Development of a homotrimeric PSMA radioligand based on the NOTI chelating platform

Abstract Background The NOTI chelating scaffold can readily be derivatized for bioconjugation without impacting its metal complexation/radiolabeling properties making it an attractive building block for the development of multimeric/-valent radiopharmaceuticals. The objective of the study was to fur...

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Main Authors: Sebastian Martin, Moritz-Valentin Schreck, Tobias Stemler, Stephan Maus, Florian Rosar, Caroline Burgard, Andrea Schaefer-Schuler, Samer Ezziddin, Mark D. Bartholomä
Format: Article
Language:English
Published: SpringerOpen 2024-12-01
Series:EJNMMI Radiopharmacy and Chemistry
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Online Access:https://doi.org/10.1186/s41181-024-00314-7
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author Sebastian Martin
Moritz-Valentin Schreck
Tobias Stemler
Stephan Maus
Florian Rosar
Caroline Burgard
Andrea Schaefer-Schuler
Samer Ezziddin
Mark D. Bartholomä
author_facet Sebastian Martin
Moritz-Valentin Schreck
Tobias Stemler
Stephan Maus
Florian Rosar
Caroline Burgard
Andrea Schaefer-Schuler
Samer Ezziddin
Mark D. Bartholomä
author_sort Sebastian Martin
collection DOAJ
description Abstract Background The NOTI chelating scaffold can readily be derivatized for bioconjugation without impacting its metal complexation/radiolabeling properties making it an attractive building block for the development of multimeric/-valent radiopharmaceuticals. The objective of the study was to further explore the potential of the NOTI chelating platform by preparing and characterizing homotrimeric PSMA radioconjugates in order to identify a suitable candidate for clinical translation. Results Altogether, three PSMA conjugates based on the NOTI-TVA scaffold with different spacer entities between the chelating unit and the Glu-CO-Lys PSMA binding motif were readily prepared by solid phase-peptide chemistry. Cell experiments allowed the identification of the homotrimeric conjugate 9 comprising NaI-Amc spacer with high PSMA binding affinity (IC50 = 5.9 nM) and high PSMA-specific internalization (17.8 ± 2.5%) compared to the clinically used radiotracer [68Ga]Ga-PSMA-11 with a IC50 of 18.5 nM and 5.2 ± 0.2% cell internalization, respectively. All 68Ga-labeled trimeric conjugates showed high metabolic stability in vitro with [68Ga]Ga-9 exhibiting high binding to human serum proteins (> 95%). Small-animal PET imaging revealed a specific tumor uptake of 16.0 ± 1.3% IA g−1 and a kidney uptake of 67.8 ± 8.4% IA g−1 for [68Ga]Ga-9. Clinical PET imaging allowed identification of all lesions detected by [68Ga]Ga-PSMA-11 together with a prolonged blood circulation as well as a significantly lower kidney and higher liver uptake of [68Ga]Ga-9 compared to [68Ga]Ga-PSMA-11. Conclusions Trimerization of the Glu-CO-Lys binding motif for conjugate 9 resulted in a ~ threefold higher binding affinity and cellular uptake as well as in an altered biodistribution profile compared to the control [68Ga]Ga-PSMA-11 due to its intrinsic high binding to serum proteins. To fully elucidate its biodistribution, future studies in combination with long-lived radionuclides, such as 64Cu, are warranted. Its prolonged biological half-life and favorable tumor-to-kidney ratio make this homotrimeric conjugate also a potential candidate for future radiotherapeutic applications in combination with therapeutic radionuclides such as 67Cu.
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spelling doaj-art-690f414b42e7461998ffb597601d58e92025-08-20T01:56:48ZengSpringerOpenEJNMMI Radiopharmacy and Chemistry2365-421X2024-12-019112310.1186/s41181-024-00314-7Development of a homotrimeric PSMA radioligand based on the NOTI chelating platformSebastian Martin0Moritz-Valentin Schreck1Tobias Stemler2Stephan Maus3Florian Rosar4Caroline Burgard5Andrea Schaefer-Schuler6Samer Ezziddin7Mark D. Bartholomä8Department of Nuclear Medicine and Molecular Imaging, Lausanne University HospitalDepartment of Nuclear Medicine, Saarland University – Medical CenterDepartment of Nuclear Medicine, Saarland University – Medical CenterDepartment of Nuclear Medicine, Saarland University – Medical CenterDepartment of Nuclear Medicine, Saarland University – Medical CenterDepartment of Nuclear Medicine, Saarland University – Medical CenterDepartment of Nuclear Medicine, Saarland University – Medical CenterDepartment of Nuclear Medicine, Saarland University – Medical CenterDepartment of Nuclear Medicine, Saarland University – Medical CenterAbstract Background The NOTI chelating scaffold can readily be derivatized for bioconjugation without impacting its metal complexation/radiolabeling properties making it an attractive building block for the development of multimeric/-valent radiopharmaceuticals. The objective of the study was to further explore the potential of the NOTI chelating platform by preparing and characterizing homotrimeric PSMA radioconjugates in order to identify a suitable candidate for clinical translation. Results Altogether, three PSMA conjugates based on the NOTI-TVA scaffold with different spacer entities between the chelating unit and the Glu-CO-Lys PSMA binding motif were readily prepared by solid phase-peptide chemistry. Cell experiments allowed the identification of the homotrimeric conjugate 9 comprising NaI-Amc spacer with high PSMA binding affinity (IC50 = 5.9 nM) and high PSMA-specific internalization (17.8 ± 2.5%) compared to the clinically used radiotracer [68Ga]Ga-PSMA-11 with a IC50 of 18.5 nM and 5.2 ± 0.2% cell internalization, respectively. All 68Ga-labeled trimeric conjugates showed high metabolic stability in vitro with [68Ga]Ga-9 exhibiting high binding to human serum proteins (> 95%). Small-animal PET imaging revealed a specific tumor uptake of 16.0 ± 1.3% IA g−1 and a kidney uptake of 67.8 ± 8.4% IA g−1 for [68Ga]Ga-9. Clinical PET imaging allowed identification of all lesions detected by [68Ga]Ga-PSMA-11 together with a prolonged blood circulation as well as a significantly lower kidney and higher liver uptake of [68Ga]Ga-9 compared to [68Ga]Ga-PSMA-11. Conclusions Trimerization of the Glu-CO-Lys binding motif for conjugate 9 resulted in a ~ threefold higher binding affinity and cellular uptake as well as in an altered biodistribution profile compared to the control [68Ga]Ga-PSMA-11 due to its intrinsic high binding to serum proteins. To fully elucidate its biodistribution, future studies in combination with long-lived radionuclides, such as 64Cu, are warranted. Its prolonged biological half-life and favorable tumor-to-kidney ratio make this homotrimeric conjugate also a potential candidate for future radiotherapeutic applications in combination with therapeutic radionuclides such as 67Cu.https://doi.org/10.1186/s41181-024-00314-7NOTIBifunctional chelatorGallium-68PSMATrimerMultimerization
spellingShingle Sebastian Martin
Moritz-Valentin Schreck
Tobias Stemler
Stephan Maus
Florian Rosar
Caroline Burgard
Andrea Schaefer-Schuler
Samer Ezziddin
Mark D. Bartholomä
Development of a homotrimeric PSMA radioligand based on the NOTI chelating platform
EJNMMI Radiopharmacy and Chemistry
NOTI
Bifunctional chelator
Gallium-68
PSMA
Trimer
Multimerization
title Development of a homotrimeric PSMA radioligand based on the NOTI chelating platform
title_full Development of a homotrimeric PSMA radioligand based on the NOTI chelating platform
title_fullStr Development of a homotrimeric PSMA radioligand based on the NOTI chelating platform
title_full_unstemmed Development of a homotrimeric PSMA radioligand based on the NOTI chelating platform
title_short Development of a homotrimeric PSMA radioligand based on the NOTI chelating platform
title_sort development of a homotrimeric psma radioligand based on the noti chelating platform
topic NOTI
Bifunctional chelator
Gallium-68
PSMA
Trimer
Multimerization
url https://doi.org/10.1186/s41181-024-00314-7
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