Targeted Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer is increasingly recognized as a heterogeneous entity that can be categorized according to histologic, molecular, and clinical subtypes. While chemotherapy remains the backbone of treatment for this disease, there are now several available targeted agents including immunotherapy, poly(adenosine diphosphate-ribose) polymerase inhibitors, and most recently a Food and Drug Administration-approved antibody-drug conjugate sacituzumab govitecan-hziy as a third-line treatment of metastatic triple-negative breast cancer. We review several actionable targets for triple-negative breast cancer and describe promising nonimmunotherapeutic agents including cyclin-dependent kinase inhibitors, androgen receptor inhibitors, mitogen-activated protein kinase inhibitors, phosphoinositide 3-kinase inhibitors, AKT (also known as protein kinase B) inhibitors, and antibody-drug conjugates.