Ask the expert: immunotherapy

There has been great progress in the field of immunotherapy in recent years, with drugs such as Keytruda and Tecentriq providing significant survival benefits to some people with advanced cancers. The Beacon spoke with 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 which 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 treatment 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.

We’ve seen the first positive trial of immunotherapy with Tecentriq (atezolizumab) added to nab-paclitaxel chemotherapy in women newly diagnosed with metastatic triple negative breast cancer. The trial will likely result in US FDA approval for Tecentriq, the first for breast cancer. The addition of immunotherapy improved progression-free survival, with an impressive increase in overall survival in the group of patients that expressed a marker called PD-L1 on their tumour surrounding immune cells.

Are there clinical trials in breast cancer?

There are many trials involving immunotherapy in breast cancer in Australia. We suggest you speak to your oncologist about this if you think immunotherapy might be for you. There is clear evidence now supporting its use for newly diagnosed metastatic triple negative patients. In metastatic HER2-positive breast cancer, data is hopefully coming this year to fully support the benefit of immunotherapy.

Drugs such as Keytruda (pembrolizumab), Opdivo (nivolumab) and Tecentriq are all being trialled in Australia. The trials are mainly in triple negative and HER2-positive metastatic breast cancer. There is one in the hormone receptor (ER) positive early-stage setting.

Are the trials open to men with metastatic breast cancer?

Yes, the trials are open to men. Patients need to speak to their oncologist.

What is your recommendation for people interested in immunotherapy?

There are many trials ongoing involving immunotherapy in early-stage triple negative breast cancer.

For people with advanced disease, particularly triple negative, 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. It is highly recommended that people have immunotherapy at this point. Patients can get their tumour biopsy tested for PD-L1 or the presence of immune cells by a pathologist. The presence of these strongly suggests that immunotherapy will be helpful.

If you have been newly diagnosed with metastatic triple negative 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. We are really trying hard in our research to work out how to make it work for everyone.

It’s important to note there are some rare but significant side effects from immunotherapy. Patients can discuss the risk and benefits with their oncologist.

Issue 84
Summer 2019