The development of different classes of immunotherapies that target cancer cells continues to be a rapidly growing area of research. The development of diagnostic tests which can predict patient response to these therapies are crucial to the clinical success of an immunotherapy candidate. Checkpoint inhibitors are one class of immunotherapy that release the breaks on immune cells, enabling them to attack cancer cells. Several checkpoint inhibitors that target the PD-1/PD-L1 axis have been approved for a variety of tumor indications. In some tumor types, the efficacy of these agents has been linked to PD-L1 expression levels, leading to the approval of several PD-L1 IHC assays as companion diagnostics. Advances in clinical research and our understanding of the tumor microenvironment underscore the importance of new markers to assess immune infiltration and abnormal activity in cellular pathways, including DNA damage repair and DNA replication. Multiple biomarker assays and methodologies, beyond PD-L1 expression, are being explored for use in selecting patients for checkpoint inhibitor studies and will be reviewed in this presentation. In addition, biomarkers that could aid in patient selection for other types of immunotherapies will be discussed.

Learning Objectives:

1. Define the different classes of immunotherapy being developed for cancer treatment

2. Identify the utility and limitations of current biomarkers for the selection of patients for checkpoint inhibitor therapy

3. Compare/contrast methods and assays being used for biomarker analysis