Neoadjuvant Therapy in Triple-Negative Breast Cancer: Current Landscape and Emerging Therapies

Triple-negative breast cancer (TNBC) remains the most aggressive subtype of breast cancer, with a higher risk of recurrence in the early-stage setting compared to other subtypes. While TNBC is defined as breast cancer that lacks estrogen receptor and progesterone receptor expression and is without human epidermal growth factor receptor 2 (HER2) overexpression, it is increasingly recognized as a very heterogeneous disease. Utilization of neoadjuvant chemotherapy (NAC), with or without immunotherapy (depending on the clinical stage), has significantly improved clinical outcomes in early-stage TNBC (particularly in Stage II and III disease). Use of NAC offers the opportunity to de-escalate surgical treatment and evaluate treatment response, allowing for improved prognostication and further tailoring of post-operative systemic therapy. However, there continues to be a need for the personalization of systemic therapy strategies according to recurrence risk. More effective systemic therapies are still needed for patients who have poor response to NAC. Conversely, there remains a need for the identification of appropriate candidates for systemic therapy de-escalation, particularly given the potentially life-altering toxicities of current chemo-immunotherapy strategies. In this review the authors outline the current neoadjuvant paradigm for early-stage TNBC and emerging therapeutic strategies in this challenging disease state, along with questions that remain unanswered in the field.