Author of

• 18972

  +

  P2.02 - Biology/Pathology (ID 616)

  • Event: WCLC 2017
  • Type: Poster Session with Presenters Present
  • Track: Biology/Pathology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/17/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)

  • 23238

    +

    P2.02-040 - Cytology Cell Block Is Suitable for Immunohistochemical Testing for PD-L1 in Lung Cancer (ID 10132)

    09:30 - 09:30  |  Author(s): S. Camilleri-Broet
    • Abstract
    • Slides

    Background:
    PD-L1 immunohistochemistry (IHC) testing is usually performed on core needle biopsy or surgical resection tissue blocks, and tumor proportion score (TPS) ≥50% is used to select patients to treat with Pembrolizumab immunotherapy. In this study, we evaluate the results using cytology cell block for PD-L1 IHC assay.
    
    Method:
    A total of 1423 consecutive cases of non-small cell lung cancer (NSCLC), including 368 cytology cell blocks, 813 small biopsies and 242 surgical resections, were included in the study. 151 cytology cell blocks had known fixation status, which were either directly fixed in formalin, or in alcohol first then refixed in formalin. IHC used Dako PD-L1 IHC 22C3 pharmDx. The TPS of ≥ 50% tumor cells was defined as positive. A total of 100 viable tumor cells were required for adequacy.
    
    Result:
    Of the cytology cell blocks, 93% of the specimens had sufficient numbers of tumor cells, and the rate was equivalent to the rate of small biopsies (93%). All resection specimens were shown to be adequate for testing. PD-L1 expression was positive in 42.1% of cytology cell blocks, statistically comparable to small biopsies (36.3%, P>0.05), but higher than in surgical resections (28.5%, p<0.05). The fixative methods did not affect the immunostaining, since the PD-L1 positive rate was of 41.9% in formalin only group, vs 40.4% in alcohol plus formalin fixed cell blocks (p>0.05). The PD-L1 positive rate appeared lower in cell blocks from bronchoalveolar lavage (BAL) (27%) as compared to fine needle aspiration (FNA, 42%) and pleural/pericardial fluid (45%), although the difference did not reach statistical significance (P>0.05).
    
    Conclusion:
    Our results demonstrate that PD-L1 IHC performs well with cytology cell blocks. The rate of positive PD-L1 was comparable between cytology blocks and small biopsies. As cytology cell blocks are commonly available from lung cancer patients, they can provide valuable resource for PD-L1 testing and can help to avoid rebiopsies. However additional correlation with clinical response will be helpful to further validate the cytology specimens.
    
    

    Only Active Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login or select "Add to Cart" and proceed to checkout.