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Understanding molecular mechanisms of Cetuximab insensitivity in Colorectal Cancer (CRC)

ABSTRACT: Mutational status of KRAS in CRC is used to aid patient stratification for Cetuximab treatment. However, only a subset (10-40%) of patients with wt KRAS respond. We analyzed 40 mCRC tumors for Cetuximab response using a functional ex vivo platform. In the subset of non-responsive tumors, mutational (KRAS/BRAF and PIK3CA) and expression (AREG/EREG) analysis of key genes, transcriptomic profiling and GSEA were carried out to elucidate the molecular mechanisms underlying the response. Our analysis revealed deregulation of multiple pathways, notably Notch and Erbb2 and combined blockade of these two nodes elicited significant antitumor response. These findings collectively indicate the dependence of Cetuximab insensitive mCRC tumors on Notch and Erbb2 for survival and progression.

ORGANISM(S): Homo sapiens

PROVIDER: GSE56386 | GEO | 2014/04/01

SECONDARY ACCESSION(S): PRJNA243086

REPOSITORIES: GEO

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Project description:KRAS mutation is a negative predictive factor for treatment with anti-epidermal growth factor receptor (EGFR) antibodies in metastatic colorectal cancer (mCRC). Novel predictive markers are required to further improve the selection of patients for this treatment. Here, we assessed the influence of modification of KRAS by gene copy number aberration (CNA) and microRNAs (miRNAs) in correlation to clinical outcome in mCRC patients treated with cetuximab in combination with chemotherapy and bevacizumab. Formalin-fixed paraffin-embedded primary tumour tissue was used from 34 mCRC patients in a phase III trial, who were selected based upon their good (n=17) or poor (n=17) progression-free survival (PFS) upon treatment with cetuximab in combination with capecitabine, oxaliplatin, and bevacizumab. Gene copy number at the KRAS locus was assessed using high resolution genome-wide array CGH and the expression levels of 17 miRNAs targeting KRAS were determined by real-time PCR. Good response was associated with 12p12.1 copy number loss, even in patients with a KRAS mutation, while copy number gain in wild-type KRAS patients was correlated with a poor response. In KRAS mutated tumours increased miR-200b and decreased miR-143 expression were associated with a good response. In wild-type KRAS patients, miRNA expression did not predict response in a multivariate model. Thus, assessment of KRAS CNA and miRNAs targeting KRAS might further optimize the selection of patients eligible for anti-EGFR therapy. Copy number detection was performed using NimbleScan and Nexus software Formalin-fixed paraffin-embedded primary tumour tissue was used from 34 metastisized colorectal cancer patients in a phase III trial (CKTO 2005-02; ClinTrials.gov NCT00208546) of the Dutch Colorectal Cancer Group (DCCG), who were selected based upon their good (n=17) or poor (n=17) progression-free survival (PFS) upon treatment with cetuximab in combination with capecitabine, oxaliplatin, and bevacizumab.

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Understanding molecular mechanisms of Cetuximab insensitivity in Colorectal Cancer (CRC)

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