Histochemical assay for evaluating expression of programmed death ligand 1 (PD-L1)

摘要

This disclosure relates to methods of assaying and scoring PD-L1 expression in tumors. Tumor samples are labeled with an antibody or antibody fragment that specifically binds to human PD-L1 and binding is detected. Binding intensity is compared to background, and tumor cells having membrane staining above background are counted. The percentage of tumor cells containing membrane staining of PD-L1 is determined and the tumor is classified as “PD-L1 positive” if the percentage of tumor cells falls above a predefined level.