Mechanism of gallium-67 uptake in tumors

Gallium-67 formulation, giving only 43% citratogallate-67 in physiological saline, has been found to show specific uptake of the radionuclide in tumours, with neglegible localization in normal organs. Chromatographic and electrophoretic examinations of gallium-67 species in the above formulation shows that gallium-67 is loosely bound. This relatively free gallium-67 is transported to the tumour by transferrin, forming a weak bond, and in the tumour is firmly bound to ferritin or other subcellular organelles. The stability of gallium complexes with ferritin, citrate ion, and transferrin follow the order: gallium-ferritin>>gallium citrate > gallium-transferrin. (Author)