Finally, twofold modification of the peptide at positions 6 and 8 (DGlu10-Ψ[Tz]-Ala11 and Tyr12-Ψ[Tz]-Gly13) combined the positive effects on stability and affinity and resulted in the highest tumor uptake in mice bearing CCK2R-positive tumor xenografts. This evidence concerns the gene CCKBR and neoplasm.