Triple-negative breast cancer is a subtype of breast cancer that represents approximately 13% of cases, according to the National Cancer Institute. The subtype lacks the three receptors (estrogen, progesterone, and HER2) commonly found in breast cancer, which presents distinct challenges that scientists continue to study. To provide insights on the unique factors, emerging research, and evolving treatment of triple-negative breast cancer, we spoke with Michelina Cairo, M.D., medical oncologist and hematologist at Texas Oncology–Houston Memorial City, during Breast Cancer Awareness Month.
What makes triple-negative breast cancer unique and how does the treatment approach differ from other types of breast cancer?
For many years, triple-negative breast cancer (TNBC) did not have a targeted treatment, unlike hormone receptor-positive or HER2-positive cancer. TNBC does not respond to hormone or HER2-directed therapies; thus, the mainstay of treatment is chemotherapy. However, the discovery that triple-negative breast cancer tends to be more immunogenic, or better at activating the immune system, has opened up doors to research on new therapies targeting and activating the immune system.
What do you consider to be the most important research breakthroughs to-date in triple-negative breast cancer, and how have you seen them impact patient care and treatment?
We have been eagerly awaiting breakthroughs in TNBC. The awareness that TNBC could be treated with immunotherapy has been tantalizing, but it was out of reach until the results of clinical trials featuring metastatic TNBC proved successful. This changed the first line treatment to include chemotherapy plus immunotherapy.
Following the recent KEYNOTE-522 clinical trial, how will the Food and Drug Administration’s approval of pembrolizumab (KEYTRUDA®) impact patients with high-risk, early-stage triple-negative breast cancer?
This is a major breakthrough in a very challenging subtype of breast cancer – made possible in part by Texas Oncology physicians and patients who participated in clinical trials that led to FDA approval. The trial results brought immunotherapy to even more patients in early stage breast cancer. For the highest risk TNBC patients, the FDA approval of pembrolizumab for early stage TNBC means there is an addition to traditional chemotherapy that can improve outcomes. Not only can we improve response to therapy, in terms of the tumor significantly shrinking down before surgery, but we can also improve survival, which is our ultimate goal.
In the future, there may be even more ways to make breast cancer types more easily recognized and targeted by the immune system."
What are you most looking forward to as research and therapies for triple-negative breast cancer continue to evolve?
I am looking forward to targeted therapy for TNBC – possibly an antibody-drug conjugate (a highly targeted biopharmaceutical drug) for TNBC in combination with immunotherapy. In the future, there may be even more ways to make breast cancer types more easily recognized and targeted by the immune system.
What do you think is important for patients diagnosed with triple-negative breast cancer to know?
It is important to know there is hope. Also, don’t forget the role for chemotherapy, which helps break down the tumor into pieces that can be recognized by the immune system and activated by immune therapies like pembrolizumab – it’s a partnership.