Author of

• 16549

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  P1.02 - Poster Session with Presenters Present (ID 454)

  • Event: WCLC 2016
  • Type: Poster Presenters Present
  • Track: Biology/Pathology
  • Presentations: 1
  • Moderators:
  • Coordinates: 12/05/2016, 14:30 - 15:45, Hall B (Poster Area)

  • 16585

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    P1.02-036 - An EGFR Tyrosine Kinase Inhibitor Sensitive Patient-Derived Lung Cancer Xenograft Model without Classical Sensitizing Mutations (ID 5398)

    14:30 - 14:30  |  Author(s): C. Ng
    • Abstract

    Background:
    Mutations in the tyrosine kinase (TK) domain of EGFR are oncogenic driver in 10-20% of lung adenocarcinoma (AdC) patients in Western countries. Approximately 90% of EGFR-TK inhibitor (TKI) sensitizing mutations occur as small in-frame deletions in exon 19 or L858R point mutations in exon 21. Recently, novel driver mutations in EGFR with oncogenic and TKI sensitizing activity have been reported. We present here an AdC patient-derived xenograft (PDX) model (PDX12) that is highly sensitive to EGFR-TKI, yet failed to demonstrate classical TKI sensitizing mechanisms.
    
    Methods:
    Comprehensive genomics profiling was used to characterize the genotype of PDX12, which was established from a resected stage IIIA AdC patient grafted in NGS mouse. The primary human lung cancer cell line (PHLC12) was extracted from its PDX model (PDX12). Aberrant EGFR cell lines used were H3255 (L858R), H2935 (exon 19 deletion), H1975 (L858R and T790M), and H1944 (wild type). Cell viability was assessed after erlotinib treatment at 1nM - 2μM for 72 hours using MTS assay. Levels of EGFR activation in both pre- and post-treatment by Western blot analysis.
    
    Results:
    PDX12 model had no known oncogenic mutations (EGFR wild type) on exons 18-21 by next-generation sequencing, RT-qPCR, and SISH, but was highly sensitive to EGFR-TKI. The IC50 to erlotinib treatment at 72 hr was 67.13 ± 7.63 nM for PHLC12, compared to 9.70 ± 2.64 nM for H3255, 64.88 ± 8.49 nM for HCC2935, > 2 μM for H1975, and > 2 μM for H1944 EGFR mutant or wild type cells, respectively. Western blot analysis demonstrated a relatively higher molecular weight band for EGFR protein with high expression level in PHLC12 when compared to other lung cancer cell lines. Using RT-qPCR, relative expression level of each EGFR domain (extracellular, tyrosine kinase, and c-terminal domain) in PHLC12 showed no difference compared to EGFR wild type. Phosphorylation status of EGFR in PHLC12 was similar in activity as compared to erlotinib sensitive cell lines.
    
    Conclusion:
    PHLC12 represents an enigmatic EGFR TKI sensitive lung PDX model without classical TKI sensitizing aberrations. Additional potential mechanisms of EGFR dependency including exon duplication, or post-translational modification of EGFR protein are being investigated.