Targeted therapy and immunotherapy drugs for metastatic breast cancer
Cancer drugs can slow the growth and spread of metastatic breast cancer or control side-effects. Targeted therapies target certain parts of the cancer cells that make them different from other cells. Immunotherapy helps the body’s immune system recognise and attack cancer cells.
Targeted therapies for metastatic breast cancer
Targeted therapies work with your body. They can help fight cancer, stop it spreading or control side-effects.
Some targeted therapy drugs are given in tablet form. Others are given into a vein through a drip.
Types of targeted therapies for metastatic breast cancer
Monoclonal antibodies
Monoclonal antibodies trigger your immune system to attack cancer cells or target the cancer cells with drugs or a radioactive substance.trigger your immune system to attack cancer cells or target the cancer cells with drugs or a radioactive substance.
Examples are, trastuzumab (Herceptin®) and pertuzumab (Perjeta®). These drugs target cancer cells that make too
much of a protein called HER2. This protein is found on the surface of some cancer cells. The drugs work by attaching to the HER2 protein and slowing down or stopping the cancer cells’ growth.
Antibody-drug conjugates
Antibody-drug conjugates combine a monoclonal antibody with an anti-cancer drug, for example a chemotherapy drug.
Antibody-drug conjugates trastuzumab deruxtecan and sacituzumab govitecan can be used in HR-positive, HER-negative and triple-negative breast cancer.
CDK4/6 inhibitors
CDK4/6 inhibitors are designed to stop enzymes that help cancer cells grow.
The types of CDK4/6 inhibitors commonly used to treat ER-positive, HER2-negative metastatic breast cancer are palbociclib (Ibrance®) and ribociclib (Kisqali®). Both of these drugs are usually given in combination with hormone therapy. Palbociclib and ribociclib are given as tablets.
PARP inhibitors
PARP inhibitors can help stop cancer cells from repairing, so that they become too damaged to survive. You may be given a PARP inhibitor if your cancer is HER2 negative with an altered BRCA gene.
Cancer growth inhibitors
Cancer growth inhibitors block the chemical signals that trigger
cancer cells to divide and grow. Lapatinib (Tyverb®)is an example of a cancer growth inhibitor. Some drugs are given as tablets. Others are given into a vein through a drip.
How does my doctor decide on which drugs to use?
Deciding which targeted therapy is best suited for you is determined in a number of ways.
Biology of the tumour
One of the main factors is the biology of the tumour – looking at the cells to see if they have receptors and proteins on their surface that a particular therapy can target. For example, the HER2 protein.
The cells are taken during a biopsy and looked at under a
microscope. Biopsies from an area of secondary cancer may also be checked – it does not have to be breast biopsy. Most people with ER-positive, HER2-negative cancers are treated with CDK4/6 inhibitors and hormonal therapy. About 1 in 5 people will have a HER2-positive breast cancer diagnosis and they will need different drug treatments.
If you had a HER2-positive breast cancer diagnosis and the cancer comes back, it may not be HER2-positive again. This is why biopsies on metastases are done, to check the biology of the tumour.
Other factors
To decide which drugs to use, your doctor may also consider:
- Previous treatments you have had
- How well you have tolerated side-effects
- Any other underlying health issues you have
There is ongoing research looking at different types of targeted drugs for metastatic breast cancer.
Side-effects of targeted therapy drugs
Side-effects depend on the drugs being used and vary from person to person.
Your doctor and nurse will explain your treatment to you in more detail and tell you about any likely side-effects.Common side-effects include:
- Flu-like symptoms – fever and chills
- Nausea
- Headaches
- Diarrhoea
Always tell your doctor or nurse if you don’t feel well or if you are having any symptoms that are troubling you.
Immunotherapy for metastatic breast cancer
Immunotherapy helps the body’s immune system recognise and attack cancer cells.
Immunotherapy drugs may be an option for some types of triple-negative breast cancer.
A test on a sample of your cancer cells can measure how much of a protein called PD-L1 is on the cells. This test can tell your doctors if immunotherapy might be helpful for you.
Immunotherapy is often combined with chemotherapy.
The most commonly used immunotherapy drugs are checkpoint inhibitors like pembrolizumab or atezolizumab. Immunotherapy is usually given as a drip into a vein in a hospital or day unit. Some drugs may be given as an injection just under the skin.
Often you will stay on immunotherapy for as long as it’s working and any side-effects are manageable. Your treating team will go through possible side-effects with you.
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