The breast cancer drug pertuzumab when added to Herceptin improved the treatment of women with early-stage, HER-2 positive breast cancer, researchers reported Friday at the annual meeting of the San Antonio Breast Cancer Symposium.
Pertuzumab is an experimental monoclonal antibody. In the study, 417 women received monoclonal antibody drug therapy before having surgery to remove the tumor. Some women also underwent chemotherapy.
Adding pertuzumab to Herceptin -- which is also known by the generic name trastuzumab -- along with the chemotherapy drug docetaxel led to a tumor eradication rate of 46%. That is 50% better than the tumor eradication rate achieved with the standard therapy of docetaxel and Herceptin combined, said the authors of the paper, from the National Cancer Institute in Milan, Italy. In 17% of the cases, the combination of Herceptin and pertuzumab alone, without chemotherapy, destroyed the tumor.
Herceptin is also a monoclonal antibody. These drugs don't cause the side effects seen with chemotherapy. Both Herceptin and pertuzumab block the function of the HER-2 protein that contributes to cancer development, but they work on different pathways. Women who do not experience a good response to one drug may fare better with a combination of monoclonal antibodies, researchers said.