title: Influence of cations on the complexation yield of DOTATATE with yttrium and lutetium: a perspective study for enhancing the 90Y and 177Lu labeling conditions.
abstract: The DOTA macrocyclic ligand can form stable complexes with many cations besides yttrium and lutetium. For this reason, the presence of competing cationic metals in yttrium-90 and lutetium-177 chloride solutions can dramatically influence the radiolabeling yield. The aim of this study was to evaluate the coordination yield of yttrium- and lutetium-DOTATATE complexes when the reaction is performed in the presence of varying amounts of competing cationic impurities. In the first set of experiments, the preparation of the samples was performed by using natural yttrium and lutetium (20.4 nmol). The molar ratio between DOTATATE and these metals was 1 to 1. Metal competitors (Pb(2+), Zn(2+), Cu(2+), Fe(3+), Al(3+), Ni(2+), Co(2+), Cr(3+)) were added separately to obtain samples with varying molar ratio with respect to yttrium or lutetium (0.1, 0.5, 1, 2 and 10). The final solutions were analyzed through ultra high-performance liquid chromatography with an UV detector. In the second set of experiments, an amount of (90)Y or (177)Lu chloride (6 MBq corresponding to 3.3 and 45 pmol, respectively) was added to the samples, and a radio-thin layer chromatography analysis was carried out. The coordination of Y(3+) and Lu(3+) was dramatically influenced by low levels of Zn(2+), Cu(2+) and Co(2+). Pb(2+) and Ni(2+) were also shown to be strong competitors at higher concentrations. Fe(3+) was expected to be a strong competitor, but the effect on the incorporation was only partly dependent on its concentration. Al(3+) and Cr(3+) did not compete with Y(3+) and Lu(3+) in the formation of DOTATATE complexes.
authors.affiliation: Nuclear Medicine Department, Santa Maria Nuova Hospital, Reggio Emilia, Italy. asti.mattia@asmn.re.it
authors.forename: Mattia
authors.initials: M
authors.lastname: Asti
authors.forename: Matteo
authors.initials: M
authors.lastname: Tegoni
authors.forename: Daniela
authors.initials: D
authors.lastname: Farioli
authors.forename: Michele
authors.initials: M
authors.lastname: Iori
authors.forename: Claudio
authors.initials: C
authors.lastname: Guidotti
authors.forename: Cathy S
authors.initials: CS
authors.lastname: Cutler
authors.forename: Pat
authors.initials: P
authors.lastname: Mayer
authors.forename: Annibale
authors.initials: A
authors.lastname: Versari
authors.forename: Diana
authors.initials: D
authors.lastname: Salvo
mesh_terms: D002412:Cations / Q000737:chemistry; D007553:Isotope Labeling / Q000379:methods* / Q000592:standards; D008187:Lutetium / Q000737:chemistry*; D015282:Octreotide / Q000031:analogs & derivatives* / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D011854:Radiochemistry / Q000379:methods* / Q000592:standards; D012015:Reference Standards; D015021:Yttrium Radioisotopes / Q000737:chemistry
chemical_list: C539274:90Y-octreotate, DOTA(0)-Tyr(3)-Thr(8)-; D002412:Cations; D009942:Organometallic Compounds; D015021:Yttrium Radioisotopes; D008187:Lutetium; C447941:lutetium Lu 177 dotatate; D015282:Octreotide