26P - Role of the Hedgehog pathway in preventing occurrence of resistance to first, second, third generation EGFR-TKIs in first line therapy of NSCLC mod...

Date 10 October 2016
Event ESMO 2016 Congress
Session Poster display
Topics Cancer biology
Basic Scientific Principles
Presenter Giuseppe Viscardi
Citation Annals of Oncology (2016) 27 (6): 1-14. 10.1093/annonc/mdw362
Authors G. Viscardi, C.M. Della Corte, F. Papaccio, G. Esposito, M. Fasano, E. Martinelli, T. Troiani, F. Ciardiello, F. Morgillo
  • Oncologia Medica, AOU Seconda Università degli Studi di Napoli (AOU-SUN), 80131 - Napoli/IT

Abstract

Background

NSCLC patients with EGFR activating mutations can be treated with different lines of EGFR tyrosine kinase inhibitors (EGFR-TKIs), and it is still unknown which is the best EGFR-TKIs in first line. This work investigates the best choice of treatment in the first line setting in EGFR mutant NSCLC models.

Methods

The in vivo model of sensitivity is represented by nude mice xenografted with human cancer NSCLC cell lines harboring the EGFR activating mutation (del ex19) HCC827, which is known to not develop T790M. Mice have been randomized to receive first line therapy with a first generation EGFR-TKIs (gefitinib), second generation EGFR-TKIs (afatinib) or third generation EGFR-TKIs (osimertinib). Additionally treatments were continued until occurrence of resistance in order to obtain new in vivo models of resistance to each generation of TKIs. Each resistant tumor has been collected and analyzed for gtene and protein expression.

Results

According to RECIST criteria, a dose-dependent decrease in tumor volume of almost all mice treated with each inhibitor was evident after 14 weeks of treatment. Response rates were similar among inhibitors. Western blot analysis on protein extract from tumors resistant to afatinib and to osimertinib showed increased levels of Hedgehog related proteins as compared to untreated controls. Preliminary results from gene analysis revealed appearance of SMO mutation (V404M) in one tumor resistant to osimertinib, with an allelic frequency of 50%, comparing to baseline.

Conclusions

These data demonstrate that, in cell models not developing T790M-mediated resistance, first, second and third generation EGFR-TKIs are equivalent in terms of tumor response. In such models, Hedgehog pathway activation plays an important role as mediator of first line EGFR-TKIs treatment suggesting new strategy of combination of Hedgehog inhibitors with EGFR-TKIs in first line to prevent the occurrence of resistance.

Clinical trial identification

Legal entity responsible for the study

Seconda Università degli Studi di Napoli

Funding

AstraZeneca

Disclosure

All authors have declared no conflicts of interest.