This is a reference antibody that mimics atezolizumab, a humanized monoclonal antibody targeting PD-L1 (also known as B7-H1 or CD274). It is used in research and development for cancer immunotherapy studies, where it blocks the PD-L1 protein on cancer cells, preventing immune evasion and enhancing T-cell mediated anti-tumor responses. Atezolizumab is clinically approved for treating malignancies such as non-small cell lung cancer, urothelial carcinoma, and triple-negative breast cancer. In clinical settings, it is administered intravenously, often in combination with chemotherapy or other immunotherapies to improve patient outcomes. This reference antibody serves as a standard for bioassays, potency testing, and preclinical research.