Contrary to what many oncologists had thought, a tumor suppressor protein known as PTEN does not reduce the effectiveness of the breast cancer drug Herceptin, according to a study by Mayo Clinic and North Central Cancer Research Group (NCCTG) investigators.
“This is the largest study to date evaluating PTEN’s presence or loss in the context of antiHER2 therapy, and we found no connection,” says the study’s lead investigator, oncologist Edith Perez, M.D., director of the Breast Clinic at Mayo Clinic in Jacksonville, Fla., and the Serene M. and Frances C. Durling Professor. “Our research team is very pleased to be able to test an important question in treatment of breast cancer and arrive at a definitive answer.”
Preclinical studies and some small patient studies had suggested that tumors with loss of PTEN expression would not benefit from Herceptin, Dr. Perez says. As a result, investigators were considering using PTEN biomarkers in clinical studies as a test of Herceptin resistance, and patients who tested positive for PTEN loss might then be offered other therapies, or invited to participate in clinical trials.
The researchers presented their findings during the American Society of Clinical Oncology Annual Meeting in Chicago.
Below is a link to an edited youtube video with Dr. Perez.