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Kwok-Kin Wong



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    OA08 - Advanced Models and "Omics" for Therapeutic Development (ID 133)

    • Event: WCLC 2019
    • Type: Oral Session
    • Track: Biology
    • Presentations: 1
    • Now Available
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      OA08.05 - Notch Inhibition Overcomes Resistance to Tyrosine Kinase Inhibitors Promoted by Gate-Keeper Mutations in EGFR-Driven Lung Adenocarcinoma  (Now Available) (ID 639)

      11:00 - 12:30  |  Author(s): Kwok-Kin Wong

      • Abstract
      • Presentation
      • Slides

      Background

      EGFR mutated lung adenocarcinoma patients treated with gefitinib and osimertinib showed a therapeutic benefit limited by the appearance of secondary mutations, such as EGFRT790M and EGFRC797S. It has been generally assumed that these secondary mutations render EGFR completely unresponsive to the inhibitors, indicating that the use of single drug to treat efficiently EGFR-driven lung adenocarcinoma might have limited value while a strategy based on combinational drug therapy could be more effective at mitigating the effects of gatekeeper mutations.

      Method

      We have combined the use of EGFR-driven genetic engineered mouse models and patient-derived xenografts, adenocarcinoma cell lines and primary samples from EGFR mutated patients.

      Result

      We uncover here that gefitinib and osimertinib increase STAT3 phosphorylation (pSTAT3) in EGFRT790M and EGFRC797S tumoral cells. Interestingly, we also found that concomitant Notch inhibition with gefitinib or osimertinib treatment induces a pSTAT3-dependent strong reduction in the levels of the transcriptional repressor HES1. Importantly, we show that tyrosine kinase inhibitor resistant tumors, with EGFRT790M and EGFRC797S mutations, are highly responsive to the combined treatment of Notch inhibitors with gefitinib and osimertinib respectively. Finally, in patients with EGFR mutations treated with tyrosine kinase inhibitors, HES1 protein levels increase during relapse and correlate with shorter progression-free survival.

      Conclusion

      Our results show that the Notch pathway plays a major role in the relapse of lung adenocarcinoma patients treated with EGFR TKIs, providing a rationale to treat patients that become resistant to EGFR TKI with a combination of the same TKI and Notch inhibitors.

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    P2.03 - Biology (ID 162)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Biology
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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      P2.03-31 - Chemokine Receptor CXCR7 Reactivates ERK Signaling to Promote Resistance to EGFR Kinase Inhibitors in NSCLC (ID 2817)

      10:15 - 18:15  |  Author(s): Kwok-Kin Wong

      • Abstract

      Background

      Activating EGFR mutations in NSCLC confer sensitivity to reversible EGFR TKIs, including gefitinib and erlotinib. Despite promising initial response, acquired resistance develops mediated by the emergence of the secondary T790M mutation or by focal amplification of MET. An epithelial­to­mesenchymal transition (EMT) is clinically linked to NSCLCs with acquired EGFR TKI resistance. The exact mechanisms of EGFR TKI resistance with EMT phenotype remain elusive.

      Method

      We have engineered EGFR­mutated NSCLC cell lines with a mesenchymal phenotype by stably depleting E­Cadherin, overexpressing Snail, or chronically exposing the cells to TGFβ1. The resulting mesenchymal cells are resistant to EGFR TKIs. We employed genomic analyses to identify commonly activated oncogenic drivers that maintain signaling pathways upon EGFR inhibition. We also used EGFR­mutated HCC4006 NSCLC cells grown resistant to gefitinib that developed a mesenchymal phenotype (HCC4006Ge­R). To extend our findings to in vivo, we have utilized matched pre- and post-EGFR TKI treatment samples from NSCLC patient and mouse models of acquired EGFR TKI resistance to test if our approach using these cell lines is instructive.

      Result

      We discovered that an atypical GPCR, C­X­C chemokine receptor type 7 (CXCR7), is commonly overexpressed in the cell line models of EGFR TKI resistance with a mesenchymal phenotype. The murine tumors driven by human EGFR exon19 deletion/T790M (TD) with acquired resistance to WZ4002 present mesenchymal phenotype and overexpress CXCR7. 50% of NSCLC patients harboring an EGFR kinase domain mutation who progressed on EGFR inhibitors showed an increase in CXCR7 expression. Using the cell line model of EGFR TKI acquired resistance with a mesenchymal phenotype, we find that CXCR7 activates the MAPK-ERK pathway via b-arrestin. Depletion of CXCR7 abrogates the MAPK pathway and significantly attenuated EGFR TKI resistance in the cells with a mesenchymal phenotype. In the long term, the depletion of CXCR7 resulted in mesenchymal to epithelial transition. Ectopic overexpression of CXCR7 in HCC4006 cells was sufficient in activation of ERK1/2 for the generation of EGFR TKI resistant cells. Furthermore, CXCL12 stimulation resulted in an increase in ERK phosphorylation while EGFR was inhibited in HCC4006Ge-R cells. Similarly, we found we found CXCL12 expression is elevated in patient samples with increased CXCR7 expression.

      Conclusion

      Taken together, we discovered that the CXCR7-CXCL12 signaling axis is necessary and sufficient for the maintenance of EGFR TKI resistance with mesenchymal phenotype and CXCR7 inhibition could significantly delay and prevent the emergence of acquired EGFR TKI resistance in EGFR mutant NSCLC.

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    P2.14 - Targeted Therapy (ID 183)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Targeted Therapy
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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      P2.14-24 - An Open-Label Randomized Phase II Study of Combining Osimertinib With and Without Ramucirumab in TKI-Naïve EGFR-Mutant Metastatic NSCLC (ID 851)

      10:15 - 18:15  |  Author(s): Kwok-Kin Wong

      • Abstract

      Background

      Osimertinib, a third-generation EGFR inhibitor, has become the first-line therapy for patients with metastatic EGFR-mutant NSCLCs since 2018. Osimertinib is well-tolerated, therefore, it opens opportunities to be combined with other therapeutic agents to enhance the treatment outcome. In preclinical models, it has been shown that upregulated VEGF signaling mediates acquired resistance to EGFR therapies. In xenograft models, combination of anti-VEGF medications with EGFR inhibitors were significantly more effective than erlotinib or gefitinib alone. Ramucirumab, a monoclonal antibody targeting VEGF receptor 2, is approved with docetaxel in as second line treatment for NSCLCs. In clinical trial evaluations, the phase 3 RELAY trial (NCT02411448) studying ramucirumab plus erlotinib in patients with metastatic untreated EGFR-mutant NSCLC patients showed a statistically significant improvement in progression-free survival in the combination group compared to erlotinib alone. A phase I study of osimertinib with ramucirumab (NCT02789345) demonstrated safety and feasibility of this combination. With strong preclinical and clinical evidence showing dual inhibition of VEGF/EGFR signaling prolongs progression-free survival for EGFR-mutant lung cancers, and demonstrated safety, we are conducting a phase 2 trial to evaluate the osimertinib ramucirumab combination’s efficacy in treatment-naïve EGFR-mutant NSCLC.

      Method

      The OSI+RAM trial is a randomized phase 2 study with the primary endpoint being progression-free survival in osi+ram group as compared to osimertinib monotherapy group. The major inclusion criteria include patients with metastatic NSCLC harboring EGFR mutations (L858R/Exon 19 del). The major exclusion criteria include prior anti-EGFR or anti-VEGF treatments. Patients with stable CNS metastasis are allowed. Based on the results from erlotinib bevacizumab (NEJ026) study, we expect an improvement of PFS from 18.9 months to 29.7 months, corresponding to a hazard ratio of 0.65. The trial plans to enroll total of 150 patients, with 100 allocating to osi+ram arm and 50 to osimertinib monotherapy. Total of 9 study sites in the USA are planned. Hoosier Cancer Research Network will facilitate the execution of the trial. The trial protocol has received IND exemption from US FDA and has been approved by IRB at MD Anderson Cancer Center. The first subject is expected to be enrolled in May 2019. A planned interim analysis will be performed after the first 75 subjects are enrolled. NCT03909334.

      Result

      Section not applicable

      Conclusion

      Section not applicable