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Y. Wang



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    ORAL 21 - Biology - Moving Beyond the Oncogene to Oncogene-Modifying Genes (ID 118)

    • Event: WCLC 2015
    • Type: Oral Session
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      ORAL21.05 - p53/KRAS Mutation Status Does Not Predict Sensitivity to Chemotherapy in NSCLC PDXs (ID 2459)

      10:45 - 12:15  |  Author(s): Y. Wang

      • Abstract
      • Presentation
      • Slides

      Background:
      The LACE-Bio group assessed the prognostic and predictive values of KRAS and p53 mutations in 1543 completely resected non-small cell lung cancer (NSCLC) tumors. The predictive value of combined KRAS/p53 mutations for survival benefit from adjuvant chemotherapy was evaluated on 49 patients and chemotherapy was deleterious in this group compared to observation (HR 2.49 CI 95% [1.10 – 5.66], p=0.03). Patients with tumors harboring combined KRAS/p53 mutations had a worse outcome when treated with adjuvant chemotherapy compared patient with double wild type (WT) tumors (HR 3.03 (95% CI [1.29 – 7.15], p=0.01, interaction p=0.06). We have compared the chemo-sensitivity of patient derived xenografts (PDXs) with double p53/KRAS mutations, single p53, single KRAS mutation or double WT. 0

      Methods:
      Surgically resected early stage lung adenocarcinomas (ADC) were implanted into non-obese diabetic severe combined immune deficient (NOD-SCID) mice. Fourteen lung ADC PDXs with various p53/KRAS status were revived and implanted: 11 engrafted and were expanded for comparison of treatment vs control. For each model, 6 replicates were included in treatment and control arms. Chemotherapy (cisplatin 3 mg/kg and vinorelbine 7 mg/kg intraperitoneally weekly) was initiated in the PDXs at tumor volumes of 150 mm[3].

      Results:
      Four models were p53/KRAS double mutant, 4 p53 mutant, 2 KRAS mutant and 1 double WT. The 4 double mutant PDXs responded to chemotherapy, 2 with reduced (SD) and 2 inhibited (PR) growth. Among the 4 PDXs with p53 mutation only, 2 responded (1 PR and 1 SD) and 2 were resistant. Among the 2 PDXs with KRAS mutation only, 1 had a complete response, but relapsed at treatment arrest and 1 achieved PR. The double WT PDX was highly sensitive to chemotherapy (PR) but also relapsed at treatment arrest.

      Conclusion:
      Among these 11 PDXs, the p53/KRAS mutation status did not predict chemo-sensitivity to cisplatin/vinorelbine, one of the most active adjuvant chemotherapy regimens in NSCLC. As these PDXs were molecularly profiled, we currently are investigating other biomarkers that might predict their sensitivity or resistance to chemotherapy.

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    P2.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 234)

    • Event: WCLC 2015
    • Type: Poster
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      P2.04-026 - Second Generation EGFR TKIs Inhibit Tumor Growth in a Chemo-Resistant Squamous Cell Lung Cancer Patient Derived Xenograft Model (ID 1265)

      09:30 - 17:00  |  Author(s): Y. Wang

      • Abstract
      • Slides

      Background:
      In clinical trials testing the efficacy of first generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), occasional responses were observed in patients with lung squamous cell carcinomas (LSCC) (Shepherd FA, et al. New Engl J Med 2005) and survival benefit was confirmed for erlotinib in a subset analysis of male, ever-smokers with LSCC (Clark GM, et al. Clin Lung Cancer 2006). Currently, the LUX-Lung 8 phase III clinical trial is comparing afatinib versus erlotinib in the second-line setting for LSCC after cisplatin-based chemotherapy (Goss GD, et al. ESMO 2014). Preclinical data indicate that high EGFR protein expression may be predictive of response to erlotinib in EGFR wild type LSCC (Cranston et al, AACR 2013). Herein we assessed and compared the anti-tumor efficacy of different EGFR inhibitors in chemo-resistant squamous cell lung cancer patient derived xenograft (PDX) models with high EGFR expression and EGFR amplification.

      Methods:
      The cryopreserved PDX model established from a resected early stage LSCC was revived in non-obese diabetic severe combined immunodeficient mice (NOD SCID), expanded and subsequently treated with chemotherapy (cisplatin 3 mg/kg and vinorelbine 7 mg/kg intraperitoneally [IP]), cetuximab 20 mg/kg IP, and daily oral schedules were followed for erlotinib 50 mg/kg, afatinib 20 mg/kg, dacomitinib 3 mg/kg. For each model, 6 mice were used in each of the different treatment and the control arms. Treatment was initiated in the PDXs at a tumor average volume of 150 mm[3].

      Results:
      The PDX was derived from a 57 year old male, smoker, following right pneumonectomy for a stage IIIB (T4N1M0) LSCC. This patient received adjuvant cisplatin/vinorelbine, but relapsed three weeks after the end of cycle 4 and died a week later. The tumor had a high EGFR expression by immunohistochemistry (H score = 300) and EGFR amplification (clusters) by fluorescent in situ hybridization. The PDX was EGFR wild type by Illumina exome sequencing and OncoCarta[TM ]MassArray mutation screen (Sequenom), also was refractory to cisplatin/vinorelbine. Reduced growth rate (stable disease, SD) was obtained with erlotinib and cetuximab. Treatment with afatinib and dacomitinib resulted in tumor growth inhibition (partial response, PR). The PDX developed resistance to dacomitinib after 100 days of treatment, but continued to be inhibited by afatinib after 215 days of treatment.

      Conclusion:
      This study shows the efficacy of second generation especially afatinib irreversible EGFR TKIs in a chemoresistant LSCC PDX, with high wild type EGFR expression and EGFR amplification. Our results lend further support to the LUX-Lung 8 trial, and also the use of PDX to model therapeutic responses in lung cancer.

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