University of California San Francisco
Helen Diller Family Comprehensive Cancer Center

Breast Cancer Lab Discoveries Quickly Lead to New Clinical Trial

By Jeffrey Norris, UCSF Science Cafe | March 3, 2010

A new strategy for treating a common form of breast cancer has emerged from lab studies by UCSF oncologist Mark Moasser, MD. Clinical trials to evaluate the treatment approach already are underway at the UCSF Helen Diller Family Comprehensive Cancer Center.

The protocol being evaluated calls for giving women intermittent, higher-than-standard dosages of a newer biological agent used to fight breast cancer.

The strategy derives from new discoveries by Moasser's lab team related to a major target in breast cancer that drives tumor growth in about one-in-four women with the disease.

Moasser's enthusiasm for new treatment ideas that are emerging from scientists' success in probing cancer cells was on display recently when he presented new research results to scientists and breast cancer advocates at an annual symposium organized by the Cancer Center's Breast Oncology Program.

The approach of using larger drug dosages with breaks in between is based on what Moasser has learned about a protein called HER2 and its associates. HER2 and its protein partner HER3 make up a biochemical team that functions to regulate growth signals.

Due to genetic mutations, the cells of "HER2-positive" breast tumors make abnormally high amounts of HER2. This abnormality helps stimulate the growth of these breast cancers.

The first drug developed to target HER2 was Herceptin, which was approved by the US Food and Drug Administration in 1998. It has become a standard treatment for HER2-positive breast cancer. Herceptin was the first approved biological treatment developed to target a specific abnormality in breast cancer. By attaching to HER2, Herceptin inhibits HER2's effectiveness in relaying growth signals.

Read more at Jeffrey Norris, UCSF Science Cafe