An improved automated radiosynthesis of [18F]FET-βAG-TOCA

Abstract

The fluorine-18 radiolabelled octreotide derivative [¹⁸F]FET-βAG-TOCA targeting somatostatin receptor type 2, has been evaluated clinically for positron emission tomography (PET) imaging of neuroendocrine tumours (NETs). We report an improved automated radiosynthesis of [¹⁸F]FET-βAG-TOCA with several advantages over the current automated GMP synthesis: 1) cartridge-based purification of 2-[¹⁸F]fluoroethylazide ([¹⁸F]FEA); 2) simple set-up for the radiolabelling on a single cassette; 3) HPLC purification using a biocompatible mobile phase. [¹⁸F]FET-βAG-TOCA was produced with a radiochemical yield of 16.7 ± 0.6% (non-decay corrected) and radiochemical purity ≥98%. The automated synthesis produced multi-patient doses (900 MBq) that were radiochemically stable (≥98%) over 4 hours. In addition, the automated procedure described can be used, with minimal adaptation, to radiolabel any alkyne-containing peptide with [¹⁸F]FEA using the GE FASTlab™ platform.