68Ga-labeled DOTA-2-deoxy-D-glucosamine as a potential radiotracer in μPET imaging

The purposes of this study were to develop an efficient method of labeling D-glucosamine hydrochloride with gallium 68 (68Ga) and investigate the imaging properties of the resulting radiotracer in a human tumor xenograft model using micro-positron emission tomography (μPET). The precursor compound 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-2-deoxy-D-glucosamine (DOTA-DG) was synthesized from D-glucosamine hydrochloride and 2-(4-isothiocyanatobenzyl)-DOTA. Radiolabeling of DOTA-DG with 68Ga was achieved in 10 minutes using microwave heating. The labeling efficiency and radiochemical purity after purification of 68Ga-DOTA-DG were ~85% and greater than 98%, respectively. In A431 cells, the percentages of 68Ga-DOTA-DG and 18F-FDG uptakes after 60 min incubation were 15.7% and 16.2%, respectively. In vivo, the mean ± standard deviation of 68Ga-DOTADG uptake values in A431 tumors were 2.38±0.30, 0.75±0.13, and 0.39±0.04 percent of the injected dose per gram of tissue at 10, 30, and 60 minutes after intravenous injection, respectively. μPET imaging of A431-bearing mice clearly delineated tumors at 60 minutes after injection of 68Ga-DOTA-DG at a dose of 3.7 MBq. 68Ga-DOTA-DG displayed significantly higher tumor-to-heart, tumor-to-brain, and tumor-to-muscle ratios than 18F-FDG did. Further studies are needed to identify the mechanism of tumor uptake of this new glucosamine-based PET imaging tracer.