GRPR and neoplasm: Despite their enhanced lipophilicity, liver levels were not significantly increased compared to [177Lu]Lu-DOTA-PP-F11N at 24 h p.i. Blood levels of both rhCCK derivatives were significantly higher than those of [177Lu]Lu-DOTA-PP-F11N but still in a comparable range to compounds addressing other tumour targets in nuclear medicine, such as PSMA-, gastrin releasing peptide receptor-, chemokine receptor CXCR4- and somatostatin-2 receptor-targeted probes [14,19,35,36,37].