Researching the influence of iron as contaminative metal on labelling dotatate with 90Y

The full text of the publication follows. Because of radiation of high beta-energy and short half-life time, 90Y is widely used for the labelling of targeted molecules that are used in the treatment of cancer. DOTATATE is an analogous of somatostatin, the naturally occurring peptide with diverse functions. The role of DOTATATE is to introduce radioactive particle in solid tumor. The aim of this study was to explore possible competition of iron ions with yttrium ions during the labelling process of DOTATATE. The importance of this research can be seen in the fact that during the process of labelling, syringes with steel needles were used. Series of different concentrations of iron were prepared. The molar ratios of DOTATATE/Fe were: 2:1, 5:1 and 10:1. After that, the standard procedure of labelling DOTATATE with yttrium was performed using 925 MBq of 90Y as 90Y chloride solution. The control of radioactivity was carried out on CAPINTEC CRC 15-BETA dose calibrator that had been previously calibrated for 90Y. The control of radiochemical purity of the radiolabelled peptide was carried out by HPLC, ITLC and by extraction chromatography Sep-Pak columns. Additionally, the concentration of contaminating Fe was confirmed by ICP-optical emission spectrometry. Obtained results showed that iron contamination of the solution significantly reduces the yield during the labelling of DOTATATE with 90Y as ions compete with iron ions in yttrium labelling. (authors)