Atezolizumab: A novel PD-L1 inhibitor in cancer therapy with a focus in bladder and non-small cell lung cancers.

In recent years, immunotherapy has come to the forefront as a major development in cancer treatment. Evasion of the immune system by tumor cells has been identified as one of the hallmarks of cancer and multiple therapies have been developed to counter this process. Programmed cell death 1 ligand 1 (PD-L1), a ligand to programmed cell death protein 1 (PD-1), is expressed by many cancer cells and the binding of PD-L1 to PD-1 results in the suppression of T-cell-mediated immune response against cancer cells. Atezolizumab is a monoclonal antibody that binds to PD-L1 and blocks its interaction with PD-1, thereby enhancing T-cell activity against tumor cells. Atezolizumab has been shown to be well tolerated with no dose-limiting toxicities in phase I trials. Atezolizumab was approved by the U.S. Food and Drug Administration in 2016 for the treatment of platinum-resistant metastatic non-small cell lung cancer (NSCLC) and urothelial cancer based on phase II and preliminary phase III studies that have shown significant improvement in objective response rate and median overall survival. There are 117 ongoing clinical trials of atezolizumab currently. Given its efficacy in NSCLC and urothelial carcinoma, atezolizumab holds much potential in the future of cancer therapeutics.