Targeted therapy may be used instead of or together with chemotherapy as a treatment for cancer. This treatment uses drugs that work in a different way to chemotherapy drugs. While chemotherapy affects all rapidly dividing cells and works by killing cancerous cells (cytotoxic), targeted therapy targets specific molecules within cells and often works by blocking cell growth (cytostatic).
Although targeted therapy minimises harm to healthy cells, it can still have side effects. Not all cancers respond to targeted therapy, and the drugs are sometimes hard to access because they are expensive, not yet developed for all types of cancer, and sometimes available only in clinical trials.
Cancer cells often become resistant to targeted therapy drugs. If this happens, your doctor will change your treatment and may suggest trying chemotherapy or another type of targeted therapy.
Topics on this page:
Types of targeted therapy
There are currently two main types of targeted therapy: monoclonal antibodies and small molecule inhibitors.
- Act like the natural antibodies that our bodies produce to fight infection and disease but are made in a laboratory (synthetic)
- Lock onto a protein on the surface of certain cells and interfere with the growth or survival of cancer cells in some way, e.g. may deliver a toxic drug to cancer cells, interrupt the growth and spread of cancer cells, or prompt cells of the immune system to attack cancer cells
- Given intravenously or as an injection under the skin (subcutaneous injection)
- Drug names end in ‘-mab’ (for monoclonal antibody), e.g. bevacizumab, rituximab
Small molecule inhibitors
- Can get inside cancer cells and block certain proteins and enzymes that tell the cancer cells to grow
- Include tyrosine kinase inhibitors (TKIs) – these block the function of a group of enzymes called tyrosine kinases, which tell cancer cells to grow, multiply and spread
- Given as tablets or capsules to be taken by mouth, usually on a daily basis over months or years
- Drug names end in ‘-ib’ (for inhibitor), e.g. imatinib, sorafenib
Side effects of targeted therapy
Side effects vary depending on the targeted therapy used, but may include:
- allergic reactions
- blood-clotting problems
- blood pressure changes.
Particular targeted therapy drugs can affect the way your heart or liver works. Some side effects that are of little concern after standard chemotherapy can be very serious if they occur with a targeted therapy – your doctor will explain what to watch out for, and will monitor you throughout treatment.