Article towards facile radiolabeling and preparation of gallium-68-/bismuth-213-dota-[thi8, met(O2)11]-substance p for future clinical application : first experiences

Please read abstract in the article.The Nuclear Technologies in Medicine and the Biosciences Initiative (NTeMBI) and the Technology Innovation Agency (TIA).http://www.mdpi.com/journal/pharmaceuticspm2022Nuclear Medicin

A decade of ubiquicidin development for PET imaging of infection : a systematic review

BACKGROUND : Ubiquicidin is a peptide fragment with selective binding to negatively charged bacterial cell membranes. Besides its earlier labelling with gamma emitting radionuclides, it has been labelled with Positron Emission Tomography (PET) radionuclides in the last decade for imaging infection and distinguishing infectious disease from sterile inflammation. This systematic review aims to evaluate the technology readiness level of PET based ubiquicidin radiopharmaceuticals. METHODS : Two independent researchers reviewed all articles and abstracts pertaining ubiquicidin and PET imaging that are currently available. Scopus, Google Scholar and PubMed/Medline were used in the search. Upon completion of the literature search all articles and abstracts were evaluated and duplicates were excluded. All non-PET articles as well as review articles without new data were deemed ineligible. RESULTS : From a total of 17 papers and 10 abstracts the studies were grouped into development, preclinical and clinical studies. Development was published in 15/17 (88%) publications and 6/10 (60%) abstracts, preclinical applications in 9/17 (53%) publications and 1/10 (10%) of abstracts. Finally, clinical studies made up 6/17 (35%) of full publications and 4/10 (40%) of the available abstracts. Development results were the most abundant. All the findings in the different areas of development of ubiquicidin as PET radiopharmaceutical are summarized in this paper. CONCLUSION : Labelling procedures are generally uncomplicated and relatively fast and there are indications of adequate product stability. The production of PET radiopharmaceuticals based on UBI will therefore not be a barrier for clinical introduction of this technology. Systematization and unification of criteria for preclinical imaging and larger clinical trials are needed to ensure the translation of this radiopharmaceutical into the clinic. Therefore a conclusion with regards to the clinical relevance of ubiquicidin based PET is not yet possible.https://www.elsevier.com/locate/nucmedbiohj2024ChemistryNuclear MedicineNon

Peptide synthesis, characterization and 68Ga-radiolabeling of NOTA-conjugated ubiquicidin fragments for prospective infection imaging with PET/CT

INTRODUCTION: Human antimicrobial peptides are of interest for the development of positron emission tomography (PET) tracers as they exhibit desirable characteristics that make them good candidates for targeting vectors. Due to their natural role in the innate immune system they selectively bind to pathogenic bacteria and yeast, whilst remaining minimally immunogenic and cytotoxic to humans. Research into ubiquicidin (UBI)-based tracers has focused on 99mTc as a radionuclide, however, the use of bi-functional chelators such as 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), in combination with 68Ga as a radionuclide, allows for a simple radiolabeling procedure which is preferable in a clinical setting using PET/CT. METHODS: The peptides fragments UBI29-41, UBI30-41 were synthesized by standard microwave Fmoc/tert-butyl (tBu)-solid phase synthetic protocols. Characterizations were performed using analytical HPLC and LC/MS. Both NOTA-conjugated peptides were exposed to natGa3 +; their complexed form was quantified by direct LC/MS injection. This complexation was utilized to testify bacterial and mammalian cell binding potential of fluorophore-linked NOTA-UBI29-41/30-41. 68Ga labeled NOTA-UBI fragments were also tested for competitive interaction to Staphylococcus aureus to proof the binding target. 68Ga was eluted from SnO2- and TiO2-based 68Ge/68Ga generators using fractionated elution and anion exchanged-based post-procession. NOTA-peptide radiolabeling was carried out including optimization of buffer molarity, NOTA-peptide concentration(s), incubation temperature and –duration as well as considering various SPE purification cartridges. RESULTS: Pure UBI29-41, UBI30-41 and NOTA-UBI30-41 were successfully characterized. Both, NOTA-UBI fragments exhibited complexation rates to natGa3 + ≥ 99%. The percentage binding was significantly higher to Staphylococcus aureus bacilli over Mt4 human leucocytes (P > 0.05) for NOTA-UBI29-41[Lys(Abz)] 0.03) after pre-incubation with excess unlabeled NOTA-UBI. Reproducible 68Ga radiolabeling ranged for 51–85% and 46–78% for NOTA-UBI29-41 and NOTA-UBI30-41, respectively. CONCLUSION: Aside from successful peptide syntheses the first ever 68Ga-radiolabeling method is reported for NOTA-UBI fragments. The NOTA-conjugation didn’t compromise the selective and specific interaction with bacterial cells in vitro. Both tracers are warranting prospective imaging of infection with PET/CT.National Research Foundation (NRF), the University of KwaZulu Natal (UKZN) and The Nuclear Technologies in Medicine and the Biosciences Initiative (NTeMBI)http://www.elsevier.com/locate/nucmedbiohb201

Evaluation of a flexible NOTA-RGD kit solution using Gallium-68 from different ⁶⁸Ge/⁶⁸Ga-generators : pharmacokinetics and biodistribution in nonhuman primates and demonstration of solitary pulmonary nodule imaging in humans

PURPOSE : Radiopharmaceuticals containing the motive tripeptide arginyl-glycyl-asparatic acid (RGD) are known to target ανβ3 integrins during tumor angiogenesis. A more generic kit radiolabeling procedure accommodating Ga-68 from different generators was developed for NOTA-RGD and evaluated for its versatile use and safety in subsequent in vivo applications. The [⁶⁸Ga]NOTA-RGD kit was further verified for its expected biodistribution and pharmacokinetics in nonhuman primates and its clinical sensitivity to detect solitary pulmonary nodules (SPN) in cancer patients. PROCEDURES : Single vial kits containing 28–56 nmol of NOTA-cyclo-Arg-Gly-Asp-d-Tyr-Lys (NOTA-RGD) and sodium acetate trihydrate buffer were formulated. Versatility of the NOTARGD radiolabeling performance and adaption to a TiO2- and a SnO2-based generator type, characterization and long-term storage stability of the kits were carried out. The blood clearance and urine recovery kinetics as well as the image-guided biodistribution of [⁶⁸Ga]NOTA-RGD was studied in a vervet monkey model. [⁶⁸Ga]NOTA-RGD kits were further tested clinically to target solitary pulmonary nodules. RESULTS : The kits could be successfully formulated warranting integrity over 3–4 months with a good [⁶⁸Ga]NOTA-RGD radiolabeling performance (radiochemical purity 995 %, decay corrected yield 76–94 %, specific activity of 8.8–37.9 GBq/μmol) The kits met all quality requirements to be further tested in vivo. [⁶⁸Ga]NOTA-RGD cleared rapidly from blood and was majorly excreted via the renal route. The liver, spleen, heart and intestines showed initial uptake with steadily declining tissue activity concentration over time. In addition, the [⁶⁸Ga]NOTA-RGD kit allowed for delineation of SPN from non-malignant lung tissue in humans. CONCLUSIONS : A more versatile radiolabeling procedure using kit-formulated NOTA-RGD and different generator types was achieved. The uncompromised in vivo behavior and efficient targeting of SPN warrants further investigations on the clinical relevance of [⁶⁸Ga]NOTA-RGD derivatives to implement initial guidelines and management of patients, with regard to integrin targeted imaging.Nuclear Technologies in Medicine and the Biosciences Initiative (NTeMBIhttps://link.springer.com/journal/113072018-06-30Nuclear Medicin

Synthesis, in vitro evaluation, and 68Ga-radiolabeling of CDP1 toward PET/CT imaging of bacterial infection

Bacterial infections are a major concern in the human health sector due to poor diagnosis and development of multidrug-resistant strains. PET/CT provides a means for the non-invasive detection and localization of the infectious foci; however, the radiotracers available are either cumbersome to prepare or their exact contribution toward the imaging is not yet established. Human antimicrobial peptides are of interest for development as PET radiotracers as they are an integral component of the immune system, non-immunogenic toward the recipient, and show selectivity toward pathogens such as bacteria. Herein we report on the potential of LL37, a human cathelicidin antimicrobial peptide, as a radiotracer for bacterial imaging. Bifunctional chelator 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid was utilized to functionalize the antimicrobial peptide, which in turn was capable of chelating gallium. The synthesized natGa-CDP1 showed bacterial selectivity and low affinity toward hepatic cells, which are favorable characteristics for further preclinical application.The Department of Science and Technology, University of KwaZulu Natal, National Research Foundation and Aspen Pharmacare.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1747-0285http://wileyonlinelibrary.com/journal/cbdd2018-10-30hj2018Nuclear Medicin

Production of high specific activity 195mPt‐cisplatinum at South African Nuclear Energy Corporation for Phase 0 clinical trials in healthy individual subjects

Platinum agents continue to be the main chemotherapeutic agents used in the first-line and second-line treatments of cancer patients. It is important to fully understand the biological profile of these compounds in order to optimize the dose given to each patient. In a joint project with the Australian Nuclear Science and Technology Organisation and the Nuclear Medicine Department at Steve Biko Academic Hospital, South African Nuclear Energy Corporation synthesized and supplied 195mPt-cisplatinum (commonly referred to as cisplatin) for a clinical pilot study on healthy volunteers. Enriched 194PtCl2 was prepared by digestion of enriched 194Pt metal (>95%) followed by thermal decomposition over a 3 h period. The 194PtCl2 was then placed in a quartz ampoule, was irradiated in SAFARI-1 up to 200 h, then decay cooled for a minimum of 34 h prior to synthesis of final product. 195mPt(NH3)2I2, formed with the addition of KI and NH4OH, was converted to the diaqua species [195mPt(NH3)2(H2O)2]2+ by reaction with AgNO3. The conversion to 195mPt-cisplatinum was completed by the addition of concentrated HCl. The final product yield was 51.7%± 5.2% (n = 5). The chemical and radionuclidic purity in each case was >95%. The use of a high flux reactor position affords a higher specific activity product (15.9±2.5MBq/mg at end of synthesis) than previously found (5MBq/mg). Volunteers received between 108 and 126MBq of radioactivity, which is equivalent to 6.8–10.0mg of carrier cisplatinum. Such high specific activities afforded a significant reduction (~50%) in the chemical dose of a carrier cisplatinum, which represents less than 10%of a typical chemotherapeutic dose given to patients. A goodmanufacturing practice GMP compliant product was produced and was administered to 10 healthy volunteers as part of an ethically approved Phase 0 clinical trial. The majority of the injected activity 27.5%± 5.8% was excreted in the urine within 5 h post injection (p.i.). Only 8.5%± 3.1% of cisplatinumremained in blood pools at 5 h,which gradually cleared over the 6-daymonitoring period p.i. At the end of the study (6 days p.i.), a total of 37.4%± 5.3% of the product had cleared from the blood into urine, and approximately 63% remained in the body. The significantly lower concentration of carrier cisplatinum used for imaging resulted in a well-tolerated product

Development of a single vial kit solution for radiolabeling of 68Ga-DKFZ-PSMA-11 and its performance in prostate cancer patients

Prostate-specific membrane antigen (PSMA), a type II glycoprotein, is highly expressed in almost all prostate cancers. By playing such a universal role in the disease, PSMA provides a target for diagnostic imaging of prostate cancer using positron emission tomography/computed tomography (PET/CT). The PSMA-targeting ligand Glu-NH-CO-NH-Lys-(Ahx)-HBED-CC (DKFZ-PSMA-11) has superior imaging properties and allows for highly-specific complexation of the generator-based radioisotope Gallium-68 (68Ga). However, only module-based radiolabeling procedures are currently available. This study intended to develop a single vial kit solution to radiolabel buffered DKFZ-PSMA-11 with 68Ga. A 68Ge/68Ga-generator was utilized to yield 68GaCl3 and major aspects of the kit development were assessed, such as radiolabeling performance, quality assurance, and stability. The final product was injected into patients with prostate cancer for PET/CT imaging and the kit performance was evaluated on the basis of the expected biodistribution, lesion detection, and dose optimization. Kits containing 5 nmol DKFZ-PSMA-11 showed rapid, quantitative 68Ga-complexation and all quality measurements met the release criteria for human application. The increased precursor content did not compromise the ability of 68Ga-DKFZ-PSMA-11 PET/CT to detect primary prostate cancer and its advanced lymphatic- and metastatic lesions. The 68Ga-DKFZ-PSMA-11 kit is a robust, ready-to-use diagnostic agent in prostate cancer with high diagnostic performance

Towards Facile Radiolabeling and Preparation of Gallium-68-/Bismuth-213-DOTA-[Thi8, Met(O2)11]-Substance P for Future Clinical Application: First Experiences

Substance P (SP) is a small peptide commonly known as a preferential endogenous ligand for the transmembrane neurokinin-1 receptor. Nuclear Medicine procedures currently involve radiolabeled SP derivatives in peptide radioligand endotherapy of inoperable glioblastoma. Promising clinical results sparked the demand for facile production strategies for a functionalized 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-[Thi8, Met(O2)11]-SP to allow for rapid Gallium-68 or Bismuth-213 complexation. Therefore, we provide a simple kit-like radiotracer preparation method that caters for the gallium-68 activity eluted from a SnO2 generator matrix as well as preliminary results on the adaptability to produce [213Bi]Bi-DOTA-[Thi8, Met(O2)11]SP from the same vials containing the same starting material. Following a phase of radioanalysis for complexation of gallium-68 to DOTA-[Thi8, Met(O2)11]SP and assessing the radiolabeling parameters, the vials containing appropriate kit-prototype material were produced in freeze-dried batches. The facile radiolabeling performance was tested and parameters for future human application were calculated to meet the criteria for theranostic loco-regional co-administration of activity doses comprising [68Ga]Ga-DOTA-[Thi8, Met(O2)11]SP mixed with [213Bi]Bi-DOTA-[Thi8, Met(O2)11]SP. [68Ga]Ga-DOTA-[Thi8, Met(O2)11]SP was prepared quantitatively from lyophilized starting material within 25 min providing the required molar activity (18 ± 4 GBq/µmol) and activity concentration (98 ± 24 MBq/mL), radiochemical purity (>95%) and sustained radiolabeling performance (4 months at >95% LE) as well as acceptable product quality (>95% for 120 min). Additionally, vials of the same starting materials were successfully adapted to a labeling strategy available for preparation of [213Bi]Bi-DOTA-[Thi8, Met(O2)11]SP providing sufficient activity for 1–2 human doses. The resultant formulation of [68Ga]Ga-/[213Bi]Bi-DOTA-[Thi8, Met(O2)11]SP activity doses was considered of adequate radiochemical quality for administration. This investigation proposes a simple kit-like formulation of DOTA-[Thi8, Met(O2)11]SP—a first-line investigation into a user friendly, straightforward tracer preparation that would warrant efficient clinical investigations in the future. Quantitative radiolabeling was accomplished for [68Ga]Ga-DOTA-[Thi8, Met(O2)11]SP and [213Bi]Bi-DOTA-[Thi8, Met(O2)11]SP preparations; a key requirement when addressing the specific route of catheter-assisted co-injection directly into the intratumoral cavities