Clinical Development of PD-1/PD-L1 Inhibitors in Breast Cancer: Still a Long Way to Go

Opinion statement Currently, only patients with metastatic triple-negative breast cancer whose tumors are PD-L1 positive are eligible for receiving immunotherapy. Other studies have explored new combinations with PD-1/PD-L1 inhibitors in different disease settings and populations. Data from neoadjuvant trials testing the addition of PD-1/PD-L1 inhibitors to standard treatment are promising and have led to increases in pathologic complete response rates; however, data on survival outcomes are still immature. There is still much work needed to optimize benefits of immunotherapy in breast cancer and correlative studies in patients treated with immunotherapy are urgently needed to inform the best strategies for further development.