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Targeted (Biologic) Therapy

Updated January 1, 2012

Targeted therapies are medicines that fight cancer by finding and killing only cancer cells. They recognize a specific feature of the cancer cell, attach to it, and destroy it.

For example, if the breast cancer tests positive for HER2, you may be able to receive a targeted therapy that affects only HER2-positive cells. Other targeted treatments block the growth of blood vessels that some tumors need to grow.

Many forms of targeted therapy are being tested in clinical trials. They are given intravenously (by vein) or by mouth as a pill. Some treatments, such as trastuzumab (Herceptin), have already been approved by the U.S. Food and Drug Administration, but others are only available to participants in clinical trials.

Types of Targeted Therapy Medicines

Some targeted therapy medicines used in breast cancer treatment target HER proteins. Others target VEGF (Vascular Endothelial Growth Factor).

HER proteins

About 25 percent of breast cancers make too much of a protein known as HER2 (human epidermal growth factor receptor), which triggers rapid cell division and growth. HER2-positive cancers tend to be more aggressive than HER2-negative cancers, but targeting the protein has opened up new treatment options.

If the cancer is HER2 positive, then its cells make too much of a receptor protein called HER2. With too many receptors, breast cancer cells pick up too many growth signals and start growing too much and too fast.

The medicine trastuzumab (Herceptin) blocks the receptors so they do not pick up as many growth signals. Trastuzumab is the standard treatment for HER2-positive breast cancers. Other therapies that target HER2 are under study.

Treatment usually is given intravenously every week or every three weeks for 52 weeks after surgery. This medicine can cause damage to the heart, so it may not be recommended if you have certain heart conditions or heart-related risks. It cannot be given with other chemotherapy medicines that can affect the heart. Your heart function will need to be monitored before and during therapy. Talk to your treatment team about any concerns you may have related to heart health.

A newer targeted therapy called lapatinib (Tykerb) blocks the effect of HER2 and a related protein, HER1, by interfering with the pathway inside the cell instead of at its surface. This medicine is FDA approved in combination with other medicines for the treatment of metastatic (stage IV) HER2 positive breast cancer

Lapatinib appears to offer several benefits over trastuzumab: it is taken as a pill, instead of given by vein, and studies suggest it poses fewer risks to the heart. Side effects include diarrhea, redness and tingling in the hands and feet, rash, stomach upset, vomiting and fatigue.

VEGF (Vascular Endothelial Growth Factor)

To get the oxygen and nutrients they need to grow and spread, tumors create new blood vessels through a process called angiogenesis.

Bevacizumab (Avastin) is a medicine that targets the VEGF protein, which plays a key role in angiogenesis. It is not FDA approved for use in breast cancer, but it is approved for use against other types of cancers. It has been studied in metastatic (stage IV) breast cancer when given with paclitaxel (Taxol) in women who have not yet gotten chemotherapy. Your doctor might offer you this treatment through a clinical trial.

Bevacizumab can cause side effects such as high blood pressure and nosebleeds, and some studies suggest a slightly higher risk of stroke and other clotting and bleeding problems.

Read about the providers who helped us to write this page in our Guide for the Newly Diagnosed.

Section on types of targeted therapy medicines reviewed by Generosa Grana, MD