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Peter B Illei



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    P3.09 - Pathology (Not CME Accredited Session) (ID 975)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/26/2018, 12:00 - 13:30, Exhibit Hall
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      P3.09-04 - Assessment of PD-L1 Expression in Cytology Samples: An Anlaysis of 263 Consecutive NSCLC Biopsies. (ID 13491)

      12:00 - 13:30  |  Presenting Author(s): Peter B Illei

      • Abstract

      Background

      FDA approved anti-PD1 therapy can be considered for first-line use in advanced NSCLC with high (≥50%) PD-L1 expression. FDA approval was based on resection and core biopsy specimens, thus excluding most cytology samples. Since the majority of lung cancer patients are diagnosed with advanced stage disease and therefore are not candidates for surgical resection, bronchoscopic biopsies targeting N1 or N2 lymph nodes and/or the primary tumor are often the first biopsies these patients are subjected to. There is a great clinical need to determine the suitability of cytology specimen in the assessment of PD-L1 expression of NSCLC since often these are the only tissue samples available in advanced stage lung cancer.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      PD-L1 immunohistochemistry was performed using the 22C3 antibody (Dako) on a Ventana automated platform on 263 consecutive clinical cytology samples in a 14 month period. The assay was cross validated with the FDA approved companion diagnostic test. The samples included 216 cell blocks of fine needle aspirates of various sites, as well as cell blocks of body cavity effusions, and 42 core biopsies of various organs (20 gauge cores). Tissue clots (majority) or cell blocks were made from the aspirates followed by fixation in 10% buffered formalin. After fixation the tissue clots, cell blocks, core biopsies and lung biopsies were subjected to routine tissue processing.

      4c3880bb027f159e801041b1021e88e8 Result

      There were 246 (93.5%) samples with adequate tumor cellularity and 17 (6.5%) samples with no or less than 100 viable tumor cells (all cell blocks). The majority of samples (n216) were tissue clots/cell blocks, followed by core biopsies (n42) and other biopsy types (n5). No (<1%) PD-L1 expression was seen in 93 (35%), low (1-49%) expression in 57 (22%) and high (≥50%) expression in 96 (36.5%) cases. High PD-L1 expression was detected in 42 of 94 (44.7%) N2, 9 of 21 (42.8%) N1 lymph nodes and in 15 of 37 (40.5%) pleural/pericardial fluids. The cohort included 37 biopsies of distant metastases with high expression detected in 12 (32.4%) samples. Interestingly, all 12 liver metastases showed no (n6) or only low (≤10%, n6) PD-L1 expression. The rest of the specimens included lung mass aspirates, as well as core biopsies and FNA of N3 lymph nodes.

      8eea62084ca7e541d918e823422bd82e Conclusion

      Tissue blocks of cytology specimens appear to be an adequate source of non-small cell carcinoma tissue for PD-L1 testing. Additional analysis is pending to determine response rates to immunotherapy in order to confirm the validity of testing results of cytology samples.

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