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Xiaoling Tong



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    P1.01 - Advanced NSCLC (Not CME Accredited Session) (ID 933)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall
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      P1.01-85 - The Prevalence of Different EGFR exon20 Mutations in 12,833 Chinese Lung Cancer Patients (ID 14141)

      16:45 - 18:00  |  Author(s): Xiaoling Tong

      • Abstract
      • Slides

      Background

      Mutations in EGFR exon20 are relatively rare in lung cancers compared to L858R/exon19 mutations, some of which have shown sensitivity to EGFR tyrosine kinase inhibitors (TKIs), and have been actively tested in clinical trials. However, due to the high-variety of EGFR exon20 alterations, it becomes increasingly difficult for their functional studies in related to clinical practice.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      We retrospectively screened 12,833 Chinese lung cancer patients that have underwent genotyping on their tumor and/or liquid biopsy samples using targeted next-generation sequencing between 2014 and 2017 for EGFR exon20 mutations as well as other concurrent EGFR mutations in the same patient.

      4c3880bb027f159e801041b1021e88e8 Result

      A total of 442 patients (3.4%) were found harboring 493 different EGFR exon20 variations, among which 49 patients (11%) carried more than one exon20 mutations. The frequencies of the most prevalent alterations were summarized in Table 1. 18% of these mutations have concurrent TKI-sensitive mutations L858R or exon19 deletion. In-frame deletion/insertions (delins or ins) and missense mutations were identified at a frequency of 53% and 47%, respectively. The short delins/ins occurred between 763~773 residues, while missense mutations dwelled at 768~820 residues, suggesting that these two types of alterations have their own manners for regulating EGFR kinase domain function. The most prevalent insertion is p.M766delinsMASV, occurred in 15.2% of all patients. Meanwhile, the diversity of inserted peptides at p.D770 and p.D771 positions is much higher than other positions with a total of 17 and 19 different insertion peptides composed of 1-5 amino acids, respectively. Missense mutations at S768 were detected in 20.4% of patients, but 60% of them were accompanied by mutations at G719. table 1.jpg

      8eea62084ca7e541d918e823422bd82e Conclusion

      This is the largest cohort of Chinese lung cancers for studying EGFR exon 20 mutations, which should be informative for functional studies, the design of targeted drugs, and the testing for existing therapies.

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    P2.13 - Targeted Therapy (Not CME Accredited Session) (ID 962)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/25/2018, 16:45 - 18:00, Exhibit Hall
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      P2.13-15 - Short-Term Responders of NSCLC to EGFR-TKIs Display High Prevalence of TP53 Mutations and Primary Resistance Mechanisms (ID 12540)

      16:45 - 18:00  |  Author(s): Xiaoling Tong

      • Abstract

      Background

      Non-small cell lung cancer (NSCLC) with activating EGFR mutations in exon 19 and 21 usually responds to EGFR tyrosine kinase inhibitors (TKI), but sometimes the responses can only be maintained for a few months. The underlying mechanisms of such short responses have not been fully elucidated.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      The genomic profiles of sixteen short-term responders (SR) that had progression free survival (PFS) of less than 6 months on the first-generation EGFR TKI were interrogated, in comparison to twelve long-term responders (LR) that had more than 24 months of PFS. All patients were diagnosed with advanced lung adenocarcinoma and harbored EGFR 19del or L855R mutation before treatment. Paired tumor samples collected before treatment and after relapse (or at the last follow-up) were subjected to next-generation sequencing of 416 cancer-relevant genes.

      4c3880bb027f159e801041b1021e88e8 Result

      SR patients were significantly younger than LR patients (p<0.001). 88% of SR patients have TP53 variations compared to 13% in LR patients (p<0.001), and 37.5% SR patients carry EGFR amplification, which is much higher than LR patients (8%). In addition, 12 SR patients (75%) were identified with other potential primary resistance mechanisms in pre-treatment samples, including PTEN loss, BIM deletion polymorphism, amplifications of EGFR, ERBB2, MET, HRAS and AKT2. Comparatively, only 3 LR patients (25%) were detected with EGFR or AKT1 amplification that could possibly exert resistance.

      8eea62084ca7e541d918e823422bd82e Conclusion

      The diversified pre-existing resistance mechanisms in SR patients revealed the complexity of defining treatment strategies even for EGFR sensitive mutations.

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