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Yingcheng Lin



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    MA16 - Novel Mechanisms for Molecular Profiling (ID 917)

    • Event: WCLC 2018
    • Type: Mini Oral Abstract Session
    • Track: Advanced NSCLC
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/25/2018, 13:30 - 15:00, Room 203 BD
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      MA16.06 - EGFR Clonality and Tumor Mutation Burden (TMB) by Circulating Tumor DNA (ctDNA) Sequencing in Advanced Non-Small Cell Lung Cancer (NSCLC) (ID 13146)

      14:05 - 14:10  |  Author(s): Yingcheng Lin

      • Abstract
      • Presentation
      • Slides

      Background

      TKI has significantly improved survival time of NSCLC pts with sensitive mutation. However, pts present different outcome while receiving TKI treatment. We conduct a prospective multicenter clinical trial to determine whether clonality of sensitive mutation is related to the efficacy of TKI. We also evaluate the consistency of TMB between tissue and blood in this cohort.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      Paired tumor and plasma samples at diagnosis were obtained from systemic treatment naïve pts with advanced NSCLC. DNA was sequenced by target-capture deep sequencing of 1021 previously annotated genes related to solid tumors. Clonal EGFR mutation was defined if EGFR mutation was in the cluster with the highest mean variated allele frequency with PyClone, and otherwise subclonal EGFR mutation. TMB of tissue (tTMB) and blood (bTMB) analysis interrogated single nucleotide variants, small insertion and deletion, with VAF ≥3 % and ≥0.5 %, respectively. TMB-high pts were identified with ≥9 mut/MB (upper quartile of data from geneplus).

      4c3880bb027f159e801041b1021e88e8 Result

      During February 2017 to April 2018, 127 advanced NSCLC pts were enrolled from 9 centers. A total of 653 somatic variations were detected in tissues. Mutations occurred most frequently in EGFR (57 %), TP53 (54 %), KRAS (9 %), ALK (8 %). In matched plasma, 405 (62 %) tumor-derived mutations were detected by pan-caner panel sequencing. A total of 90 EGFR mutations were detected in 73 pts, most of which occurred in tyrosine kinase domain (L858R, 41%; Ex19del, 33%). Most EGFR mutation were clonal in tissue and plasma, with a consistence of 83 % in paired samples. In addition, bTMB was significantly correlated to tTMB (Pearson r= 0.85, p-value= 1.8e-30), with a consistence of 89 %. Interestingly, high TMB was observed in a small fraction of patients (8 %) with driver mutations, such as mutations in EGFR, ALK fusion, ERBB2 and PIK3CA.

      8eea62084ca7e541d918e823422bd82e Conclusion

      Deep sequencing with the pan-cancer panel can effectively detect mutations and evaluate TMB in both tissue and blood with high consistence. EGFR mutations can be clonal or subclonal in both tissue and blood. Prospective multicenter study is ongoing to determine the EGFR clonality as a predictive factor for the TKI efficacy in NSCLC (TRACELib-NSCLC, NCT03059641).

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    P3.12 - Small Cell Lung Cancer/NET (Not CME Accredited Session) (ID 978)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/26/2018, 12:00 - 13:30, Exhibit Hall
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      P3.12-12 - Genomic Profiling of Pulmonary Large-Cell Neuroendocrine Carcinoma (LCNEC) Reveals Distinct Mutational Landscape (ID 13244)

      12:00 - 13:30  |  Author(s): Yingcheng Lin

      • Abstract
      • Slides

      Background

      The controversial classification of lung neuroendocrine tumor has been amended a few times since recognised as a separate entity. LCNEC shares clinical features with small cell lung carcinoma (SCLC) and they were both classified as lung neuroendocrine carcinoma according to the 2015 WHO lung primary pathology classification, numerous studies have revealed barely satisfactory outcomes when it was treated as SCLC. However the underlying molecular basis for such commonalities and discrepancies are poorly understood. In this study, we interrogated the genomic landscape of LCNEC and SCLC along with their histologically related subtypes: carcinoids and atypical carcinoids to define the molecular pattern of LCNEC.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      We performed targeted sequencing in 35 tissue samples using a panel covering 520 cancer related genes, spanning 1.6MB of human genome, with an average sequencing depth of 1,418x. Among them, 15 were diagnosed with SCLC, 9 with LCNEC, 6 with carcinoid and 5 with atypical carcinoid.

      4c3880bb027f159e801041b1021e88e8 Result

      On average, LCNEC exhibited 13.5 mutations per million base pairs (Mb) and a C:G>A:T transversion rate of 34%, which is indicative of tobacco exposure. LCNEC had SCLC (16.7 Mb) had comparable TMB (p=0.18), which is significantly higher than carcinoids (1.2/Mb, p<0.001) and atypical carcinoids (2.4/Mb, p<0.001). The most frequently mutated gene in LCNEC is TP53 (89%, 8/9), followed by NOTCH1 (33%), KEAP1 (22%), RB1 (22%) and a few chromatin modifiers, including KMT2D (33%), KMT2C (33%). Co-mutation in TP53 and RB1, a hallmark of SCLC, was found in 22% (2/9) of LCNEC patients; in contrast, 80% of SCLC patients harbored concurrent mutation. 67% carcinoid (4/6) and 20% (1/5) atypical carcinoid patients had no mutation identified from this panel. No classic lung adenocarcinoma driver mutations were found in any subtype. Copy number analyses revealed significantly higher copy number variation (CNV) in SCLC and LCNEC comparing with carcinoids and atypical carcinoids, which yield virtually no CNV. Our analysis revealed a comparable CNV status of SCLC and LCNEC (p=0.158), with an enrichment in amplification of chromatin modifiers.

      8eea62084ca7e541d918e823422bd82e Conclusion

      Our study, comprehensively characterized 4 subtypes of neuroendocrine tumors, revealed a high TMB and CG:AT transversion rate in LCNEC patients as well as a distinctive mutation landscape, with an enrichment of mutations occurring at chromatin remodelers. Furthermore, LCNEC has comparable TMB and CNV status as SCLC, which are significantly higher than carcinoid and atypical carcinoids.

      6f8b794f3246b0c1e1780bb4d4d5dc53

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