CD274 and breast cancer: In breast cancer, several PD-1/PD-L1 inhibitors, such as pembrolizumab, avelumab and atezolizumab, are in clinical trials (Emens, 2018), although only atezolizumab as a first-line therapy has been approved by the FDA to treat patients with advanced metastatic TNBC expressing PD-L1 (Soare and Soare, 2019).