A one-pot radiosynthesis of [18 F]PARPi.
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ABSTRACT:
SUBMITTER: Wilson TC
PROVIDER: S-EPMC7551923 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:[18F]PARPi is currently undergoing clinical trials as a PET tracer for many applications. However, only manual radiosynthesis was reported; this has several drawbacks, including an increased risk of contamination from the operator, and the need to limit the starting activity. The automation of the previously reported protocol for [18F]PARPi synthesis is challenging, as it requires transferring microvolumes of reagents, which many platforms cannot accommodate. We report a revised, high yield, and automated protocol for the radiosynthesis of [18F]PARPi, with final doses of over 20 GBq.
| S-EPMC9317788 | biostudies-literature
Project description:Arylboronates capture aqueous (18)F-fluoride in one step to afford a highly polar (18)F-labeled aryltrifluoroborate anion ((18)F-ArBF(3) (-)) that clears rapidly in vivo. To date however, there is little data to show that a ligand labeled with a prosthetic (18)F-ArBF(3) (-) will provide functional images. RGD, a high-affinity ligand for integrins that are present on the cell surface of numerous tumors, has been labeled in many formats with many different radionuclides, and as such represents a well-established ligand that can be used to evaluate new labeling methods. Herein we have labeled RGD with a prosthetic (18)F-ArBF(3) (-) via two approaches for the first time: 1) a RGD-boronate bioconjugate is directly labeled in one step and 2) an alkyne-modified arylborimidine is first converted to the corresponding (18)F-ArBF(3) (-) which is then conjugated to an RGD-azide via Cu(+)-mediated [2+3] dipolar cycloaddition in one pot over two steps. RGD-(18)F-ArBF(3) (-) bionconjugates were produced in reasonable radiochemical yields using low amounts of (18)F-fluoride anion (10-50 mCi). Despite relatively low specific activities, good tumor images are revealed in each case.
| S-EPMC3545361 | biostudies-literature
Project description:Background(S)-[18F]FETrp is a promising PET radiotracer for imaging IDO1 activity, one of the main enzymes involved in the tryptophan metabolism that plays a key role in several diseases including cancers. To date, the radiosynthesis of this tryptophan analogue remains highly challenging due to partial racemization occurring during the nucleophilic radiofluorination step. This work aims to develop a short, epimerization-free and efficient automated procedure of (S)-[18F]FETrp from a corresponding enantiopure tosylate precursor.ResultsEnantiomerically pure (S)- and (R)-FETrp references as well as tosylate precursors (S)- and (R)-3 were obtained from corresponding Na-Boc-(L and D)-tryptophan in 2 and 4 steps, respectively. Manual optimisation of the radiolabelling conditions resulted in > 90% radiochemical conversion with more than 99% enantiomeric purity. Based on these results, the (S)-[18F]FETrp radiosynthesis was fully automated on a SynChrom R&D EVOI module to produce the radiotracer in 55.2 ± 7.5% radiochemical yield, 99.9% radiochemical purity, 99.1 ± 0.5% enantiomeric excess, and molar activity of 53.2 ± 9.3 GBq/µmol (n = 3).ConclusionsTo avoid racemisation and complicated purification processes, currently encountered for the radiosynthesis of (S)-[18F]FETrp, we report herein significant improvements, including a versatile synthesis of enantiomerically pure tosylate precursor and reference compound and a convenient one-pot two-step automated procedure for the radiosynthesis of (S)-[18F]FETrp. This optimised and robust production method could facilitate further investigations of this relevant PET radiotracer for imaging IDO1 activity.
| S-EPMC10987429 | biostudies-literature
Project description:Availability of PET imaging radiotracers targeting α-synuclein aggregates is important for early diagnosis of Parkinson's disease and related α-synucleinopathies, as well as for the development of new therapeutics. Derived from a pyrazole backbone, 11C-labelled derivatives of anle138b (3-(1,3-benzodioxol-5-yl)-5-(3-bromophenyl)-1H-pyrazole)-an inhibitor of α-synuclein and prion protein oligomerization-are currently in active development as the candidates for PET imaging α-syn aggregates. This work outlines the synthesis of a radiotracer based on the original structure of anle138b, labelled with fluorine-18 isotope, eminently suitable for PET imaging due to half-life and decay energy characteristics (97% β+ decay, 109.7 min half-life, and 635 keV positron energy). A three-step radiosynthesis was developed starting from 6-[18F]fluoropiperonal (6-[18F]FP) that was prepared using (piperonyl)(phenyl)iodonium bromide as a labelling precursor. The obtained 6-[18F]FP was used directly in the condensation reaction with tosylhydrazide followed by 1,3-cycloaddition of the intermediate with 3'-bromophenylacetylene eliminating any midway without any intermediate purifications. This one-pot approach allowed the complete synthesis of [18F]anle138b within 105 min with RCY of 15 ± 3% (n = 3) and Am in the range of 32-78 GBq/µmol. The [18F]fluoride processing and synthesis were performed in a custom-built semi-automated module, but the method can be implemented in all the modern automated platforms. While there is definitely space for further optimization, the procedure developed is well suited for preclinical studies of this novel radiotracer in animal models and/or cell cultures.
| S-EPMC10052605 | biostudies-literature
Project description:BackgroundFormamides are common motifs of biologically-active compounds (e.g. formylated peptides) and are frequently employed as intermediates to yield a number of other functional groups. A rapid, simple and reliable route to [carbonyl-11C]formamides would enable access to this important class of compounds as in vivo PET imaging agents.ResultsA novel radiolabelling strategy for the synthesis of carbon-11 radiolabelled formamides ([11C]formamides) is presented. The reaction proceeded with the conversion of a primary amine to the corresponding [11C]isocyanate using cyclotron-produced [11C]CO2, a phosphazene base (2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine, BEMP) and phosphoryl chloride (POCl3). The [11C]isocyanate was subsequently reduced to [11C]formamide using sodium borohydride (NaBH4). [11C]Benzyl formamide was obtained with a radiochemical yield (RCY) of 80% in 15 min from end of cyclotron target bombardment and with an activity yield of 12%. This novel method was applied to the radiolabeling of aromatic and aliphatic formamides and the chemotactic amino acid [11C]formyl methionine (RCY = 48%).ConclusionsThis study demonstrates the feasibility of 11C-formylation of primary amines with the primary synthon [11C]CO2. The reactivity is proportional to the nucleophilicity of the precursor amine. This novel method can be used for the production of biomolecules containing a radiolabelled formyl group.
| S-EPMC7462944 | biostudies-literature
Project description:N-(2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)ethyl)-6-fluoronicotinamide ([(18)F]FNEM), a novel prosthetic agent that is thiol-specific, was synthesized using a one-pot two-step strategy: (1) (18)F incorporation by a nucleophilic displacement of trimethylammonium substrate under mild conditions; (2) amidation of the resulting 6-[(18)F]fluoronicotinic acid 2,3,5,6-tetrafluorophenyl ester with N-(2-aminoethyl)maleimide trifluoroacetate salt. The radiosynthesis of the maleimide tracer was completed in 75 min from [(18)F]fluoride with 26 ± 5% decay uncorrected radiochemical yield, and specific activity of 19-88 GBq/μmol (decay uncorrected). The in vitro cell uptake, in vivo biodistribution, and positron emission tomography (PET) imaging properties of its conjugation product with [Cys(40)]-exendin-4 were described. [(18)F]FNEM-Cys(40)-exendin-4 showed specific targeting of glucagon-like peptide 1 receptor (GLP-1R) positive insulinomas and comparable imaging results to our recently reported [(18)F]FPenM-Cys(40)-exendin-4.
| S-EPMC4224565 | biostudies-other
Project description:[18 F]NS12137 (exo-3-[(6-[18 F]fluoro-2-pyridyl)oxy]8-azabicyclo[3.2.1]octane) is a highly selective norepinephrine transporter (NET) tracer. NETs are responsible for the reuptake of norepinephrine and dopamine and are linked to several neurodegenerative and neuropsychiatric disorders. The aim of this study was to develop a copper-mediated 18 F-fluorination method for the production of [18 F]NS12137 with straightforward synthesis conditions and high radiochemical yield and molar activity. [18 F]NS12137 was produced in two steps. Radiofluorination of [18 F]NS12137 was performed via a copper-mediated pathway starting with a stannane precursor and using [18 F]F- as the source of the fluorine-18 isotope. Deprotection was performed via acid hydrolysis. The radiofluorination reaction was nearly quantitative as was the deprotection based on HPLC analysis. The radiochemical yield of the synthesis was 15.1 ± 0.5%. Molar activity of [18 F]NS12137 was up to 300 GBq/μmol. The synthesis procedure is straightforward and can easily be automated and adapted for clinical production.
| S-EPMC6619244 | biostudies-literature
Project description:BackgroundHuman papillomavirus- (HPV-) associated oropharyngeal squamous cell carcinomas (OPSCCs) are clinically and pathologically distinct from HPV-negative tumors. Here, we explore whether HPV affects functional biomarkers, including γH2AX, RAD51, and PARP1. Moreover, the role of [18F]PARPi as a broadly applicable imaging tool for head and neck carcinomas is investigated.MethodsHPV-positive and HPV-negative cell lines were used to evaluate the γH2AX, RAD51, and PARP1 expression with immunoblotting and immunofluorescence. Effects of external beam ionizing radiation were investigated in vitro, and survival was investigated via colony-formation assay. [18F]PARPi uptake experiments were performed on HPV-negative and HPV-positive cell lines to quantify PARP1 expression. PARP1 IHC and γH2AX foci were quantified using patient-derived oropharyngeal tumor specimens.ResultsDifferences in DNA repair were detected, showing higher RAD51 and γH2AX expression in HPV-positive cell lines. Clonogenic assays confirm HPV-positive cell lines to be significantly more radiosensitive. PARP1 expression levels were similar, irrespective of HPV status. Consequently, [18F]PARPi uptake assays demonstrated that this tracer is internalized in cell lines independently from their HPV status.ConclusionThe HPV status, often used clinically to stratify patients, did not affect PARP1 levels, suggesting that PARP imaging can be performed in both HPV-positive and HPV-negative patients. This study confirms that the PET imaging agent [18F]PARPi could serve as a general clinical tool for oropharyngeal cancer patients.
| S-EPMC8205605 | biostudies-literature
Project description:Fluorine-18 labeled N-(4-chloro-3-(((fluoro-18F)methyl-d2)thio)phenyl)picolinamide, [18F]mG4P027, is a potent positron emission tomography (PET) radiotracer for metabotropic glutamate receptor 4 (mGluR4). Our previous in vitro and in vivo evaluations have demonstrated that this tracer is promising for further translational studies. To automate the radiosynthesis of [18F]mG4P027, significant modifications were made to the manual process by carefully examining this process and addressing the root causes of the challenges associated with its automation. We successfully implemented its automated radiosynthesis using the TRACERlab FX2N module and consequently, obtained a high-purity radiolabeled [18F]mG4P027 in high yield, meeting the requirements for future human studies.
| S-EPMC10371389 | biostudies-literature
Project description:Induction of apoptosis is often necessary for successful cancer therapy, and the non-invasive monitoring of apoptosis post-therapy could assist in clinical decision making. Isatins are a class of compounds that target activated caspase-3 during apoptosis. Here we report the synthesis of the 5-iodo-1,2,3-triazole (FITI) analog of the PET tracer [18F]ICMT11 as a candidate tracer for imaging of apoptosis with SPECT, as well as PET. Labelling with radioiodine (123,125I) was achieved in 55?±?12% radiochemical yield through a chelator-accelerated one-pot cycloaddition reaction mediated by copper(I) catalysis. The caspase-3 binding affinity and selectivity of FITI compares favourably to that of [18F]ICMT11 (Ki = 6.1?±?0.9?nM and 12.4?±?4.7?nM, respectively). In biodistribution studies, etoposide-induced cell death in a SW1222 xenograft model resulted in a 2-fold increase in tumour uptake of the tracer. However, the tumour uptake was too low to allow in vivo imaging of apoptosis with SPECT.
| S-EPMC6917698 | biostudies-literature