ANPEP and neoplasm: Similarly to previous studies, APN/CD13 overexpressing HT1080 and receptor negative HT29 cell lines and corresponding tumour-bearing athymic nude mice were used to assess the in vitro and in vivo performance of monomeric [64Cu]Cu-DOTA-NGR1 and dimeric [64Cu]Cu-DOTA-NGR2 [36,43].