Brain pretargeted nuclear imaging for the diagnosis of various neurodegenerative diseases is a quickly developing field. The tetrazine ligation is currently the most explored approach to achieve... Show moreBrain pretargeted nuclear imaging for the diagnosis of various neurodegenerative diseases is a quickly developing field. The tetrazine ligation is currently the most explored approach to achieve this goal due to its remarkable properties. In this work, we evaluated the performance of F-537-Tetrazine, previously developed by Biogen, and N-(3-[18F]fluoro-5-(1,2,4,5-tetrazin-3-yl)benzyl)propan-1-amine, previously developed in our group, thereby allowing for the direct comparison of these two imaging probes. The evaluation included synthesis, radiolabeling and a comparison of the physicochemical properties of the compounds. Furthermore, their performance was evaluated by in vitro and in vivo pretargeting models. This study indicated that N-(3-[18F] fluoro-5-(1,2,4,5-tetrazin-3-yl)benzyl)propan-1-amine might be more suited for brain pretargeted imaging. Show less
Rotteveel, L.; Kurakula, K.; Kooijman, E.J.M.; Schuit, R.C.; Verlaan, M.; Schreurs, M.; ... ; Windhorst, A.D. 2022
The transforming growth factor beta (TGF beta) pathway plays a complex role in cancer biology, being involved in both tumour suppression as well as promotion. Overactive TGF beta signalling has... Show moreThe transforming growth factor beta (TGF beta) pathway plays a complex role in cancer biology, being involved in both tumour suppression as well as promotion. Overactive TGF beta signalling has been linked to multiple diseases, including cancer, pulmonary arterial hypertension, and fibrosis. One of the key meditators within this pathway is the TGF beta type I receptor, also termed activin receptor-like kinase 5 (ALK5). ALK5 expression level is a key determinant of TGF beta signalling intensity and duration, and perturbation has been linked to diseases. A validated ALK5 positron emission tomography (PET) tracer creates an opportunity, therefore, to study its role in human diseases. To develop ALK5 PET tracers, two small molecule ALK5 kinase inhibitors were selected as lead compounds, which were labelled with carbon-11 and fluorine-18, respectively. [C-11]LR111 was synthesized with a yield of 17 +/- 6%, a molar activity of 126 +/- 79 GBq. mol(-1) and a purity of > 95% (n = 44). [18F]EW-7197 was synthesized with a yield of 10 +/- 5%, a molar activity of 183 & PLUSMN; 126 GBq. mol(-1) and a purity of > 95% (n = 11). Metabolic stability was evaluated in vivo in mice, showing 39 +/- 2% of intact [11C]LR111 and 21 +/- 2% of intact [F-18]EW-7197 in blood plasma at 45 min p.i. In vitro binding experiments were conducted in breast cancer MDAMB-231 and lung cancer A431 cell lines. In addition, both tracers were used for PET imaging in MDA-MB-231 xenograft models. Selective uptake of [F-18]EW-7197 and [C-11]LR111 was observed in MDA-MB-231 cells, in the MDA-MB-231 tumour xenografts in vivo and in the autoradiograms. As [C-11]LR111 and [F-18]EW-7197 showed selectivity of binding to ALK5 in vivo and in vitro. Both tracers are thereby valuable tools for the detection of ALK5 activity. Show less
INTRODUCTION\nMETHODS\nRESULTS\nCONCLUSION\nRadiotherapy of cancer requires both alpha- and beta-particle emitting radionuclides, as these radionuclide types are efficient at destroying different... Show moreINTRODUCTION\nMETHODS\nRESULTS\nCONCLUSION\nRadiotherapy of cancer requires both alpha- and beta-particle emitting radionuclides, as these radionuclide types are efficient at destroying different types of tumors. Both classes of radionuclides require a vehicle, such as an antibody or a polymer, to be delivered and retained within the tumor. Polyglutamic acid (pGlu) is a polymer that has proven itself effective as a basis of drug-polymer conjugates in the clinic, while its derivatives have been used for pretargeted tumor imaging in a research setup. trans-Cyclooctene (TCO) modified pGlu is suitable for pretargeted imaging or therapy, as well as for intratumoral radionuclide therapy. In all cases, it becomes indirectly radiolabeled via the bioorthogonal click reaction with the tetrazine (Tz) molecule carrying the radionuclide. In this study, we report the radiolabeling of TCO-modified pGlu with either lutetium-177 (177Lu), a beta-particle emitter, or actinium-225 (225Ac), an alpha-particle emitter, using the click reaction between TCO and Tz.\nA panel of Tz derivatives containing a metal ion binding chelator (DOTA or macropa) connected to the Tz moiety directly or through a polyethylene glycol (PEG) linker was synthesized and tested for their ability to chelate 177Lu and 225Ac, and click to pGlu-TCO. Radiolabeled 177Lu-pGlu and 225Ac-pGlu were isolated by size exclusion chromatography. The retention of 177Lu or 225Ac by the obtained conjugates was investigated in vitro in human serum.\nAll DOTA-modified Tzs efficiently chelated 177Lu resulting in average radiochemical conversions (RCC) of >75%. Isolated radiochemical yields (RCY) for 177Lu-pGlu prepared from 177Lu-Tzs ranged from 31% to 55%. TLC analyses detected <5% unchelated 177Lu for all 177Lu-pGlu preparations over six days in human serum. For 225Ac chelation, optimized RCCs ranged from 61 ± 34% to quantitative for DOTA-Tzs and were quantitative for the macropa-modified Tz (>98%). Isolated radiochemical yields (RCY) for 225Ac-pGlu prepared from 225Ac-Tzs ranged from 28% to 51%. For 3 out of 5 225Ac-pGlu conjugates prepared from DOTA-Tzs, the amount of unchelated 225Ac stayed below 10% over six days in human serum, while 225Ac-pGlu prepared from macropa-Tz showed a steady release of up to 37% 225Ac.\nWe labeled TCO-modified pGlu polymers with alpha- and beta-emitting radionuclides in acceptable RCYs. All 177Lu-pGlu preparations and some 225Ac-pGlu preparations showed excellent stability in human plasma. Our work shows the potential of pGlu as a vehicle for alpha- and beta-radiotherapy of tumors and demonstrated the usefulness of Tz ligation for indirect radiolabeling. Show less
Rotman, M.; Welling, M.M.; Boogaard, M.L. van den; Moursel, L.G.; Graaf, L.M. van der; Buchem, M.A. van; ... ; Weerd, L. van der 2015
The tumor-associated structure N-acetyl-galactosamine-O-Ser/Thr (Tn antigen), which is overexpressed in various tumor cell types, notably of the breast, ovary and colon, is an interesting... Show moreThe tumor-associated structure N-acetyl-galactosamine-O-Ser/Thr (Tn antigen), which is overexpressed in various tumor cell types, notably of the breast, ovary and colon, is an interesting determinant that is useful for cancer diagnosis and follow-up. The aim of this research was to study different assay strategies in order to determine the most sensitive system for further application in epitope characterization and binding assessment. The tetrameric isolectin obtained from Vicia villosa seeds (VVLB4) shows high affinity for the tumor-associated structure. A monoclonal antibody against VVLB4, MabVV(34), was generated, and the interaction between MabVV(34) and VVLB4 was studied by means of binding and inhibition assays. Several synthetic peptides (10 amino acid sequences) designed from the amino acid sequence of VVLB4 and obtained from trypsin digestion were tested to determine which amino acids were involved in the interaction between MabVV(34) and VVLB4. The further unraveling of this epitope was investigated by inhibition using designed synthetic peptides as well as mixtures mimicking variable density effect. Under the experimental circumstances, MabVV(34) was able to inhibit the binding of VVLB4 to Tn. Two of the four peptide sequences assayed showed better inhibition properties. Finally, mixtures containing these selected sequences allowed the evaluation of binding and inhibition as a function of Tn density. We conclude that the present study facilitates the further development of a specific Tn marker and may contribute to the development of Tn-like radiolabelled peptides or Tn-specific radiolabelled fragments providing a highly selective tool for cancer diagnosis and treatment. This strategy may contribute to characterize the new generation of radiopharmaceuticals for diagnosis and therapy based on biomolecules like antibodies, fragments or peptides, whose application is directly guided by their specific molecular recognition. (C) 2010 Published by Elsevier Inc. Show less
![Synthesis and preclinical evaluation of [C-11]LR111 and [F-18]EW-7197 as PET tracers of the activin-receptor like kinase-5](/sites/all/modules/custom/islandora_solr_search/images/defaultimg.png?solr_nav%5Bid%5D=aeb79da6b5f719f275b7&solr_nav%5Bpage%5D=0&solr_nav%5Boffset%5D=1)
