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Craig Barker



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    MA15 - Colliding Approaches - EGFR and Immunotherapy (ID 916)

    • Event: WCLC 2018
    • Type: Mini Oral Abstract Session
    • Track: Targeted Therapy
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/25/2018, 13:30 - 15:00, Room 107
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      MA15.03 - PD-L1 Expression in Untreated EGFRm Advanced NSCLC and Response to Osimertinib and SoC EGFR-TKIs in the FLAURA Trial (ID 12989)

      13:40 - 13:45  |  Author(s): Craig Barker

      • Abstract
      • Presentation
      • Slides

      Background

      In the Phase III FLAURA trial (NCT02296125), osimertinib significantly improved PFS relative to SoC EGFR-TKIs (gefitinib/erlotinib) in patients with untreated Ex19del/L858R positive (EGFRm) NSCLC. EGFRm NSCLC tumors can exhibit high PD-L1 expression, an important biomarker for immunotherapy treatment decisions. The frequency and clinical relevance of exhibiting both biomarkers prior to treatment are unclear. We report PD-L1 expression in patients with EGFRm advanced NSCLC and association with clinical outcomes following EGFR-TKI treatment.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      Tissue samples from 994 patients with advanced NSCLC were screened for EGFR Ex19del/L858R mutations for enrolment in FLAURA; 556 were randomized to treatment. 197 tissue-blocks from the screened population (including EGFR mutation-positive and -negative samples) were tested for PD-L1 using the SP263 (Ventana) immunohistochemical assay; positive tumour cell (TC) staining PD-L1 TC≥25% and TC≥1% thresholds were applied. PFS was investigator-assessed, per RECIST 1.1, according to PD-L1-expressers (TC≥1%) or -negatives (TC<1%) in randomized patients.

      4c3880bb027f159e801041b1021e88e8 Result

      193/197 blocks had sufficient tumor tissue for staining. 65/193 patients were EGFR mutation-negative. 128/193 patients were EGFR mutation-positive: 106/128 were randomized to treatment (osimertinib: 54; SoC: 52). The table presents PD-L1 expression according to EGFR mutation status. For PD-L1-expressers (TC≥1%), median PFS was 18.4 months for osimertinib and 6.9 months for SoC (HR 0.30 [95% CI 0.15, 0.60]). For PD-L1-negative patients (TC<1%), median PFS was 18.9 months for osimertinib and 10.9 months for SoC (HR 0.37 [95% CI 0.17, 0.74]).

      PD-L1 TC≥1%, n (%)

      PD-L1 TC≥25%, n (%)

      EGFR mutation-negative (n=65)

      Screened population (n=65)

      44 (68)

      23 (35)

      EGFR mutation-positive (n=128)

      Screened population (n=128)

      65 (51)

      10 (8)

      Randomized to treatment (n=106)

      52 (49)

      8 (8)

      Randomized to osimertinib (n=54)

      28 (52)

      3 (6)

      Randomized to SoC EGFR-TKI (n=52)

      24 (46)

      5 (10)

      8eea62084ca7e541d918e823422bd82e Conclusion

      There was PFS benefit with osimertinib versus SoC regardless of whether tumors were PD-L1-expressers (TC≥1%) or -negatives (TC<1%). Using the TC≥25% threshold, PD-L1 prevalence was lower in EGFR mutation-positive than mutation-negative samples; there were insufficient patients with TC≥25% tumors for PFS assessment.

      These results support the efficacy of EGFR-TKIs, including osimertinib, as first-line treatment of EGFRm advanced NSCLC, irrespective of PD-L1 expression.

      6f8b794f3246b0c1e1780bb4d4d5dc53

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