Background: Molecular targeted therapy including the use of monoclonal antibodies directed against the immune checkpoints PD-L1 and PD-1 receptor have remarkably improved the therapeutic response and survival of cancer patients. The tumor expression level of PD-L1 can predict the response rate to checkpoint inhibitors. We evaluated whether the time interval between tumor tissue sampling/paraffinization and immunohistochemistry affects the staining level of PD-L1 in non-small cell lung cancer (NSCLC).
Methods: This study comprised 137 patients with NSCLC. Tumors were stained with 22C3 or 28-8 antibodies.
Results: There was a significant correlation between the immunoreactivity rate of tumor tissues obtained using 22C3 and 28-8 clones. No statistical difference in immunoreactivity between archival and recent samples stained either with 22C3 or 28-8 antibodies was observed. The immunoreactivity rate achieved with 22C3 or 28-8 antibodies significantly correlated with tumor histological type and size, but not with specimen storage time, age, gender, smoking history, clinical stage, or lymph node metastasis.
Conclusion: In brief, the results of this study show that the time interval between tissue sampling/paraffinization and immunohistochemical analysis has no influence on the immunoreactivity rate of PD-L1 in NSCLC.
Keywords: Archival specimen; PD-L1; immune checkpoint inhibitor; molecular targeted therapy; non-small cell lung cancer.
© 2018 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.