CSI Laboratories, a private national reference laboratory specializing in cancer diagnostics, announced the availability of a PD-L1 (programmed death-ligand 1) immunohistochemical (IHC) protein expression assay that can be used to potentially predict a patient’s response to several commercially available PD-1/PD-L1 inhibitor therapies.

Presently, there are multiple PD-1/PD-L1 inhibitor therapies on the market including Bristol-Myers Squibb’s Opdivo, Merck’s Keytruda, and Roche’s Tecentriq. All of these immunotherapies utilize the body’s own immune system to effectively identify and eliminate tumor cells. CSI’s PD-L1 IHC assay works to classify tumor specimens based on their PD-L1 tumor cell and immune cell reactivity by utilizing the Yale Unified Scoring System (YUSS) for four different PD-1/PD-L1 inhibitor therapies. The YUSS chart, developed by Yale University Professor of Pathology, David Rimm, M.D., Ph.D., is a consolidated scoring system for four of the anti-PD-1/anti-PD-L1 immunotherapies: pembrolizumab, nivolumab, atezolizumab, and durvalumab.

With the YUSS chart, CSI’s comprehensive approach to PD-L1 diagnostics allows for only one immunohistochemical assay to be run, instead of running multiple different assays for each of the different therapies. “This approach will be ideal for pathologists and their community oncologists who are attempting to determine the best course of treatment for a patient but who are also faced with choosing from multiple similar therapies,” said CSI’s Director of Surgical Pathology, Steve Kargas, MD, Ph.D. “We chose to implement the YUSS Scoring system as a solution to the elaborate maze of PD-L1 assays and therapies currently available and expect it to become the standard of care regarding interpretation of this immunostain. Based on research studies by Dr. Rimm at Yale University, we believe that pathologists and oncologists will find the usage of the YUSS chart to be both time and cost-effective, and also be equally efficacious in determining therapeutic options compared to performing other assays individually.”