Molecular Imaging of Mesothelioma with T99mc-ECG and G68a-ECG

We have developed ethylenedicysteine-glucosamine (ECG) as an alternative to 18F-fluoro-2-deoxy-D-glucose (18F-FDG) for cancer imaging. ECG localizes in the nuclear components of cells via the hexosamine biosynthetic pathway. This study was to evaluate the feasibility of imaging mesothelioma with T99mc-ECG and G68a-ECG. ECG was synthesized from thiazolidine-4-carboxylic acid and 1,3,4,6-tetra-O-acetyl-2-amino-D-glucopyranose, followed by reduction in sodium and liquid ammonia to yield ECG (52%). ECG was chelated with T99mc/tin (II) and G68a/69Ga chloride for in vitro and in vivo studies in mesothelioma. The highest tumor uptake of T99mc-ECG is 0.47 at 30 min post injection, and declined to 0.08 at 240 min post injection. Tumor uptake (%ID/g), tumor/lung, tumor/blood, and tumor/muscle count density ratios for T99mc-ECG (30–240 min) were 0.47±0.06 to 0.08±0.01; 0.71±0.07 to 0.85±0.04; 0.47±0.03 to 0.51±0.01, and 3.49±0.24 to 5.06±0.25; for G68a-ECG (15–60 min) were 0.70±0.06 to 0.92±0.08; 0.64±0.05 to 1.15±0.08; 0.42±0.03 to 0.67±0.07, and 3.84±0.52 to 7.00±1.42; for 18F-FDG (30–180 min) were 1.86±0.22 to 1.38±0.35; 3.18±0.44 to 2.92±0.34, 4.19±0.44 to 19.41±2.05 and 5.75±2.55 to 3.33±0.65, respectively. Tumor could be clearly visualized with T99mc-ECG and G68a-ECG in mesothelioma-bearing rats. T99mc-ECG and G68a-ECG showed increased uptake in mesothelioma, suggesting they may be useful in diagnosing mesothelioma and also monitoring therapeutic response.