Abstract 1322
Background
Monoclonal antibodies against the Epidermal Growth Factor Receptor (EGFR) such as cetuximab or panitumumab are used for the treatment of metastatic colorectal cancer (mCRC) patients. Unfortunately, most patients develop resistance against these therapies within months. Several studies have shown that aberrations in the RAS pathway are responsible for resistance. However, even in metastases that are refractory to anti-EGFR treatment a significant fraction of RAS wild-type (wt) cells remain. These findings suggest a cross-talk between RAS mutant and wt cells in mediating resistance in the wt compartment.
Methods
We used mouse and patient-derived organoids from mCRC as well as CRC cell lines to test the contribution of extracellular vesicles in mediating resistance in RAS wt cells. Using conditioned media, transfection experiments and liquid biopsies (plasma and urine) from patients differential expression of the let-7g microRNA was demonstrated in microvesicles from cetuximab sensitive and resistant cells. Changes in expression of the let-7g microRNA were further analysed by in-situ hybridization in tissues.
Results
Basal let-7g expression from pre-treatment plasma and urine samples of RAS wt patients correlated with clinical outcome and changes in let-7g circulating levels mirrored clinical behaviour. In-situ hybridization in tissues confirmed changes in expression of the let-7g microRNA observed in plasma and urine samples.
Conclusions
Our data suggest that let-7g microRNA might function as a paracrine mediator of anti-EGFR resistance and might be exploited as a non-invasive biomarker of resistance to cetuximab treatment. Further work is ongoing to characterize the molecular mechanisms underpinning let-7g mediated effect on anti-EGFR sensitivity in RAS wt CRC cells.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
N. Valeri: Speaker Bureau / Expert testimony: Bayer; Speaker Bureau / Expert testimony: Eli Lilly; Speaker Bureau / Expert testimony: Pfizer; Speaker Bureau / Expert testimony: Merck. All other authors have declared no conflicts of interest.
Resources from the same session
5071 - Expression of estrogen receptor and programmed cell death-ligand 1 can be complementary prognostic factors in HPV-positive oropharyngeal squamous cell carcinoma
Presenter: Soohyeon Kwon
Session: Poster Display session 3
Resources:
Abstract
5306 - Real-world data of clinicopathologic characteristics of young oropharyngeal cancer patients.
Presenter: Maria Nieva
Session: Poster Display session 3
Resources:
Abstract
3407 - The clinical significance and biological mechanisms of miR-499a in high-tobacco exposed head and neck squamous cell carcinoma
Presenter: Shiqi Gong
Session: Poster Display session 3
Resources:
Abstract
3310 - Liquid biopsy for mutational profiling of locoregional recurrent and/or metastatic squamous cell carcinoma of the head and neck
Presenter: Rachel Galot
Session: Poster Display session 3
Resources:
Abstract
2362 - Blood-based testing of mutations in patients with Head and neck squamous cell carcinoma (HNSCC) using highly sensitive SafeSEQ technology
Presenter: Florentia Fostira
Session: Poster Display session 3
Resources:
Abstract
4533 - The head and neck Lung Immune Prognostic Index (HN-LIPI): a prognostic Score for Immune Checkpoint Inhibitors (ICI) in Recurrent or Metastatic Squamous Cell Carcinoma of the Head and Neck (R/M SCCHN) patients.
Presenter: Ruth Gabriela Herrera Gomez
Session: Poster Display session 3
Resources:
Abstract
5262 - Immune-related adverse events (irAEs) and outcome in recurrent/metastatic (R/M) Head and Neck Squamous Cell Carcinoma (HNSCC) patients (pts) treated by immune-checkpoints inhibitors (ICI)
Presenter: Neus Baste Rotllan
Session: Poster Display session 3
Resources:
Abstract
3725 - Intratumoral and peripheral exploratory biomarker analysis in patients with locoregional, recurrent head and neck squamous cell carcinoma (rHNSCC) treated with RM-1929 photoimmunotherapy
Presenter: Jack Bui
Session: Poster Display session 3
Resources:
Abstract
2533 - A nomogram based prognostic score to predict overall survival (OS) in recurrent-metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) patients (pts) treated with immune checkpoint inhibitors (ICI).
Presenter: Luay Mousa
Session: Poster Display session 3
Resources:
Abstract
2929 - Changes of the Commensal Microbiome during Treatment are Associated with Clinical Response in the Nasopharyngeal Carcinoma Patients
Presenter: Tingting Huang
Session: Poster Display session 3
Resources:
Abstract