Innovations in Breast Cancer Therapy
Written by Dr Niamh O’Reilly
October is breast cancer awareness month and Breast Cancer Network Australia (BCNA) is hosting a series of events to raise awareness and generate funding for research (1). Australia’s National Breast Cancer Foundation is also celebrating 25 years by highlighting Australian research and fundraising milestones which has enhanced the understanding of breast cancer biology and contributed to better outcomes for patients (2). Here, we discuss the impact of breast cancer in Australia, how therapies have evolved and the emerging evidence that immunotherapies are providing new hope for the treatment of previously incurable breast cancers (5).
Increasing Incidence of Breast Cancer
Despite significant advancements in the diagnosis and treatment of breast cancer, it remains the second most common cause of death from cancer in Australian women (3). One in eight women are at risk of developing breast cancer by the age of 85 and it is estimated that 18,235 new cases of breast cancer will be diagnosed in Australia (148 males and 18,087 females) in 2018 (4). This represents an increase of over 1,400 new cases since 2014 (4). It is estimated that more than 3000 women will die from breast cancer in Australia this year (4).
How Targeted Therapies Have Changed Breast Cancer Treatment
Improvement in early diagnosis and new therapy options has led to an increase in the five-year survival rate among people diagnosed with breast cancer to 91% (4). Among the most significant advancements was the introduction of targeted therapies designed to attack a specific type of breast cancer based on the biological or molecular signature of the cancer cells. Unlike chemotherapy drugs, targeted therapies aim to kill cancer cells while causing little harm to healthy cells.
One example of an effective targeted therapy is trastuzumab for the treatment of patients with HER2 positive breast cancer. Overexpression of the HER2 receptor occurs in one in four women with breast cancer (7) and can cause rapidly growing cancer that spreads early. Trastuzumab works by attaching itself to HER2 receptors on the surface of breast cancer cells, blocking them from receiving growth signals. Since its availability on the Pharmaceutical Benefits Scheme (PBS) in 2010, trastuzumab has significantly improved survival rates among those with HER2 positive breast cancer (2).
However, there remains an unmet need for new therapies to treat patients with breast cancer that is unresponsive to currently available targeted and conventional therapies.
Immunotherapy in Breast Cancer
There is growing evidence that immuno-oncology therapies such as checkpoint inhibitors and chimeric antigen receptor T-cell (CAR-T) therapies may be effective for treating breast cancer (5, 6). Checkpoint inhibitor therapies (PD-1/PD-L1 and CTLA-4 blockades) bind to proteins on the surface of T-cells thereby allowing the T-cells to recognise and attack cancer cells. Checkpoint inhibitors are available in Australia for the treatment of melanoma, non-small cell lung cancer and urothelial cancer. The Pharmaceutical Benefits Advisory Committee will continue to review the clinical evidence for checkpoint inhibitors with appropriate consideration of unmet clinical needs, clinical effectiveness and cost-effectiveness (8).
There are multiple clinical studies underway to examine the use of checkpoint inhibitors for treating triple-negative breast cancer (TNBC) with preliminary data from two studies showing PD-1/PD-L1 inhibitors yield response rates of 19% in women with heavily pre-treated TNBC (5). TNBC is an aggressive form of breast cancer lacking expression of receptors linked to current targeted therapies.
The use of checkpoint inhibitors in treating breast cancer will likely require correlation to specific biomarkers identified using companion diagnostics (5). The use of biomarkers and companion diagnostics may help to ensure patients who are most likely to respond are selected for treatment, which is a useful strategy to maximise the clinical effectiveness and cost-effectiveness of these innovative therapies.
CRC’s range of medical affairs services includes expertise demonstrating the value of innovative immuno-oncology therapies for a range of different stakeholders.
- Breast Cancer Network Australia, Events 2018. Available at: https://www.bcna.org.au/events/2018/
- National Breast Cancer Foundation, 25 Years of Impact. 2018. Available at: https://nbcf.org.au/25years/
- What is Breast Cancer. Cancer council Australia. 2018. Available at: https://www.pinkribbon.com.au/women-and-cancer/breast-cancer/
- Australian Government, Breast Cancer Statistics. 2018. Available at: https://breast-cancer.canceraustralia.gov.au/statistics
- McArthur H L. 2016. Breast Cancer in Focus. Checkpoint Inhibitors in Breast Cancer: Hype or Promise? Clinical Advances in Hematology & Oncology.
- Tan A R. 2018. Checkpoint Inhibitors in Breast Cancer: Changing the Therapeutic Landscape. Available at: https://am.asco.org/checkpoint-inhibitors-breast-cancer-changing-therapeutic-landscape
- Iverson D. The Herceptin debate: what price a woman’s life? Available at: https://media.uow.edu.au/opinions/UOW025806.html
- August 2018 PBAC special meeting, Brief Outcome. Available at: http://www.pbs.gov.au/info/industry/listing/elements/pbac-meetings/agenda/august-2018-pbac-special-meeting