Targeted Therapy

What Types of Targeted Therapy Are There?

There are two broad categories of targeted-therapy medication. The first, monoclonal antibodies, attach themselves to cell surfaces, blocking chemical interactions that are critical to the cancer’s health. The second form, small-molecule drugs, pass inside cells and bond with proteins to prevent them from performing their function. An example of a small-molecule drug is a tyrosine-kinase inhibitor.

Below is a more complete description of some targeted-therapy drugs:

Angiogenesis inhibitors: Angiogenesis inhibitors are medications that interfere with cancer’s ability to spur blood-vessel creation. They do this either as monoclonal antibodies or as tyrosine-kinase inhibitors. The goal of anti-angiogenic drugs is to gradually starve a tumor of oxygen and nutrients, leaving it weak and isolated. Angiogenesis inhibitors are used with a wide range of cancers.

Apoptosis-inducing drugs: Apoptosis is the medical name for a cell’s natural death process. Cancer cells have evolved ways of halting or delaying apoptosis that can be counteracted by medications. Apoptosis-inducing drugs can unblock the chemical signals that initiate the dying sequence. Some medications also weaken cancer by preventing the repair of the cell’s internal structures.

Hormonal therapies: Hormones are naturally produced chemical substances that help to regulate human physiology. Some cancers have developed an ability to use hormones as a stimulus for growth. Hormonal therapies deprive cancer cells of this fuel, either by blocking receptor sites or by reducing the body’s hormonal levels. These therapies are used chiefly with breast and prostate cancers.

Monoclonal antibodies: Monoclonal antibodies are lab-produced proteins with immunological properties. Most are taken intravenously and, once in the bloodstream, seek out cancer cells with signature mutations and then lock onto them to keep them from functioning properly. Monoclonal antibodies also force cancer cells to absorb the damaging effects of radiation and chemotherapy treatments.

Tyrosine-kinase inhibitors: Tyrosine kinases are enzymes that behave like power switches for cellular proteins. They’re especially important in controlling the growth of cells. Tyrosine kinases in cancer cells seem to be stuck in a permanent “on” position, causing these cells to reproduce more rapidly than normal ones. Tyrosine-kinase inhibitors block this behavior, reducing the growth stimulus supplied by cellular proteins.

mTOR inhibitors: mTOR inhibitors are similar to tyrosine-kinase inhibitors. mTOR is a protein in mammals that regulates cell growth and division. Cancerous versions of mTOR stimulate greater reproduction; mTOR inhibitors prevent this effect. mTOR inhibitors are often used with kidney and neuroendocrine cancers.

What Are the Side Effects of Targeted Therapy?

Targeted therapy tends to produce fewer or less severe side effects than chemotherapy and other cancer treatments but it isn’t without negative outcomes. Depending on the type of medication and other factors, you may experience one or more of the following:

• Fatigue and anemia
• Nausea and vomiting
• Bleeding
• High blood pressure (hypertension)
• Headaches and fevers
• Swelling
• Oral sores
• Allergic reactions
• Diarrhea or constipation
• Rashes, itchiness, and other skin problems
• Slow-healing cuts and wounds
• Hair loss
• Troubled breathing

More serious side effects include blood clots, secondary cancers, heart damage, and other major organ problems.