New Treatment Controls Breast Cancer Growth in Study

Article date: June 4, 2012

By Stacy Simon

Researchers have found that a new drug worked better than the standard treatment for keeping a type of advanced breast cancer from worsening. The drug, trastuzumab emtansine (T-DM1), is so far available only through clinical trials. Researchers presented their findings June 2 at the 48th annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago.

The study involved nearly 1,000 women with metastatic HER2-positive breast cancer. Metastatic means it has spread outside the breast to other parts of the body. HER2-positive means the breast cancer cells have too much of the protein human epidermal growth factor receptor 2 (HER2), and tend to grow and spread more aggressively. The women in the study had all stopped responding to the standard treatment for HER2-positive breast cancer, chemotherapy and Herceptin (trastuzumab).

Some of the patients in the study received the next level of standard drug treatment, capecitabine (Xeloda) plus lapatinib. The others received the new treatment, T-DM1. T-DM1 is made up of the Herceptin antibody linked to the toxic chemotherapy drug DM-1. With this drug, the antibody part acts as a homing device to deliver the chemotherapy drug directly to the cancer cell.

For those who received T-DM1, the cancer worsened about 3 months later than those who received the standard treatment. After 2 years, about 65% of the patients who received T-DM1 were still alive, compared to 48% of those who received the standard treatment.

The most common side effects of T-DM1 were low levels of platelets (cells that help the blood to clot), and abnormal lab tests of liver function. The side effects went away with a break in treatment. Side effects of the standard treatment (capecitabine plus lapatinib) included diarrhea, vomiting, and pain and swelling in the hands and feet.

Len Lichtenfeld, MD, deputy chief medical officer of the American Cancer Society, wrote in his blog that the findings have real implications for patient care. He wrote, “This is a large study, and it shows success in an area where there are few treatment options.”

Reviewed by: Members of the ACS Medical Content Staff

ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases. For reprint requests, please contact permissionrequest@cancer.org.