As the diagnosis of breast cancer continues to rise in Australia, new treatment options have also improved significantly, and one of which is the breakthrough of Enhertu treatment for patients diagnosed with metastatic HER2-low breast cancer.
In this blog, we will explore what HER2-low breast cancer is and how Enhertu treatment can help prolong and improve the lives of patients having the type of cancer.
Understanding HER2-low Breast Cancer
To help us understand what HER2-low breast cancer is, it’s important for us to know about a protein called Human Epidermal Growth Factor Receptor 2 (HER2). This protein is normally present in human cells and plays a role in regulating cell growth and survival.
In the context of cancer, too much HER2 can make cells grow uncontrollably and spread aggressively leading to a serious complication.
For a person to have a complete breast cancer diagnosis, healthcare experts will use the procedure called immunohistochemistry test (IHC) to classify the amount of HER2 levels and status present in the surface of a cancer cell.
The IHR test results come in various ranges. This includes:
- HER2-positive with a score of 3+ can indicate a significant over expression of the HER2 protein on the cancer cells. This suggests that the cancer cells are more likely to grow uncontrollably and spread aggressively.
- HER2-negative with a score of 0 to 1+, indicates that the breast cancer cells do not overexpress HER2 proteins. This typically suggests a less aggressive form of cancer.
- Equivocal with a score of 2+ indicates that breast cancer cells may or may not overexpress HER2 protein. This suggests that doctors will need to conduct another testing to clarify the HER2 status.
Following the presentation of the DESTINY-BREAST04, a randomised, multicenter, open-label clinical trial that enrolled patients with unresectable or metastatic breast cancer, at the 2022 American Society of Clinical Oncology (ASCO) meeting, led by Dr. Shanu Modi, a medical oncologist at Memorial Sloan Kettering Cancer Center in New York, the term “HER2-low” was introduced.
This new classification has the potential to enhance the survival rate for approximately 50% of patients with metastatic breast cancer today. The HER2 low refers to cases where HER2 expression results are in between 1 and 2, but not enough to be considered HER2-positive.
As Dr. Modi noted, understanding whether a cancer is HER2-positive, HER2-negative, or HER2-low is crucial for treatment planning. This is particularly important as HER2-low can now be detected using commonly available tests, offering new hope for patients with this form of breast cancer.
Dr. Jane Lowe Meisel, an ASCO breast cancer expert, also emphasised that the introduction of the HER2-low category could revolutionise breast cancer classification and significantly expand the population eligible for HER2-targeted therapies, ultimately improving survival rates for many patients.
HER2-low Breast Cancer Treatment
During the ASCO 2022 meeting, Dr. Meisel stated that the newly classified HER2-low form of breast cancer is quite difficult to treat. For years, treatment options for patients with this type of breast cancer were limited, highlighting the need for targeted therapies that could offer better outcomes.
At the same meeting, major findings highlighted the HER2-low breast cancer treatment, especially with the approval of trastuzumab deruxtecan (Enhertu).
The DESTINY-Breast04 trial showed Enhertu improved survival in HER2-low metastatic breast cancer, ASCO updated guidelines to recommend this therapy for patients who’ve previously undergone chemotherapy. This development is especially relevant for those with HER2-low expression, which was previously considered HER2-negative.
The impact of this milestone has reached Australia. On 28th August 2024, the Federal Minister for Health and Aged Care, The Hon. Mark Butler MP announced the expansion of the Pharmaceutical Benefit Scheme (PBS) to include Enhertu (trastuzumab deruxtecan) for people diagnosed with HER2-low metastatic breast cancer.
The announcement had a significant impact on people diagnosed with this disease, making the treatment more affordable for them.
With the expansion of the PBS, patients will be required to pay no more than $31.60 per prescription, or as little as $7.70 with a concession card. Since July 2022, the Australian government has allocated additional funding for 235 new and revised listings on the PBS.
“Enhertu is a life changing breast cancer drug, and now the Albanese Government is making it cheaper and available for women with a type of metastatic breast cancer.”
The Hon Mark Butler MP
Minister for Health and Aged Care
Approximately 1,700 Australians are expected to benefit from this annual listing, which would otherwise require a payment of $160,000 for a full course of treatment.
Furthermore, the DESTINY-Breast04 trial demonstrated that using Enhertu to target low levels of HER2 was more effective than standard chemotherapy for patients with HER2-low metastatic breast cancer. Patients treated with Enhertu had a 50% lower risk of disease progression or death, and a 36% lower risk of death, compared to those receiving standard chemotherapy, regardless of hormone-receptor status.
During the press briefing at the ASCO 2022 meeting, Dr. Meisel emphasised that the findings are anticipated to transform the treatment approach for metastatic HER2-low breast cancer, calling them a “huge win for patients.”
Enhertu’s approval represents a significant advancement in breast cancer therapy, expanding options for patients who previously had limited targeted treatment choices. Through its innovative mechanism, Enhertu provides new hope for those with HER2-low breast cancer, reflecting ongoing progress in personalised cancer treatment.
A Brighter Future for HER2-Low Breast Cancer Patients
In conclusion, the introduction of the HER2-low category and the approval of Enhertu are major milestones in the fight against breast cancer.
These advancements have brought new hope to patients who previously had limited treatment options. By targeting low levels of HER2, Enhertu offers a promising alternative to traditional therapies, improving survival rates and quality of life for many.
As research continues to evolve, treatments like Enhertu pave the way for more personalised, effective cancer therapies, offering brighter prospects for patients battling this challenging disease.
Take Control Of Your Health Journey
If you or a loved one are facing the challenges of breast cancer, Tasman Health Care, alongside our dedicated health providers, encourages you to stay hopeful and keep fighting. We are here to offer unwavering support, expert care, and personalised treatment options.
Whether you’re seeking information on groundbreaking treatments like Enhertu or need resources to manage your health, our compassionate team is committed to providing the care and guidance you deserve.
Reach out to us today, and let us be part of your journey toward better health!
Visit our website at https://tasmanhealthcare.com.au/ or reach out to 07 5613 2480.
