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Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model
PURPOSE: Melanocortin receptor 1 (MC1R) is overexpressed in melanoma and may be a molecular target for imaging and peptide receptor radionuclide therapy. (68)Gallium ((68)Ga) labeling of DOTA-conjugated peptides is an established procedure in the clinic for use in positron emission tomography (PET)...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6548402/ https://www.ncbi.nlm.nih.gov/pubmed/31163066 http://dx.doi.org/10.1371/journal.pone.0217883 |
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author | von Hacht, Jan Lennart Erdmann, Sarah Niederstadt, Lars Prasad, Sonal Wagener, Asja Exner, Samantha Beindorff, Nicola Brenner, Winfried Grötzinger, Carsten |
author_facet | von Hacht, Jan Lennart Erdmann, Sarah Niederstadt, Lars Prasad, Sonal Wagener, Asja Exner, Samantha Beindorff, Nicola Brenner, Winfried Grötzinger, Carsten |
author_sort | von Hacht, Jan Lennart |
collection | PubMed |
description | PURPOSE: Melanocortin receptor 1 (MC1R) is overexpressed in melanoma and may be a molecular target for imaging and peptide receptor radionuclide therapy. (68)Gallium ((68)Ga) labeling of DOTA-conjugated peptides is an established procedure in the clinic for use in positron emission tomography (PET) imaging. Aim of this study was to compare a standard labeling protocol against the (68)Ga-DOTA peptide purified from the excess of unlabeled peptide. PROCEDURES: The MC1R ligand DOTA-NAPamide was labeled with (68)Ga using a standard clinical protocol. Radioactive peptide was separated from the excess of unlabeled DOTA-NAPamide by HPLC. Immediately after the incubation of peptide and (68)Ga (95°C, 15 min), the reaction was loaded on a C18 column and separated by a water/acetonitrile gradient, allowing fractionation in less than 20 minutes. Radiolabeled products were compared in biodistribution studies and PET imaging using nude mice bearing MC1R-expressing B16/F1 xenograft tumors. RESULTS: In biodistribution studies, non-purified (68)Ga-DOTA-NAPamide did not show significant uptake in the tumor at 1 h post injection (0.78% IA/g). By the additional HPLC step, the molar activity was raised around 10,000-fold by completely removing unlabeled peptide. Application of this rapid purification strategy led to a more than 8-fold increase in tumor uptake (7.0% IA/g). The addition of various amounts of unlabeled DOTA-NAPamide to the purified product led to a blocking effect and decreased specific tumor uptake, similar to the result seen with non-purified radiopeptide. PET imaging was performed using the same tracer preparations. Purified (68)Ga-DOTA-NAPamide, in comparison, showed superior tumor uptake. CONCLUSIONS: We demonstrated that chromatographic separation of radiolabeled from excess unlabeled peptide is technically feasible and beneficial, even for short-lived isotopes such as (68)Ga. Unlabeled peptide molecules compete with receptor binding sites in the target tissue. Purification of the radiopeptide therefore improved tumor uptake. |
format | Online Article Text |
id | pubmed-6548402 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-65484022019-06-17 Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model von Hacht, Jan Lennart Erdmann, Sarah Niederstadt, Lars Prasad, Sonal Wagener, Asja Exner, Samantha Beindorff, Nicola Brenner, Winfried Grötzinger, Carsten PLoS One Research Article PURPOSE: Melanocortin receptor 1 (MC1R) is overexpressed in melanoma and may be a molecular target for imaging and peptide receptor radionuclide therapy. (68)Gallium ((68)Ga) labeling of DOTA-conjugated peptides is an established procedure in the clinic for use in positron emission tomography (PET) imaging. Aim of this study was to compare a standard labeling protocol against the (68)Ga-DOTA peptide purified from the excess of unlabeled peptide. PROCEDURES: The MC1R ligand DOTA-NAPamide was labeled with (68)Ga using a standard clinical protocol. Radioactive peptide was separated from the excess of unlabeled DOTA-NAPamide by HPLC. Immediately after the incubation of peptide and (68)Ga (95°C, 15 min), the reaction was loaded on a C18 column and separated by a water/acetonitrile gradient, allowing fractionation in less than 20 minutes. Radiolabeled products were compared in biodistribution studies and PET imaging using nude mice bearing MC1R-expressing B16/F1 xenograft tumors. RESULTS: In biodistribution studies, non-purified (68)Ga-DOTA-NAPamide did not show significant uptake in the tumor at 1 h post injection (0.78% IA/g). By the additional HPLC step, the molar activity was raised around 10,000-fold by completely removing unlabeled peptide. Application of this rapid purification strategy led to a more than 8-fold increase in tumor uptake (7.0% IA/g). The addition of various amounts of unlabeled DOTA-NAPamide to the purified product led to a blocking effect and decreased specific tumor uptake, similar to the result seen with non-purified radiopeptide. PET imaging was performed using the same tracer preparations. Purified (68)Ga-DOTA-NAPamide, in comparison, showed superior tumor uptake. CONCLUSIONS: We demonstrated that chromatographic separation of radiolabeled from excess unlabeled peptide is technically feasible and beneficial, even for short-lived isotopes such as (68)Ga. Unlabeled peptide molecules compete with receptor binding sites in the target tissue. Purification of the radiopeptide therefore improved tumor uptake. Public Library of Science 2019-06-04 /pmc/articles/PMC6548402/ /pubmed/31163066 http://dx.doi.org/10.1371/journal.pone.0217883 Text en © 2019 von Hacht et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article von Hacht, Jan Lennart Erdmann, Sarah Niederstadt, Lars Prasad, Sonal Wagener, Asja Exner, Samantha Beindorff, Nicola Brenner, Winfried Grötzinger, Carsten Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model |
title | Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model |
title_full | Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model |
title_fullStr | Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model |
title_full_unstemmed | Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model |
title_short | Increasing molar activity by HPLC purification improves (68)Ga-DOTA-NAPamide tumor accumulation in a B16/F1 melanoma xenograft model |
title_sort | increasing molar activity by hplc purification improves (68)ga-dota-napamide tumor accumulation in a b16/f1 melanoma xenograft model |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6548402/ https://www.ncbi.nlm.nih.gov/pubmed/31163066 http://dx.doi.org/10.1371/journal.pone.0217883 |
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