Cancer chemotherapy is almost always applied to patients with one or more diagnosed
metastases and is expected to impact these lesions, thus providing significant benefits to the patient. The outcome of
metastasis is determined by the interplay between the specific subpopulation of metastatic cells and host homeostatic factors in specific microenvironments. In clinical practice,
metal-based drugs are represented by
platinum compounds, which are constituents of a wide variety of chemotherapeutic regimens, and are only rarely active against tumour
metastases unless they are combined with drugs that target specific pathways characterizing the
malignancy of the tested tumour. On experimental grounds, a number of complexes based on
ruthenium and other metals have been frequently studied in vitro using models and experimental conditions mimicking one or more steps of the metastatic process, such as invasion and migration. The
ruthenium-based
drug,
NAMI-A, is the only one to have been subject to clinical testing for the treatment of metastatic tumours. The capacity of
NAMI-A to modulate the relationship established between metastatic cells and their microenvironment suggests that
metal-based drugs shall be viewed as an opportunity for the treatment of tumour
metastases.