Howard A. Burris, MD, FASCO from the Sarah Cannon Research Institute, Nashville, TN, summarizes the Phase I trial of the combination of inhibitors of IDO1 (GDC-0919) and PD-L1 (atezolizumab) in patients with advanced or metastatic solid tumors. Dr Burris explains that blocking IDO1 leads to a more favorable environment for immunotherapy. This response was seen in various tumor types, such as melanoma, pancreatic, ovarian and prostate cancer, with durable and long-lasting benefits. Recorded at the American Society of Oncology (ASCO) 2017 Annual Meeting held in Chicago, IL.