Radiosynthesis of a Novel PET Fluoronicotinamide for Melanoma Tumour PET Imaging; [18F]MEL050.

[¹⁸F]6-Fluoro-N-[2-(diethylamino)ethyl]nicotinamide [¹⁸F]MEL050 is a novel nicotinamide-based radiotracer, designed to target random metastatic dissemination of melanoma tumours by targeting melanin. Preclinical studies suggest that [¹⁸F]MEL050 has an excellent potential to improve diagnosis and staging of melanoma. Here we report the radiochemical optimization conditions of [¹⁸F]MEL050 and its large scale automated synthesis using a GE FXFN automated radiosynthesis module for clinical, phase-1 investigation. [¹⁸F]MEL050 was prepared via a one-step synthesis using no-carrier added K[¹⁸F]F-Krytpofix® 222 (DMSO, 170°C, 5min) followed by HPLC purification. Using 6-chloro-N-[2-(diethylamino)ethyl]nicotinamide as precursor, [¹⁸F]MEL050 was obtained in 40–46% radiochemical yield (nondecay corrected), in greater than 99.9% radiochemical purity and specific activity ranging from 240 to 325GBqμmol^-1. Total synthesis time including formulation was 40min and [¹⁸F]MEL050 was stable (99.8%) in PBS for 6h. [ABSTRACT FROM AUTHOR]