Recent KEYNOTE study data has led to confusion over the significance of PD-L1 as a predictive biomarker of immunotherapy response. The lack of a standardized assay for PD-L1 also makes things trickier. In this interview, Fred Hirsch, MD, PhD, CEO of the International Association for the Study of Lung Cancer (IASLC), from the University of Colorado, Denver, CO, discusses the standardization of PD-L1 assays. Dr Hirsch gives an update on the results of the Blueprint PD-L1 IHC Assay Comparison Project, which is investigating how comparable the results of the five main PD-L1 assays are. This video was recorded at the European Lung Cancer Congress (ELCC) 2018, held in Geneva, Switzerland.