There has been great progress in the field of immunotherapy in recent years, with drugs such as Keytruda providing significant survival benefits to some people with advanced cancers. The Inside Story spoke with Associate Professor Sherene Loi, Medical Oncologist and Head of the Translational Breast Cancer Genomics and Therapeutics Laboratory at Peter MacCallum Cancer Centre in Melbourne, about the role of immunotherapy in breast cancer.
What is immunotherapy?
The body’s immune system plays an important role in protecting us against cancer. We all have lots of cells in our bodies that mutate and have the potential to become cancer – the immune system eliminates those cells. In some people, however, the mutated cells can eventually outwit the immune system and develop into cancer.
Cancer turns off the immune system, stopping it from killing the mutated cells. Immunotherapy drugs work by reactivating the immune system to fight the cancer cells.
Does immunotherapy look promising for breast cancer?
Yes, certainly, and in fact many people do not realise we have been using an immunotherapy drug in breast cancer for many years – Herceptin (trastuzumab). Herceptin works by targeting the tumour but it also activates the immune system.
It appears that immunotherapy is going to be most effective in some of the more aggressive types of breast cancer – triple negative and HER2-positive.
Are there clinical trials in breast cancer?
Until recently, there have not been a lot of immunotherapy trials in breast cancer because (1) there are already a lot of effective treatments for breast cancer and (2) breast cancer hasn’t traditionally been a type of cancer that has been thought to be modulated by the immune system.
Now, however, there are a lot of trials underway, including in Australia. Drugs such as Keytruda (pembrolizumab), Opdivo (nivolumab) and Tecentriq (atezolizumab) are all being trialled in Australia.
The trials are mainly in triple negative metastatic breast cancer. However, there is a HER2-positive trial that is now closed to recruitment. We expect another HER2 trial to open next year.
In breast cancer, immunotherapy is generally given in combination with chemotherapy. Trials are looking at which combinations will give the best outcomes.
We have given Keytruda (pembrolizumab) on its own to women who have a type of cancer where it has been shown to work. When it works it’s fantastic and it means those women have a very good quality of life, without the side effects of chemotherapy.
There is a lot of excitement because we are seeing some long-term responses with immunotherapy in clinical trials. My team has conducted some of the first breast cancer trials in Australia and we have patients who are two years down the track who are perfectly fine. That is very exciting for people with advanced breast cancer. What we need to work out now is how to make more patients respond.
Are the trials open to men with metastatic breast cancer?
Yes, the trials are open to men who have triple negative or HER2-positive disease.
What is your recommendation for people interested in immunotherapy?
Early breast cancer is very curable, so we don’t talk to people with early stage disease about immunotherapy.
For people with advanced disease, particularly triple negative disease, the best time to have immunotherapy is when you are first diagnosed. This is because immunotherapy works best in people who have not had a lot of treatment and who do not have a lot of disease.
If you have been newly diagnosed with metastatic triple negative or HER2-positive breast cancer, I would encourage you to talk to your clinician about participating in a clinical trial.
There are many centres across the country now offering immunotherapy trials, although these are mainly in the major centres. If you live in a regional or rural area, talk to your doctor about your options to join a trial.
If you can’t get onto a trial, you can pay for immunotherapy, but it is very expensive – between $5,000 and $7,500 every three to six weeks.
Immunotherapy is not the answer for everyone, but when it works it is really good for patients. We are really trying hard in our research to work out how to make it work for everyone.