Synthesis and Preclinical Characterization of [(18)F]FPBZA: A Novel PET Probe for Melanoma

Introduction. Benzamide can specifically bind to melanoma cells. A (18)F-labeled benzamide derivative, [(18)F]N-(2-diethylaminoethyl)-4-[2-(2-(2-fluoroethoxy) ethoxy)ethoxy]benzamide ([(18)F]FPBZA), was developed as a promising PET probe for primary and metastatic melanoma. Methods. [(18)F]FPBZA was synthesized via a one-step radiofluorination in this study. The specific uptake of [(18)F]FPBZA was studied in B16F0 melanoma cells, A375 amelanotic melanoma cells, and NB-DNJ-pretreated B16F0 melanoma cells. The biological characterization of [(18)F]FPBZA was performed on mice bearing B16F0 melanoma, A375 amelanotic melanoma, or inflammation lesion. Results. [(18)F]FPBZA can be prepared efficiently with a yield of 40–50%. The uptake of [(18)F]FPBZA by B16F0 melanoma cells was significantly higher than those by A375 tumor cells and NB-DNJ-pretreated B16F0 melanoma cells. B16F0 melanoma displayed prominent uptake of [(18)F]FPBZA at 2 h (7.81 ± 0.82 %ID/g), compared with A375 tumor and inflammation lesion (3.00 ± 0.71 and 1.67 ± 0.56 %ID/g, resp.). [(18)F]FPBZA microPET scan clearly delineated B16F0 melanoma but not A375 tumor and inflammation lesion. In mice bearing pulmonary metastases, the lung radioactivity reached 4.77 ± 0.36 %ID/g at 2 h (versus 1.16 ± 0.23 %ID/g in normal mice). Conclusions. Our results suggested that [(18)F]FPBZA PET would provide a promising and specific approach for the detection of primary and metastatic melanoma lesions.