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
2459 - Does bevacizumab increase joint pain ? Preliminary results of BEVARTHRALGIA Study
Presenter: Vauleon Enora
Session: Poster Display session 1
Resources:
Abstract
4913 - Prostatic cancer androgen deprivation therapy and bone health in carcinoma prostate.
Presenter: Gouri Shankar Bhattacharyya
Session: Poster Display session 1
Resources:
Abstract
1352 - Patterns of care for patients with metastatic bone disease in solid tumors – a cross-sectional study (SAKK 95/16)
Presenter: Michael Mark
Session: Poster Display session 1
Resources:
Abstract
6002 - Infection-Related Mortality in Different Types of Cancers
Presenter: Mohamed Gouda
Session: Poster Display session 1
Resources:
Abstract
5643 - Survival Trends in Critically ill Oncology Patients: impact of patient’s eligibility to post-ICU chemotherapy
Presenter: Edith Borcoman
Session: Poster Display session 1
Resources:
Abstract
3097 - Development and validation of a multivariable prediction model for 6-month mortality in older cancer patients: the GeriAtrIc-Tumor Score of PrEdiction for Early Death (GAIT SPEED)
Presenter: Angeli Angeli
Session: Poster Display session 1
Resources:
Abstract
856 - A Longitudinal Tracking and Quantitative Assessment of Paclitaxel-Induced Peripheral Neurotoxicity
Presenter: Ayumu Matsuoka
Session: Poster Display session 1
Resources:
Abstract
1662 - Efficiency of controlled cryotherapy in prevention of chemotherapy induced peripheral neuropathy (CIPN)
Presenter: Trudi Schaper
Session: Poster Display session 1
Resources:
Abstract
2766 - The Validity of Evaluations for Chemotherapy-Induced Peripheral Neuropathy (CIPN)
Presenter: Teppei Yamada
Session: Poster Display session 1
Resources:
Abstract
5683 - Prevention of chemoradiation-related mucositis in patients with head and neck cancer using dexamethasone-based mouthwash: A phase II randomized double-blind, placebo-controlled study
Presenter: Naiyarat Prasongsook
Session: Poster Display session 1
Resources:
Abstract