Triple negative breast cancers are those that do not rely on oestrogen or progesterone hormones, or the HER2 protein to help the cancer grow. Therefore they do not respond to treatments that block these receptors, such as hormone therapy drugs and Herceptin.
However, they are particularly responsive to chemotherapy and this has been the mainstay of treatment for triple negative breast cancer for many years.
Research is now focusing on identifying receptors and other targets in triple negative breast cancer cells to help develop new treatment options.
A number of subtypes of triple negative breast cancer have been identified to date, each with different molecular characteristics and with different targets for treatment. It is likely that additional subtypes of triple negative metastatic breast cancer will be identified as research continues. This is a growing and exciting area of research.
Currently targeted treatments for triple negative breast cancers are only available in clinical trials. The treatments closest on the horizon for general use are:
PARP inhibitors are effective for BRCA mutation-related metastatic breast cancers and may be used alone or in combination with chemotherapy. In cancer treatment, blocking PARP (an enzyme involved in the repair of damaged DNA) may help keep cancer cells from repairing their damaged DNA, causing them to die. The PARP inhibitor olaparib, which is used to treat ovarian cancer, is currently being studied in a clinical trial for breast cancer.
Androgen blocking therapies
Some cases of triple negative breast cancer have been shown to have androgen receptors, much like some breast cancers have oestrogen receptors. Trials are currently investigating the use of androgen blocking treatments in this subtype of breast cancer.
Immunotherapies are targeted treatments used successfully in other cancers, such as melanoma. Trials are showing positive results for the treatment of triple negative breast cancer also. These include with pembrolizumab (Keytruda) for a particular subtype of triple negative breast cancer that tests positive for PDL-1.
If you are interested in knowing more about potential new treatments for this type of breast cancer you may like to talk to your medical oncologist.