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Mei Wan Rebecca Yeung
MA16 - Prioritizing Use of Technology to Improve Survival of Lung Cancer Subgroups and Outcomes with Chemotherapy and Surgery (ID 142)
- Event: WCLC 2019
- Type: Mini Oral Session
- Track: Treatment in the Real World - Support, Survivorship, Systems Research
- Presentations: 1
- Now Available
MA16.02 - T790M Allelic Fraction Level Did Not Correlate Survival in T790M Positive NSCLC – Observations from an Early Access Program (Now Available) (ID 1809)
15:45 - 17:15 | Author(s): Mei Wan Rebecca Yeung
Osimertinib is an irreversible third-generation EGFR-TKI indicated for patients with metastatic EGFR T790M mutation positive NSCLC after progression of initial TKI therapy. An early access program (EAP) was started in 2015 providing ethical access of Osimertinib to patients with metastatic NSCLC running out of treatment options in Hong Kong. As some prior data suggested that T790M allele fraction (AF) correlated survival outcomes in patients receiving Osimertinib, we try to validate it with data from this EAP. Survival outcomes and safety data of Osimertinib in the real world practice under this EAP were also analysed. (NCT03219970)
This retrospective analysis included EAP patients who had advanced or metastatic NSCLC harbouring EGFR T790M mutation that progressed on prior TKI ± chemotherapy. EAP subjects received Osimertinib at 80mg daily until disease progression, intolerable toxicities or death. The T790M mutation can be assessed by any approved molecular tests in any specimen types.
The AF levels in patients with T790M mutation confirmed by quantitative plasma genotyping (QPG) using ddPCR technique of the same vendor were retrieved. The primary objective was to assess the relationship of post-Osimertinib overall survival (OS) and T790M AF level. Secondary objectives included investigator-assessed response, time to discontinuation (TTD) of Osimertinib, safety (Osimertinib-related adverse events of special interest, AESIs) and OS of all EAP participants.
From Sep 2015 to Feb 2017, 156 patients enrolled in the EAP and received treatment. At time of data cut-off (11 Oct 2018), 74 (47%) were alive. Median follow-up was 23.4 (range: 1–30) months, median age 62 years, 62% female, 26% ECOG PS ≥2, 96.8% with metastatic disease. Besides T790M, 56% of patients had exon 19 deletions and 41% had exon 21 L858R mutations.
Ninety-one patients had QPG using ddPCR method with AF data. OS, best response rate and TTD were not significantly related to T790M AF level as a continuous variable (p=0.20; hazard ratio 1.022, 95% CI 0.989 to 1.057), confirmed through sensitivity analysis with different AF threshold values.
The investigator assessed best response rate was 41.7% (65/156) and disease control rate was 62.2% (97/156). Median TTD was 15.77 (12.43, 18.98) months. Median OS was 21.88 (95% CI 19.14–26.21) months. AESIs were reported in 7.7% of patients overall: 5.8% QTc prolongation and 1.9% pneumonitis.
T790M AF level did not correlate with TTD and OS in this EAP cohort but the limitations should not be overlooked. The survival outcomes concurs other reported series.
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