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BACKGROUND: Somatic mutations in the epidermal growth factor receptor (EGFR) intracellular signalling pathways predict non-response to cetuximab in the treatment of advanced colorectal cancer (aCRC). We hypothesised that common germline variants within these pathways may also play similar roles. METHODS: We analysed 54 potentially functional, common, inherited EGFR pathway variants in 815 patients with aCRC treated with oxaliplatin-fluoropyrimidine chemotherapy plus cetuximab. Primary endpoints were response and skin rash (SR). We had >85% power to detect ORs=1.6 for variants with minor allele frequencies >20%. RESULTS: We identified five potential biomarkers for response and four for SR, although none remained significant after correction for multiple testing. Our initial data supported a role for Ser313Pro in PIK3R2 in modulating response to cetuximab-in patients with KRAS wild-type CRCs, 36.4% with one allele encoding proline responded, as compared with 71.2% homozygous for allele encoding serine (OR 0.23, 95% CI 0.09 to 0.56, p=0.0014), and this association was predictive for cetuximab (pinteraction=0.017); however, independent replication failed to validate this association. No previously proposed predictive biomarkers were validated. CONCLUSIONS: Our study highlights the need to validate potential pharmacogenetic biomarkers. We did not find strong evidence for common germline biomarkers of cetuximab response and toxicity.

Original publication

DOI

10.1136/jmedgenet-2016-104317

Type

Journal

J Med Genet

Publication Date

10/03/2017

Keywords

Pharmacogenetics, biomarkers., cetuximab, colorectal cancer