0001)). Tumor imaging with SPECT/MRI clearly improved after co-injection of PA. Conclusions Co-administration of PA increased in vivo tumor targeting capacity of [111In]SB3, making this an attractive combination for GRPR-targeted tumor imaging.
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Affiliation(s)
- Ingrid L Bakker
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands.
| | - Sandra T van Tiel
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands
| | - Joost Haeck
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands
| | - Gabriela N Doeswijk
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands
| | - Erik de Blois
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands
| | - Marcel Segbers
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands
| | - Theodosia Maina
- Molecular Radiopharmacy, INSRATES, NCSR "Demokritos", Athens, Greece
| | - Berthold A Nock
- Molecular Radiopharmacy, INSRATES, NCSR "Demokritos", Athens, Greece
| | - Marion de Jong
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands
| | - Simone U Dalm
- Department of Radiology and Nuclear Medicine, Erasmus MC, Room No. Na2510, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands
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Fassbender TF, Schiller F, Mix M, Maecke HR, Kiefer S, Drendel V, Meyer PT, Jilg CA. Accuracy of [ 68Ga]Ga-RM2-PET/CT for diagnosis of primary prostate cancer compared to histopathology. Nucl Med Biol 2019; 70:32-38. [PMID: 30836254 DOI: 10.1016/j.nucmedbio.2019.01.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 01/17/2019] [Accepted: 01/21/2019] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Prostate cancer (PCa) often shows an overexpression of the gastrin-releasing peptide receptor (GRPr). Therefore, GRPr is a possible theragnostic target. An interesting antagonist GRPr-ligand is RM2 or BAY86-7548. This study examines the accuracy of positron emission tomography (PET) with [68Ga]Ga-RM2 for diagnostic imaging of primary PCa (pPCa) compared to histopathology in patients undergoing radical prostatectomy (RP). METHODS [68Ga]Ga-RM2-PET examinations were performed in 15 patients before RP. All prostate specimens were histopathologically examined based on predefined spatial octants. Each prostate volume on PET was subdivided into octants, which were correlated to histopathology and evaluated according to presence of tumor by two experienced examiners. Additionally, PET data was evaluated by volume of interest (VOI) analyses in terms of maximum standardized uptake value (SUVmax) and normalized SUVmax relative to background activity (rSUVmax). Receiver operating characteristic (ROC) curves for SUVmax and rSUVmax were calculated. RESULTS At least one focus of increased [68Ga]Ga-RM2 uptake corresponding to a tumor manifestation on histology was found in 14 of 15 patients (93%). Spatial concordance of visual PET readings with histopathology was very variable. Intraindividual agreement reached from ≤2 octants in three, 3-5 octants in six to ≥6 octants in six patients, resulting in a relatively low correlation of visual PET readings with histopathology (accuracy = 0.63; p = 0.0018). Lesion-based analysis found a sensitivity of 69% and a positive predictive value of 73%. Concordantly, the octant-based ROC curves for SUVmax and rSUVmax indicated a relatively low diagnostic performance (area under the curve of 0.59 and 0.61, respectively). CONCLUSIONS [68Ga]Ga-RM2-PET shows only a relatively low diagnostic accuracy for pPCa compared to histopathology on an octant basis, which may be explained to some extent by methodological weaknesses. Further studies need to explore, whether the observed high interindividual variability of agreement between [68Ga]Ga-RM2-PET and histopathology can be explained by different tumor biologies or other coincident prostatic pathologies.
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Affiliation(s)
- Thomas F Fassbender
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Florian Schiller
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Michael Mix
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Helmut R Maecke
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.
| | - Selina Kiefer
- Department of Pathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Vanessa Drendel
- Department of Pathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Philipp T Meyer
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.
| | - Cordula A Jilg
- Department of Urology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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Morgat C, Schollhammer R, Macgrogan G, Barthe N, Vélasco V, Vimont D, Cazeau AL, Fernandez P, Hindié E. Comparison of the binding of the gastrin-releasing peptide receptor (GRP-R) antagonist 68Ga-RM2 and 18F-FDG in breast cancer samples. PLoS One 2019; 14:e0210905. [PMID: 30645633 PMCID: PMC6333408 DOI: 10.1371/journal.pone.0210905] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 01/03/2019] [Indexed: 12/30/2022] Open
Abstract
The Gastrin-Releasing Peptide Receptor (GRPR) is over-expressed in estrogen receptor (ER) positive breast tumors and related metastatic lymph nodes offering the opportunity of imaging and therapy of luminal tumors. 68Ga-RM2 binding and 18F-FDG binding in tumoral zones were measured and compared using tissue micro-imaging with a beta imager on 14 breast cancer samples (10 primaries and 4 associated metastatic lymph nodes). Results were then assessed against ER expression, progesterone receptor (PR) expression, HER2 over-expression or not and Ki-67 expression. GRPR immunohistochemistry (IHC) was also performed on all samples. We also retrospectively compared 68Ga-RM2 and 18F-FDG bindings to 18F-FDG SUVmax on the pre-therapeutic PET/CT examination, if available. 68Ga-RM2 binding was significantly higher in tumors expressing GRPR on IHC than in GRPR-negative tumors (P = 0.022). In ER+ tumors, binding of 68Ga-RM2 was significantly higher than 18F-FDG (P = 0.015). In tumors with low Ki-67, 68Ga-RM2 binding was also significantly increased compared to 18F-FDG (P = 0.029). Overall, the binding of 68Ga-RM2 and 18F-FDG displayed an opposite pattern in tumor samples and 68Ga-RM2 binding was significantly higher in tumors that had low 18F-FDG binding (P = 0.021). This inverse correlation was also documented in the few patients in whom a 18F-FDG PET/CT examination before surgery was available. Findings from this in vitro study suggest that GRPR targeting can be an alternative to 18F-FDG imaging in ER+ breast tumors. Moreover, because GRPR antagonists can also be labeled with lutetium-177 this opens new avenues for targeted radionuclide therapy in the subset of patients with progressive metastatic disease following conventional treatments.
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Affiliation(s)
- Clément Morgat
- Nuclear Medicine Department, University Hospital of Bordeaux, Bordeaux, France
- Univ. Bordeaux, INCIA, UMR-CNRS 5287, Talence, France
- CNRS, INCIA, UMR 5287, Talence, France
- * E-mail:
| | - Romain Schollhammer
- Nuclear Medicine Department, University Hospital of Bordeaux, Bordeaux, France
- Univ. Bordeaux, INCIA, UMR-CNRS 5287, Talence, France
- CNRS, INCIA, UMR 5287, Talence, France
| | - Gaétan Macgrogan
- Surgical Pathology Unit, Department of BioPathology, Institut Bergonié, Bordeaux, France
- INSERM, ACTION U1218, Bordeaux, France
| | | | - Valérie Vélasco
- Surgical Pathology Unit, Department of BioPathology, Institut Bergonié, Bordeaux, France
- INSERM, ACTION U1218, Bordeaux, France
| | - Delphine Vimont
- Univ. Bordeaux, INCIA, UMR-CNRS 5287, Talence, France
- CNRS, INCIA, UMR 5287, Talence, France
| | | | - Philippe Fernandez
- Nuclear Medicine Department, University Hospital of Bordeaux, Bordeaux, France
- Univ. Bordeaux, INCIA, UMR-CNRS 5287, Talence, France
- CNRS, INCIA, UMR 5287, Talence, France
| | - Elif Hindié
- Nuclear Medicine Department, University Hospital of Bordeaux, Bordeaux, France
- Univ. Bordeaux, INCIA, UMR-CNRS 5287, Talence, France
- CNRS, INCIA, UMR 5287, Talence, France
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Nicolas GP, Morgenstern A, Schottelius M, Fani M. New Developments in Peptide Receptor Radionuclide Therapy. J Nucl Med 2018; 60:jnumed.118.213496. [PMID: 30573642 DOI: 10.2967/jnumed.118.213496] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 12/14/2018] [Indexed: 12/16/2022] Open
Abstract
Peptide Receptor Radionuclide Therapy (PRRT) is an established treatment for non-operable or metastatic neuroendocrine neoplasms that express highly and frequently somatostatin receptors. More generally, PRRT is an attractive therapy option for delivering cytotoxic radiation to tumor cells through specific binding of a radiolabeled peptide to a molecular target. The development of imaging companions gave rise to the concept of radiotheranostics, important for in vivo tumor detection, characterization, staging but also, and more importantly, for individual patient selection and treatment. The success of somatostatin receptor targeting paved the way for the clinical translation of other peptide-based radiopharmaceuticals targeting, e.g. the receptors Cholecystokinin 2, Gastrin Releasing Peptide (GRPR), Neurokinin-1 and C-X-C motif chemokine 4 (CXCR4). While historically the Auger emitter 111In and the high-energy β- emitter 90Y were used, the vast majority of PRRT are currently performed with the medium-energy β- emitter 177Lu, while α emitters are increasingly studied in various clinical applications.
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Affiliation(s)
| | | | | | - Melpomeni Fani
- University Hospital Basel, University of Basel, Switzerland
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Cristofani R, Montagnani Marelli M, Cicardi ME, Fontana F, Marzagalli M, Limonta P, Poletti A, Moretti RM. Dual role of autophagy on docetaxel-sensitivity in prostate cancer cells. Cell Death Dis 2018; 9:889. [PMID: 30166521 PMCID: PMC6117300 DOI: 10.1038/s41419-018-0866-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 07/02/2018] [Accepted: 07/06/2018] [Indexed: 11/25/2022]
Abstract
Prostate cancer (PC) is one of the leading causes of death in males. Available treatments often lead to the appearance of chemoresistant foci and metastases, with mechanisms still partially unknown. Within tumour mass, autophagy may promote cell survival by enhancing cancer cells tolerability to different cell stresses, like hypoxia, starvation or those triggered by chemotherapic agents. Because of its connection with the apoptotic pathways, autophagy has been differentially implicated, either as prodeath or prosurvival factor, in the appearance of more aggressive tumours. Here, in three PC cells (LNCaP, PC3, and DU145), we tested how different autophagy inducers modulate docetaxel-induced apoptosis. We selected the mTOR-independent disaccharide trehalose and the mTOR-dependent macrolide lactone rapamycin autophagy inducers. In castration-resistant PC (CRPC) PC3 cells, trehalose specifically prevented intrinsic apoptosis in docetaxel-treated cells. Trehalose reduced the release of cytochrome c triggered by docetaxel and the formation of aberrant mitochondria, possibly by enhancing the turnover of damaged mitochondria via autophagy (mitophagy). In fact, trehalose increased LC3 and p62 expression, LC3-II and p62 (p62 bodies) accumulation and the induction of LC3 puncta. In docetaxel-treated cells, trehalose, but not rapamycin, determined a perinuclear mitochondrial aggregation (mito-aggresomes), and mitochondria specifically colocalized with LC3 and p62-positive autophagosomes. In PC3 cells, rapamycin retained its ability to activate autophagy without evidences of mitophagy even in presence of docetaxel. Interestingly, these results were replicated in LNCaP cells, whereas trehalose and rapamycin did not modify the response to docetaxel in the ATG5-deficient (autophagy resistant) DU145 cells. Therefore, autophagy is involved to alter the response to chemotherapy in combination therapies and the response may be influenced by the different autophagic pathways utilized and by the type of cancer cells.
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Affiliation(s)
- Riccardo Cristofani
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy
| | - Marina Montagnani Marelli
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy
| | - Maria Elena Cicardi
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy
| | - Fabrizio Fontana
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy
| | - Monica Marzagalli
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy
| | - Patrizia Limonta
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy
| | - Angelo Poletti
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy.
| | - Roberta Manuela Moretti
- Department of Excellence: Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università degli Studi di Milano, Milano, Italy
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Läppchen T, Kiefer Y, Holland JP, Bartholomä MD. In vitro and in vivo evaluation of the bifunctional chelator NODIA-Me in combination with a prostate-specific membrane antigen targeting vector. Nucl Med Biol 2018; 60:45-54. [DOI: 10.1016/j.nucmedbio.2018.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 02/14/2018] [Accepted: 03/07/2018] [Indexed: 01/21/2023]
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Maina T, Nock BA, Kulkarni H, Singh A, Baum RP. Theranostic Prospects of Gastrin-Releasing Peptide Receptor–Radioantagonists in Oncology. PET Clin 2017; 12:297-309. [DOI: 10.1016/j.cpet.2017.02.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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PET and PET/CT with radiolabeled choline in prostate cancer: a critical reappraisal of 20 years of clinical studies. Eur J Nucl Med Mol Imaging 2017; 44:1751-1776. [PMID: 28409220 DOI: 10.1007/s00259-017-3700-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/31/2017] [Indexed: 12/12/2022]
Abstract
We here aim to provide a comprehensive and critical review of the literature concerning the clinical applications of positron emission tomography/computed tomography (PET/CT) with radiolabeled choline in patients with prostate cancer (PCa). We will initially briefly summarize the historical context that brought to the synthesis of [11C]choline, which occurred exactly 20 years ago. We have arbitrarily grouped the clinical studies in three different periods, according to the year in which they were published and according to their relation with their applications in urology, radiotherapy and oncology. Studies at initial staging and, more extensively, studies in patients with biochemical failure, as well as factors predicting positive PET/CT will be reviewed. The capability of PET/CT with radiolabeled choline to provide prognostic information on PCa-specific survival will also be examined. The last sections will be devoted to the use of radiolabeled choline for monitoring the response to androgen deprivation therapy, radiotherapy, and chemotherapy. The accuracy and the limits of the technique will be discussed according to the information available from standard validation processes, including biopsy or histology. The clinical impact of the technique will be discussed on the basis of changes induced in the management of patients and in the evaluation of the response to therapy. Current indications to PET/CT, as officially endorsed by guidelines, or as routinely performed in the clinical practice will be illustrated. Emphasis will be made on methodological factors that might have influenced the results of the studies or their interpretation. Finally, we will briefly highlight the potential role of positron emission tomography/magnetic resonance and of new radiotracers for PCa imaging.
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Morgat C, MacGrogan G, Brouste V, Vélasco V, Sévenet N, Bonnefoi H, Fernandez P, Debled M, Hindié E. Expression of Gastrin-Releasing Peptide Receptor in Breast Cancer and Its Association with Pathologic, Biologic, and Clinical Parameters: A Study of 1,432 Primary Tumors. J Nucl Med 2017; 58:1401-1407. [DOI: 10.2967/jnumed.116.188011] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 02/17/2017] [Indexed: 12/15/2022] Open
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Maina T, Nock BA. From Bench to Bed: New Gastrin-Releasing Peptide Receptor-Directed Radioligands and Their Use in Prostate Cancer. PET Clin 2017; 12:205-217. [PMID: 28267454 DOI: 10.1016/j.cpet.2016.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Gastrin-releasing peptide receptors (GRPRs) are overexpressed in prostate and breast cancer, and are therefore attractive molecular targets for diagnosis and therapy with radiolabeled GRPR-directed peptide probes. The amphibian tetradecapeptide bombesin or the mammalian gastrin-releasing peptide and neuromedin C have been modified with a variety of chelators. As a result, labeling with radiometals attractive for SPECT or PET imaging and for radionuclide therapy has led to the development of peptide radioligands suitable for in vivo targeting of prostate cancer. A shift of paradigm from internalizing GRPR-agonists to antagonists has occurred owing to the higher biosafety and superior pharmacokinetics of radioantagonists.
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Affiliation(s)
- Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Agia Paraskevi, Attikis, Athens 15310, Greece.
| | - Berthold A Nock
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Agia Paraskevi, Attikis, Athens 15310, Greece
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Qiao J, Grabowska MM, Forestier IS, Mirosevich J, Case TC, Chung DH, Cates JM, Matusik RJ, Manning HC, Jin R. Activation of GRP/GRP-R signaling contributes to castration-resistant prostate cancer progression. Oncotarget 2016; 7:61955-61969. [PMID: 27542219 PMCID: PMC5308703 DOI: 10.18632/oncotarget.11326] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/27/2016] [Indexed: 11/25/2022] Open
Abstract
Numerous studies indicate that androgen receptor splice variants (ARVs) play a critical role in the development of castration-resistant prostate cancer (CRPC), including the resistance to the new generation of inhibitors of androgen receptor (AR) action. Previously, we demonstrated that activation of NF-κB signaling increases ARVs expression in prostate cancer (PC) cells, thereby promoting progression to CRPC. However, it is unclear how NF-κB signaling is activated in CRPC. In this study, we report that long-term treatment with anti-androgens increases a neuroendocrine (NE) hormone - gastrin-releasing peptide (GRP) and its receptor (GRP-R) expression in PC cells. In addition, activation of GRP/GRP-R signaling increases ARVs expression through activating NF-κB signaling. This results in an androgen-dependent tumor progressing to a castrate resistant tumor. The knock-down of AR-V7 restores sensitivity to antiandrogens of PC cells over-expressing the GRP/GRP-R signaling pathway. These findings strongly indicate that the axis of Androgen-Deprivation Therapy (ADT) induces GRP/GRP-R activity, activation NF-κB and increased levels of AR-V7 expression resulting in progression to CRPC. Both prostate adenocarcinoma and small cell NE prostate cancer express GRP-R. Since the GRP-R is clinically targetable by analogue-based approach, this provides a novel therapeutic approach to treat advanced CRPC.
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Affiliation(s)
- Jingbo Qiao
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Pediatric Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Magdalena M. Grabowska
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Prostate Cancer Center and Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ingrid S. Forestier
- Department of Biochemistry, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico
| | - Janni Mirosevich
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Prostate Cancer Center and Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Thomas C. Case
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Prostate Cancer Center and Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dai H. Chung
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Pediatric Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Justin M.M. Cates
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Robert J. Matusik
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Prostate Cancer Center and Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - H. Charles Manning
- Institute of Imaging Science and Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Renjie Jin
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Prostate Cancer Center and Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
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Stoykow C, Erbes T, Maecke HR, Bulla S, Bartholomä M, Mayer S, Drendel V, Bronsert P, Werner M, Gitsch G, Weber WA, Stickeler E, Meyer PT. Gastrin-releasing Peptide Receptor Imaging in Breast Cancer Using the Receptor Antagonist (68)Ga-RM2 And PET. Theranostics 2016; 6:1641-50. [PMID: 27446498 PMCID: PMC4955063 DOI: 10.7150/thno.14958] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/08/2016] [Indexed: 01/07/2023] Open
Abstract
Introduction: The gastrin-releasing peptide receptor (GRPR) is overexpressed in breast cancer. The present study evaluates GRPR imaging as a novel imaging modality in breast cancer by employing positron emission tomography (PET) and the GRPR antagonist 68Ga-RM2. Methods: Fifteen female patients with biopsy confirmed primary breast carcinoma (3 bilateral tumors; median clinical stage IIB) underwent 68Ga-RM2-PET/CT for pretreatment staging. In vivo tumor uptake of 68Ga-RM2 was correlated with estrogen (ER) and progesterone (PR) receptor expression, HER2/neu status and MIB-1 proliferation index in breast core biopsy specimens. Results: 13/18 tumors demonstrated strongly increased 68Ga-RM2 uptake compared to normal breast tissue (defined as PET-positive). All PET-positive primary tumors were ER- and PR-positive (13/13) in contrast to only 1/5 PET-negative tumors. Mean SUVMAX of ER-positive tumors was 10.6±6.0 compared to 2.3±1.0 in ER-negative tumors (p=0.016). In a multivariate analysis including ER, PR, HER2/neu and MIB-1, only ER expression predicted 68Ga-RM2 uptake (model: r2=0.55, p=0.025). Normal breast tissue showed inter- and intraindividually variable, moderate GRPR binding (SUVMAX 2.3±1.0), while physiological uptake of other organs was considerably less except pancreas. Of note, 68Ga-RM2-PET/CT detected internal mammary lymph nodes with high 68Ga-RM2 uptake (n=8), a contralateral axillary lymph node metastasis (verified by biopsy) and bone metastases (n=1; not detected by bone scan and CT). Conclusion: Our study demonstrates that 68Ga-RM2-PET/CT is a promising imaging method in ER-positive breast cancer. In vivo GRPR binding assessed by 68Ga-RM2-PET/CT correlated with ER expression in primary tumors of untreated patients.
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Ding H, Kothandaraman S, Gong L, Williams MM, Dirksen WP, Rosol TJ, Tweedle MF. A human GRPr-transfected Ace-1 canine prostate cancer model in mice. Prostate 2016; 76:783-95. [PMID: 26940014 PMCID: PMC5867903 DOI: 10.1002/pros.23172] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/11/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND A versatile drug screening system was developed to simplify early targeted drug discovery in mice and then translate readily from mice to a dog prostate cancer model that more fully replicates the features of human prostate cancer. METHODS We stably transfected human cDNA of the GRPr bombesin (BBN) receptor subtype to canine Ace-1 prostate cancer cells (Ace-1(huGRPr) ). Expression was examined by (125) I-Tyr(4) -BBN competition, calcium stimulation assay, and fluorescent microscopy. A dual tumor nude mouse xenograft model was developed from Ace-1(CMV) (vector transfected Ace-1) and Ace-1(huGRPr) cells. The model was used to explore the in vivo behavior of two new IRDye800-labeled GRPr binding optical imaging agents: 800-G-Abz4-t-BBN, from a GRPr agonist peptide, and 800-G-Abz4-STAT, from a GRPr antagonist peptide, by imaging the tumor mice and dissected organs. RESULTS Both agents bound Ace-1(huGRPr) and PC-3, a known GRPr-expressing human prostate cancer cell line, with 4-13 nM IC50 against (125) I-Tyr(4) -BBN, but did not bind Ace-1(CMV) cells (vector transfected). Binding was blocked by bombesin. Ca(2+) activation assays demonstrated that Ace-1(huGPRr) expressed biologically active GRPr. Both Ace-1 cell lines grew in the flanks of 100% of the nude mice and formed tumors of ∼0.5 cm diameter in 1 week. In vivo imaging of the mice at 800 nm emission showed GRPr+: GRPr- tumor signal brighter by a factor of two at 24 h post IV administration of 10 nmol of the imaging agents. Blood retention (4-8% ID at 1 h) was greater by a factor >10 and cumulative urine accumulation (28-30% at 4 h) was less by a factor 2 compared to a radioactive analog of the t-BBN containing agent, (177) LuAMBA, probably due to binding to blood albumin, which we confirmed in a mouse serum assay. CONCLUSIONS The dual tumor Ace-1(CMV) /Ace-1(huGRPr) model system provides a rapid test of specific to nonspecific binding of new GRPr avid agents in a model that will extend logically to the known Ace-1 orthotopic canine prostate cancer model. Prostate 76:783-795, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Haiming Ding
- Department of Radiology, The Wright Center for Innovation in Biomolecular Imaging, The Wexner Medical Center, The Ohio State University, Columbus, Ohio
| | - Shankaran Kothandaraman
- Department of Radiology, The Wright Center for Innovation in Biomolecular Imaging, The Wexner Medical Center, The Ohio State University, Columbus, Ohio
| | - Li Gong
- Department of Radiology, The Wright Center for Innovation in Biomolecular Imaging, The Wexner Medical Center, The Ohio State University, Columbus, Ohio
| | - Michelle M. Williams
- Department of Radiology, The Wright Center for Innovation in Biomolecular Imaging, The Wexner Medical Center, The Ohio State University, Columbus, Ohio
| | - Wessel P. Dirksen
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio
| | - Thomas J. Rosol
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio
| | - Michael F. Tweedle
- Department of Radiology, The Wright Center for Innovation in Biomolecular Imaging, The Wexner Medical Center, The Ohio State University, Columbus, Ohio
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Moreno P, Ramos-Álvarez I, Moody TW, Jensen RT. Bombesin related peptides/receptors and their promising therapeutic roles in cancer imaging, targeting and treatment. Expert Opin Ther Targets 2016; 20:1055-73. [PMID: 26981612 DOI: 10.1517/14728222.2016.1164694] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Despite remarkable advances in tumor treatment, many patients still die from common tumors (breast, prostate, lung, CNS, colon, and pancreas), and thus, new approaches are needed. Many of these tumors synthesize bombesin (Bn)-related peptides and over-express their receptors (BnRs), hence functioning as autocrine-growth-factors. Recent studies support the conclusion that Bn-peptides/BnRs are well-positioned for numerous novel antitumor treatments, including interrupting autocrine-growth and the use of over-expressed receptors for imaging and targeting cytotoxic-compounds, either by direct-coupling or combined with nanoparticle-technology. AREAS COVERED The unique ability of common neoplasms to synthesize, secrete, and show a growth/proliferative/differentiating response due to BnR over-expression, is reviewed, both in general and with regard to the most frequently investigated neoplasms (breast, prostate, lung, and CNS). Particular attention is paid to advances in the recent years. Also considered are the possible therapeutic approaches to the growth/differentiation effect of Bn-peptides, as well as the therapeutic implication of the frequent BnR over-expression for tumor-imaging and/or targeted-delivery. EXPERT OPINION Given that Bn-related-peptides/BnRs are so frequently ectopically-expressed by common tumors, which are often malignant and become refractory to conventional treatments, therapeutic interventions using novel approaches to Bn-peptides and receptors are being explored. Of particular interest is the potential of reproducing with BnRs in common tumors the recent success of utilizing overexpression of somatostatin-receptors by neuroendocrine-tumors to provide the most sensitive imaging methods and targeted delivery of cytotoxic-compounds.
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Affiliation(s)
- Paola Moreno
- a Digestive Diseases Branch, Cell Biology Section, NIDDK , National Institutes of Health , Bethesda , MD , USA
| | - Irene Ramos-Álvarez
- a Digestive Diseases Branch, Cell Biology Section, NIDDK , National Institutes of Health , Bethesda , MD , USA
| | - Terry W Moody
- b Center for Cancer Research, Office of the Director , NCI, National Institutes of Health , Bethesda , MD , USA
| | - Robert T Jensen
- a Digestive Diseases Branch, Cell Biology Section, NIDDK , National Institutes of Health , Bethesda , MD , USA
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Chatalic KL, Konijnenberg M, Nonnekens J, de Blois E, Hoeben S, de Ridder C, Brunel L, Fehrentz JA, Martinez J, van Gent DC, Nock BA, Maina T, van Weerden WM, de Jong M. In Vivo Stabilization of a Gastrin-Releasing Peptide Receptor Antagonist Enhances PET Imaging and Radionuclide Therapy of Prostate Cancer in Preclinical Studies. Theranostics 2016; 6:104-17. [PMID: 26722377 PMCID: PMC4679358 DOI: 10.7150/thno.13580] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 09/25/2015] [Indexed: 12/18/2022] Open
Abstract
A single tool for early detection, accurate staging, and personalized treatment of prostate cancer (PCa) would be a major breakthrough in the field of PCa. Gastrin-releasing peptide receptor (GRPR) targeting peptides are promising probes for a theranostic approach for PCa overexpressing GRPR. However, the successful application of small peptides in a theranostic approach is often hampered by their fast in vivo degradation by proteolytic enzymes, such as neutral endopeptidase (NEP). Here we show for the first time that co-injection of a NEP inhibitor (phosphoramidon (PA)) can lead to an impressive enhancement of diagnostic sensitivity and therapeutic efficacy of the theranostic (68)Ga-/(177)Lu-JMV4168 GRPR-antagonist. Co-injection of PA (300 µg) led to stabilization of (177)Lu-JMV4168 in murine peripheral blood. In PC-3 tumor-bearing mice, PA co-injection led to a two-fold increase in tumor uptake of (68)Ga-/(177)Lu-JMV4168, 1 h after injection. In positron emission tomography (PET) imaging with (68)Ga-JMV4168, PA co-injection substantially enhanced PC-3 tumor signal intensity. Radionuclide therapy with (177)Lu-JMV4168 resulted in significant regression of PC-3 tumor size. Radionuclide therapy efficacy was confirmed by production of DNA double strand breaks, decreased cell proliferation and increased apoptosis. Increased survival rates were observed in mice treated with (177)Lu-JMV4168 plus PA as compared to those without PA. This data shows that co-injection of the enzyme inhibitor PA greatly enhances the theranostic potential of GRPR-radioantagonists for future application in PCa patients.
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47
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Chatalic KLS, Kwekkeboom DJ, de Jong M. Radiopeptides for Imaging and Therapy: A Radiant Future. J Nucl Med 2015; 56:1809-12. [PMID: 26514175 DOI: 10.2967/jnumed.115.161158] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/26/2015] [Indexed: 01/15/2023] Open
Abstract
Radiopeptides are powerful tools for diagnostic imaging and radionuclide therapy of various diseases. Since the introduction of the first radiopeptide into the clinical setting to diagnose neuroendocrine tumors about 25 y ago, many advances have been made in the field. This short review highlights novel strategies to improve the application of radiopeptides for imaging and therapy.
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Affiliation(s)
- Kristell L S Chatalic
- Department of Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands Department of Radiology, Erasmus MC, Rotterdam, The Netherlands; and Department of Urology, Erasmus MC, Rotterdam, The Netherlands
| | - Dik J Kwekkeboom
- Department of Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Marion de Jong
- Department of Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands Department of Radiology, Erasmus MC, Rotterdam, The Netherlands; and
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Chang L, Graham PH, Ni J, Hao J, Bucci J, Cozzi PJ, Li Y. Targeting PI3K/Akt/mTOR signaling pathway in the treatment of prostate cancer radioresistance. Crit Rev Oncol Hematol 2015; 96:507-17. [PMID: 26253360 DOI: 10.1016/j.critrevonc.2015.07.005] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 05/20/2015] [Accepted: 07/08/2015] [Indexed: 12/19/2022] Open
Abstract
The phosphatidylinositol-3-kinase/Akt and the mammalian target of rapamycin (PI3K/Akt/mTOR) pathway is one of the most frequently activated signaling pathways in prostate cancer (CaP) and other cancers, and responsible for the survival, metastasis and therapeutic resistance. Recent advances in radiation therapy indicate that activation of this pathway is closely associated with cancer radioresistance, which is a major challenge for the current CaP radiation treatment. Therefore, targeting this pathway by inhibitors to enhance radiosensitivity has great potential for clinical benefits of CaP patients. In this review, we summarize the recent findings in the PI3K/Akt/mTOR pathway in CaP radiotherapy research and discuss the potential use of the PI3K/Akt/mTOR pathway inhibitors as radiosensitizers in the treatment of CaP radioresistance in preclinical studies to explore novel approaches for future clinical trials.
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Affiliation(s)
- Lei Chang
- Cancer Care Centre and Prostate Cancer Institute, St. George Hospital, Sydney, NSW, Australia; St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia
| | - Peter H Graham
- Cancer Care Centre and Prostate Cancer Institute, St. George Hospital, Sydney, NSW, Australia; St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia
| | - Jie Ni
- Cancer Care Centre and Prostate Cancer Institute, St. George Hospital, Sydney, NSW, Australia; St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia
| | - Jingli Hao
- Cancer Care Centre and Prostate Cancer Institute, St. George Hospital, Sydney, NSW, Australia; St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia
| | - Joseph Bucci
- Cancer Care Centre and Prostate Cancer Institute, St. George Hospital, Sydney, NSW, Australia; St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia
| | - Paul J Cozzi
- St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia; Department of Surgery, St. George Hospital, Sydney, NSW, Australia
| | - Yong Li
- Cancer Care Centre and Prostate Cancer Institute, St. George Hospital, Sydney, NSW, Australia; St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia.
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Lohrmann C, Zhang H, Thorek DLJ, Desai P, Zanzonico PB, O'Donoghue J, Irwin CP, Reiner T, Grimm J, Weber WA. Cerenkov Luminescence Imaging for Radiation Dose Calculation of a ⁹⁰Y-Labeled Gastrin-Releasing Peptide Receptor Antagonist. J Nucl Med 2015; 56:805-11. [PMID: 25840974 DOI: 10.2967/jnumed.114.149054] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 02/27/2015] [Indexed: 12/15/2022] Open
Abstract
UNLABELLED (90)Y has been used to label various new therapeutic radiopharmaceuticals. However, measuring the radiation dose delivered by (90)Y is challenging because of the absence of suitable γ emissions and its low abundance of positron emissions. For the treatment of prostate cancer, radiolabeled gastrin-releasing peptide receptor (GRPr) antagonists have yielded promising results in mouse models. In this study, we evaluated whether Cerenkov luminescence imaging (CLI) could be used to determine radiation doses of a (90)Y-labeled GRPr antagonist in nude mice. METHODS Mice bearing subcutaneous prostate cancer xenografts were injected with 0.74-18.5 MBq of the (90)Y-labeled GRPr antagonist DOTA-AR and underwent in vivo and ex vivo CLI at 1-48 h after injection. After imaging, animals were sacrificed, their tumors and organs were harvested, and the activity concentration was measured by liquid scintillation counting. In a second set of experiments, Cerenkov photon counts for tumor and kidney on in vivo CLI were converted to activity concentrations using conversion factors determined from the first set of experiments. RESULTS (90)Y-DOTA-AR concentration in the 3 tumor models ranged from 0.5% to 4.8% of the injected activity per gram at 1 h after injection and decreased to 0.05%-0.15 injected activity per gram by 48 h after injection. A positive correlation was found between tumor activity concentrations and in vivo CLI signal (r(2) = 0.94). A similar correlation was found for the renal activity concentration and in vivo Cerenkov luminescence (r(2) = 0.98). Other organs were not distinctly visualized on the in vivo images, but ex vivo CLI was also correlated with the radioactivity concentration (r(2) = 0.35-0.94). Using the time-activity curves from the second experiment, we calculated radiation doses to tumor and kidney of 0.33 ± 0.12 (range, 0.21-0.66) and 0.06 ± 0.01 (range, 0.05-0.08) Gy/MBq, respectively. CONCLUSION CLI is a promising, low-cost modality to measure individual radiation doses of (90)Y-labeled compounds noninvasively. The use of Cerenkov imaging is expected to facilitate the development and comparison of (90)Y-labeled compounds for targeted radiotherapy.
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Affiliation(s)
- Christian Lohrmann
- Molecular Imaging and Therapy Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Hanwen Zhang
- Radiochemistry and Imaging Sciences Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Daniel L J Thorek
- Division of Nuclear Medicine, Department of Radiology, Johns Hopkins Medicine, Baltimore, Maryland
| | - Pooja Desai
- Radiochemistry and Imaging Sciences Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Pat B Zanzonico
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York; and
| | - Joseph O'Donoghue
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York; and
| | - Christopher P Irwin
- Radiochemistry and Imaging Sciences Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Thomas Reiner
- Radiochemistry and Imaging Sciences Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Jan Grimm
- Molecular Imaging and Therapy Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Wolfgang A Weber
- Molecular Imaging and Therapy Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, New York, New York
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50
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Dalm SU, Martens JWM, Sieuwerts AM, van Deurzen CHM, Koelewijn SJ, de Blois E, Maina T, Nock BA, Brunel L, Fehrentz JA, Martinez J, de Jong M, Melis M. In vitro and in vivo application of radiolabeled gastrin-releasing peptide receptor ligands in breast cancer. J Nucl Med 2015; 56:752-7. [PMID: 25791989 DOI: 10.2967/jnumed.114.153023] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/04/2015] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED Breast cancer (BC) consists of multiple subtypes defined by various molecular characteristics, for instance, estrogen receptor (ER) expression. Methods for visualizing BC include mammography, MR imaging, ultrasound, and nuclear medicine-based methods such as (99m)Tc-sestamibi and (18)F-FDG PET, unfortunately all lacking specificity. Peptide receptor scintigraphy and peptide receptor radionuclide therapy are successfully applied for imaging and therapy of somatostatin receptor-expressing neuroendocrine tumors using somatostatin receptor radioligands. On the basis of a similar rationale, radioligands targeting the gastrin-releasing peptide receptor (GRP-R) might offer a specific method for imaging and therapy of BC. The aim of this study was to explore the application of GRP-R radioligands for imaging and therapy of BC by introducing valid preclinical in vitro and in vivo models. METHODS GRP-R expression of 50 clinical BC specimens and the correlation with ER expression was studied by in vitro autoradiography with the GRP-R agonist (111)In-AMBA. GRP-R expression was also analyzed in 9 BC cell lines applying (111)In-AMBA internalization assays and quantitative reverse transcriptase polymerase chain reaction. In vitro cytotoxicity of (177)Lu-AMBA was determined on the GRP-R-expressing BC cell line T47D. SPECT/CT imaging and biodistribution were studied in mice with subcutaneous and orthotopic ER-positive T47D and MCF7 xenografts after injection of the GRP-R antagonist (111)In-JMV4168. RESULTS Most of the human BC specimens (96%) and BC cell lines (6/9) were found to express GRP-R. GRP-R tumor expression was positively (P = 0.026, χ(2)(4) = 12,911) correlated with ER expression in the human BC specimens. Treatment of T47D cells with 10(-7) M/50 MBq of (177)Lu-AMBA resulted in 80% reduction of cells in vitro. Furthermore, subcutaneous and orthotopic tumors from both BC cell lines were successfully visualized in vivo by SPECT/CT using (111)In-JMV4168; T47D tumors exhibited a higher uptake than MCF7 xenografts. CONCLUSION Targeting GRP-R-expressing BC tumors using GRP-R radioligands is promising for nuclear imaging and therapy, especially in ER-positive BC patients.
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Affiliation(s)
- Simone U Dalm
- Departments of Nuclear Medicine and Radiology, Erasmus MC, Rotterdam, The Netherlands
| | - John W M Martens
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC, Rotterdam, The Netherlands
| | - Anieta M Sieuwerts
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC, Rotterdam, The Netherlands
| | | | - Stuart J Koelewijn
- Departments of Nuclear Medicine and Radiology, Erasmus MC, Rotterdam, The Netherlands
| | - Erik de Blois
- Departments of Nuclear Medicine and Radiology, Erasmus MC, Rotterdam, The Netherlands
| | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece; and
| | - Berthold A Nock
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece; and
| | - Luc Brunel
- Institut des Biomolécules Max Mousseron, UMR5247, CNRS-UM1-UM2, Montpellier, France
| | - Jean-Alain Fehrentz
- Institut des Biomolécules Max Mousseron, UMR5247, CNRS-UM1-UM2, Montpellier, France
| | - Jean Martinez
- Institut des Biomolécules Max Mousseron, UMR5247, CNRS-UM1-UM2, Montpellier, France
| | - Marion de Jong
- Departments of Nuclear Medicine and Radiology, Erasmus MC, Rotterdam, The Netherlands
| | - Marleen Melis
- Departments of Nuclear Medicine and Radiology, Erasmus MC, Rotterdam, The Netherlands
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