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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
- Coordinates: 9/25/2018, 13:30 - 15:00, Room 107
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): Alexander Kohlmann
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)
EGFR mutation-positive (n=128)
Screened population (n=128)
Randomized to treatment (n=106)
Randomized to osimertinib (n=54)
Randomized to SoC EGFR-TKI (n=52)
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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