CDK4/6 inhibitors: A potential therapeutic approach for triple negative breast cancer

Triple negative breast cancer (TNBC) cells lack expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor‐2 (HER‐2). Thus, TNBC does not respond to hormone‐based therapy. TNBC is also an aggressive subtype associated with poorer prognoses compared to other breast cancers. Conventional chemotherapeutics are used to manage TNBC although systemic relapse is common with limited benefits being reported as well as adverse events being documented. Here, we discuss current therapies for TNBC in the neo‐ and adjuvant settings, as well as recent advancements in the targeting of PD‐L1‐positive tumors and inclusion of PARP inhibitors for TNBC patients with BRCA mutations. The recent development of cyclin‐dependent kinase (CDK) 4/6 inhibitors in ER‐positive breast cancers has demonstrated significant improvements in progression free survival in patients. Here, we review preclinical data of CDK 4/6 inhibitors and describe current clinical trials assessing these in TNBC disease.