Aluminum-[18 F]Fluoride Radiolabeling Optimization by Design of Experiments Approach

International audienceAimFluorine-18 (18F) is the most favorable positron emitter for tumor imaging. However, direct 18F-labeling of biomolecules is challenging as it involves multiple steps and stringent conditions that are generally not suitable for biomolecules whose integrity may be altered. Over the past decade, an elegant new approach has been developed by coordination of aluminum fluoride {Al-18F}. The objective of this work was to optimize radiolabeling yield by applying a Design of Experiments (DoE) approach. MethodsTo evaluate {Al-18F} complexation, NODA-MP-C4 was prepared as a model compound from the commercially available NODA-MP-NCS. This model bears a thiourea function to mimic that present in the final conjugates. The corresponding radioactive complex Al18F-NODA-MP-C4 was obtained following the most common reported radiofluorination conditions (acetate buffer, reflux). DoE was designed and analyzed using Ellistat® software (v6.8). Based on extensive reported results and our previous work, three experimental factors were investigated: pH, NODA concentration ([NODA]) and NODA/aluminium ratio (NODA/Al). ResultsThe three factors studied (pH, [NODA], NODA/Al) were found to be significant. No interaction between factors was found significant in this model. Statistics gave R² adjusted and R² predicted to be 81.8 % and 73.1 % respectively, suggesting a valid and predictive model. Optimal set of conditions were pH = 4.5, [NODA] = 465 µM and NODA/Al = 1:1. The set of three runs gave respectively 80.4, 75.9 and 79.1 % of radiolabeling yield (78.5 % ± 2.3 % (n= 3)), demonstrating the robustness of these conditions, and giving the highest radiolabeling yield obtained so far.ConclusionsRadiolabeling optimization by using a DoE approach was obtained with a satisfactory yield while reducing the number of experiments and improving radioprotection of workers