In fact, the drugs were so powerful that they shriveled tumors in mice that would have weighed several pounds in a human being. Unlike some anticancer drugs, though, endostatin and angiostatin do not harm normal cells. In addition, the new drugs suppress metastasis, the process by which tumor cells spread to other sites in the body. You always have the risk that something will fail. How the Drugs Work Scientists are excited about the new drugs because cancer is a difficult disease to treat with existing medicines.
Tumor cells can do things with their genes that are amazing.
They can shuffle their genetic information. They can amplify certain genes. They can turn off some genes and mutate others. Because you're dealing with a moving target, cancer can be hard to hit with a killing drug. In addition, conventional cancer therapies often cause severe side effects.