In a recent study, researchers found that the new drug trastuzumab emtansine (T-DM1) worked better to control the growth of HER2-positive metastatic breast cancer than the current standard treatment. HER2-positive metastatic breast cancer is breast cancer that has spread to other parts of the body and has too much of a protein called human epidermal growth factor receptor 2 (HER2). The current standard treatment for this type of breast cancer is chemotherapy with capecitabine (Xeloda) combined with the targeted therapy lapatinib (Tykerb). Targeted therapy is a treatment that targets the cancer's specific genes, proteins, or the tissue environment that contributes to cancer growth and survival.
Lapatinib and trastuzumab (Herceptin) are targeted therapies used for breast cancer treatment that specifically target HER2. This new drug, trastuzumab emtansine, is a combination of two types of drugs, one that targets HER2 and one that is more similar to chemotherapy.
In this study, nearly 1,000 patients with metastatic HER2-positive breast cancer who had already received chemotherapy and treatment with trastuzumab received either trastuzumab emtansine or capecitabine plus lapatinib every three weeks until the cancer worsened or the side effects became severe. For the patients receiving trastuzumab emtansine, the cancer worsened about three months later than those receiving capecitabine and lapatinib. After two years, about 65% of the patients receiving trastuzumab emtansine were living with their disease, compared with about 48% of those receiving capecitabine and lapatinib.
The most common severe side effects for patients receiving trastuzumab emtansine were thrombocytopenia (low levels of platelets, the cells that help the blood to clot) and signs of liver function problems. However, these side effects went away with a break in treatment. Patients receiving capecitabine and lapatinib were more likely to need the dose of treatment reduced because of the side effects, which included diarrhea, vomiting, and hand-foot syndrome (redness, swelling, and pain on the palms of the hands or the soles of the feet)
What this means for patients
“The drug worked significantly better than a very effective approved therapy for HER2-positive metastatic breast cancer,” said lead author Kimberly L. Blackwell, MD, Professor of Medicine and Assistant Professor of Radiation Oncology at Duke Cancer Institute at Duke University in North Carolina. “Also, as a doctor who takes care of a lot of patients with breast cancer, I'm pleased that this drug has very few side effects. For patients facing metastatic breast cancer, this is a breakthrough.” Trastuzumab emtansine is currently only available in clinical trials. Talk with your doctor about all treatment options available to you, including clinical trials.
Questions to Ask Your Doctor
- What type of breast cancer do I have? What is the stage?
- Is my cancer HER2-positive? What does this mean?
- What are my treatment options?
- What treatment plan do you recommend? Why?
- What clinical trials are open to me?
- What are the side effects of treatment? How will they be managed?
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