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.
CCK2R antagonists: from SAR to clinical trials Novak, Doroteja; Anderluh, Marko; Kolenc Peitl, Petra
Drug discovery today,
August 2020, 2020-08-00, 20200801, Letnik:
25, Številka:
8
Journal Article
Recenzirano
•The CCK2 receptor is involved in numerous (patho)physiological processes.•Many CCK2 receptor antagonists have shown promising results in in-vivo animal models.•High attrition rates are seen in ...clinical settings due to off-target effects.•Netazepide (YF476) and nastorazepide (Z-360) are in Phase II clinical trials.•Nastorazepide (Z-360) serves as a lead compound for development of imaging agents.
The widespread involvement of the cholecystokinin-2/gastrin receptor (CCK2R) in multiple (patho)physiological processes has propelled extensive searches for nonpeptide small-molecule CCK2R antagonists. For the past three decades, considerable research has yielded numerous chemically heterogeneous compounds. None of these entered into the clinic, mainly because of inadequate biological effects. However, it appears that the ultimate goal of a clinically useful CCK2R antagonist is now just around the corner, with the most promising compounds, netazepide and nastorazepide, now in Phase II clinical trials. Here, we illustrate the structure–activity relationships (SARs) of stablished CCK2R antagonists of various structural classes, and the most recent proof-of-concept studies where new applicabilities of CCK2R antagonists as visualizing agents are presented.
The quest for the first clinically useful CCK2R antagonist: is it a never-ending story, or are we on the verge of a breakthrough?
The cholecystokinin‐2/gastrin receptor (CCK2R) is considered a suitable target for the development of radiolabelled antagonists, due to its overexpression in various tumours, but no such compounds ...are available in clinical use. Therefore, we designed novel 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid‐conjugated ligands based on CCK2R antagonist Z360/nastorazepide. As a proof of concept that CCK2R antagonistic activity can be retained by extending the Z360/nastorazepide structure using suitable linker, we present herein three compounds containing various PEG linkers synthesised on solid phase and in solution. The antagonistic properties were measured in a functional assay in the A431‐CCK2R cell line (in the presence of agonist G17), with IC50 values of 3.31, 4.11 and 10.4 nM for compounds containing PEG4, PEG6 and PEG12, respectively. All compounds were successfully radiolabelled with indium‐111, lutetium‐177 and gallium‐68 (incorporation of radiometal >95 %). The gallium‐68‐labelled compounds were stable for up to 2 h (PBS, 37 °C). log D7.4 values were determined for indium‐111‐ and gallium‐68‐labelled compounds, showing improved hydrophilicity compared to the reference compound.
The overexpression of CCK2R in several tumours makes it a target of interest for the development of radiolabelled ligands. We have successfully radiolabelled a series of PEG‐containing CCK2R antagonists with either radiodiagnostic or therapeutic radionuclides. The favourable hydrophilicity, stability and retained antagonistic properties hold promise for potential progress into in vivo studies for this type of compound.
Purpose
Insulinomas are the most common functioning neuroendocrine neoplasms of the pancreas, typically diagnosed due to characteristic symptoms. In the vast majority, the treatment is surgical and ...curative, requiring accurate localization of the tumour; conventional imaging, including somatostatin receptor molecular imaging, is negative in up to 10 % of cases. Recently, labelled glucagon-like peptide receptor (GLP-1R) analogues were introduced as a sensitive diagnostic method for localization of insulinomas. The aim of this study was to assess the diagnostic accuracy of a Tc-99m-labelled GLP-1R agonist Lys
40
(AhxHYNIC-
99m
TcEDDA)NH
2
-exendin-4 for localization of occult insulinoma.
Procedures
Eight patients (all females; age range 35–75 years) with biochemically proven insulinoma and with negative or inconclusive conventional imaging (consisting of somatostatin receptor scintigraphy, computed tomography, endoscopic ultrasound and magnetic resonance imaging) were enrolled. Whole-body single-photon emission tomography/computed tomography (SPECT/CT) imaging was performed 4 h post-injection of 740 MBq of Lys
40
(AhxHYNIC-
99m
TcEDDA)NH
2
-exendin-4. Surgical treatment was performed based on imaging findings. Histology of the removed lesions and biochemical and clinical symptom resolution was considered as the gold standard for analysis of the imaging results.
Results
Focal uptake of Lys
40
(AhxHYNIC-
99m
TcEDDA)NH
2
-exendin-4 was found in all patients, leading to successful removal of the offending lesion and complete biochemical and symptomatic resolution. Histological analysis confirmed insulinoma in all included patients.
Conclusions
Lys
40
(AhxHYNIC-
99m
TcEDDA)NH
2
-exendin-4 SPECT/CT appears to be an excellent molecular imaging method for preoperative localization of an occult insulinoma, surpassing conventional imaging methods. If routinely available, it could be considered as a method of choice due to its favorable combination of imaging characteristics.
This guideline on current good radiopharmacy practice (cGRPP) for small-scale preparation of radiopharmaceuticals represents the view of the Radiopharmacy Committee of the European Association of ...Nuclear Medicine (EANM). The guideline is laid out in the format of the EU Good Manufacturing Practice (GMP) guidelines as defined in EudraLex volume 4. It is intended for non-commercial sites such as hospital radiopharmacies, nuclear medicine departments, research PET centres and in general any healthcare establishments. In the first section, general aspects which are applicable to all levels of operations are discussed. The second section discusses the preparation of small-scale radiopharmaceuticals (SSRP) using licensed generators and kits. Finally, the third section goes into the more complex preparation of SSRP from non-licensed starting materials, often requiring a purification step and sterile filtration. The intention is that the guideline will assist radiopharmacies in the preparation of diagnostic and therapeutic SSRP’s safe for human administration.
Background
To fulfil good manufacturing requirements, analytical methods for the analysis of pharmaceuticals for human and vetinary use must be validated. The International Conference on ...Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) has published guidance documents on the requirements for such validation activities and these have been adopted by the European Medicines Agency, The U.S. Food and Drug Administration (FDA) and other regulatory bodies. These guidance documents do not, however, fully address all the specific tests required for the analysis of radiopharmaceuticals. This guideline attempts to rectify this shortcoming, by recommending approaches to validate such methods.
Results
Recommedations for the validation of analytical methods which are specific for radiopharmaceutials are presented in this guideline, along with two practical examples.
Conclusions
In order to comply with good manufacturing practice, analytical methods for radiopharmaceuticals for human use should be validated.
With the development of ever more radiopharmaceuticals suitable for theranostic applications, translation of novel compounds from the preclinical stage towards clinical application becomes a ...bottleneck for the advances in Nuclear Medicine. This review article summarizes the current regulatory framework for clinical trials with radiopharmaceuticals in the European Union, provides a general overview of the documentation required, and addresses quality, safety, and clinical aspects to be considered. By using a recent successful example of translating a theranostic peptide radioligand, namely 111In‐CP04, which targets receptors expressed in medullary thyroid carcinoma, the pathway from the preclinical development over establishing the required pharmaceutical documentation to designing and submitting a clinical trial is reviewed. Details regarding preclinical data, generation of the documentation, and final successful application are described. This article should provide an insight in an ever more complex process to bring innovations in the field of radiopharmaceuticals into patients.
With the development of ever more radiopharmaceuticals suitable for theranostic use, translation of novel compounds from the preclinical stage towards clinical application becomes a bottleneck for the advances in Nuclear Medicine. This review article summarizes the current regulatory framework for clinical trials with radiopharmaceuticals in the EU and provides insight in a more and more complex process to bring innovations in the field of radiopharmaceuticals into patients.
Abstract Background We investigated the effects of intracoronary transplantation of CD34+ cells on myocardial perfusion in patients with nonischemic dilated cardiomyopathy (DCM). Methods and Results ...We enrolled 21 patients with DCM (left ventricular ejection fraction LVEF <40%, New York Heart Association functional class III) who underwent peripheral stem cell mobilization with granulocyte-colony stimulating factor (G-CSF). CD34+ cells were collected by means of apheresis. Patients underwent myocardial perfusion imaging, and CD34+ cells were injected in the coronary artery supplying viable segments with reduced myocardial perfusion and regional dysfunction. Myocardial perfusion imaging was repeated 6 months later. Clinical response to stem cell therapy was predefined as a change in LVEF >5%. The majority of patients were men (81%) with an overall mean age 53 ± 9 years, LVEF 25 ± 5%, and 6-minute walking distance 354 ± 71 m. Myocardial perfusion defects at rest were observed in 86% of patients and were more common in the left anterior descending territory (50%). At 6 months' follow-up, there was a significant improvement in rest myocardial perfusion scores (6.3 ± 5.8 vs 3.1 ± 4.3; P < .001), LVEF (25 ± 7% vs 29 ± 8%; P = .005), and 6-minute walking distance (354 ± 71 m vs 404 ± 91 m; P < .001). Responders to stem cell therapy had lower summed rest perfusion score at both baseline (3.2 ± 3.0 vs 9.1 ± 6.3; P = .015) and follow-up (1.0 ± 1.5 vs 5.0 ± 5.1; P = .028). Conclusions CD34+ cell transplantation may lead to improved myocardial perfusion in patients with nonischemic DCM. Patients with less severe myocardial perfusion defects at baseline may have an increased likelihood to respond to intracoronary CD34+ cell transplantation.
A variety of radiolabelled minigastrin analogues targeting the cholecystokinin 2 (CCK2) receptor were developed and compared in a concerted preclinical testing to select the most promising ...radiotracer for diagnosis and treatment of medullary thyroid carcinoma (MTC). DOTA–DGlu–DGlu–DGlu–DGlu–DGlu–DGlu–Ala–Tyr–Gly–Trp–Met–Asp–Phe–NH2 (CP04) after labelling with 111In displayed excellent characteristics, such as high stability, receptor affinity, specific and persistent tumour uptake and low kidney retention in animal models. Therefore, it was selected for further clinical evaluation within the ERA-NET project GRAN-T-MTC. Here we report on the development of a pharmaceutical freeze-dried formulation of the precursor CP04 for a first multi-centre clinical trial with 111In-CP04 in MTC patients.
The kit formulation was optimised by adjustment of buffer, additives and radiolabelling conditions. Three clinical grade batches of a final kit formulation with two different amounts of peptide (10 or 50μg) were prepared and radiolabelled with 111In. Quality control and stability assays of both the kits and the resulting radiolabelled compound were performed by HPLC analysis.
Use of ascorbic acid buffer (pH4.5) allowed freeze-drying of the kit formulation with satisfactory pellet-formation. Addition of methionine and gentisic acid as well as careful selection of radiolabelling temperature was required to avoid extensive oxidation of the Met11-residue. Trace metal contamination, in particular Zn, was found to be a major challenge during the pharmaceutical filling process in particular for the 10μg formulation. The final formulations contained 10 or 50μg CP04, 25mg ascorbic acid, 0.5mg gentisic acid and 5mg l-methionine. The radiolabelling performed by incubation of 200–250MBq 111InCl3 at 90°C for 15min resulted in reproducible radiochemical purity (RCP) >94%. Kit-stability was proven for >6months at +5°C and at +25°C. The radiolabelled product was stable for >4h at +25°C.
A kit formulation to prepare 111In-CP04 for clinical application was developed, showing high stability of the kit as well as high RCP of the final product.
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