A new type of therapy that prevents the metastatic spread of breast cancer in a mouse model of breast cancer is presented online this week in Nature Biotechnology. Although the safety and efficacy of this therapy needs to be researched before testing in humans, the study provides a proof of principle that could one day prove beneficial for treating breast cancer.
Metastasis is responsible for the vast majority of cancer related deaths, but several factors have hampered the development of therapeutics for patients with these secondary tumors. One problem has been insufficient understanding of the molecular mechanisms involved in cancer invasion and progression, as well as a resulting lack of targets for therapeutic intervention. Recently, there has been a focus on a class of nucleic acid molecules ― called microRNAs ― that are important in controlling the expression of genes in normal cells, but are also implicate in the development and progression of disease. Some microRNAs are key regulators of metastasis formation. In addition, a new type of drug termed antagomirs ― which are nucleic acid molecules capable of binding to complementary microRNA sequence ― have recently been described that can target specific cellular microRNAs for destruction.
Robert Weinberg and colleagues now show the feasibility of using antagomirs in cancer metastasis treatment. By inhibiting a pro-metastatic microRNA with intravenously injected antagomir, they prevent the establishment of new metastases from aggressive breast tumors in mice. Their antagomir therapy has no effect on the growth of the primary tumor or on established metastases, but reduces the number of newly formed metastases by about 80%.