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Satoru Moriyama



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    P2.06 - Mesothelioma (Not CME Accredited Session) (ID 955)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/25/2018, 16:45 - 18:00, Exhibit Hall
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      P2.06-37 - Four Immunohistochemical Assays to Measure the PD-L1 Expression in Malignant Pleural Mesothelioma (ID 11757)

      16:45 - 18:00  |  Author(s): Satoru Moriyama

      • Abstract
      • Slides

      Background

      Malignant pleural mesothelioma (MPM) is a rare disease with no effective standardized systemic therapy. Immune checkpoint inhibitors (ICIs) targeting the programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway are expected to be a novel therapy for MPM patients. However, the PD-L1 expression, which is a predictor of the response to ICIs, is unclear in MPM.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      We studied the PD-L1 expression using four immunohistochemical, companion diagnostic assays (SP142, SP263, 28-8 and 22C3) in 32 MPM patients. The PD-L1 expression in tumor cells (TCs) and immune cells (ICs) was evaluated to clarify the rate of PD-L1 expression and the concordance among the four assays in MPM. The cut-off values were set at 1% TC or 1% IC for SP142, 25% TC for SP263, 1% TC for 28-8, and 1% TC for 22C.

      4c3880bb027f159e801041b1021e88e8 Result

      The positivity rate of PD-L1 expression was 53.1% for SP142, 28.1% for SP263, 53.1% for 28-8, and 56.3% for 22C3. Nine cases were positive and 10 were negative for all assays. Discordance among the four assays was found in 13 cases. The concordance rates between SP142 and 22C3 and between 28-8 and 22C3 were the highest (84.4%). The concordance rates between SP263 and the other three assays were low (71.9% to 75.0%). 000001.jpg

      8eea62084ca7e541d918e823422bd82e Conclusion

      The PD-L1 expression in MPM was almost equivalent for three of the assays. Given the cut-off values set in our study, these findings suggested that these assays, except for SP263, can be used for accurate PD-L1 immunostaining in MPM.

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