Blocking studies confirmed the receptor specificity of [68Ga]Ga-DOTA-CCK-66, as its tumor uptake at 1 h decreased significantly from 19.53 ± 2.95 %ID/g to 7.90 ± 1.35 %ID/g after co-injection with the unlabeled ligand (p = 0.003). This evidence concerns the gene CCK and neoplasm.