Molecular Targets of Triple-Negative Breast Cancer: Where Do We Stand?

SIMPLE SUMMARY: Triple-negative breast cancer (TNBC) is one of the most aggressive breast cancer subtypes, largely due to heterogeneity and lack of treatment options. Due to absence of targetable hormone receptor expression, chemotherapy is the current standard of care for TNBC. However, recurrence and metastasis following treatment with chemotherapy and radiation remain major contributors to mortality. To develop more effective treatments of TNBC, molecular pathways involved in tumor growth, vascularization, and apoptosis have been investigated as potential targets. In this review, we outline promising biological targets that may be implicated in future TNBC treatments. ABSTRACT: Triple-negative breast cancer (TNBC) is a highly aggressive form of breast cancer. Due to its heterogeneity and lack of hormone receptor expression, this subtype is more likely to metastasize and resist treatment attempts than are other forms of breast cancer. Due to the absence of targetable receptors, chemotherapy and breast conserving surgery have been the predominant treatment options for patients. However, resistance to chemotherapy and local recurrence of the tumors is frequent. Emerging immunotherapies have begun to change treatment plans for patients diagnosed with TNBC. In this review, we discuss the various immune pathways identified in TNBC and the role they play as targets for new potential treatment choices. Various therapeutic options that inhibit key pathways in cellular growth cycles, DNA repair mechanisms, epithelial mesenchymal transition, and immunosuppression have been shown to improve survival in patients with this disease. With promising results thus far, continued studies of immunotherapy and neoadjuvant therapy options for TNBC are likely to alter the treatment course for these diagnoses in the future.