Targeted therapies are the cornerstone of precision medicine, which uses information about your genes and proteins to prevent, diagnose and treat disease.
Cancer-directed targeted therapies focus on signaling cancer cell molecules that help them grow, divide and spread.
While most standard chemotherapies act on all rapidly dividing normal and cancerous cells, targeted therapies interact with specific targeted cell components. The targeted approach to treatment sometimes results in less chemotherapy-like side effects on normal tissues.
Examples of targeted therapies include:
- Small-molecule drugs: Small enough to enter cells easily, these pills or capsules are used to block cancer related molecules inside cells.
- Monoclonal antibodies: Because they aren’t able to enter cells easily, monoclonal antibodies attach to targets on the outer surface of cancer cells. Monoclonal antibodies are usually delivered through an IV.
How do targeted therapies work?
Most interfere with specific genes or proteins in the cancer cell; these help tumors grow and spread throughout the body. Targeted therapies can:
- Keep cancer cells from growing. Healthy cells naturally divide to make new cells when they get a signal. But some cancer cells have changes —mutations — in certain genes, telling them to divide whether or not they receive a signal. Certain targeted therapies interfere with these altered genes and their abnormal proteins, preventing them from telling the cells to divide. This helps slow down cancer’s uncontrolled growth.
- Help the immune system destroy cancer cells. Certain targeted therapies can mark cancer cells, allowing your immune system to recognize and destroy them.
- Interfere with signals that help form blood vessels. To grow beyond a certain size, tumors send signals to form new blood vessels. Some targeted therapies interfere with these signals, preventing a blood supply from forming, keeping tumors small. If a tumor already has a blood supply, these targeted treatments can cause blood vessels to die. And the tumor shrinks.
- Deliver cell-killing substances to cancer cells. When combined with toxins, chemotherapy drugs and radiation, monoclonal antibodies attach to targets on the surface of cancer cells. The cell-killing toxins are released and cause the cells to die. Cells without the target on the cell surface are generally not exposed to the toxic agent.
- Cause cancer cell death. Healthy cells die in an orderly fashion when damaged or no longer needed. But cancer cells avoid this dying process. Some targeted therapies can cause cancer cells to go through the process of cell death.
- Deprive cancer of the hormones it needs to grow. Some breast and prostate cancers need certain hormones to grow. Hormone therapies are a type of targeted therapy that can work in two ways: 1.) By preventing your body from making specific hormones. 2.) By preventing the hormones from acting on your cells, including cancer cells.
Who can receive targeted therapies?
Your Virginia G. Piper Cancer Care Network doctor can help you determine if targeted therapy is right for you.
Most of the time, your doctor will need to biopsy your tumor (remove a piece of it) to see if it has targets for which drugs have been developed. Many targeted therapies are used with advanced cancer. Some, however — such as hormonal therapy for breast and prostate cancers — are used in patients with early-stage cancer that has been removed by surgery or treated with radiation.
Length and frequency of treatment
It depends on:
- Your type and stage of cancer
- Your response to treatment
- The type of targeted therapy
You may have treatment every day, every week or every month. Some targeted therapies are given in cycles — a period of treatment followed by a period of rest. The rest period gives your body a chance to recover and build new healthy cells.
Your doctor will examine you to determine if the treatment is working. You'll also receive blood tests, X-rays and different types of scans.
Are there side effects with targeted therapies?
The side effects depend on the type of targeted therapy you receive and how your body reacts to it.
Some of the common side effects of targeted therapy can include diarrhea, skin rash or nausea. Other side effects can include:
- Problems with blood clotting and wound healing
- High blood pressure
- Mouth sores
- Nail changes
- Loss of hair color
- Elevated liver enzymes
- Very rarely, with certain targeted therapies, a hole (perforation) forming through the wall of the esophagus, stomach, small intestine, large bowel, rectum, or gallbladder
Not all side effects occur in all patients. Just like response to treatment, tolerance of treatment also varies from individual to individual. Doctors have medicines that may prevent the side effects or treat them if they do occur. Most side effects of targeted therapy go away after treatment ends.