Recent advances in atezolizumab-based programmed death-ligand 1 (PD-L1) blockade therapy for breast cancer

Breast cancer, the most common cancer in women worldwide, is curable in - 70-80 % of patients with early-stage, non-metastatic disorder. However, advanced breast cancer with distant organ metastases is incurable with available therapeutics. Thus, scientists have sought emerging strategies for treating metastatic breast cancers., Immune checkpoint inhibitors (ICIs) have represented a significant development in breast cancer immunotherapy. Now, targeting immune checkpoint molecules (e.g., programmed cell death protein 1 (PD-1) and programmed cell death ligand 1 (PD-L1)) have attracted increasing attention in the context of breast cancer therapy, chiefly triple-negative breast cancer (TNBC). Atezolizumab, a humanized IgG1 monoclonal antibody (mAb), has been designed to interfere with the binding of the PD-Ll ligand to its receptor. Targeting PD-L1 using atezolizumab potentiates T-cell responses to the tumor and consequently boosts tumor responses. The results of the IMpassion130 trial have recently led to the approval of the combination of atezolizumab and nab-paclitaxel to treat unresectable locally advanced or metastatic patients with PD-L1-positive TNBC. Herein, we summarize the clinical efficacy of atezolizumab in treating breast cancer and briefly discuss the possible immune-related adverse events (irAEs).