Herceptin and Breast Cancer

James Metz, MD
Abramson Cancer Center of the University of Pennsylvania
Last Modified: November 1, 2001

Herceptin is a monoclonal antibody that was approved by the Food and Drug Administration for the treatment of a special type ofmetastatic breast cancer in September of 1998. It is directed at those breast cancers, which overexpress a specific protein on the surfaceof the cancer cell. This protein is called HER-2/neu (pronounced Her Two New). It is found to be overexpressed in about 30% ofbreast cancers. Those cancers that overexpress HER-2/neu may be more aggressive than those that do not.

Recent studies have shown Herceptin to be of benefit to patients with metastatic breast cancer who have overexpression of HER-2/neu. One study of metastatic breast cancer patients receiving doxorubicin-cyclophosphamide (AC) or paclitaxol chemotherapy randomizedpatients to receive Herceptin along with the other drugs or no additional therapy. There were significant improvements in time todisease progression and response rates in the group that received Herceptin in addition to the other chemotherapy.

Acute side effects of Herceptin included fever and chills. There has also been an increased incidence of gastrointestinal problems suchas diarrhea when given in combination with chemotherapy. One major side effect of concern is an increased risk of cardiac toxicitywhen Herceptin is combined with anthracycline based chemotherapy. A study showed 27% percent of patients experienced cardiactoxicity compared with only 7% of those taking anthracycline alone and 11% of those taking the paclitaxol and Herceptin combination.Since this is a new treatment, more side effects may become evident as increased numbers of patients utilize the treatment.

Herceptin is currently being evaluated as a treatment for other solid tumors with overexpression of HER-2/neu. Herceptin is onlyapproved for the treatment of certain types of breast cancer, but there are a number of studies evaluating other cancers. Patients who areinterested in this new treatment should ask their physician if they are eligible to participate in the ongoing clinical trials.