Breast Cancer: Study Reveals New Drug Target

by VR Sreeraman on Nov 10 2007 6:59 PM

Researchers have identified a new target for drugs to help treat the most common form of breast cancer in the developing world, a study released Thursday said.

The target is a molecular "switch" in the protein-making machinery of the cancer cell that enables a tumor to aggressively develop its own blood supply.

Women with what is called locally advanced breast cancer can develop tumors that grow anywhere from 2 centimeters to 10 centimeters in diameter.

The tumors are unusually large in many cases -- they are often the size of a plum by the time they are diagnosed -- due to the extremely dense network of blood vessels feeding them oxygen and nutrients.

"Our study shows that an unusual molecular switch occurs that is essential for the development of these large tumors. We think that this switch could be a target for new therapies," said Robert Schneider, professor of molecular pathogenesis at New York University School of Medicine.

In a paper in the journal Molecular Cell, Schneider and colleagues at New York University School of Medicine describe how two proteins (4E-BP1 and eIF4G) which are present at elevated levels in locally advanced breast cancer cells selectively increase the action of certain messenger, or mRNA, molecules.

The effect of that process is to increase several fold the production of certain growth factors that drive tumor angiogenesis -- the formation of the tumor's own blood vessels.

"The switch gives us the ability to shut off production of growth factors in the tumor at their source," said Schneider.

He said several experimental drugs were in development that would target the "switch," with a view to curbing its growth.

If the drugs are shown to be successful in clinical trials, they could eventually be combined with a cocktail of chemotherapy drugs to eliminate the malignancy.

"This research opens new avenues for the development of targeted approaches in the treatment of one of the most common lethal forms of breast cancer worldwide," said Silvia Formenti, a co-author and professor of radiation oncology at NYU School of Medicine.

The researchers are also hopeful that the two proteins that are over-expressed or super abundant in locally advanced breast cancer cells could serve as a biomarker for this type of cancer, making it easier to screen for.

Early indications are that it is a reliable guide to the presence of this cancer 85 percent of the time, Schneider said.

Locally advanced breast cancer accounts for about 50 percent of breast cancer cases in developing nations. Patients often have a high level of treatment failure because the cancer is so far advanced by the time it is detected.