On November 15, the FDA expanded the approved use of trastuzumab (Herceptin) for the treatment of HER2-positive breast cancer after lumpectomy or mastectomy.

Trastuzumab is a targeted therapy against the HER2 protein on cancer cells. When an excessive amount of HER2 protein is present, it causes cancer cells to grow more rapidly and standard chemotherapy may be less effective. In 1998, the FDA approved trastuzumab for the treatment of metastatic breast cancer. This approval expands its use to women with cancer only in the breast or lymph nodes which has been removed with surgery. Additional information about trastuzumab is available at http://www.cancer.gov/cancertopics/druginfo/fda-trastuzumab.

The two studies leading to this new approved indication were conducted by the NCI-sponsored Cooperative Groups, a multicenter clinical trials group. Patients in both trials received standard chemotherapy after surgery for breast cancer; approximately half the patients were also given trastuzumab. The results from both trials, which included information on nearly 4,000 women, were combined and analyzed in 2005.

Due to positive results, NCI ended the studies early. The results showed that women who received trastuzumab combined with chemotherapy had fewer relapses for up to 3 years after surgery. The estimated 3-year disease-free rates were 87 percent in women receiving trastuzumab and chemotherapy and 75 percent in those receiving chemotherapy alone. It is too soon to know whether trastuzumab combined with chemotherapy will increase the cure rate or lower the risk of death from breast cancer.