We investigated the concordance of programmed death-ligand 1 (PD-L1) expression between primary cancer at initial diagnosis and metastasis at recurrence in resected non-small cell lung cancer (NSCLC). PD-L1 expression was evaluated using the SP142 assay in 37 NSCLC patients with paired primary lung cancer and surgically resected metastases at recurrence. PD-L1 positivity was defined as immunohistochemistry (IHC) and also evaluated by RNA in situ hybridization (RISH). The concordance rate of PD-L1 between primaries and metastases and correlation with clinicopathological factors were analyzed. PD-L1 expression was higher in squamous cell carcinoma, wild-type EGFR, and smokers than in non-squamous carcinoma, mutant EGFR, and never smokers, respectively. PD-L1 positivity was observed in 18.9% of primaries and 21.6% of metastases. IHC demonstrated 78.4% concordance of PD-L1 positivity between primary and metastatic cancers. In 10.8% of cases, PD-L1 positivity was higher in primaries than in metastases, and vice versa in the remaining 10.8%. By PD-L1 RISH, 35.1% of primaries and 27.0% of metastases demonstrated PD-L1 positivity. There was 62.2% concordance in PD-L1 by RISH between the primaries and metastases. Our results thus highlight the clinical importance of replacing metastases with primary archival tissue, particularly when re-biopsy is difficult at recurrence.
Bibliographical noteFunding Information:
Hye Ryun Kim, Yoon Jin Cha, Min Hee Hong, Manoj Gandhi, Shauna Levinson, Inkyung Jung, Jin Gu Lee, Chang Young Lee, Byoung Chul Cho, Sang-Jun Ha, and Hyo Sup Shim Resources: Provision of study materials, reagents, materials, patients, laboratory samples, animals, instrumentation, computing resources, or other analysis tools. Hye Ryun Kim, Hyo Sup Shim Data curation: Management activities to annotate (produce metadata), scrub data and maintain research data (including software code, where it is necessary for interpreting the data itself) for initial use and later re-use. Hye Ryun Kim, Byoung Chul Cho, Sang-Jun Ha, and Hyo Sup Shim Writing –Preparation, creation and/or presentation of the published work, specifically writing the initial draft (including substantive translation). Hye Ryun Kim, Sang-Jun Ha, and Hyo Sup Shim Visualization: Preparation, creation and/ or presentation of the published work, specifically visualization/data presentation. Hye Ryun Kim, Sang-Jun Ha, and Hyo Sup Shim Supervision: Oversight and leadership responsibility for the research activity planning and execution, including mentorship external to the core team. Hye Ryun Kim, Byoung Chul Cho, Sang-Jun Ha, and Hyo Sup Shim Project administration: Management and coordination responsibility for the research activity planning and execution. Byoung Chul Cho, Sang-Jun Ha, and Hyo Sup Shim Funding acquisition: Acquisition of the financial support for the project leading to this publication. Hye Ryun Kim, Byoung Chul Cho Final approval of manuscript: All authors.
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