The determined in vitro uptake of about 0.6–4.4% of [68Ga]KISS1-54 is comparable to the uptake levels of other radiotracers targeting cell receptors, e.g., RGD- or NRG-peptides that bind to integrin or aminopeptidase N, respectively, expressed on activated endothelial and tumor cells [29,30]. This evidence concerns the gene ANPEP and neoplasm.