New insights into the cancer genome have led to many new targeted therapies for advanced breast cancer. This promising field of cancer treatment identifies and attacks cancer cells more effectively. Here are seven things you need to know about this new group of precision drugs.

1. What are targeted therapies?

Targeted therapies use information about your genes and proteins to prevent, diagnose, and treat cancer. The therapies aim to attack specific cancer cells without harming healthy cells.

2. How does targeted therapy differ from standard chemotherapy?

Standard chemotherapy works by killing both normal and rapidly dividing cancerous cells. Targeted therapies are designed to block the spread of molecular targets associated with cancer.

Cancer cells are different from healthy cells. Targeted therapies can detect cancerous cells and then destroy or impede their growth without harming non-cancerous cells. This type of treatment is considered a kind of chemotherapy, although it works differently. Targeted therapies also tend to have fewer side effects than standard chemotherapy drugs.

3. How are targeted therapies developed?

The first step in developing a targeted therapy is to identify molecular markers that play a key role in cancer cell growth and survival. Once a marker is identified, a therapy is developed that interferes with the production or survival of cancer cells. This can be done by either reducing the activity of the marker or preventing it from binding to a receptor it normally activates.

4. What are the approved targeted therapies and how do they work?

  • Hormone therapies slow or stop the growth of hormone-sensitive tumors that require certain hormones to grow.
  • Signal transduction inhibitors block the activities of molecules that participate in signal transduction, the process by which a cell responds to signals from its environment.
  • Gene expression modulators (GEM) modify the function of proteins that play a role in controlling gene expression.
  • Apoptosis inducers cause cancer cells to undergo apoptosis, the process of controlled cell death.
  • Angiogenesis inhibitors block the growth of new blood vessels, thereby restricting the blood supply necessary for tumors to grow.
  • Immunotherapies trigger the immune system to destroy cancer cells.
  • Monoclonal antibodies (mAb or moAb) deliver toxic molecules to target and kill specific cancer cells by behaving like a magnet to find and them and block their reproduction.

5. Who is a candidate for targeted therapy?

When the U.S. Food and Drug Administration approves a particular targeted therapy, they define the specific circumstances when it can be used. They also define who is a good fit for treatment. In general, targeted therapies are used to treat people who have a particular mutation that the treatment can detect. They work to destroy or inhibit the cancerous cells of that mutation. Targeted therapy may also be an option for people whose cancer did not respond to other therapies, has spread, or is not suitable for surgery.

6. Are there limitations of targeted therapy?

Cancer cells can become resistant by mutating so that the targeted therapy is no longer effective. If so, the tumor can find a new pathway to achieve growth that does not depend on the target. In some instances, targeted treatment may work best by combining two therapies or more traditional chemotherapy drugs.

7. What are the common side effects of targeted therapy?

The most common side effects of targeted therapies include:

  • weakness
  • nausea
  • vomiting
  • diarrhea
  • headaches
  • difficulty
  • breathing
  • rashes

Other side effects include hair depigmentation, problems with blood clotting and wound healing, and high blood pressure.