EGFR Expression Is Unreliable to Decide for Cetuximab Treatment in Patients with Metastatic Colorectal Cancer: Results from “ERBITUX-OUEST”

Purpose: Although controversial, assessment of epidermal growth factor receptor (EGFR) expression is required for the approved indications of Cetuximab in metastatic colorectal cancer (mCRC). With the objective of improving patient selection, “ERBITUX-OUEST” study aimed at analyzing EGFR status in a large cohort of mCRC patients who received cetuximab without preliminary EGFR screening, and assessing the correlation between EGFR status and response to treatment retrospectively. Patients and methods: 332 patients treated with Irinotecan Cetuximab based regimen after progression on irinotecan or oxaliplatin therapy were included. EGFR status was assessed using three available immunohistochemistry (IHC) tests and in situ hybridization in case of negativity. Clinical outcomes of EGFR-positive and EGFR-non-detected (or considered as negative with at least one test) patients were compared. Results: Of the 332 samples centrally screened, 194 were classified as full-positive (i.e., EGFR-positive for all three tests), 86 as full-negative, and 52 as discordant. One third of the 131 negative samples with FDA approved test should be reclassified as positive with at least one of the two others tests. Regarding results from FDA approved test only, neither objective response rate (ORR), progression-free survival (PFS) nor overall survival (OS) differed significantly between EGFR-negative and EGFR-positive patients (P = 0.788, 0.326 and 0.888, respectively). Similarly, comparison of full-negative to other groups did not show any significant difference in terms of ORR (P = 0.507), PFS (P = 0.222) or OS (P = 0.686). Conclusion: These data strongly argue against mCRC patients selection for Cetuximab treatment based on EGFR expression as measured by currently available IHC technics.

Spectrum of EGFR aberrations and potential clinical implications:insights from integrative pan-cancer analysis

Background:Human epidermal growth factor receptor(EGFR)is an oncogenic gene and one of top targets of precision therapy in lung cancer with EGFR mutations.Although there are many reports for some individual cancers,comprehensive profiling of EGFR mutations,overexpression,amplification,DNA methylation,and their clinical associations across many different cancers simultaneously was not available.This study aimed to fill the gap and provide insights to the alteration spectrum of EGFR and its therapeutic and prognostic implications.Methods:The Cancer Genome Atlas(TCGA)datasets for 32 cancer types involving 11,314 patients were analyzed for alterations(mutations and amplification/deletion),abnormal expression and DNA methylation in EGFR gene.Mutation frequency,genomic location distribution,functional impact,and clinical targeted therapy implication were compared among different cancer types,and their associations with patient survival were analyzed.Results:EGFR alteration frequency,mutation sites across functional domains,amplification,overexpression,and DNA methylation patterns differed greatly among different cancer types.The overall mutation frequency in all cancers combined was relatively low.Targetable mutations,mainly in lung cancer,were primarily found in the Pkinase_Tyr domain.Glioblastoma multiforme had the highest rate of alterations,but it was dominated by gene amplification and most mutations were in the Furin-like domain where targeted therapy was less effective.Low-grade glioma often had gene amplification and increased EGFR expression which was associated with poor outcome.Colon and pancreatic adenocarcinoma had very few EGFR mutations;however,high EGFR expression was significantly associated with short patient survival.Squamous cell carcinoma regardless of their sites(the head and neck,lung,or esophagus)exhibited similar characteristics with an alteration frequency of about 5.0%,was dominated by gene amplification,and had increased EGFR expression generally associated with short patient survival.DNA methylation was highly associated with EGFR expression and patient outcomes in some cancers.Conclusions:EGFR aberration type,frequency,distribution in functional domains,and expression vary from cancer to cancer.While mutations in the Pkinase_Tyr domain are more important for treatment selection,increased expression from amplification or deregulation affects more tumor types and leads to worse outcome,which calls for new treatment strategies for these EGFR-driven tumors.