The cell adhesion protein nectin-4 emerged as a valid therapeutic target for antibody- and peptide-drug conjugates in cancer. To support patient stratification for such targeted therapies, there is a clinical need for molecular imaging agents capable of quantifying nectin-4 levels noninvasively in vivo. For this purpose, we developed 64Cu- and 68Ga-labeled ligands derived from bicyclic peptide-drug conjugate BT8009. A library of peptides was prepared with a major focus on the bioisosteric replacement of the original methionine residue due to its susceptibility to oxidation. The peptides were characterized for their binding behavior to nectin-4, and radiopharmacological characterization of selected radioligands was performed using urothelial carcinoma cell lines and tumor xenograft models derived thereof. The suitability of the most promising ligand from the preclinical studies, NECT-224, for PET imaging purposes was also demonstrated in a first-in-human application using [68Ga]Ga-NECT-224. The results suggest its further clinical development, but also that of [64Cu]Cu-NECT-224.

Department of Physics and Measurements University of Chemistry and Technology Technická 5 Prague 16628 Czech Republic

German Cancer Consortium Partner Site Dresden 01307 Dresden Germany

German Cancer Research Center 69120 Heidelberg Germany

Institute of Radiopharmaceutical Cancer Research Helmholtz Zentrum Dresden Rossendorf Bautzner Landstraße 400 01328 Dresden Germany

Institute of Resource Ecology Helmholtz Zentrum Dresden Rossendorf Bautzner Landstraße 400 01328 Dresden Germany

Klinik und Poliklinik für Nuklearmedizin University Hospital Carl Gustav Carus at the Technische Universität Dresden Fetscherstraße 74 01307 Dresden Germany

Klinik und Poliklinik für Urologie University Hospital Carl Gustav Carus at the Technische Universität Dresden Fetscherstraße 74 01307 Dresden Germany

National Center for Tumor Diseases 01307 Dresden Germany

School of Science Faculty of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstraße 4 01069 Dresden Germany

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