Development of an automated radiosynthesis for [68Ga]Ga-NODAGA[40Lys]-Exendin-4 in sodium acetate buffer

Background [ ⁶⁸ Ga]Ga-NODAGA[40Lys]-Exendin-4 ( ⁶⁸ Ga-Ex-4) is a new PET radiopharmaceutical targeting GLP-1-R that showed great specificity and sensitivity in the topographic diagnosis of benign insulinoma. We herein report the development of a new method for ⁶⁸ Ga-Ex-4 radiolabeling in sodium acetate buffer, automated on the miniAllinOne synthesizer. Results Key parameters were reaction volume, due to low amount of peptide, and pH. At a reaction volume of 2.65 and pH 2.9, the reaction yielded 80% of ⁶⁸ Ga-Ex-4. The use of polysorbate and cooling of the solution allows to decrease the adsorption on the reaction vial (from 29 to 2% of total activity remaining on the vial). ⁶⁸ Ga-Ex-4 is purified on a HLB cartridge. Final product was obtained within 40 minutes, with a mean radiochemical purity of 97% and a production yield of 67%. Conclusions We have successfully developed a new radiolabeling method for [ ⁶⁸ Ga]Ga-NODAGA-[40Lys]Exendin-4, automated on a miniAllinOne synthesizer and using sodium acetate buffer, suitable for clinical application.