Clinical Approach to Triple-Negative Breast Cancer

Sarah S. Mougalian, MD:Triple-negative breast cancer is one of the most complex and aggressive types of breast cancer. It makes up about 15% of all of the types of breast cancer. It’s particularly challenging to treat because there are no specific targeted therapies available for … triple-negative breast cancer, unlike hormone receptor-positive or HER2-positive disease. Triple-negative breast cancers are more aggressive. They tend to present younger, require more treatment, and present at more advanced stages.

Triple-negative breast cancer is one of the most difficult-to-treat types of breast cancer. There is an increased risk of recurrence within the first 3 to 5 years with this type of cancer. Furthermore, it has a different pattern of spread then other types of breast cancer, with more visceral metastases, more soft-tissue disease. And finally, because it is more aggressive, and without targeted options available for this disease, we were limited only to cytotoxic chemotherapy, except for very, very recently.

In early-stage breast cancer in the adjuvant and the neoadjuvant setting, we’re really limited to cytotoxic chemotherapy for the treatment of triple-negative breast cancer. However, a lot of research is being done in the metastatic setting as well as in the early-stage setting. Primarily in the metastatic setting, we have made some strides in terms of personalization of treatment for triple-negative breast cancer. For example, the recent IMpassion130 data includes nab-paclitaxel in combination with atezolizumab for triple-negative breast cancers for which there is PD-L1 expression. And secondly, the use of PARP inhibitors such as olaparib, talazoparib forBRCAmutation carriers. There’s a lot of additional work to be done looking at specific other gene mutations and other types of targeted therapies. There is plenty of research ongoing, in those regards.

The current approach to the treatment of metastatic triple-negative breast cancer includes sequencing of cytotoxic chemotherapies. Generally speaking, that’s single-agent therapies used one after another.

Recently, the FDA approved the combination of atezolizumab and nab-paclitaxel for use in the first-line treatment of metastatic triple-negative breast cancer in patients whose cancer or whose immune cells express PD-L1. However, the remainder of treatment options that are currently FDA approved are just cytotoxic chemotherapies. This can be anthracyclines, taxanes, antimetabolites, among others, which can be used in no particular sequence. They are used one after another.

I typically reach for a taxane in the first-line setting. However, this can really depend on the patient’s prior treatment and prior history. For patients who’ve already received an anthracycline or a taxane, I might reach for an antimetabolite such as capecitabine, or for people with a lot of visceral disease, perhaps a combination of gemcitabine and carboplatin, and, of course, use a PARP inhibitor for those who have aBRCAmutation.

I recently started checking PD-L1 status in the immune cells of triple-negative breast cancers to consider the use of immunotherapy in combination with a taxane in the first-line setting as per the recent IMpassion130 data.

Transcript edited for clarity.