NEW HAVEN, Conn., Feb. 21 (UPI) -- U.S. scientists have found genetic markers that identify breast cancer subtypes resistant to Herceptin, a primary treatment for HER2-positive breast cancer.
The Yale and Harvard universities scientists say their findings could help refine therapy for cancer patients with that class of tumor.
The researchers discovered HER2-positive tumors that did not respond to Herceptin expressed certain basal markers, growth factors and growth factor receptors. One of those, insulin-growth factor receptor, or IGF-1R, was associated with a Herceptin response rate that was half that of tumors not expressing IGF-1R.
The researchers also determined resistant tumors continue to over-express the HER2 growth factor protein. That, said the scientists, is a significant finding given that many scientists had thought loss of HER2 was likely responsible for Herceptin resistance.
Yale Associate Professor Dr. Lyndsay Harris said the findings might make it possible to identify Herceptin resistant patients and treat them with additional drugs to restore their Herceptin sensitivity.
"Our goal is to see what the tumor tells us before any treatment starts and tailor therapy accordingly," she said.
The study appears in the journal of Clinical Cancer Research.
