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Charmi Patel



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    P2.09 - Pathology (ID 174)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Pathology
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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      P2.09-33 - Prevalence of ROS1 (SP384)-Reactive Type II Pneumocyte Staining in Lung Tissue (ID 1907)

      10:15 - 18:15  |  Author(s): Charmi Patel

      • Abstract
      • Slides

      Background

      Availability of a positive control sample is important to ascertain that specimen preparation and immunohistochemistry (IHC) processes are performed correctly. Lack of proper control tissue may result in an invalid IHC interpretation. Given the low prevalence (1-2%) of ROS1 gene fusions (which leads to overexpression of ROS1) in non-small cell lung cancer (NSCLC), the feasibility of using ROS1-fusion positive NSCLC tissue as a control sample is challenging. ROS1 wild-type (WT) protein expression has been shown to be absent in normal lung tissue; however, ROS1 reactivity has been observed in reactive type II pneumocytes in non-neoplastic lung tissue. Hence, we sought to characterize the prevalence of VENTANA ROS1 (SP384) Rabbit Monoclonal Primary Antibody (ROS1 (SP384)) reactive type II pneumocytes in normal or benign lung tissue in order to assess the feasibility of using type II pneumoctyes as a control tissue for ROS1 (SP384).

      Method

      One hundred seventy-seven (177) formalin-fixed, paraffin-embedded (FFPE) normal or benign lung tissue samples were randomly procured. Tissues sectioned at 4 μm were stained with hematoxylin and eosin (H&E), Rabbit Monoclonal Negative Control Ig, and ROS1 (SP384) IHC. ROS1 (SP384)-stained specimens were evaluated for presence of type II pneumocytes. If present, type II pneumocytes were evaluated for reactivity based on a 0 to 3-point stain intensity scale. Reactivity was defined as any staining greater than 0. Data was analyzed for percent distribution for a range of stain intensities.

      Result

      Out of the 177 specimens evaluated, 165 ROS1 (SP384)-stained slides were evaluable (12 cases were unacceptable due to tissue loss or were identified as neoplastic lung tissue). Type II pneumocytes were present in all 165 evaluable samples. Forty-seven type II pneumocyte samples (28.5%, 47/165) demonstrated no staining with ROS1 (SP384) while 71.5% of the type II pneumocyte samples (118/165) demonstrated reactivity with ROS1 (SP384). In addition, 23.0% (38/165) of the type II pneumocyte samples demonstrated a stain intensity of at least 2.

      Conclusion

      Herein, this cohort demonstrates a high prevalence of ROS1 reactivity in type II pneumocytes, with a range of stain intensities, in normal or benign lung tissue with VENTANA ROS1 (SP384) Rabbit Monoclonal Primary Antibody. This finding suggests that use of reactive type II pneumocytes in normal or benign lung tissue as a control tissue for ROS1 (SP384) is feasible.

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