The most common targeted therapies available in Australia target HER2-positive breast cancer. They are:
- trastuzumab (Herceptin®)
- lapatinib (Tykerb®) (currently only used for metastatic breast cancer).
These drugs work by stopping HER2-positive cancer cells from growing and dividing. They are not effective for women with HER2-negative breast cancer.
Another targeted therapy sometimes used in the treatment of metastatic breast cancer is bevacizumab (Avastin®). It works by blocking the action of a growth factor called VEGF (vascular endothelial growth factor).
The number of available targeted therapies are likely to increase with time as we get more evidence about other treatments.
HER2 receptors
HER2 is a protein that helps cells to grow and divide.
Some women with breast cancer have higher than normal levels of the HER2 protein. This is called ‘HER2-positive breast cancer’. About one in five people have HER2-positive breast cancer.
HER2-positive breast cancer is a more aggressive form of breast cancer than HER2-negative disease.
The pathology report shows whether a woman's breast cancer cells are HER2 positive.
Types of targeted therapy
Trastuzumab (Herceptin®) is usually recommended for women with HER2-positive early breast cancer. In women with very small cancers and no involved lymph nodes, the benefit of treatment with trastuzumab is not yet known.
Targeted therapies available for women with HER2-positive metastatic breast cancer are:
Another targeted therapy is bevacizumab (Avastin®). The routine addition of bevacizumab to chemotherapy for women with metastatic breast cancer is not recommended because the benefits do not outweigh the additional adverse effects. The use of bevacizumab should be discussed with the treating doctor.
Lapatinib
Lapatinib (Tykerb®) is a biological therapy for women with HER2-positive metastatic breast cancer.
Clinical trials have shown that when given in combination with a chemotherapy drug called capecitabine, lapatinib slows the progression of metastatic breast cancer.
When is lapatinib recommended?
Lapatinib may be offered to women whose metastatic breast cancer has stopped responding to a combination of trastuzumab and chemotherapy.
Lapatinib will not benefit women with HER2-negative breast cancer.
What does treatment with lapatinib involve?
Lapatinib is a tablet that is taken every day (usually 5–6 tablets a day). It’s taken with a chemotherapy drug called capecitabine.
Side effects of lapatinib
Common side effects of lapatinib include diarrhoea, hand–foot syndrome, anaemia and nausea. Other possible side effects include dyspepsia, liver dysfunction and rash.
Trastuzumab
Trastuzumab (Herceptin®) is a drug used to treat a type of breast cancer called ‘HER2-positive breast cancer’.
What does treatment with trastuzumab involve?
Trastuzumab is given by slow intravenous (I.V.) infusion. A healthcare professional gives the infusion once a week or once every 3 weeks. The dose depends on the woman’s weight.
The first dose of trastuzumab is higher. This is called a ‘loading dose’. It will usually take about 90 minutes and can be slowed or stopped if the woman feels uncomfortable. If the woman doesn’t react to the first infusion, the other infusions will be quicker and the dose will be lower.
- For women with HER2-positive early breast cancer, the current recommendation is to give trastuzumab at the same time as chemotherapy (usually after breast cancer surgery). Trastuzumab can only be given with some types of chemotherapy. This means that trastuzumab treatment may not start right at the beginning of chemotherapy. The current recommendation is to give trastuzumab for 1 year.
- For women with HER2-positive metastatic breast cancer, trastuzumab may be given on its own or with other treatments. Treatment with trastuzumab will usually continue as long as the woman is benefiting from treatment, and as long as the benefits outweigh the risks and side effects.
Trastuzumab can be given at the same time as radiotherapy. However, we don’t yet know the long-term effects of giving trastuzumab at the same time as radiotherapy.
Side effects of trastuzumab
The most significant side effect of trastuzumab is the risk of heart problems.
This risk is increased if trastuzumab is given with anthracycline chemotherapy drugs. Therefore trastuzumab should not be given at the same time as anthracycline chemotherapy (epirubicin (Pharmorubicin®), doxorubicin (Adriamycin®)).
Trastuzumab is generally not recommended for patients with pre-existing heart problems. For women with no pre-existing problemns, the heart will be checked before and during treatment. If heart problems develop while on trastuzumab, heart checks will be more frequent and the woman may be referred to a cardiologist.
Symptoms of heart problems include feeling faint because of low blood pressure, breathing difficulties, tightness in the chest, chest pains, shortness of breath or an irregular heartbeat.
Other possible side effects of trastuzumab include reactions such as chills and fever. Clinical trials looking at the side effects of trastuzumab in women with early breast cancer have not been running for long. Therefore, we do not yet know the long-term side effects of trastuzumab.
Questions to ask
Listed below are some questions that may be helpful when talking about targeted therapies for breast cancer:
- Can I benefit from treatment with a targeted therapy? Which one is suitable for me?
- What are my other treatment options if targeted therapies are not of benefit to me?
- How much will treatment cost?
- When will I start treatment with targeted therapy if I am having other treatments?
- How will treatment be given?
- Will I need to go to hospital to receive my treatment?
- How often will I have treatment?
- Will I need any extra tests or follow-up if I am receiving a targeted therapy?
- What are the possible side effects of the targeted therapy you are recommending?
- When are side effects likely to occur?
- Who should I contact if side effects happen?
- How can I manage side effects if they develop?
- Can I take part in any clinical trials?
