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L. Seymour

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    ORAL 06 - Next Generation Sequencing and Testing Implications (ID 90)

    • Event: WCLC 2015
    • Type: Oral Session
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      ORAL06.03 - Genome-Wide Gene Copy Number Analysis by OncoScan<sup>TM</sup> FFPE Assay in 976 Resected NSCLC From LACE-Bio2 (ID 1561)

      10:45 - 12:15  |  Author(s): L. Seymour

      • Abstract
      • Presentation
      • Slides

      Genome wide SNP array studies have identified systematic gene copy number aberrations (CNA) in non-small cell lung cancer (NSCLC), but their prognostic implication is unknown. This study aimed to investigate associations between CNAs and survival using the LACE-Bio bio-bank. The LACE-Bio consortium includes large clinical trials comparing adjuvant platinum-based chemotherapy to observation after complete resection of stage I-III NSCLC.

      DNA was extracted from FFPE tumor samples from 3 pivotal adjuvant chemotherapy trials (CALGB 9633, IALT, JBR.10); 1013 samples were profiled using Affymetrix OncoScan[TM] arrays with over 300,000 probes and normalized relative to a pool of normal tissues. Segmentation was performed using the CBS algorithm and minimally recurrent regions (MCR) across the series identified by CGHregions. All analyses were performed on the level of MCRs. CNAs were correlated with clinicopathological factors and adjusted for the False Discovery Rate (FDR). The primary endpoint, disease-free survival (DFS), was assessed via univariate Cox models stratified by trial and adjusted for treatment, age, sex, PS, histology, T, and N stage.

      Among 976 successfully profiled samples, 414 (42%) were adenocarcinoma (ADC), 430 (44%) squamous cell carcinoma (SCC) and 132 (14%) other NSCLC; 710 (73%) were male. Across the 431 MCRs identified, patients had on average 94 (SD 69) CNAs: 51 gains and 43 losses. A gain or loss was observed in at least 10% of patients for 177 and 166 regions respectively. The most common gains (up to 48%) were on chromosomes 1p, 3q, 5p, 6p, and 22q. The most common losses (up to 40%) were on chromosomes 3p, 8p and 9p. The size of 253 of the 431 MCRs (59%) was smaller or equal to 3Mb (and 79% ≤10 Mb). Sensitivity analyses on the subset of samples with optimal quality (n=777, defined by MAPD<0.3) gave consistent results. The CNA frequency of 195 regions was significantly different with FDR≤0.05 between ADC and SCC (of which 49% regions of size ≤3Mb and 71% ≤10Mb); the most significant were more gains in 3q, 22q and 12 in SCC and more losses in 3p, 4, 5q in SCC. With a median follow-up of 5.3 years, 510 DFS events and 451 deaths were recorded. In univariate analyses for DFS, 13 regions in loci 19p11–13, 7p12, 9p21, 15q14 had a raw p-value <0.005 (FDR<0.13, the top 8 corresponded to FDR≤0.05); 9 of those 13 regions were of size ≤3Mb (12 regions ≤10Mb). In adjusted analyses, 10 of the 13 regions retained raw adjusted p-values ≤0.005 (FDR≤0.15). Losses of focal regions including CDKN2A/B and STK11 (≤3Mb) were associated with poorer DFS: the hazard ratio (HR) for a 2-fold copy number decrease in region 9p21.3 (including CDKN2A/B) was 1.50 (95% CI: 1.2–1.9, P<0.001, FDR=0.02), and the HR for a 2-fold copy number decrease in 19p13 (including STK11) was 2.4 (1.3–4.3, P=0.005, FDR=0.15). Similar results were obtained for overall survival and lung-cancer specific survival. Results of histology-specific analyses will be presented.

      These large-scale genome-wide analyses of gene CNA provide new candidate prognostic markers for stage I-III NSCLC.

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