Discoveries
Investigators find drug shrinks breast tumors in mice
Almost one-third of the 190,000-plus breast cancers diagnosed in the United States each year are not fueled by the estrogen in women's bodies, so estrogen-blocking treatments like the drug tamoxifen don't stop them.
In a study offering new hope against such cancers, researchers at Dana-Farber report that, in mice, these "estrogen receptor-negative" (ER-) breast tumors were halted and shrunk by an investigational drug aimed at a new target in the cancer cells. Known as Go6976, the drug hits a crucial control point in cancer cells that allows them to grow when they shouldn't, and keeps them from dying when they should. The control point is a protein that normally is inactive in healthy cells, but which gets improperly activated in breast tumors that lack estrogen receptors. As a result, the cells are goaded into uncontrolled growth.
In the study, the drug was injected into mouse breast cancer cells implanted in the animals' skin. Go6976 prevented tumors from enlarging in 10 mice that received the medication soon after the cells were implanted. In 10 mice treated later with the drug, even large tumors stopped growing or shrank, the researchers found. When the rodents' lungs and livers were examined under a micro-scope, they showed no ill effects of treatment.
"This drug is inhibiting the growth of tumors and causing fully grown tumors to regress and go away, and the mice show no signs of toxicity," according to Debajit Biswas, PhD, who led the study with Arthur Pardee, PhD, both of the Department of Cancer Biology. Encouraging as the results are, the researchers caution that a great deal of work lies ahead before this approach can be tested in humans.
The study was published in Proceedings of the National Academy of Sciences.
