Triple negative breast cancer (TNBC) is sub-type of breast cancer that lacks the receptors for hormones or HER2 protein that are found in hormone receptor positive breast cancer and HER2 positive breast cancer, respectively. About ten percent of New Zealand women diagnosed with breast cancer will be triple negative. TNBC is more common in younger women (under the age of 44) [1] and tends to be more aggressive than other sub-types. Between 15 and 25% of those diagnosed with TNBC carry BRCA gene mutations [2].
TNBC is usually treated with surgery, radiation therapy and chemotherapy. Because it lacks hormone or HER2 receptors, it will not respond to hormonal (endocrine) therapy or anti-HER2 therapy.
Chemotherapy for TNBC often involves two or three drugs. The main types used to treat TNBC are anthracyclines (e.g. doxorubicin), mitotic inhibitors (e.g. taxanes such as paclitaxel or docetaxel), alkylating agents (e.g. cyclophosphamide) and platinum-based drugs (e.g. carboplatin).
Chemotherapy may be given before surgery (called ‘neoadjuvant’ chemotherapy) and/or after surgery ('adjuvant' chemotherapy). With neoadjuvant treatment, the tumour’s response to the treatment can be assessed, and changes to the treatment plan made if necessary. If the tumour shrinks enough, less surgery may be required. Neoadjuvant treatment also allows time for testing for BRCA gene mutations, which can affect the choice of chemotherapy drug. A patient’s guide to making decisions about neoadjuvant treatment developed by Breast Cancer Trials can be read here.
Research has shown that TNBC is not in fact a single type of breast cancer, but a group that can be subdivided further based on tumour characteristics. For example, TNBC tumours with high levels of tumour infiltrating lymphocytes (TILs, a type of immune system cell) can be a sign of a better prognosis than those with low numbers of TILs. Some TNBC tumours exhibit high levels of a biomarker called PD-L1; whereas others have lower PD-L1 levels. Some TNBC tumours have BRCA gene mutations, but others do not.
Understanding the TIL, PD-L1 and BRCA status of TNBC tumours can help to guide decisions about which chemotherapy drugs to use and the best combinations and sequences in which to use them.
Research has also led to more targeted treatments with ‘breakthrough’ medicines such as immune checkpoint inhibitors, PARP inhibitors and antibody drug conjugates. Unfortunately New Zealand lags behind other countries in the availability of such medicines to treat TNBC. You can read more about the treatment of TNBC in New Zealand here.
The immune checkpoint inhibitor pembrolizumab (brand name Keytruda) was approved and funded for treatment of advanced (metastatic) TNBC by Pharmac in October 2024. However, its use to treat early TNBC is still ‘under assessment’ (September 2025), and only patients able to pay privately for this medicine can access it at present. The supplier of this medicine has set up a cost-share programme to help reduce the costs for those with early TNBC. In Australia this medicine is fully funded for both early and advanced TNBC. You can read more about New Zealand efforts to get public funding for pembrolizumab for early TNBC here.
The PARP inhibitor olaparib (brand name Lynparza) is recommended for treating early-stage and advanced breast cancer in those with BRCA gene mutations, after chemotherapy. BCAC and a group of New Zealand breast cancer specialists applied to Pharmac for funding for olaparib for breast cancer in July 2024, but this is still ‘under review’ (September 2025). In the meantime, a cost-share programme has been set up by the supplier to help reduce the costs for New Zealand women paying for their olaparib treatment. It is fully funded in Australia.
Sacituzumab govitecan (brand name Trodelvy) is an antibody drug conjugate useful for treating advanced TNBC after other therapies have stopped working. An application for funding this medicine was lodged with Pharmac in June 2023. It was given a ‘high priority’ rating, but it remains on the ‘options for investment’ list (September 2025). As with olaparib, there is a cost-share programme to help with costs. It is also fully funded in Australia.
References:
[1] 30,000 Voices: Te Rēhita Mate Utaetae – Breast Cancer Foundation National Register 2003-2020. Click here to read.
[2] Mutai et al. The impact of germline BRCA pathogenic variants in locally advanced, triple negative breast cancer treated with platinum-based neoadjuvant chemotherapy. Breast Cancer Res Treat. 2024 Jun;205(2):241-248. Click here to read.
18 September 2025
