title: Novel neurotensin analogues for radioisotope targeting to neurotensin receptor-positive tumors.
abstract: The increased expression of the neurotensin (NT) receptor NTS1 by different cancer cells, such as pancreatic adenocarcinoma and ductal breast cancer cells, as compared to normal epithelium, offers the opportunity to target these tumors with radiolabeled neurotensin analogues for diagnostic or therapeutic purposes. The aim of the present study was to design and synthesize new neurotensin radioligands and to select a lead molecule with high in vivo tumor selectivity for further development. Two series of neurotensin analogues bearing DTPA were tested: a series of NT(8-13) analogues, with DTPA coupled to the α-NH(2), sharing the same peptide sequence with analogues previously developed for radiolabeling with technetium or rhenium, as well as an NT(6-13) series in which DTPA was coupled to the ε-NH(2) of Lys(6). Changes were introduced to stabilize the bonds between Arg(8)-Arg(9), Pro(10)-Tyr(11), and Tyr(11)-Ile(12) to provide metabolic stability. Structure-activity studies of NT analogues have shown that the attachment of DTPA induces an important loss of affinity unless the distance between the chelator and the NT(8-13) sequence, which binds to the NTS1 receptor, is increased. The doubly stabilized DTPA-NT-20.3 exhibits a high affinity and an elevated stability to enzymatic degradation. It shows specific tumor uptake and high tumor to blood, to liver, and to intestine activity uptake ratios and affords high-contrast planar and SPECT images in an animal model. The DTPA-NT-20.3 peptide is a promising candidate for imaging neurotensin receptor-positive tumors, such as pancreatic adenocarcinoma and invasive ductal breast cancer. Analogues carrying DOTA are being developed for yttrium-90 or lutetium-177 labeling.
authors.affiliation: Inserm, U773, Paris, France.
authors.forename: Faisal
authors.initials: F
authors.lastname: Alshoukr
authors.forename: Cedric
authors.initials: C
authors.lastname: Rosant
authors.forename: Veronique
authors.initials: V
authors.lastname: Maes
authors.forename: Jallane
authors.initials: J
authors.lastname: Abdelhak
authors.forename: Olivier
authors.initials: O
authors.lastname: Raguin
authors.forename: Samuel
authors.initials: S
authors.lastname: Burg
authors.forename: Laure
authors.initials: L
authors.lastname: Sarda
authors.forename: Jacques
authors.initials: J
authors.lastname: Barbet
authors.forename: Dirk
authors.initials: D
authors.lastname: Tourwé
authors.forename: Didier
authors.initials: D
authors.lastname: Pelaprat
authors.forename: Anne
authors.initials: A
authors.lastname: Gruaz-Guyon
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000378:metabolism; D000818:Animals; D001943:Breast Neoplasms / Q000175:diagnosis / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D007205:Indium Radioisotopes / Q000378:metabolism / Q000493:pharmacokinetics*; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009369:Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D009496:Neurotensin / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000493:pharmacokinetics; D010190:Pancreatic Neoplasms / Q000175:diagnosis / Q000378:metabolism; D004369:Pentetic Acid / Q000378:metabolism* / Q000493:pharmacokinetics; D018028:Receptors, Neurotensin / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D007205:Indium Radioisotopes; D008024:Ligands; D018028:Receptors, Neurotensin; C114036:neurotensin type 1 receptor; D009496:Neurotensin; D004369:Pentetic Acid