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M.L. Veigl



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    MINI 09 - Drug Resistance (ID 107)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      MINI09.02 - Transcriptome-Metabolome Reprogramming of EGFR-Mutant NSCLC Contributes to Early Adaptive Drug-Escape via BCL-xL Mitochondrial Priming (ID 3085)

      16:45 - 18:15  |  Author(s): M.L. Veigl

      • Abstract
      • Slides

      Background:
      Precision therapy using EGFR small molecular inhibitors is the current standard-of-care in treatment of advanced non-small cell lung cancer (NSCLC) patients (pts) with EGFR mutations. Nonetheless, emergence of acquired resistance to therapy invariably occurs despite effective initial response. Classical rebiopsy studies of EGFR-mutant pts at clinical tumor progression based on RECIST criteria have identified diverse resistance mechanisms involving T790M-EGFR, MET amplification or activation and AXL upregulation. Tumor cells within minimal or microscopic residual disease during drug response may constitute founder cells for future disease relapse. The mechanisms of molecular changes intrinsic to these early therapeutic survivors are not yet well-understood. Our studies focus on tumor cells adaptation early during therapy to map the initial course of molecular drug resistance emergence and evolution.

      Methods:
      Drug-sensitive model studies of EGFR-mutant lung cancer were performed using HCC827 and PC-9 cells (exon 19 deletions EGFR) under erlotinib, and H1975 (T790M/L858R-EGFR) cells under CL-387,785 inhibition. Affymetrix microarray profiling was performed in triplicate at 0h, 8h, 9d and 9d tyrosine kinase inhibitor (TKI) followed by 7d drug-washout. Both in vitro and in vivo xenograft analyses, immunofluorescence, immunohistochemistry, time-lapse video microscopy analysis were conducted. Mass-spectrometry based global metabolomics profiling was also conducted under similar conditions as in gene expression profiling.

      Results:
      We identified an early adaptive and reversible drug-escape within EGFR-mutant cells that could emerge as early as 9 days during course of effective therapy with molecular drug resistance. Principal component analysis (PCA) of gene expression profiling data identified distinct transcriptome signatures in each cell state. Of note, the prosurvival cell state was independent of MET pathway activation, and had a TKI cytotoxicity escape at 100x higher IC50. The drug resistant cell state was associated with reversible cellular quiescence, suppressed Ki-67 expression, and profoundly inhibited cellular motility and migration. Transcriptome gene expression profiling revealed a remarkable adaptive genome-wide signature reprogramming, centered on the autocrine TGFβ2 cascade that involved pathways of cell adhesion, cell cycle regulation, cell division, glycolysis, and gluconeogenesis. Global metabolomic profiling of cellular metabolites in HCC827 cells under erlotinib inhibition also revealed a concurrent adaptive reprogramming of cellular metabolism during the early drug-resistant cell state, with suppression of glycolysis, TCA cycle, amino acids metabolism, and lipid bioenergetics. Our studies identified a direct link of TGFβ2 within the drug escaping cells, with the metabolic-bioenergetics quiescence, reverse Warburg metabolism and mitochondrial BCL-2/BCL-xL priming. Furthermore, this adaptive drug-resistant cell state also displayed an increased EMT and cancer stem cell signaling as adaptation to the drug treatment and that could be overcome by broad BCL-2/BCL-xL BH3 mimetic ABT-263, but not BCL-2 only mimetic ABT-199.

      Conclusion:
      We identified and characterized the emergence of early adaptive drug-escape within EGFR-mutant NSCLC cells amid an overall precision therapy excellent response, through a MET-independent mechanism. The profoundly drug-resisting prosurvival cell state undertook remarkable cellular transcriptome-metabolome adaptive reprogramming coorindated through autocrine TGFβ2 signaling augmentation. Our study results have important implications in lung cancer drug-resistant minimal/microscopic disease and future therapeutic remedies in precision therapy.

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