Author of

• 11543

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  P2.06 - Poster Session 2 - Prognostic and Predictive Biomarkers (ID 165)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11557

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    P2.06-014 - Quantitative test of mutant EGFR and its effect on efficacy of EGFR TKI in advanced NSCLC (ID 1327)

    09:30 - 09:30  |  Author(s): C. Zhao
    • Abstract

    Background
    It is reported that abundance of EGFR mutations is related with efficacy of EGFR TKI in advanced NSCLC patients with mutant EGFR. This study was designed to investigate influence of EGFR mutations and their abundance on efficacy of EGFR TKI by a quantitative method.

    Methods
    190 NSCLC treated with EGFR TKI and available tissue for EGFR mutations were enrolled into the study; 113 were FFPE specimen, and 62 were fresh tissue. EGFR mutation was detected with the kit of AmoyDx ARMS and percentage of mutant EGFR was tested with the method of an Allele Specific PCR with Competitive Blocker (ASB-PCR). In this assay, copies of EGFR mutants were calibrated by standard curve, and the mutation rates were estimated through normalizing by copies of a conserved sequence in EGFR exon2. The relationship between abundance of EGFR mutations and efficacy of EGFR TKI was analyzed.

    Results
    Of 190 samples, 15 were censored due to EGFR exon2 copies less than 100; finally, 175 enrolled into data analysis. Mutant percentage less than 0.1% was defined as wild-type, 0.1%~2% as low abundance, 2%~20% as moderate abundance, and more than 20% as high abundance. The mutant rate was 56.6% and 62.3% by using AmoyDx ARMS and ASB-PCR methods, respectively. The accordance rate of EGFR mutations was 89.7% by two methods. Of 175 samples, 20, 27 and 62 harbored low, moderate and high abundances of mutant EGFR, respectively; 66 were wild-type EGFR. Median progress free survival (mPFS) was 4.9 (95% CI, 3.4 to 6.4), 8.3 (95% CI, 3.3 to 13.3) and 16.0 months (95% CI, 10.4 to 21.7) in patients with low, moderate and high abundances of mutant EGFR (p =0.012). The mPFS of low abundance was not longer than that of those patients with wild-type EGFR (2.0 months, 95% CI, 0.2 to 4.1; p=0.261). Objective response rate (ORR) was 67.7%, 44.4%, 25.0% and 19.7%, and disease control rate (DCR) was 90.3%, 81.5%, 55.0% and 45.5% in patients with high, moderate, low abundance and wild-type EGFR, respectively (p<0.001). But ORR and DCR were no difference between low abundance and WT groups (p=0.754; p=0.610, respectively).

    Conclusion
    The abundance of EGFR mutations could affect the efficacy of EGFR-TKI, and quantitation of mutant EGFR could better predict for efficacy of EGFR TKI in advanced NSCLC.