Special Issues
PD-L1 expression is a rational biomarker to predict response to PD-1/PD-L1 ICI therapy, and has been studied extensively in clinical trials. A recurring theme emerging from available clinical data is that high levels of tumor cell membrane PD-L1 expression correlate with better outcomes with PD-1/PD-L1 blockade.
More recently, immunologic therapy has emerged as an important treatment option for many types of cancers, based on demonstrations of unprecedented efficacy. This radical shift in treatment has come with the recognition of the essential role of the immune system in the surveillance and eradication of neoplastic cells, particularly modulation of the immune checkpoint protein cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4) and the programmed death-1 (PD-1) receptor and its ligand, PD-L1.