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Tomohito Saito

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    MA 05 - Immuno-Oncology: Novel Biomarker Candidates (ID 658)

    • Event: WCLC 2017
    • Type: Mini Oral
    • Track: Immunology and Immunotherapy
    • Presentations: 1
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      MA 05.06 - Comparison Study of PD-L1 Immunohistochemistry Assays with 22C3 and 28-8: Analysis on Surgical Specimens of NSCLC. (ID 8423)

      15:45 - 17:30  |  Presenting Author(s): Tomohito Saito

      • Abstract
      • Presentation
      • Slides

      The checkpoint inhibitors programmed cell death and its ligand (PD-L1) antibodies are promising treatment agents for patients with advanced non-small cell lung cancer (NSCLC). Their clinical efficacy is predicted by drug-tailored PD-L1 immunohistochemistry (IHC) assays. We aimed to identify the similarity and distinction of 22C3 and 28-8 IHC tests.

      Three hundred and ninety consecutive cases of completely resected NSCLC between January 2009 and September 2014 that had adequate tissue samples were investigated. From the archived samples, 5-μm thick sections were cut and stained with PD-L1 IHC 22C3 PharmDx and 28-8 PharmDx (Dako, Santa Clara, CA). The staining and evaluation in 22C3 and 28-8 test were performed by two separate laboratories. PD-L1 expression and high PD-L1 expression were defined as ≥1% and ≥50% of tumor cells stained, respectively. Statistical significance was defined as a p-value of <0.05.

      The study population included 288 patients with adenocarcinomas, 70 with squamous cell carcinomas, 18 with large cell carcinomas, 9 with adenosquamous carcinoma and 5 with pleomorphic carcinoma. Two hundred and ninety-three patients had pStage I; 47, pStage II; and 46, p Stage IIIA tumors. Two hundred and twenty-nine specimens showed no PD-L1 expression with either 22C3 or 28-8. The detection rate of PD-L1 expression was 36.9% (144 cases) with 22C3 and 35.6% (139 cases) with 28-8, respectively (p= 0.710). The detection rate of high PD-L1 expression was 16.9% (66 cases) with 22C3 and 9.0% (35 cases) with 28-8 (p= 0.0013). The Spearman correlation coefficient was 0.866 (95% confidence interval, 0.838–0.890; p< 0.0001). Figure 1

      22C3 IHC assay may be more sensitive to detect high PD-L1 expression in NSCLC compard to 28-8 IHC assay, whereas 22C3 and 28-8 showed no significant difference to detect PD-L1 expression. Further investigation is necessary to reveal clinical, pathological and molecular background. This approach will help better interpretation of PD-L1 IHC results.

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