GRPR and neoplasm: It could be shown for both agents 1 and 2 that they were taken up by GRPR- and PSMA-expressing PC3 and LNCaP tumor cells by specific interaction with the respective target receptors showing good affinities (1: IC50(GRPR): 11.1 ± 0.5 nM, IC50(PSMA): 1.2 ± 1.4 nM; 2: IC50(GRPR): 9.0 ± 1.8 nM, IC50(PSMA): 25.0 ± 5.4 nM) in the same range or slightly decreased compared to the corresponding peptide monomers.