CD274 and triple-negative breast carcinoma: Preclinical studies using immune-compromised NSG mice with triple negative breast cancer (TNBC) tumor implants have shown 111In-labeled atezolizumab (SPECT imaging) 110 and 64Cu-atezolizumab (PET imaging) 111 uptake was 2-fold higher in PD-L1 high expressing cells compared to PD-L1 low expressing cells.