Author of

• 18374

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  P3.02b - Poster Session with Presenters Present (ID 494)

  • Event: WCLC 2016
  • Type: Poster Presenters Present
  • Track: Advanced NSCLC
  • Presentations: 1
  • Moderators:
  • Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)

  • 18496

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    P3.02b-122 - Characterization of Afatinib Resistant Lung Cancer Cells (PC9/Afa) and Reversal of Resistance by T790M Specific Tyrosine Kinase Inhibitors (ID 4955)

    14:30 - 14:30  |  Author(s): A.M. Lin
    • Abstract

    Background:
    Human non-small cell lung cancer (NSCLC) cells harboring epidermal growth factor receptors (EGFR) mutation are sensitive to EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib and afatinib. Despite of in vitro activity against resistance mutation T790M, lung cancer patients harboring EGFR mutations treated with afatinib still develop resistance in a median of 12 months. Several reports indicated that T790M can be detected in afatinib resistant NSCLC patients’ tumor samples. We reported previously that gefitinib resistant EGFR mutant PC9/gef cells do not contain resistant mutation T790M and the resistance seemed to be conferred by acquired N-ras mutation. Here we characterized the afatinib resistant EGFR mutant lung cancer cells.
    
    Methods:
    In order to study the resistance mechanism of irreversible inhibitor afatinib in EGFR mut cells, we developed afatinib resistant PC9/afa cells using stepwise increment of afatinib in the medium of wild type PC9 cells. Several clones were selected for further experiments. Downstream signals of EGFR in cells were studied using western blot. Growth of cells as well as xenografts upon EGFR inhibitors were studied.
    
    Results:
    In contrast to PC9/gef cells, most clones of PC9/afa cells develop acquired T790M mutations. PC9/afa cells are more than 100-fold resistant to afatinib compared to PC9 cells. Afatinib at 10-100nM inhibit EGFR, HER2, HER3, AKT and ERK phosphorylation in PC9/afa cells. However, same degree of inhibition can be achieved by less than 10nM in PC9 wild type cells. WZ8040 is an EGFR-TKI with high inhibitory activity against T790M and activating mutations, but with less activity against wild type EGFR. WZ8040 inhibited cell growth of PC9/wt and PC9/afa cells (B2 and C4) more significant than that of PC9/gef and PC9/WZ cells. WZ8040 inhibited EGF-induced phosphorylation of EGFR, AKT and ERK in PC9/wt and PC-9/afa cells (B2 and C4). Using an in vivo model xenografting with PC-9/wt and PC-9/afa cells, oral administration of WZ8040 (50 mg/kg) consistently reduced the tumor growth of PC9/wt and PC-9/afa cells.
    
    Conclusion:
    T790M mutation is the dominant resistant mechanism of afatinib resistant EGFR mutant PC9/afa cells and use of 3[rd] generation EGFR TKI successfully reversed afatinib resistance in PC9/afa cells.