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H. Ujiie



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    P3.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 226)

    • Event: WCLC 2015
    • Type: Poster
    • Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
    • Presentations: 1
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      P3.08-038 - Targetable Cancer-Associated Antigens for Immunotherapy in Malignant Pleural Mesothelioma (MPM) - Mesothelin, CA125 and WT-1 (ID 3165)

      09:30 - 09:30  |  Author(s): H. Ujiie

      • Abstract

      Background:
      Mesothelin (MSLN), CA125 (also know as mucin-16, MUC16) and WT-1 are cancer-associated antigens currently under investigation as targets for tumor-specific immunotherapy, based on published observations that antigen-specific immune responses to these antigens prolong survival. In solid malignancies, we (Clin Cancer Res 2012, 2013) and others have published the role of MSLN in promoting tumor aggressiveness. Additionally, MSLN has been demonstrated to interact with CA125 in promoting invasion and metastasis, resulting in poor clinical outcomes. In this study, we investigated the individual and correlative expressions of MSLN, CA125 and WT-1 in both epithelioid and non-epithelioid MPMs.

      Methods:
      All available H&E-stained slides from patients who were diagnosed with MPM (1989-2010) were reviewed; tumors were classified according to the WHO classification. We constructed tissue microarrays (6 tumor cores/tumor) from 273 patients (epithelioid=224; non-epithelioid, including biphasic and sarcomatoid =49). MSLN, CA125, and WT-1 immunohistochemistry were performed, and total scores for each antigen were determined by assessing the combined intensity and distribution of the antigen expression.

      Results:
      Epithelioid MPMs demonstrated positive MSLN expression in 92% of patient samples (73% high-moderate expression), CA125 expression in 72% (19% high-moderate), and WT-1 in 94% (63% high-moderate) (Fig.1A). Triple positive antigen expression was recognized in 68% of patients; co-expression of two antigens was demonstrated in 23% of epithelioid MPMs (Fig.1B). In non-epithelioid MPMs, MSLN, CA125, and WT-1 were positive in 57% (16% high-moderate), 33% (2% high-moderate), and 98% (43% high-moderate) of patient tumors, respectively. Triple and double antigen co-expression were demonstrated in 29% and 33% of non-epithelioid MPMs, respectively. Only 1% of epithelioid and 2% of non-epithelioid MPMs demonstrated absence of expression of all three antigens: MSLN, CA125, and WT-1.Figure 1



      Conclusion:
      Our observation from a large cohort of MPM patients inclusive of all histological subtypes demonstrating greater than 98% positive expression of at least one of the three cancer-associated antigens in epithelioid and non-epithelioid MPMs, with strong antigen expression and high frequency of double and triple antigen expression, provides rationale to develop targeted therapies to these cancer-associated antigens for the treatment of MPM patients We are initiaiting a phase I clinical trial (NCT02414269) of mesothelin-targeted T-cell therapy for MPM patients at our center.