Author of

• 13754

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  P1.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 224)

  • Event: WCLC 2015
  • Type: Poster
  • Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)

  • 13791

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    P1.08-037 - PD-L1 Expression in Surgically Resected Thymic Epithelial Tumor (ID 1488)

    09:30 - 09:30  |  Author(s): M. Kwak
    • Abstract

    Background:
    Blockade of the immune checkpoint programmed death receptor ligand-1 (PD-L1)/PD-1 pathway has recently shown clinical activity across many tumor types. PD-L1 protein expression by immunohistochemistry (IHC) is emerging as a predictive biomarker of response to these therapies. Hence, we studied PD-L1 expression in a thymic epithelial tumor (TET).
    
    Methods:
    Of the patients who previously underwent resection of TET at Samsung Medical Center between January 2000 and January 2013, 220 patients who had available tissue block for immunohistochemistry were included. Formalin-fixed paraffin embedded tumor samples were stained with murine monoclonal antibody (clone h5H1) to human PD-L1. PD-L1 staining was classified based on intensity and moderate or strong intensity in 5% or more of tumor tissues was considered as positive PD-L1 expression.
    
    Results:
    The median age was 52 years (range, 18-81), and 57.7% of patients were male. WHO histologic type was mostly B2 (N=96, 43.6%), followed by C (N=48, 21.8%), B3 (N=47, 21.4%) and neuroendocrine tumor (N=17, 7.7%). R0 resection was possible in 193 patients (87.7%). Positive PD-L1 expression was observed in 83 samples (37.7%). PD-L1 expression and histologic type was significantly correlated, with high PD-L1 expression in histologic type B2/B3/C (7.1% vs. 42.4% in type A/AB/neuroendocrine tumor vs. type B2/B3/C; P<0.001). PD-L1 expression did not affect overall survival both in univariate and multivariate survival analysis.
    
    Conclusion:
    In TET, PD-L1 expression was positive in 37.7% and it was more frequently observed in aggressive histology (B2/B3/C). PD-1/PD-L1 targeting agents could be a promising therapy for TET.