title: In vitro and in vivo evaluation of melanin-binding decapeptide 4B4 radiolabeled with 177Lu, 166Ho, and 153Sm radiolanthanides for the purpose of targeted radionuclide therapy of melanoma.
abstract: Melanoma is a malignancy with increasing incidence. Although primary tumors that are localized to the skin can be successfully treated by surgical removal, there is no satisfactory treatment for metastatic melanoma, a condition that has currently an estimated 5-year survival of just 6%. During the last decade, β- or α-emitter-radiolabeled peptides that bind to different receptors on a variety of tumors have been investigated as potential therapeutic agents in both the preclinical and clinical settings with encouraging results. A recent study demonstrated that 188-Rhenium ((188)Re)-labeled, via HYNIC ligand, fungal melanin-binding decapeptide 4B4 was effective against experimental MNT1 human melanoma and was safe to normal melanized tissues. The availability of radiolanthanides with diverse nuclear emission schemes and half-lives provides an opportunity to expand the repertoire of peptides for radionuclide therapy of melanoma. The melanin-binding decapeptide 4B4 was radiolabeled with (177)Lu, (166)Ho, and (153)Sm via a DO3A chelate. The stability studies of Ln*-DO3A-4B4 in phosphate-buffered saline, serum, and a hydroxyapatite assay demonstrated that (177)Lu-labeled peptide was more stable than (166)Ho- and (153)Sm-labeled peptides, most likely because of the smallest ionic radius of the former allowing for better complexation with DO3A. Binding of Ln*-DO3A-4B4 to the lysed highly melanized MNT1 melanoma cells demonstrated the specificity of peptides binding to melanin. In vivo biodistribution data for (177)Lu-DO3A-4B4 given by intraperitoneal administration to lightly pigmented human metastatic A2058 melanoma-bearing mice demonstrated very high uptake in the kidneys and low tumor uptake. Intravenous administration did not improve the tumor uptake. The plausible explanation of low tumor uptake of (177)Lu-DO3A-4B4 could be its decreased ability to bind to melanin during in vitro binding studies in comparison with (188)Re-HYNIC-4B4, exacerbated by the very fast clearance from the blood and the kidneys "sink" effect.
authors.affiliation: Department of Chemistry, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10065, USA.
authors.forename: Beau
authors.initials: B
authors.lastname: Ballard
authors.forename: Zewei
authors.initials: Z
authors.lastname: Jiang
authors.forename: Clifford E
authors.initials: CE
authors.lastname: Soll
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Revskaya
authors.forename: Cathy S
authors.initials: CS
authors.lastname: Cutler
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Dadachova
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Francesconi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems / Q000379:methods; D005260:Female; D006801:Humans; D028581:Lanthanoid Series Elements / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D008543:Melanins / Q000378:metabolism*; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000532:radiotherapy; D051379:Mice; D008819:Mice, Nude; D009842:Oligopeptides / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D028581:Lanthanoid Series Elements; D008543:Melanins; D009842:Oligopeptides; D019275:Radiopharmaceuticals