Trials of Immunotherapy in Triple Negative Breast Cancer

Purpose of Review Triple negative breast cancer (TNBC) is an aggressive subtype with frequent chemotherapy resistance. In recent years, advances in immunotherapy have yielded promising new therapeutic strategies for the treatment of TNBC; studies evaluating immune check point inhibitors (ICIs) in combination with chemotherapy have shown encouraging results in both early and advanced stages of disease. Recent Findings Atezolizumab plus nab-paclitaxel resulted in improved progression-free survival (PFS) and overall survival (OS) compared to nab-paclitaxel alone in patients with programmed death-ligand 1-positive (PD-L1+) metastatic TNBC (mTNBC). However, atezolizumab plus paclitaxel did not improve outcomes. Pembrolizumab plus chemotherapy improved PFS compared to chemotherapy alone in patients with PD-L1+ mTNBC, and follow-up for OS is ongoing. The addition of pembrolizumab and atezolizumab to neoadjuvant chemotherapy increased pathologic complete response rates, regardless of PD-L1 status, and event-free survival is pending. Several other combinations of ICIs with targeted agents are under investigation to enhance the host immune response and are discussed in this review. TNBC has a poor prognosis with limited treatment options. Recent studies have demonstrated encouraging results by adding ICIs to chemotherapy, although optimal combinations remain to be defined. In this review, we highlight advances in TNBC treatment including ICIs and targeted agents and also discuss future directions.