Wednesday, September 23, 2015

Biomarker may predict which HER2-negative breast cancer patients will benefit from targeted therapy

CANCER DIGEST – Sept. 22, 2015 – A new study has demonstrated that brief exposure to a targeted therapy can tell doctors which HER2-negative patients will respond — and which should switch to another kind of treatment.

If confirmed in clinical trials, the biomarker would provide physicians invaluable information regarding the effectiveness of Avastin (bevacizumab). Such early results would spare patients weeks of the medication’s sometimes severe side effects, not to mention its high cost, and allow them to pursue options with greater chances for success. The multi-center team led by Case Western Reserve published its findings in this month’s International Journal of Cancer.

Avastin is one of the most expensive drugs currently marketed. In many countries with national health services, the use of bevacizumab has been restricted based on cost-benefit calculations that suggest the drug is not cost-effective. The current cost of Avastin therapy is around $2,838 per month.

Nevertheless, some breast cancer patients achieve a significant survival benefit from bevacizumab while others do not.  Consequently Lyndsay Harris, MD, Professor of Medicine and colleagues along with researchers from Brown University, Yale University, and Philips Research North America collaborated in a research study to find a way to tell early on whether bevacizumab might work.

In the study, researchers examined tumor tissue from HER2-negative breast cancer patients before therapy began. Then patients received a single dose of bevacizumab, and 10 to 14 days later, tumor tissue was collected again and examined. They found that tumors that showed a decrease in the activity of a signaling molecule called TGF-beta, was associated with a more than 90 percent cure rate for those patients.

Avastin was FDA approved in 2008 as an anti-angiogenesis agent that blocks the blood vessel formation tumors needs to grow. It was hailed at the time as a significant advance in breast cancer therapy, however, long term follow-up clinical trials showed no improvement in overall survival as compared to other chemotherapy drugs, and thus the FDA retracted approval of bevacizumab for breast cancer in 2011. 

“Our finding is not so much about the single drug,” Harris said. “What matters most is we can identify biomarkers to help us select therapy properly. In our study, we have found this signature to be specifically useful in response to bevacizumab, but it may be useful in predicting response to other anti-angiogenic agents as well and should be tested.”

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