Endocrine Abstracts

Objectives: DOTA^MZOL is a DOTA-conjugated bisphosphonate which can be used for diagnostic (⁴⁴Sc, ⁶⁸Ga) or therapeutic (¹⁷⁷Lu) applications. The aim of this study was to evaluate the adaption of the radiolabelling process on an automated module utilizing NaCl-post processing, with regard to clinical application and additional radiation protection point of view.

Methods: ⁶⁸Ga was obtained from a 1.5 years old 1.85 GBq ⁶⁸Ge/⁶⁸Ga-generator (iThemba, South Africa). ⁴⁴Sc was obtained from a 180 MBq ⁴⁴Ti/⁴⁴Sc-generator (Johannes Gutenberg-University institute of nuclear chemistry Mainz, Germany). DOTA^MZol was provided from ITG Garching (Germany). Radiolabelling was performed on an automated cassette module (GAIA, Elysia-Raytest GmbH, Germany). Compared to standard ⁶⁸Ga-synthesis adjustment in hard-, software and reagent were made. Synthesis route based on Meckel et al. was used¹, but had to be optimized in terms of temperature, reaction time, buffer, pH-value, reaction vial and quality control. These optimization on ⁶⁸Ga-Sythesis could be transferred and used for radiolabelling with ⁴⁴Sc.

Results: The reactor screening showed DOTA^MZOl is sensitive to reaction vials and therefore in need of a specific vial, otherwise unplanned side products are obtained. Furthermore an automated method was obtained for ⁶⁸Ga and a manual method for ⁴⁴Sc which both could be validated and established. The new quality control gives clear and reliable evidence on impurities.

Conclusion: A new Synthesis route for DOTA^MZOL was developed with reduced manual interference which reduced radiation exposure of the operator. It was possible to minimize the effect of the reactor and develop an automated method for modules. The procedures guarantee save preparation and high purity of ⁶⁸Ga-DOTA^MZOL as well as ⁴⁴Sc-DOTA^MZOL for clinical application.

Acknowledgement: We thank ITG Garching for support and put DOTA^MZOl at our disposal.

Literature: 1. J Nucl Med, 1 May 2015 vol. 56 no. supplement 3, 1054.