A new drug has been approved by the Food and Drug Administration (FDA) for the treatment of HER2 positive breast cancer. This new treatment drug, Kadcyla, combines traztuzumab (herceptin) with emtansine, a powerful chemotherapy agent.
HER2 positive breast cancer affects around 20-25% of women with breast cancer. HER (human epidermal growth factor receptor) -2 is a protein which influences the growth rate of certain cancer cells. Breast cancer cells can express a large of number of HER2 receptors which stimulate the cancer cells to grow and divide. HER2 positive breast cancers tend to be faster growing and have a poorer prognosis than HER2 negative breast cancers. Women diagnosed with breast cancer are tested for HER2 levels of the cancer cells and this is usually done by either Immunohistochemistry (IHC) or Fluorescent in-situ hybridisation (FISH). Treatment options include surgery (lumpectomy/mastectomy), chemotherapy or newly available targeted therapies.
The use of chemotherapy drugs can however be toxic in a number of individuals as the drugs do not spare normals cells as well as the cancer cells. A new drug therapy developed by Roche Genentech couples Herceptin, a monoclonal antibody, with emtansine, a potent chemotherapy drug. The drug, known as TDM-1, acts as a one-two punch with Herceptin initially binding to the HER2 protein, blocking the receptor and preventing the cancer cells from growing and dividing, followed by delivery of emtansine to the cancer cell destroying it from the inside out. The advantage of this therapy is that normal cells are not destroyed therefore limiting the toxic effects associated with chemotherapy alone. A phase III clinical trial found TDM-1 to have greater progression free survival when compared to treatment with two current chemotherapy drugs.
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