Abstract 4156
Background
Molecular mechanisms driving acquired resistance to anti-EGFR therapies in metastatic Colorectal Cancer (mCRC) are complex but generally involve the activation of the downstream RAS-RAF-MEK-MAPK pathway.
Methods
In order to understand the mechanism underlying MEK inhibitor (MEKi) resistance, we generated three different MEKi resistant models, two all RAS WT (SW48-MR and LIM1215-MR) and one mutated in RAS (HCT116-MR).
Results
These models showed features related to the gene signature of Colorectal Cancer CMS4 with upregulation of immune pathway as confirmed by Microarray and Western blot analysis. In particular, moving forward the MEKi phenotype we assisted to the loss of epithelial features and acquisition of mesenchymal markers and morphology. Moreover, this change in the morphology is accompanied by up-regulation of PD-L1 expression and activation of EGFR and its downstream pathway, independently of cell line status mutation. To extend these in vitro findings, we performed an in vivo study using MC38 and CT26 MEKi resistant syngeneic models that we have previously generated. Combined treatment of MEKi, EGFR inhibitor (EGFRi) and PD-L1inhibitor (PD-L1i) resulted in a marked inhibition of tumor growth in both MC38–MR and CT26-MR xenograft model.
Conclusions
These results suggest a strategy to potentially overcome immunotherapy resistance in CMS4-like tumors and to improve the efficacy of MEK inhibition by co-treatment with other agents providing an additional therapeutic strategy via modulation of host immune responses.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
5189 - Association between serum HGF levels and neutrophil counts in small cell lung cancer and their impact on survival
Presenter: Laura Moliner
Session: Poster Display session 1
Resources:
Abstract
3539 - Prognostic role of RLF/MYCL1 and circPVT1 in SCLC.
Presenter: Clelia Tiziana Storlazzi
Session: Poster Display session 1
Resources:
Abstract
3438 - High-biologically effective dose radiotherapy improve the survival of small cell lung cancer patients with brain metastases: a propensity-matching analysis
Presenter: Qingyang Zhuang
Session: Poster Display session 1
Resources:
Abstract
3232 - Phase 1 open-label study evaluating the safety, pharmacokinetics, and preliminary efficacy of ABBV-181 and rovalpituzumab tesirine (ROVA-T) in patients with small cell lung cancer
Presenter: Emiliano Calvo
Session: Poster Display session 1
Resources:
Abstract
3633 - Activity of the novel Aurora kinase B inhibitor AZD2811 in biomarker-defined models of small cell lung cancer
Presenter: Carminia Maria Della Corte
Session: Poster Display session 1
Resources:
Abstract
3745 - Multi-level proteomics identifies FABP5 as a primary chemoresistance mediator in extensive-stage small cell lung cancer
Presenter: Yamei Chen
Session: Poster Display session 1
Resources:
Abstract
5049 - CLEPSIDRA trial: a pilot, biomarker-guided study to assess safety, tolerability, dose finding and efficacy of iadademstat in combination with platinum-etoposide in patients with relapsed, extensive-stage small cell lung cancer
Presenter: Alejandro Navarro Mendivil
Session: Poster Display session 1
Resources:
Abstract
5997 - Phased Avelumab combined with chemotherapy as first-line treatment for patients with advanced small-cell lung cancer (SCLC): The PAVE study, a Hellenic Cooperative Oncology Group Study
Presenter: Helena Linardou
Session: Poster Display session 1
Resources:
Abstract
4502 - Tobacco use in lung cáncer (LC) patients (p) in Spain
Presenter: Enric Carcereny Costa
Session: Poster Display session 1
Resources:
Abstract
4369 - Biomarker testing of lung cancer in Spain
Presenter: Delvys Rodriguez Abreu
Session: Poster Display session 1
Resources:
Abstract