CD274 and triple-negative breast carcinoma: In March 2019, atezolizumab, a monoclonal antibody targeting Programmed Death Ligand 1 (PD-L1), was approved by the US Food and Drug Administration in combination with nab-paclitaxel as first-line therapy for unresectable or metastatic PD-L1 positive triple negative breast cancer (TNBC) based on results of the IMpassion-130 trial.