Bone-seeking radiopharmaceuticals based on phosphonic acids and 68Ga (review)

Bone metastases cause severe bone pain, growing with solid tumor progression, and lead to significant decreasing patients quality of life. Nowadays positron emission tomography (PET) is the most informative method of radionuclide imaging. PET is highly sensitive non-invasive method of visualization of biochemical and molecular processes in the body. It enables to detect tumor lesions when structure changes are not determined or are not specific. Now radiopharmaceuticals based on 18F are available for bone metastases detection by PET. Their major disadvantage is cyclotron-based synthesis of 18F that limits the application of 18F-containing radiopharmaceuticals. During the last 15-17 years the interest in 68Ga has increased drastically around the world. 68Ga is the promising generator-based radionuclide with appropriate nuclear properties (Т1/2=68 min, b+=89%, E+bmax=1,9 MeV) for radiosynthesis of a broad spectrum of radiopharmaceuticals. In this work nuclear-physical, chemical and biological properties of gallium-68 (68Ga) are presented. The approaches to synthesis of new bone-seeking compounds based on phosphonic acids and 68Ga are highlighted in detail. Thorough data about experimental studies and clinical application of the most promising compounds are also shown in this article.