In the study, treating mice with the dual-target approach turned aggressive tumors with invasive fingers penetrating surrounding tissues and many metastases into tiny balls with few or no metastases.
"It's the combination of approaches—there's a synergy between the two," McDonald said. "You add two and two, and you get 10."
The two targets are both proteins that scientists have known for years are involved in cancer. Both play important roles in malignant tumors.
The first, called c-MET, is involved in two processes associated with the most deadly cancers. A clinical marker of cancer aggressiveness, c-MET drives tumor invasion into surrounding tissues. It is also involved in metastasis—the spread of cancer cells to other parts of the body where they can establish new tumors.
The second target is a protein known as vascular endothelial cell growth factor (VEGF). VEGF is a protein that promotes the growth of new blood vessels. Growing tumors hijack this process to expand their network of blood vessels to provide nutrients. Drugs blocking VEGF have been developed based on the simple assumption that tumors cannot grow if you choke off their blood supply.
Drugs that target these molecules are in development, and a few are already on the market. The U.S. Food and Drug Administration (FDA) approved the first of these in 2004 to treat metastatic colon cancer. That drug, called Avastin, is manufactured by the South San Francisco-based company Genentech. Avastin was approved for metastatic breast cancer in 2008 under the FDA's accelerated approval program.