In addition to chemotherapy, another systemic treatment for invasive ductal carcinoma (IDC) is HER2 targeted therapy. Go to “Hormone Receptor Status of Invasive Ductal Carcinoma” to learn more about HER2 receptor status, which determines the need for HER2 targeted therapy to treat breast cancer. If your cancer tests positive for HER2 proteins, HER2 targeted therapy is almost always included in the treatment plan. HER2 targeted therapy is usually combined with or follows chemotherapy and radiation therapy treatments, unless these other systemic and localized treatments are not necessary.
Invasive ductal carcinoma cells that are HER2 positive make too much of the HER2 protein which is triggered by the presence of HER2 genes. The surface of these cells may also have an excessive quantity of HER2 receptors. Having too many receptors causes the breast cancer cells to receive too many growth signals, which causes them to start growing rapidly. The most effective way to stop, or at least slowdown, this growth process is to block the receptors on the cells’ surface to reduce the number of growth signals they receive. The two primary treatments that serve this purpose are Herceptin (trastuzumab), Tykerb/Tyverb (lapatinib), and Perjata (pertuzumab).
Herceptin is administered intravenously weekly for at least one year, although treatment can continue after that point is indicated. Herceptin works on the surface of the cancer cells to block the otherwise uncontrolled cell growth. Herceptin can be used to 25% of breast cancer cases that come back as HER2 positive. In situations where the invasive ductal carcinoma is advanced, Herceptin may be administered prior to surgery to help with the process of shrinking the tumors. Herceptin does have a known risk of causing heart damage, so it is not the first recommended treatment for individuals who have specific heart conditions or other heart-related risks. It is also not advisable for Herceptin to be administered with other chemotherapy medications that are known to possibly cause damage to the heart.
Tykerb is a form of anti-HER2 therapy that works within the cells, as opposed to the cell surface like Herceptin. Within HER2 positive breast cancer cells, protein signals are used by the HER2 receptors to cause these cells to divide and grow abnormally. These protein signals are called kinases. These kinases have control over the number of energy cells have to multiply and grow. The breast cancer cells that express too much HER2 can possibly have an excessive amount of kinase activity, which causes the cancer cells to grow too rapidly. The way Tykerb works is by interfering with the HER2-related kinases within the cell, which limits the availability of energy these breast cancer cells have to multiply and grow. Tykerb is administered orally. It has received U.S. Food and Drug Administration (FDA) approval to:
- Be given concurrently with the chemotherapy medication Xeloda (capecitabine) for the treatment of advanced stage breast cancer that is HER2 positive and has stopped being responsive to anthracyclines, Herceptin, and taxanes.
- Be given concurrently with the hormonal therapy medicine Femara (letrozole) for the treatment of postmenopausal women who have been diagnosed with cancer that is hormone-receptor-positive, HER2 positive, and metastatic.
The medication Perjeta works similarly to Herceptin by blocking breast cancer cells from receiving growth signals by attaching itself to HER2 receptors on the surface of these cells. Since Perjeta and Herceptin target different areas of the HER2 receptor, it is believed that the two medicines work in a way that compliments one another. Perjeta is administered intravenously, and it has received FDA approval for use in conjunction with the chemotherapy drug Taxotere (docetaxel) and Herceptin for the treatment of HER2 positive breast cancer that is also metastatic and has not yet received treatment with chemotherapy or Herceptin.
There are additional therapies that are targeted to work on specific cancer cell growth processes. These are similar to hormonal and HER2 targeted therapies, as they all interfere with the specific processes used to grow and thrive by breast cancer cells. One example of this is Avastin (bevacizumab), which is a medication used to target the vascular endothelial growth factor (VEGF) protein. This particular protein has a key role in the stimulation of the process cancer cells utilize in the creation of new blood vessels. This process is known as angiogenesis. In order to grow and thrive, cancer cells need to create new blood vessels in order to get the nutrients and oxygen they need. Sometimes Avastin is used alongside the chemotherapy drug Taxol (paclitaxel) for the treatment of advanced breast cancer.
There are new targeted therapy medications currently being studied in a number of clinical trials.