© 2005-2012 American Society of Clinical Oncology (ASCO). All rights reserved worldwide.
Adding lapatinib (Tykerb) to capecitabine (Xeloda) controls cancer growth more effectively than capecitabine alone in women with advanced breast cancer that continues to get worse despite treatment with trastuzumab (Herceptin), according to a new study. Capecitabine is approved by the U.S. Food and Drug Administration (FDA) to treat advanced breast cancer that has continued to grow despite prior therapy.
Women participating in this clinical trial were diagnosed with HER-2/neu-positive cancers, which are fast-growing and difficult to treat. Trastuzumab is the first approved drug to treat HER-2/neu-positive breast cancers; however, this drug stops working in some women. Lapatinib is a drug in the form of a pill taken by mouth. It works by blocking the HER-2/neu protein on the inside of the cancer cells, whereas trastuzumab blocks that protein on the outside of cancer cells.
"Trastuzumab is a very effective drug that has substantially improved the available treatments for women with metastatic breast cancer that produces large amounts of the HER-2/neu protein. However, because trastuzumab eventually stops controlling these cancers, there is a need for effective, alternative treatments that block the function of HER-2/neu in another way," said Charles E. Geyer, Jr., MD, Director of Breast Medical Oncology at Allegheny General Hospital in Pittsburgh and lead author of the study. "These results indicate that lapatinib can be effective in helping control the growth of breast cancers that are not being controlled by trastuzumab."
From March 2004 to November 2005, researchers compared the time it took for cancer to grow or spread between 160 women who received lapatinib plus capecitabine and 161 women who received capecitabine alone.
Lapatinib controlled the disease for nearly 37 weeks for the patients receiving lapatinib and capecitabine, compared with nearly 20 weeks for the patients taking only capecitabine. In addition, cancer spread to the brain in only four women treated with lapatinib, compared with 11 women who were not treated with capecitabine only. Side effects were generally similar between the two groups; however, more women receiving lapatinib experienced mild to moderate diarrhea (58%) compared with women who did not receive this drug (39%), and more women treated with lapatinib had a mild rash (30%), compared with the women who did not receive this drug (18%).
What This Means For Patients
For women with HER-2/neu-positive breast cancer that no longer responds to trastuzumab treatment, this study shows that lapatinib can delay the growth of cancer. However, it is too soon to know yet whether lapatinib treatment helps women live longer.