The following therapies target specific receptors that control the growth of cancer cells.
Whereas chemotherapy targets all rapidly dividing cells, targeted therapies, because of their specificity, are less likely to harm healthy cells.
Biological therapies, one type of targeted therapy, use laboratory-manufactured proteins to harness the body’s immune system to help destroy cancer cells. These target molecules on the surface of cancer cells. Other targeted therapies use drugs containing small molecules which enter the cells and block the signals that the cancer relies on for growth.
Targeted therapies for HER2 positive breast cancer
This is the most widely used biological treatment for breast cancer and is used to treat both early and advanced HER2 positive breast cancer. Around 20% of breast cancers have too many copies of the HER2 (Human Epidermal growth factor Receptor 2) gene which in turn makes too many HER2 proteins (receptors) on the surface of breast cancer cells. These cancers are known as HER2 positive. The receptors receive signals which direct the cells to grow and multiply.
Herceptin is a monoclonal antibody which has been manufactured in a laboratory and has been designed to recognise and bind to the HER2 proteins on the surface of cancer cells. It slows or stops the growth of HER2 positive breast cancer by attaching itself to the receptors and blocking growth signals. It also stimulates the body’s immune system to destroy the cancer cells.
A 12-month course of Herceptin to treat early breast cancer has been publicly funded in New Zealand since 2008. In advanced/metastatic breast cancer the treatment is funded for as long as the patient continues to benefit.
Herceptin does not benefit people whose cancers have tested negative for HER2 receptors.
How is Herceptin given?
In early breast cancer Herceptin is given in conjunction with a chemotherapy regimen then continued every 3 weeks to complete 12 months of treatment. It is administered by infusion into a vein or port. The treatment is given in a hospital or clinic, and usually takes about 30 minutes, although the first dose is given more slowly over 90 minutes to check for any adverse reactions.
Herceptin can also be given as a subcutaneous injection, which is injected under the skin in the thigh, over a period of 2-5 minutes, however this is not yet publicly funded in NZ .
Read more about Herceptin in this patient information booklet:
Possible side effects:
- Infusion reactions
- These may include fever and chills, muscle aches, especially with the first dose.
- Nausea, vomiting
- Headache, dizziness
- Shortness of breath
- Bruising due to low platelet count.
- Heart problems
This is a serious but less common side effect. Herceptin can damage the heart muscle and reduce its ability to pump effectively. Your doctor will monitor your heart health before, during and after treatment, and you will have a scan before and during the course of treatment to ensure your heart is functioning properly. Heart problems are more common in people who were treated with both Herceptin and anthracycline chemotherapy such as Adriamycin.
For more information about Herceptin and possible side effects see the Medsafe consumer information.
This is another monoclonal antibody treatment which is used to treat advanced/metastatic HER2 positive breast cancer. It is also given by intravenous infusion.
Perjeta is used at the same time as Herceptin and Docetaxel chemotherapy. Perjeta is currently indicated for patients with HER2 positive metastatic breast cancer who have not received previous anti-HER2 therapy or chemotherapy for their metastatic disease.
As of January 2017, Perjeta is funded for use in the NZ public health system, although this applies only to people diagnosed from that date. This decision will be reviewed and BCFNZ is urging Pharmac to extend this cover to those who are already being treated for metastatic HER2 positive disease.
For more information about Perjeta and possible side effects see the Medsafe consumer information.
Trastuzumab emtansine (Kadcyla)/TDM-1
This is known as an antibody drug conjugate, combining an antibody and a chemotherapy drug. It can be used to treat metastatic HER2 positive disease.
Kadcyla uses the monoclonal antibody in trastuzumab to deliver a powerful chemotherapy drug (DM-1) directly to the inside of the cancer cells while minimising the effects on healthy tissues.
Kadcyla is also not funded by Pharmac for use in the public health system so patients must pay for their treatment. Roche NZ provides an access programme to cap the cost.
For more information about Kadcyla and possible side effects see the Medsafe consumer information:
Other targeted therapies
Lapatinib is a small-molecule drug belonging to a group known as Tyrosine Kinase Inhibitors which target both HER2 and epidermal growth factor receptor (EGFR) pathways. It is publicly funded for people with metastatic HER2 positive breast cancer which has not been treated with Herceptin or for people who have not been able to tolerate Herceptin in this setting. It is in tablet form, taken orally.
Lapatinib is a tablet which is given in combination with capecitabine (Xeloda) or paclitaxel (Taxol). It can also be given with an aromatase inhibitor.
The most common side effects are diarrhoea, fatigue, nausea and skin rashes.
Lapatinib is beneficial to a small number of people who:
- Have cancer that has spread to their brain
- Are not able to tolerate trastuzumab (Herceptin) or its mode of delivery (intravenous)
- Demonstrate resistance to trastuzumab
- Do not respond to trastuzumab
For more information about Tykerb and possible side effects see the Medsafe consumer information.
This is a newer small molecule inhibitor, targeting cyclin-dependent kinases (CDK4/6) which are proteins that help mediate endocrine resistance. Indicated for use in post-menopausal women with metastatic ER positive, HER2 negative breast cancer, who have not received prior hormone therapy for their metastatic disease. It is given in conjunction with letrozole or fulvestrant.
This therapy is delivered as a pill, taken once a day for three weeks, followed by a week for recovery before starting again.
Palbociclib is registered for use but not currently funded in New Zealand.
Everolimus ( Afinitor)
Everolimus belongs to a class of drugs known as mTOR inhibitors, targeting the mTOR proteins which help cancer cells grow and divide. It can be used in post-menopausal women with advanced hormone-receptor positive, HER2 negative breast cancer, in conjuction with exemestane ( Aromasin). Although it is publicly funded in Australia, it is unfortunately not funded in New Zealand.
Kisqali (ribociclib, formerly called LEE011)
Kisqali, another CDK4/6 inhibitor, can be used in combination with an aromatase inhibitor as initial therapy to treat advanced-stage or metastatic hormone-receptor-positive, HER2-negative breast cancer in postmenopausal women. Kisqali is a tablet, taken by mouth.
It is not registered for use or funded in NZ.
Access to unapproved medicines
Q. Can my doctor obtain a drug that’s not approved in NZ for me?
A: Yes. Section 25 of the Medicines Act 1981 permits an authorised prescriber – e.g. your doctor – to "procure the sale or supply of any medicine" for a particular patient in his or her care. "Any medicine" includes approved and unapproved medicines.
Your doctor would contact the company that makes the drug and request it for you (you’ll have to pay for it). The medicine can then be imported and used to treat you, without involving government agencies like Medsafe or Pharmac.
However, if a third party (e.g. a NZ pharmacy or local distributor) sells or supplies the unapproved medicine to your doctor, they must fill in a form on the Medsafe website saying that they did so.
An example of an unapproved medicine would be Kisqali (ribociclib), approved in the USA in March 2017 for treatment of advanced ER+ breast cancer.
Q. Can my doctor prescribe a drug that’s approved in NZ, but not approved for breast cancer?
A: Yes. Again, your doctor can prescribe any medicine, but if you’re using it for a purpose that’s not approved in NZ, he or she needs to inform you that it’s an unapproved use. Unfortunately, you’d most likely have to pay for the drug yourself.
If using that particular drug for breast cancer would be highly experimental, you’d need to provide written consent to the treatment.
An example is the drug Afinitor (everolimus), which is approved and funded in NZ for a type of brain cancer, and approved (but not funded) for kidney and pancreatic cancers. Your doctor can prescribe it for your breast cancer, but you will need to pay for it. Since Afinitor is widely used in breast cancer treatment overseas, it wouldn’t be considered experimental and you wouldn’t have to give written consent.
For further information visit: http://www.medsafe.govt.nz/profs/RIss/unapp.asp