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
6068 - Study of Photodynamic therapy in vitro
Presenter: Irene Jiménez Munguía
Session: Poster Display session 1
Resources:
Abstract
3011 - The potential of neratinib plus dasatinib in overcoming and preventing neratinib resistance in HER2-positive breast cancer models
Presenter: Neil Conlon
Session: Poster Display session 1
Resources:
Abstract
2644 - Novel HDACi, MHY446, induces apoptosis via regulation of mitochondria-endoplasmic reticulum interaction in HCT116 human colorectal cancer cells
Presenter: Nam Deuk Kim
Session: Poster Display session 1
Resources:
Abstract
3085 - Dual inhibition of TGF-β and AXL as a novel treatment for colorectal cancer
Presenter: Davide Ciardiello
Session: Poster Display session 1
Resources:
Abstract
1314 - PARP inhibition enhances cisplatin sensitivity in cervical cancer by modulating β-catenin signaling
Presenter: Minakshi Mann
Session: Poster Display session 1
Resources:
Abstract
2417 - Synergistic effect of DSF combined treatment with cisplatin in atypical teratoid/rhabdoid tumors (AT/RT)
Presenter: Seung Ah Choi
Session: Poster Display session 1
Resources:
Abstract
1149 - Reactive oxygen species induced by OSU-A9 inhibit the growth of duodenal cancer and gastric cancer cells through dephosphorylating intranuclear pyruvate kinase muscle isozyme M2
Presenter: Li-Yuan Bai
Session: Poster Display session 1
Resources:
Abstract
1862 - New therapy for intrahepatic cholangiocarcinoma targeted to cancer associated fibroblasts
Presenter: Takahiro Yamanaka
Session: Poster Display session 1
Resources:
Abstract
782 - Macrophage-cancer cell fusion is mediated by Phosphatidylserine-CD36 receptor interaction and induced by ionizing radiation
Presenter: Ivan Shabo
Session: Poster Display session 1
Resources:
Abstract
3181 - Effects of Three Products in the Prevention and Treatment of Chemotherapy and Radiation Therapy-Induced Oral Mucositis
Presenter: Francesca Zannier
Session: Poster Display session 1
Resources:
Abstract