Drug control of solid tumour metastases: a critical view.

Metastasis of solid tumours represent the target of election for the pharmacological treatment of cancer. Nevertheless, commonly used treatments do not represent any selective approach, provided that drugs are mostly unspecific cytotoxics. Today many strategies adopted to interfere with metastasis growth concern the interaction with biological signals of the metastatic cells or of the host. One difference should be made between anti-metastatic and anti-metastasis drugs, in that only the latter realise the goal of selectively destroying metastasis wherever they are. In this context many agents active on newly identified molecular targets are more effective in preventing metastasis formation than in inhibiting their growth. NAMI-A, an innovative ruthenium compound, seems to provide optimism for the future and, in laboratory models, it is very active on lung metastases independently of the stage of their growth. The success of NAMI-A against metastasis should stimulate laboratory studies with appropriate experimental models to predict clinical activity, since the use of experimental conditions closely similar to those of human tumours should help the identification of more active compounds.