Comparison of Four PD-L1 Immunohistochemical Assays in Lung Cancer

Introduction Four different programmed death ligand 1 immunohistochemical assays are approved or in development as companion or complementary diagnostics to different immunotherapeutic agents in lung carcinoma. We sought to determine whether these assays are technically equivalent and whether one antibody can be used on an alternate staining platform. Methods Serial sections of tissue microarrays constructed from 368 cases of resected lung cancer were stained for 22C3 and 28-8 on the Dako Link 48 platform (Dako, Carpinteria, Ca) and for SP142 and SP263 on the Ventana Benchmark Ultra platform (Ventana Medical Systems, Tucson, AZ) strictly as per product insert. A protocol was developed to use the 22C3 antibody on the Ventana Benchmark Ultra platform. Results Differences in mean tumor cell and immune cell staining were observed between the four assays ( p Conclusions Concordance between the four programmed death ligand 1 immunohistochemical assays when performed and scored as intended show that apart from 28-8 and 22C3, they cannot be used interchangeably in clinical practice. A protocol was successfully developed to use 22C3 on an alternate platform, which may help to overcome some barriers to implementation.