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C.-. Xu



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    JCHS - Joint IASLC - Chinese Society for Clinical Oncology - Chinese Alliance Against Lung Cancer Session (ID 239)

    • Event: WCLC 2015
    • Type: Joint Chinese/ English Session
    • Track: Other
    • Presentations: 1
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      JCHS.08 - Role of T790M Mutation in EGFR-TKI Rechallenge for Patients with EGFR-Mutant Advanced Non-Small Cell Lung Cancer (ID 3525)

      C.-. Xu

      • Abstract
      • Presentation
      • Slides

      Background:
      Epidermal growth factor receptor (EGFR) exon 20 T790M mutation may have a predictive role before EGFR-tyrosine kinase inhibitors (TKIs) treatment and it also might have a prognostic role after acquired resistance to EGFR-TKIs. However, its role in EGFR-TKI rechallenge after failure of initial EGFR-TKIs in EGFR-mutant advanced non-small cell lung cancer (NSCLC) remains unknown.

      Methods:
      We retrospectively evaluated the clinical course of 515 EGFR-mutant advanced NSCLC patients who received first generation EGFR-TKIs (gefitinib or erlotinib) from December 2009 to November 2014 at Guangdong General Hospital. Of these 515 patients, 65 patients recieved same EGFR-TKI rechallenge, including 51 patients who underwent rebiopsy and secondary EGFR mutation detection after failure of initial EGFR-TKIs. EGFR detection was performed by Sanger sequencing or Amplification Refractory Mutation System (ARMS) methods. Progression-free survival (PFS) and overall survival (OS) were both calculated from commencement of EGFR-TKI rechallenge. Survival data were analyzed using the Kaplan-Meier method and log-rank test.

      Results:
      EGFR activating mutations still existed in all the 51 patients who received rebiopsy and 18 patients were with T790M mutation while 33 patients were without T790M. The median PFS for the T790M+ and T790M- groups were 1.8 months (95%CI 1.180~2.420) and 2.0 months (95%CI 1.100~2.900), respectively (P=0.261). The median OS for the two groups were 7.7 months (95%CI 6.548~8.852) and 6.8 months (95%CI 4.730~8.870), respectively (P=0.565). No statistical difference was found in PFS or OS between two groups(Figure 1). Fig 1. Kaplan-Meier curves of patients in two groups. (A)Progression-free survival. (B) Overall survival.

      Conclusion:
      EGFR T790M mutation is neither a predictive nor a prognostic factor for first generation EGFR-TKI rechallenge in EGFR-mutant advanced NSCLC patients, indicating that whether T790M occurs or not, same EGFR-TKI rechallenge could not be recommended as a good strategy to overcome the resistance to first generation EGFR-TKIs.

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    MINI 03 - PD1 Axis Inhibition and EGFR (ID 101)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Treatment of Advanced Diseases - NSCLC
    • Presentations: 1
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      MINI03.09 - Role of T790M Mutation in EGFR-TKI Rechallenge for Patients with EGFR-Mutant Advanced Non-Small Cell Lung Cancer (ID 1031)

      C.-. Xu

      • Abstract
      • Presentation
      • Slides

      Background:
      Epidermal growth factor receptor (EGFR) exon 20 T790M mutation may have a predictive role before EGFR-tyrosine kinase inhibitors (TKIs) treatment and it also might have a prognostic role after acquired resistance to EGFR-TKIs. However, its role in EGFR-TKI rechallenge after failure of initial EGFR-TKIs in EGFR-mutant advanced non-small cell lung cancer (NSCLC) remains unknown.

      Methods:
      We retrospectively evaluated the clinical course of 515 EGFR-mutant advanced NSCLC patients who received first generation EGFR-TKIs (gefitinib or erlotinib) from December 2009 to November 2014 at Guangdong General Hospital. Of these 515 patients, 65 patients recieved same EGFR-TKI rechallenge, including 51 patients who underwent rebiopsy and secondary EGFR mutation detection after failure of initial EGFR-TKIs. EGFR detection was performed by Sanger sequencing or Amplification Refractory Mutation System (ARMS) methods. Progression-free survival (PFS) and overall survival (OS) were both calculated from commencement of EGFR-TKI rechallenge. Survival data were analyzed using the Kaplan-Meier method and log-rank test.

      Results:
      EGFR activating mutations still existed in all the 51 patients who received rebiopsy and 18 patients were with T790M mutation while 33 patients were without T790M. The median PFS for the T790M+ and T790M- groups were 1.8 months (95%CI 1.180~2.420) and 2.0 months (95%CI 1.100~2.900), respectively (P=0.261). The median OS for the two groups were 7.7 months (95%CI 6.548~8.852) and 6.8 months (95%CI 4.730~8.870), respectively (P=0.565). No statistical difference was found in PFS or OS between two groups(Figure 1). Figure 1 Fig 1. Kaplan-Meier curves of patients in two groups. (A)Progression-free survival. (B) Overall survival.



      Conclusion:
      EGFR T790M mutation is neither a predictive nor a prognostic factor for first generation EGFR-TKI rechallenge in EGFR-mutant advanced NSCLC patients, indicating that whether T790M occurs or not, same EGFR-TKI rechallenge could not be recommended as a good strategy to overcome the resistance to first generation EGFR-TKIs.

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    MINI 16 - EGFR Mutant Lung Cancer 2 (ID 130)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Treatment of Advanced Diseases - NSCLC
    • Presentations: 1
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      MINI16.13 - A Randomized Controlled Trial of Erlotinib versus Gefitinib in Advanced Non-Small-Cell Lung Cancer Harboring EGFR Mutations (CTONG0901) (ID 2762)

      C.-. Xu

      • Abstract
      • Presentation
      • Slides

      Background:
      For non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations, preclinical data showed the superiority of exon 19 mutations to exon 21 mutations in both response to EGFR tyrosine kinase inhibitors (TKIs) and survival. Meanwhile, retrospective studies demonstrated that erlotinib was significantly superior to gefitinib in progression-free survival (PFS) for advanced NSCLC patients with EGFR mutations. However, no randomized controlled trials compared erlotinib to gefitinib in advanced NSCLC patients with EGFR exon 19 or 21 mutations.

      Methods:
      We conducted a randomized controlled trial (CTONG 0901;NCT01024413) comparing erlotinib to gefitinib in advanced NSCLC harboring EGFR exon 19 or 21 mutations from July 2009 to July 2014. Eligible patients were randomized to receive erlotinib (150 mg, qd) or gefitinib (250 mg, qd) at the ratio of 1:1 in any line settings. The primary endpoint was PFS, and the secondary endpoints included overall survival (OS), objective response rate (ORR), post-progression survival (PPS), and toxicities.

      Results:
      The last follow-up was on March 30, 2015. Totally, 256 patients (148 with exon 19 mutations and 108 with exon 21 mutations), of whom 165, 83 and 9 were in the first, second or further-line settings respectively, were randomized to receive erlotinib or gefitinib. Median PFS was 12.4 (95%CI: 10.6~14.1) months in erlotinib arm and 10.4 (95%CI: 8.8~11.9) months in gefitinib arm, HR=0.80 (0.61~1.05), p=0.100; ORR, median PPS and OS were 56.3% versus 52.3% (p=0.530), 6.9 (95%CI: 4.3~9.5) versus 6.9 (95%CI: 4.5~9.2) months (p=0.784), and 22.4 (95%CI: 17.9~27.0) versus 20.5 (95%CI: 17.1~23.8) months (HR=0.90 [0.67~1.22]; p=0.496) respectively. There were no significant differences in toxicities between the two arms, p>0.05. In the four subgroups (the first-line, second or further-line setting, exon 19 and 21 mutations), except for median PFS being 11.4 versus 7.9 months (HR=0.58 [0.37~0.90], p=0.015) in the second or further-line setting, no significant differencs were observed in median PFS and OS respectively between the two arms, p>0.05. Receiving erlotinib or gefitinib treatment, EGFR exon 19 mutant patients were superior to those with exon 21 mutations in terms of ORR (62.2% versus 43.5%, p=0.003), median PPS (9.1 [95%CI: 7.0~11.2] versus 4.6 [95%CI: 3.4~5.8] months, p=0.011 ) and OS (24.8 [95%CI: 20.9~28.8] versus 17.7 [95%CI: 15.1~20.3] months, HR=0.66 [0.48~0.89], p=0.006) respectively, even though there was no significantly difference in median PFS (11.4 [95%CI: 9.6~13.2] versus 11.1 [95%CI: 9.4~12.9] months, HR=0.80 [0.60~1.05], p=0.101). Multivariant Cox regression analysis showed that subsequent EGFR TKIs, combination of subsequent EGFR TKIs and local treatment, as well as subsequent chemotherapy were prognostic factors for OS, p<0.05.

      Conclusion:
      Erlotinib was not significantly superior to gefitinib in advanced NSCLC with either exon 19 or 21 mutations in response and survival, with similar toxicities. However, EGFR exon 19 mutant patients had remarkably increased ORR, PPS and OS than those with exon 21 mutations after taking erlotinib or gefitinib. Subsequent treatments after failure to EGFR TKIs were significantly prognostic factors for OS.

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    MINI 26 - Circulating Tumor Markers (ID 148)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      MINI26.13 - Serial ctDNA Assessment of Response and Resistance to EGFR-TKI for Patients with EGFR-L858R Mutant Lung Cancer from a Prospective Trial (ID 3107)

      C.-. Xu

      • Abstract
      • Presentation
      • Slides

      Background:
      Plasma circulating tumor DNA (ctDNA) has been widely accepted as a form of liquid biopsy to detect EGFR mutations in NSCLC for its high concordance rate with tumor tissues. There are some retrospective studies about the ctDNA quantitative changes of EGFR mutations in EGFR-TKI treatment, but there is no report about serial ctDNA assessment of response and resistance to EGFR-TKI by detecting the dynamic changes of EGFR mutations during the whole course of EGFR-TKI treatment based on prospective clinical trial.

      Methods:
      Based on a randomized trial initiated to compare erlotinib with gefitinib in advanced NSCLC harboring EGFR exon 21 L858R mutation in tumor tissues (CTONG0901, NCT01024413), we prospectively collected serial plasma samples as preplanned schedule (baseline, one week after treatment, one month after treatment and then every 8 weeks until disease progression) and quantitatively detected EGFR L858R mutation in ctDNA by using fluorescence quantitative polymerase chain reaction. We made a serial ctDNA assessment of response and resistance to EGFR-TKI and its correlation with survival outcomes. Four patients’ serial plasma samples were selected to undergo next generation sequencing (NGS).

      Results:
      From 108 patients enrolled in the trial, serial plasma of 80 patients were collected as schedule and tested the quantity of L858R. As a whole, the quantity of L858R decreased to the lowest level when patients achieved best response to EGFR-TKI and increased to the highest level when disease progressed. Further analysis by Ward's Hierarchical Clustering Method showed that the dynamic changes of quantity of L858R could be categorized into two groups, Ascend Group and Stable Group (Figure 1A). Median progression-free survival (PFS) was 11.1 months (95%CI=6.6-15.6) and 7.5 months (95%CI=1.4-13.6) in two groups, respectively (HR=0.57, 95%CI=0.34-0.97, P=0.035) (Figure 1B). Median overall survival was 20.1 months (95%CI=15.7~24.5) vs. 16.4 months (95%CI=13.3~19.6) (HR=0.73, 95% CI =0.38~1.38, P=0.322). In multivariate Cox proportional hazards regression analysis, changing group was independent predictive factor for PFS. In plasma samples of 4 patients underwent NGS, similar dynamic changing characteristics were confirmed and more genetic mutations were found. Detailed data will be presented on site.Figure 1



      Conclusion:
      This is the first report about serial ctDNA assessment of response and resistance to EGFR-TKI by detecting the dynamic changes of EGFR mutation based on a prospective clinical trial. The quantity of plasma L858R has different changing patterns during EGFR-TKI treatment and higher L858R mutation abundance on EGFR-TKI resistance is correlated with longer PFS.

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