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Preparation and preclinical evaluation of a 68Ga-labelled c(RGDfK) conjugate comprising the bifunctional chelator NODIA-Me


Läppchen, Tilman; Holland, Jason P; Kiefer, Yvonne; Bartholomä, Mark D (2018). Preparation and preclinical evaluation of a 68Ga-labelled c(RGDfK) conjugate comprising the bifunctional chelator NODIA-Me. EJNMMI Radiopharmacy and Chemistry, 3:6.

Abstract

Background
We recently developed a chelating platform based on the macrocycle 1,4,7-triazacyclononane with up to three, five-membered azaheterocyclic arms for the development of 68Ga- and 64Cu-based radiopharmaceuticals. Here, a 68Ga-labelled conjugate comprising the bifunctional chelator NODIA-Me in combination with the αvß3-targeting peptide c(RGDfK) has been synthesized and characterized. The primary aim was to evaluate further the potential of our NODIA-Me chelating system for the development of 68Ga-labelled radiotracers.
Results
The BFC NODIA-Me was conjugated to c(RGDfK) by standard peptide chemistry to obtain the final bioconjugate NODIA-Me-c(RGDfK) 3 in 72% yield. Labelling with [68Ga]GaCl3 was accomplished in a fully automated, cGMP compliant process to give [68Ga]3 in high radiochemical yield (98%) and moderate specific activity (~ 8 MBq nmol− 1). Incorporation of the Ga-NODIA-Me chelate to c(RGDfK) 2 had only minimal influence on the affinity to integrin αvß3 (IC50 values [natGa]3 = 205.1 ± 1.4 nM, c(RGDfK) 2 = 159.5 ± 1.3 nM) as determined in competitive cell binding experiments in U-87 MG cell line. In small-animal PET imaging and ex vivo biodistribution studies, the radiotracer [68Ga]3 showed low uptake in non-target organs and specific tumor uptake in U-87 MG tumors.
Conclusion
The results suggest that the bifunctional chelator NODIA-Me is an interesting alternative to existing ligands for the development of 68Ga-labelled radiopharmaceuticals.

Abstract

Background
We recently developed a chelating platform based on the macrocycle 1,4,7-triazacyclononane with up to three, five-membered azaheterocyclic arms for the development of 68Ga- and 64Cu-based radiopharmaceuticals. Here, a 68Ga-labelled conjugate comprising the bifunctional chelator NODIA-Me in combination with the αvß3-targeting peptide c(RGDfK) has been synthesized and characterized. The primary aim was to evaluate further the potential of our NODIA-Me chelating system for the development of 68Ga-labelled radiotracers.
Results
The BFC NODIA-Me was conjugated to c(RGDfK) by standard peptide chemistry to obtain the final bioconjugate NODIA-Me-c(RGDfK) 3 in 72% yield. Labelling with [68Ga]GaCl3 was accomplished in a fully automated, cGMP compliant process to give [68Ga]3 in high radiochemical yield (98%) and moderate specific activity (~ 8 MBq nmol− 1). Incorporation of the Ga-NODIA-Me chelate to c(RGDfK) 2 had only minimal influence on the affinity to integrin αvß3 (IC50 values [natGa]3 = 205.1 ± 1.4 nM, c(RGDfK) 2 = 159.5 ± 1.3 nM) as determined in competitive cell binding experiments in U-87 MG cell line. In small-animal PET imaging and ex vivo biodistribution studies, the radiotracer [68Ga]3 showed low uptake in non-target organs and specific tumor uptake in U-87 MG tumors.
Conclusion
The results suggest that the bifunctional chelator NODIA-Me is an interesting alternative to existing ligands for the development of 68Ga-labelled radiopharmaceuticals.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:1 December 2018
Deposited On:07 Mar 2019 08:28
Last Modified:24 Apr 2019 12:20
Publisher:SpringerOpen
ISSN:2365-421X
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1186/s41181-018-0043-2
Project Information:
  • : FunderSNSF
  • : Grant IDPP00P2_163683
  • : Project TitleAdvanced radiochemical methods for multi-modal imaging with nanomedicines
  • : FunderH2020
  • : Grant ID676904
  • : Project TitleNanoSCAN - Developing multi-modality nanomedicines for targeted annotation of oncogenic signaling pathways

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