Development of Trackable Anticancer Agents Based on Metal Complexes

The design of trackable anticancer agents is of major interest for the future development of therapeutics based on nonplatinum metal complexes such as Ru(II), Os(II), or Au(I) derivatives, and more particularly for the understanding of the mechanism of action of these metal-based drugs. This review reports the synthesis and the first biological studies of original trackable complexes, in which the metal complex was coupled to an imaging probe, such as a fluorophore (coumarin, borodipyrromethene derivative (BODIPY), porphyrin), or a chelating agent (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)) for radioisotopic imaging PET (positron emission tomography) or SPECT (single photon emission computed tomography). In the case of fluorescent theranostics, the photophysical properties of the different compounds were studied and the cell uptake could be evaluated on different cell lines, by microscopy imaging. A fluorescent smart probe based on coumarin-phosphine, whose fluorescence strongly depends on the coordination of the metal was also studied, revealing a nonusual cellular target with respect to the classical gold therapeutic systems. In the last section, the synthesis of new potential fluorescent trackable-radiotherapeutics is also presented.