The impact of in-situ NEP and ACE inhibition on tumor targeting and pharmacokinetics of NT-based radioligands has been assessed for the first time employing three structurally related analogs, namely 99mTc-DT1 (99mTc-[N4-Gly7]NT(7-13)), 99mTc-DT5 (99mTc-[N4-βAla7,Dab9]NT(7-13)), and 99mTc-DT6 (99mTc-[N4-βAla7,Dab9,Tle12]]NT(7-13)), as examples. This evidence concerns the gene ACE and neoplasm.