Targeting the core program of metastasis with a novel drug combination.

BACKGROUND: We previously reported that metastases are generally characterized by a core program of gene expression that activates tissue remodeling/vascularization, alters ion homeostasis, induces the oxidative metabolism, and silences extracellular matrix interactions. This core program distinguishes metastases from their originating primary tumors as well as from their destination host tissues. Therefore, the gene products involved are potential targets for anti-metastasis drug treatment.

METHODS: Because the silencing of extracellular matrix interactions predisposes to anoiks in the absence of active survival mechanisms, we tested inhibitors against the other three components.

RESULTS: Individually, the low-specificity VEGFR blocker pazopanib (in vivo combined with marimastat), the antioxidant dimethyl sulfoxide (or the substitute atovaquone, which is approved for internal administration), and the ionic modulators bumetanide and tetrathiomolybdate inhibited soft agar colony formation by breast and pancreatic cancer cell lines. The individual candidate agents have a record of use in humans (with limited efficacy when administered individually) and are available for repurposing. In combination, the effects of these drugs were additive or synergistic. In two mouse models of cancer (utilizing 4T1 cells or B16-F10 cells), the combination treatment with these medications, applied immediately (to prevent metastasis formation) or after a delay (to suppress established metastases), dramatically reduced the occurrence of disseminated foci.

CONCLUSIONS: The combination of tissue remodeling inhibitors, suppressors of the oxidative metabolism, and ion homeostasis modulators has very strong promise for the treatment of metastases by multiple cancers.