Author of

• 25520

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  Poster Display session (Friday) (ID 65)

  • Event: ELCC 2018
  • Type: Poster Display session
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 4/13/2018, 12:30 - 13:00, Hall 1

  • 25356

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    155P - Antitumoral efficacy of dual blockade of EGFR signaling by osimertinib in combination with selumetinib or cetuximab in activated EGFR human NSCLC tumor models (ID 536)

    12:50 - 12:50  |  Author(s): S. La Monica
    • Abstract

    Background:
    Osimertinib is the gold standard for activated-EGFR-NSCLC patient treatment. The aim of this work was to test the efficacy of a complete EGFR-inhibition by the addition of the monoclonal antibody, cetuximab, or the MEK1/2-inhibitor, selumetinib, to osimertinibin EGFR-mutated-NSCLC in vivo models.
    
    Methods:
    We evaluated combinations of osimertinib plus selumetinib/cetuximab in HCC827(E746-A759del/T790M-), H1975(L858R/T790M+) and PC9-T790M (E746-A759del /T790M+) xenografts, in second line after the developing of resistance to osimertinib and in first line, and we explored mechanisms of resistance to these treatments.
    
    Results:
    The addition of selumetinib or cetuximab to osimertinib in second line reverted the sensibility to osimertinib in the majority of mice, with a response rate (RR) of 50–80%, and a median PFS (mPFS) of first plus second line of therapy of 28 weeks. The early use of combinations in first line increased the RR to 90%, with amPFSnot reached in all combination arms in the three xenografts models, with a statistically significant superiority (p < 0,005) as compared to osimertinib, that achieved in first line a mPFS of 17–18 weeks. Moreover, on ex vivo primary cell cultures obtained from osimertinib plus selumetinib-resistant tumors, we found hedgehog pathway activation and we demonstrated that triple combination with a Smo inhibitor plus osimertinib.
    
    Conclusions:
    We demonstrated that a dual vertical EGFR blockade with osimertinib plus selumetinib/cetuximab is a novel effective therapeutic option in EGFR-mutated-NSCLC and that Hedgehog pathway activation and its interplay with MAPK is involved in resistance to these combination treatments.
    
    Clinical trial identification:
    
    
    Legal entity responsible for the study:
    University of Campania “L. Vanvitelli”
    
    Funding:
    AstraZeneca partially supported
    
    Disclosure:
    All authors have declared no conflicts of interest.