Author(s)

Wanyu Zhang

Corresponding Author

Wanyu Zhang

ABSTRACT

Triple-negative breast cancer (TNBC), the subtype of breast cancer marked by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2), is known for its lack of systematic therapies and poor prognosis. The mainstream method of treating TNBC is cytotoxic chemotherapy, which is proven to be effective in both adjuvant and neoadjuvant settings. Nevertheless, as chemotherapy appears to generate nondurable responses and cells start to grow resistant to certain chemotherapy drugs, immunotherapy seems to be a new way out for TNBC patients. Treatments of immunotherapy involve cancer vaccines and immune checkpoint blockade. The latter is the focus of this article. Immune checkpoint blockade, especially when combined with other therapies, is shown to be promising, improving the patients’ progression-free survival and overall survival. Yet as an emerging set of therapies, the efficacy and safety of the combination of drugs are still to be determined. Numerous clinical trials are designed and implemented to test the effectiveness and safety of both single-agent immune checkpoint inhibitors and their conjugation with other therapies including chemotherapies, radiotherapies, and cryotherapies. In this article, the design and results of recent clinical studies involving immune checkpoint inhibitor drugs are summarized. The drugs include programmed cell death protein 1 (PD-1) inhibitors pembrolizumab and nivolumab, programmed death ligand 1 (PD-L1) inhibitors atezolizumab, avelumab, and durvalumab, and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) inhibitors ipilimumab and tremelimumab.

KEYWORDS

Triple-negative breast cancer, immunotherapy, checkpoint inhibitors, PD-1, PD-L1, CTLA-4