Comparison of four PD-L1 immunohistochemical assays in lung cancer

Introduction: Four different PD-L1 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, and for SP142 and SP263 on the Ventana Benchmark Ultra platform, strictly as per product insert. A protocol was developed to use the 22C3 antibody on the Ventana Benchmark Ultra platform. Results: Differences in mean TC and IC staining were observed between the four assays (p