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N.T. McDonald

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    MO01 - Lung Cancer Biology - Techniques and Platforms (ID 90)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Biology
    • Presentations: 1
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      MO01.07 - Inhibition of the IGF-1R signaling pathway potentiates responses to ALK inhibitors in both ALK TKI naive and ALK TKI resistant lung cancer (ID 1660)

      10:30 - 12:00  |  Author(s): N.T. McDonald

      • Abstract
      • Presentation
      • Slides

      Oncogenic fusions involving the gene encoding the anaplastic lymphoma kinase (ALK) define a new clinically relevant molecular subset of lung cancer. The majority of patients with ALK+ lung cancer are highly responsive to ALK tyrosine kinase inhibitor (TKI) therapy, however, the efficacy of these ALK inhibitors is limited by the development of acquired resistance. Additional strategies using rationally selected therapeutic agents/combinations of agents are needed to both delay and overcome acquired resistance to ALK inhibition. Based upon an intriguing clinical observation from a patient with ALK+ lung cancer who had an ‘exceptional response’ to an IGF-1R monoclonal antibody (MAb), we report a novel therapeutic synergism between ALK inhibitors and IGF-1R inhibitors.

      A series of experimental approaches including cell culture models, in vitro assays, and a study of patient tumor samples prior to and at the time of acquired resistance to ALK TKI therapy were employed to test the hypothesis that IGF-1R can be targeted therapeutically to enhance anti-tumor responses in ALK+ NSCLC.

      Across multiple different ALK+ lung cancer cell lines, including a novel ALK+ cell line developed from a patient prior to ALK TKI therapy, IGF-1R inhibitors (TKIs and MAbs) sensitized ALK+ lung cancer cells to the effects of ALK blockade as assessed by standard cell viability assays. Similar to IGF-1R, ALK fusions co-immunoprecipitated with the adaptor protein, IRS-1, and treatment with ALK inhibitors decreased IRS-1 protein levels. Furthermore, siRNA mediated knock-down of IRS-1 impaired the proliferation of ALK+ lung cancer cells and enhanced the anti-tumor effects of ALK inhibitors. The IGF-1R pathway was activated in cell culture models of ALK TKI resistance, and combined ALK/IGF-1R inhibition in the resistant cells blocked reactivation of downstream signaling and markedly improved therapeutic efficacy in vitro. Finally, IGF-1R and IRS-1 levels were increased in biopsy samples from a patient with advanced ALK+ lung cancer post crizotinib therapy.

      Collectively, these data support a role for the IGF-1R/IRS-1 signaling pathway in both the ALK TKI sensitive and ALK TKI resistant states and suggest that this rationally selected combination of inhibitors may be an effective strategy to attempt to delay or overcome acquired resistance to therapeutic ALK inhibition. Intriguingly, the ‘second generation’ ALK TKI, LDK-378, which has demonstrated an overall response rate of 70% in patients with both crizotinib naïve and crizotinib resistant ALK+ lung cancer, can inhibit both ALK and IGF-1R in vitro. We speculate, based on these data, that this surprising response rate may be due to LDK-378’s ability to simultaneously inhibit both targets.

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