Updates in treatments for TNBC
Triple-negative breast cancer (TNBC) is an aggressive form of cancer. It’s harder to treat than other subtypes and often affects younger women (many patients are diagnosed in their 40s and 50s). TNBC cells lack the hormone receptors for estrogen, progesterone and HER2 - this means patients can’t have hormone therapy or Herceptin. Currently, the only options for TNBC patients are surgery and chemotherapy. We really need new TNBC-targeted drugs.
An immunotherapy trial involving 902 women with untreated, stage IV TNBC, has shown promise. Researchers combined immune-boosting drug Tecentriq (Atezolizumab) with chemotherapy. For some women on the trial, their life expectancy increased by an impressive ten months. However, the treatment didn’t work for all patients, only those with high levels of a specific molecule called PD-L1. For these patients, their immune cells attacked and destroyed the cancer.
Tecentriq is currently unfunded in New Zealand but is Medsafe approved to treat some advanced lung cancers and bladder cancers. Tecentriq can be prescribed for TNBC – you should discuss compassionate access or capped private prices with your oncologist. Alternatively, you can ring one of our nurses to discuss further.
Recent research has revealed that the existing drug estradiol (commonly used to treat menopausal symptoms), could be repurposed for subgroups of TNBC that have a specific estrogen-beta receptor (different from the usual estrogen receptor which TNBC patients lack). The American researchers hope to start a phase II clinical trial. This kind of investigation, which repurposes a current drug, can be faster moving as it’s already been approved for human use. You should talk to your oncologist about whether you can use estradiol.
Some anti-psychotic drugs have been shown to also have anti-cancer properties. Pimozide is a commonly used antipsychotic which could have future potential as a treatment for TNBC. Although the investigations are only in the very early laboratory tests, the drug has shown to effectively block the pathways which cause breast cancer to grow and spread. Pimozide significantly reduced the size and number of TNBC cells in mice, and almost totally stopped tumours from spreading to the lung. The research team behind the preliminary investigations is seeking funding for human clinical trials.
BCFNZ funds Dr Sarah Young at Otago University, who is working on developing a virus-based vaccine for TNBC. Sarah and her team have successfully developed a virus that works in breast cancer cell lines, they now need to figure out how it might work in patients, in combination with existing drugs. If they can find a combination that works they will be able to move to human clinical trials.
It’s clear that finding new ways to treat TNBC is an important, international priority in breast cancer research. A new treatment plan is desperately needed for women diagnosed with this subtype of the disease. It is encouraging to see the progression of new drugs into clinical trials as well as the repurposing of currently approved drugs. The research seems to be moving in a positive direction and we hope to see more studies emerge here in New Zealand.