Targeted cancer drugs work by ‘targeting’ those differences that help a cancer cell to survive and grow. Find out what they are and when you might have this treatment.
How they work
Cancer cells have changes in their genes (DNA) that make them different from normal cells. These changes mean that they behave differently. Cancer cells can grow faster than normal cells and sometimes spread. Targeted cancer drugs work by ‘targeting’ those differences that a cancer cell has.
The changes in genes that cause one cancer type are often different to the genetic changes causing another. For example, the changes that make a lung cancer grow can be different to ones that make a breast cancer grow. And the changes in the genes of one person who has lung cancer might be different to the changes in someone else with lung cancer.
Targeted drugs target those differences that help a cancer to grow. There are many different targets on cancer cells and different drugs that target them.
Different ways of working
Targeted drugs might:
- stop cancer cells from dividing and growing
- seek out cancer cells and kill them
- encourage the immune system to attack cancer cells
- stop cancers from growing blood vessels
- help carry other treatments such as chemotherapy, directly to the cancer cells
You might hear some targeted drugs called biological therapies.
Why you might have targeted drug therapy
Targeted drugs are not suitable for all types of cancers. They are one of the main treatment for some cancers. For example, melanoma and some types of leukaemia. And they are in clinical trials for other types of cancer.
Whether you have targeted therapy depends on:
- the type of cancer you have
- how far your cancer has spread (the stage)
- other cancer treatments you’ve had
Before you have some types of targeted drugs you might need to have tests using some of your cancer cells or a blood sample to find out whether the treatment is likely to work. These tests look for changes in certain proteins or genes.
Your consultant can tell you if this applies to your treatment. This is not the case for all targeted drugs and you don’t always need this test.
To test your cancer cells, your consultant needs a sample (biopsy) of your cancer. They might be able to use some tissue from a biopsy or operation you have already had.
You might have a targeted drug with other treatments, such as chemotherapy and radiotherapy. Or you might have it on its own.
Types of targeted drugs
There are many different types of targeted drugs that can be grouped according to the effect they have. So for example, cancer growth blockers stop the proteins that trigger the cancer cell to divide and grow.
Some targeted drugs stop cancers from growing blood vessels. A cancer needs a good blood supply to provide itself with food and oxygen and to remove waste products. The process of growing new blood vessels is called angiogenesis. Anti angiogenic drugs can slow the growth of the cancer and sometimes shrink it.
Other groups include a particular type of drug, such as a monoclonal antibody. These target specific proteins on cancer cells.
There isn't a simple way of grouping targeted drugs that is easy to follow. This can sometimes be confusing. Some drugs belong to more than one group because they work in more than one way. For example, a drug that works by blocking cancer cell growth may also be a monoclonal antibody.
Some monoclonal antibodies trigger the immune system to attack and kill cancer cells. So these monoclonal antibodies are also a type of immunotherapy.
For ease, we have grouped targeted drug therapy into:
- monoclonal antibodies
- cancer growth blockers
- drugs that block cancer blood vessel growth
- PARP inhibitors
Ask your specialist about targeted drugs. They can explain:
- whether this treatment is suitable for you
- what the aim of treatment would be
- what it would involve and the side effects