Emerging Theranostic Tracers in the Context of Radiopharmaceutical Drug Development

A special issue of Pharmaceuticals (ISSN 1424-8247).

Deadline for manuscript submissions: closed (31 January 2017) | Viewed by 96872

Special Issue Editors

Department of Nuclear Medicine, University Hospital, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany
Interests: theranostics; radiopharmaceutical sciences; radiolabeling chemistry; radiometals for medicinal purposes; PET tracers, dosimetry for individualized treatment-planning, nuclide production, automatization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Theranostics is a portmanteau consisting of the two words therapy and diagnostics and exemplifies the tight relationship of both disciplines. In nuclear medicine the possibility of labelling a molecular targeting vector (e.g., peptides) either with diagnostic (e.g., positron or gamma-emitters) or therapeutic radionuclides paved the way for a personalized treatment, taking the advantage of imaging diagnostics for early detection, staging, therapy selection, planning and follow-up in cancer therapy.
Since the first theranostic application in the mid-1940s of radioiodine (123I: γ-emitter, imaging; 131I: β- and γ-emitter, therapy and imaging) for therapy of differentiated thyroid cancers the number of theranostic agents and the number of clinical applications is increasing successively. Subsequently, nuclear medicine becomes more and more important, especially in oncology, where this engaging of imaging and therapy leads to increased therapeutic efficiency in cancer treatment.
We would like to invite you, to contribute review or original research articles covering the different facets of this emerging field of research, which will be published as a Special Issue on “Emerging Theranostic Tracers in the Context of Radiopharmaceutical Drug Development”.
Areas of interest include, but are not limited to:
•    Development of theranostic radiopharmaceuticals
•    Pre-clinical and clinical application of theranostics in oncology
•    Production, radiolabelling and application of new isotopes for theranostics (imaging and/or therapy)
•    PET/SPECT imaging for dosimetry and therapy monitoring

Prof. Dr. Klaus Kopka
Dr. Elisabeth Eppard
Guest Editors

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Keywords

  • Theranostics
  • Imaging (PET, SPECT)
  • Endoradiotherapy
  • Nuclear medicine
  • Dosimetry

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Published Papers (11 papers)

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Research

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3699 KiB  
Article
Procedures for the GMP-Compliant Production and Quality Control of [18F]PSMA-1007: A Next Generation Radiofluorinated Tracer for the Detection of Prostate Cancer
by Jens Cardinale, René Martin, Yvonne Remde, Martin Schäfer, Antje Hienzsch, Sandra Hübner, Anna-Maria Zerges, Heike Marx, Ronny Hesse, Klaus Weber, Rene Smits, Alexander Hoepping, Marco Müller, Oliver C. Neels and Klaus Kopka
Pharmaceuticals 2017, 10(4), 77; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10040077 - 27 Sep 2017
Cited by 86 | Viewed by 18878
Abstract
Radiolabeled tracers targeting the prostate-specific membrane antigen (PSMA) have become important radiopharmaceuticals for the PET-imaging of prostate cancer. In this connection, we recently developed the fluorine-18-labelled PSMA-ligand [18F]PSMA-1007 as the next generation radiofluorinated Glu-ureido PSMA inhibitor after [18F]DCFPyL and [...] Read more.
Radiolabeled tracers targeting the prostate-specific membrane antigen (PSMA) have become important radiopharmaceuticals for the PET-imaging of prostate cancer. In this connection, we recently developed the fluorine-18-labelled PSMA-ligand [18F]PSMA-1007 as the next generation radiofluorinated Glu-ureido PSMA inhibitor after [18F]DCFPyL and [18F]DCFBC. Since radiosynthesis so far has been suffering from rather poor yields, novel procedures for the automated radiosyntheses of [18F]PSMA-1007 have been developed. We herein report on both the two-step and the novel one-step procedures, which have been performed on different commonly-used radiosynthesisers. Using the novel one-step procedure, the [18F]PSMA-1007 was produced in good radiochemical yields ranging from 25 to 80% and synthesis times of less than 55 min. Furthermore, upscaling to product activities up to 50 GBq per batch was successfully conducted. All batches passed quality control according to European Pharmacopoeia standards. Therefore, we were able to disclose a new, simple and, at the same time, high yielding production pathway for the next generation PSMA radioligand [18F]PSMA-1007. Actually, it turned out that the radiosynthesis is as easily realised as the well-known [18F]FDG synthesis and, thus, transferable to all currently-available radiosynthesisers. Using the new procedures, the clinical daily routine can be sustainably supported in-house even in larger hospitals by a single production batch. Full article
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6052 KiB  
Article
Comparison of In Vitro Assays in Selecting Radiotracers for In Vivo P-Glycoprotein PET Imaging
by Renske M. Raaphorst, Heli Savolainen, Mariangela Cantore, Evita Van de Steeg, Aren Van Waarde, Nicola A. Colabufo, Philip H. Elsinga, Adriaan A. Lammertsma, Albert D. Windhorst and Gert Luurtsema
Pharmaceuticals 2017, 10(3), 76; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10030076 - 20 Sep 2017
Cited by 4 | Viewed by 6712
Abstract
Positron emission tomography (PET) imaging of P-glycoprotein (P-gp) in the blood-brain barrier can be important in neurological diseases where P-gp is affected, such as Alzheimer´s disease. Radiotracers used in the imaging studies are present at very small, nanomolar, concentration, whereas in vitro assays [...] Read more.
Positron emission tomography (PET) imaging of P-glycoprotein (P-gp) in the blood-brain barrier can be important in neurological diseases where P-gp is affected, such as Alzheimer´s disease. Radiotracers used in the imaging studies are present at very small, nanomolar, concentration, whereas in vitro assays where these tracers are characterized, are usually performed at micromolar concentration, causing often discrepant in vivo and in vitro data. We had in vivo rodent PET data of [11C]verapamil, (R)-N-[18F]fluoroethylverapamil, (R)-O-[18F]fluoroethyl-norverapamil, [18F]MC225 and [18F]MC224 and we included also two new molecules [18F]MC198 and [18F]KE64 in this study. To improve the predictive value of in vitro assays, we labeled all the tracers with tritium and performed bidirectional substrate transport assay in MDCKII-MDR1 cells at three different concentrations (0.01, 1 and 50 µM) and also inhibition assay with P-gp inhibitors. As a comparison, we used non-radioactive molecules in transport assay in Caco-2 cells at a concentration of 10 µM and in calcein-AM inhibition assay in MDCKII-MDR1 cells. All the P-gp substrates were transported dose-dependently. At the highest concentration (50 µM), P-gp was saturated in a similar way as after treatment with P-gp inhibitors. Best in vivo correlation was obtained with the bidirectional transport assay at a concentration of 0.01 µM. One micromolar concentration in a transport assay or calcein-AM assay alone is not sufficient for correct in vivo prediction of substrate P-gp PET ligands. Full article
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2426 KiB  
Article
Folate Receptor-Positive Gynecological Cancer Cells: In Vitro and In Vivo Characterization
by Klaudia Siwowska, Raffaella M. Schmid, Susan Cohrs, Roger Schibli and Cristina Müller
Pharmaceuticals 2017, 10(3), 72; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10030072 - 15 Aug 2017
Cited by 60 | Viewed by 9600
Abstract
The folate receptor (FR) is expressed in a variety of gynecological cancer types. It has been widely used for tumor targeting with folic acid conjugates of diagnostic and therapeutic probes. The cervical KB tumor cells have evolved as the standard model for preclinical [...] Read more.
The folate receptor (FR) is expressed in a variety of gynecological cancer types. It has been widely used for tumor targeting with folic acid conjugates of diagnostic and therapeutic probes. The cervical KB tumor cells have evolved as the standard model for preclinical investigations of folate-based (radio) conjugates. In this study, a panel of FR-expressing human cancer cell lines—including cervical (HeLa, KB, KB-V1), ovarian (IGROV-1, SKOV-3, SKOV-3.ip), choriocarcinoma (JAR, BeWo) and endometrial (EFE-184) tumor cells—was investigated in vitro and for their ability to grow as xenografts in mice. FR-expression levels were compared in vitro and in vivo and the cell lines were characterized by determination of the sensitivity towards commonly-used chemotherapeutics and the expression of two additional, relevant tumor markers, HER2 and L1-CAM. It was found that, besides KB cells, its multiresistant KB-V1 subclone as well as the ovarian cancer cell lines, IGROV-1 and SKOV-3.ip, could be used as potentially more relevant preclinical models. They would allow addressing specific questions such as the therapeutic efficacy of FR-targeting agents in tumor (mouse) models of multi-resistance and in mouse models of metastases formation. Full article
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1619 KiB  
Article
Assessment of Bone Metastases in Patients with Prostate Cancer—A Comparison between 99mTc-Bone-Scintigraphy and [68Ga]Ga-PSMA PET/CT
by Lena Thomas, Caroline Balmus, Hojjat Ahmadzadehfar, Markus Essler, Holger Strunk and Ralph A. Bundschuh
Pharmaceuticals 2017, 10(3), 68; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10030068 - 31 Jul 2017
Cited by 47 | Viewed by 8256
Abstract
Purpose: Bone scintigraphy is the standard of reference in bone metastases in prostate cancer patients. However, new radiotracers employed in prostate-specific membrane antigen (PSMA)-ligands has led to the growing importance of PET/CT as diagnostic tool. The aim of our study was to investigate [...] Read more.
Purpose: Bone scintigraphy is the standard of reference in bone metastases in prostate cancer patients. However, new radiotracers employed in prostate-specific membrane antigen (PSMA)-ligands has led to the growing importance of PET/CT as diagnostic tool. The aim of our study was to investigate the difference between bone scan and PSMA-PET/CT for the detection of bone metastases in prostate cancer. Methods: Thirty patients with bone metastases originating from prostate cancer were examined by 99mTc-MDP bone scan and 68Ga-PSMA-PET/CT within an average of 21 days. Bone scans were analyzed visually according to the number of lesions and using the software package ExiniBONE by Exini Diagnostics. PET/CT data was analyzed visually. Numbers of detected lesions were compared for the different methods for the whole patient and for different regions. In addition, results were compared to serum prostate-specific antigen (PSA), alkaline phosphatase (ALP), bone alkaline phosphatase (bALP), pro gastrin releasing peptide (pGRP) and eastern cooperative oncology group (ECOG) performance status. Results: In the bone scans, visual and semiautomatic lesion detection showed similar results with an average of 19.4 and 17.8 detected bone lesion per patient. However, in PSMA-PET/CT, on average double the numbers of lesions (40.0) were detected. The largest differences were found in the thorax and pelvis, which can be explained by the advantages of tomographic imaging. Bland-Altman analysis showed greater differences in patients with large numbers of bone metastases. Conclusion: No significant difference was found when using semiautomatic analysis compared to visual reading for bone scans. Fewer bone metastases were detected in bone scans than in PSMA-PET/CT. However, in none of our patients would the difference have led to clinical consequences. Therefore, it seems that for patients undergoing PSMA-PET/CT, there is no need to perform additional bone scans if the appropriate PET/CT protocols are applied. Full article
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3343 KiB  
Article
A Short-Term Biological Indicator for Long-Term Kidney Damage after Radionuclide Therapy in Mice
by Giovanni Pellegrini, Klaudia Siwowska, Stephanie Haller, Daniel J. Antoine, Roger Schibli, Anja Kipar and Cristina Müller
Pharmaceuticals 2017, 10(2), 57; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10020057 - 21 Jun 2017
Cited by 12 | Viewed by 4741
Abstract
Folate receptor (FR)-targeted radionuclide therapy using folate radioconjugates is of interest due to the expression of the FR in a variety of tumor types. The high renal accumulation of radiofolates presents, however, a risk of radionephropathy. A potential option to address this challenge [...] Read more.
Folate receptor (FR)-targeted radionuclide therapy using folate radioconjugates is of interest due to the expression of the FR in a variety of tumor types. The high renal accumulation of radiofolates presents, however, a risk of radionephropathy. A potential option to address this challenge would be to use radioprotectants, such as amifostine. Methods for early detection of kidney damage that—in this case—cannot be predicted based on dose estimations, would facilitate the development of novel therapies. The aim of this study was, therefore, to assess potentially changing levels of plasma and urine biomarkers and to determine DNA damage at an early stage after radiofolate application. The identification of an early indicator for renal damage in mice would be useful since histological changes become apparent only several months after treatment. Mice were injected with different quantities of 177Lu-folate (10 MBq, 20 MBq and 30 MBq), resulting in mean absorbed kidney doses of ~23 Gy, ~46 Gy and ~69 Gy, respectively, followed by euthanasia two weeks (>85% of the mean renal radiation dose absorbed) or three months later. Whereas all investigated biomarkers remained unchanged, the number of γ-H2AX-positive nuclei in the renal cortex showed an evident dose-dependent increase as compared to control values two weeks after treatment. Comparison with the extent of kidney injury determined by histological changes five to eight months after administration of the same 177Lu-folate activities suggested that the quantitative assessment of double-strand breaks can be used as a biological indicator for long-term radiation effects in the kidneys. This method may, thus, enable faster assessment of radiopharmaceuticals and protective measures by preventing logistically challenging long-term investigations to detect kidney damage. Full article
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12577 KiB  
Article
The Beginning and Development of the Theranostic Approach in Nuclear Medicine, as Exemplified by the Radionuclide Pair 86Y and 90Y
by Frank Rösch, Hans Herzog and Syed M. Qaim
Pharmaceuticals 2017, 10(2), 56; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10020056 - 20 Jun 2017
Cited by 103 | Viewed by 11375
Abstract
In the context of radiopharmacy and molecular imaging, the concept of theranostics entails a therapy-accompanying diagnosis with the aim of a patient-specific treatment. Using the adequate diagnostic radiopharmaceutical, the disease and the state of the disease are verified for an individual patient. The [...] Read more.
In the context of radiopharmacy and molecular imaging, the concept of theranostics entails a therapy-accompanying diagnosis with the aim of a patient-specific treatment. Using the adequate diagnostic radiopharmaceutical, the disease and the state of the disease are verified for an individual patient. The other way around, it verifies that the radiopharmaceutical in hand represents a target-specific and selective molecule: the “best one” for that individual patient. Transforming diagnostic imaging into quantitative dosimetric information, the optimum radioactivity (expressed in maximum radiation dose to the target tissue and tolerable dose to healthy organs) of the adequate radiotherapeutical is applied to that individual patient. This theranostic approach in nuclear medicine is traced back to the first use of the radionuclide pair 86Y/90Y, which allowed a combination of PET and internal radiotherapy. Whereas the β-emitting therapeutic radionuclide 90Y (t½ = 2.7 d) had been available for a long time via the 90Sr/90Y generator system, the β+ emitter 86Y (t½ = 14.7 h) had to be developed for medical application. A brief outline of the various aspects of radiochemical and nuclear development work (nuclear data, cyclotron irradiation, chemical processing, quality control, etc.) is given. In parallel, the paper discusses the methodology introduced to quantify molecular imaging of 86Y-labelled compounds in terms of multiple and long-term PET recordings. It highlights the ultimate goal of radiotheranostics, namely to extract the radiation dose of the analogue 90Y-labelled compound in terms of mGy or mSv per MBq 90Y injected. Finally, the current and possible future development of theranostic approaches based on different PET and therapy nuclides is discussed. Full article
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4994 KiB  
Article
Syntheses of Radioiodinated Pyrimidine-2,4,6-Triones as Potential Agents for Non-Invasive Imaging of Matrix Metalloproteinases
by Hans-Jörg Breyholz, Klaus Kopka, Michael Schäfers and Stefan Wagner
Pharmaceuticals 2017, 10(2), 49; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10020049 - 30 May 2017
Cited by 8 | Viewed by 4819
Abstract
Dysregulated expression or activation of matrix metalloproteinases (MMPs) is observed in many kinds of live-threatening diseases. Therefore, MMP imaging for example with radiolabelled MMP inhibitors (MMPIs) potentially represents a valuable tool for clinical diagnostics using non-invasive single photon emission computed tomography (SPECT) or [...] Read more.
Dysregulated expression or activation of matrix metalloproteinases (MMPs) is observed in many kinds of live-threatening diseases. Therefore, MMP imaging for example with radiolabelled MMP inhibitors (MMPIs) potentially represents a valuable tool for clinical diagnostics using non-invasive single photon emission computed tomography (SPECT) or positron emission tomography (PET) imaging. This work includes the organic chemical syntheses and in vitro evaluation of five iodinated barbiturate based MMPIs and the selection of derivative 9 for radiosyntheses of isotopologues [123I]9 potentially useful for MMP SPECT imaging and [124I]9 for MMP PET imaging. Full article
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1806 KiB  
Article
Theranostic Value of Multimers: Lessons Learned from Trimerization of Neurotensin Receptor Ligands and Other Targeting Vectors
by Simone Maschauer, Jürgen Einsiedel, Dominik Reich, Harald Hübner, Peter Gmeiner, Hans-Jürgen Wester, Olaf Prante and Johannes Notni
Pharmaceuticals 2017, 10(1), 29; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10010029 - 10 Mar 2017
Cited by 15 | Viewed by 5403
Abstract
Neurotensin receptor 1 (NTS1) is overexpressed on a variety of cancer entities; for example, prostate cancer, ductal pancreatic adenocarcinoma, and breast cancer. Therefore, it represents an interesting target for the diagnosis of these cancers types by positron emission tomography (PET) [...] Full article
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Review

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6740 KiB  
Review
Novel Radiolabeled Bisphosphonates for PET Diagnosis and Endoradiotherapy of Bone Metastases
by Nina Pfannkuchen, Marian Meckel, Ralf Bergmann, Michael Bachmann, Chandrasekhar Bal, Mike Sathekge, Wolfgang Mohnike, Richard P. Baum and Frank Rösch
Pharmaceuticals 2017, 10(2), 45; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10020045 - 18 May 2017
Cited by 42 | Viewed by 7529
Abstract
Bone metastases, often a consequence of breast, prostate, and lung carcinomas, are characterized by an increased bone turnover, which can be visualized by positron emission tomography (PET), as well as single-photon emission computed tomography (SPECT). Bisphosphonate complexes of 99mTc are predominantly used [...] Read more.
Bone metastases, often a consequence of breast, prostate, and lung carcinomas, are characterized by an increased bone turnover, which can be visualized by positron emission tomography (PET), as well as single-photon emission computed tomography (SPECT). Bisphosphonate complexes of 99mTc are predominantly used as SPECT tracers. In contrast to SPECT, PET offers a higher spatial resolution and, owing to the 68Ge/68Ga generator, an analog to the established 99mTc generator exists. Complexation of Ga(III) requires the use of chelators. Therefore, DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), NOTA (1,4,7-triazacyclododecane-1,4,7-triacetic acid), and their derivatives, are often used. The combination of these macrocyclic chelators and bisphosphonates is currently studied worldwide. The use of DOTA offers the possibility of a therapeutic application by complexing the β-emitter 177Lu. This overview describes the possibility of diagnosing bone metastases using [68Ga]Ga-BPAMD (68Ga-labeled (4-{[bis-(phosphonomethyl))carbamoyl]methyl}-7,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl)acetic acid) as well as the successful application of [177Lu]Lu-BPAMD for therapy and the development of new diagnostic and therapeutic tools based on this structure. Improvements concerning both the chelator and the bisphosphonate structure are illustrated providing new 68Ga- and 177Lu-labeled bisphosphonates offering improved pharmacological properties. Full article
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3094 KiB  
Review
Current Status of Radiopharmaceuticals for the Theranostics of Neuroendocrine Neoplasms
by Melpomeni Fani, Petra Kolenc Peitl and Irina Velikyan
Pharmaceuticals 2017, 10(1), 30; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10010030 - 15 Mar 2017
Cited by 42 | Viewed by 10749
Abstract
Abstract: Nuclear medicine plays a pivotal role in the management of patients affected by neuroendocrine neoplasms (NENs). Radiolabeled somatostatin receptor analogs are by far the most advanced radiopharmaceuticals for diagnosis and therapy (radiotheranostics) of NENs. Their clinical success emerged receptor-targeted radiolabeled peptides as [...] Read more.
Abstract: Nuclear medicine plays a pivotal role in the management of patients affected by neuroendocrine neoplasms (NENs). Radiolabeled somatostatin receptor analogs are by far the most advanced radiopharmaceuticals for diagnosis and therapy (radiotheranostics) of NENs. Their clinical success emerged receptor-targeted radiolabeled peptides as an important class of radiopharmaceuticals and it paved the way for the investigation of other radioligand-receptor systems. Besides the somatostatin receptors (sstr), other receptors have also been linked to NENs and quite a number of potential radiolabeled peptides have been derived from them. The Glucagon-Like Peptide-1 Receptor (GLP-1R) is highly expressed in benign insulinomas, the Cholecystokinin 2 (CCK2)/Gastrin receptor is expressed in different NENs, in particular medullary thyroid cancer, and the Glucose-dependent Insulinotropic Polypeptide (GIP) receptor was found to be expressed in gastrointestinal and bronchial NENs, where interestingly, it is present in most of the sstr-negative and GLP-1R-negative NENs. Also in the field of sstr targeting new discoveries brought into light an alternative approach with the use of radiolabeled somatostatin receptor antagonists, instead of the clinically used agonists. The purpose of this review is to present the current status and the most innovative strategies for the diagnosis and treatment (theranostics) of neuroendocrine neoplasms using a cadre of radiolabeled regulatory peptides targeting their receptors. Full article
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2885 KiB  
Review
188Re(V) Nitrido Radiopharmaceuticals for Radionuclide Therapy
by Alessandra Boschi, Petra Martini and Licia Uccelli
Pharmaceuticals 2017, 10(1), 12; https://0-doi-org.brum.beds.ac.uk/10.3390/ph10010012 - 19 Jan 2017
Cited by 19 | Viewed by 7185
Abstract
The favorable nuclear properties of rhenium-188 for therapeutic application are described, together with new methods for the preparation of high yield and stable 188Re radiopharmaceuticals characterized by the presence of the nitride rhenium core in their final chemical structure. 188Re is [...] Read more.
The favorable nuclear properties of rhenium-188 for therapeutic application are described, together with new methods for the preparation of high yield and stable 188Re radiopharmaceuticals characterized by the presence of the nitride rhenium core in their final chemical structure. 188Re is readily available from an 188W/188Re generator system and a parallelism between the general synthetic procedures applied for the preparation of nitride technetium-99m and rhenium-188 theranostics radiopharmaceuticals is reported. Although some differences between the chemical characteristics of the two metallic nitrido fragments are highlighted, it is apparent that the same general procedures developed for the labelling of biologically active molecules with technetium-99m can be applied to rhenium-188 with minor modification. The availability of these chemical strategies, that allow the obtainment, in very high yield and in physiological condition, of 188Re radiopharmaceuticals, gives a new attractive prospective to employ this radionuclide for therapeutic applications. Full article
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