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Updated: May 27, 2026
Validated Immunochemical Assay for Comprehensive Determination of the Human Epidermal Growth Factor Receptor 2 Released from and Bound to Cells
Published on: May 9, 2025
Rational identification of an optimal antibody mixture for targeting the epidermal growth factor receptor
Klaus Koefoed1, Lucilla Steinaa, Josefine Nielsen Søderberg
1Symphogen A/S, Lyngby, Denmark.
Abstract:
The epidermal growth factor receptor (EGFR) is frequently dysregulated in human malignancies and a validated target for cancer therapy. Two monoclonal anti-EGFR antibodies (cetuximab and panitumumab) are approved for clinical use. However, the percentage of patients responding to treatment is low and many patients experiencing an initial response eventually relapse. Thus, the need for more efficacious treatments remains. Previous studies have reported that mixtures of antibodies targeting multiple distinct epitopes are more effective than single mAbs at inhibiting growth of human cancer cells in vitro and in vivo. The current work describes the rational approach that led to discovery and selection of a novel anti-EGFR antibody mixture Sym004, which is currently in Phase 2 clinical testing. Twenty-four selected anti-EGFR antibodies were systematically tested in dual and triple mixtures for their ability to inhibit cancer cells in vitro and tumor growth in vivo. The results show that targeting EGFR dependent cancer cells with mixtures of antibodies is superior at inhibiting their growth both in vitro and in vivo. In particular, antibody mixtures targeting non-overlapping epitopes on domain III are efficient and indeed Sym004 is composed of two monoclonal antibodies targeting this domain. The superior growth inhibitory activity of mixtures correlated with their ability to induce efficient EGFR degradation.
Insights
Discovering novel antibody mixtures targeting the epidermal growth factor receptor (EGFR) offers a superior approach to inhibiting cancer cell growth. This strategy, exemplified by the Sym004 mixture, enhances treatment efficacy compared to single antibodies.
Area of Science:
- Oncology
- Immunotherapy
- Molecular Biology
Background:
- Epidermal growth factor receptor (EGFR) is a key target in cancer therapy, but current treatments with single monoclonal antibodies (mAbs) like cetuximab and panitumumab show limited response rates and eventual relapse.
- There is a critical need for more effective anti-EGFR therapies to overcome treatment resistance in various human malignancies.
Purpose of the Study:
- To rationally discover and select a novel mixture of anti-EGFR antibodies with enhanced efficacy.
- To evaluate the anti-cancer potential of antibody combinations targeting distinct EGFR epitopes.
Main Methods:
- Systematic in vitro and in vivo testing of 24 selected anti-EGFR antibodies in dual and triple combinations.
- Assessment of antibody mixtures' ability to inhibit cancer cell growth and tumor progression.
- Analysis of EGFR degradation as a mechanism for growth inhibition.
Main Results:
- Antibody mixtures targeting EGFR-dependent cancer cells demonstrated superior inhibition of cancer cell growth in vitro and tumor growth in vivo compared to single antibodies.
- Mixtures targeting non-overlapping epitopes on domain III of EGFR were particularly efficient.
- The enhanced efficacy of antibody mixtures correlated with their ability to induce significant EGFR degradation.
Conclusions:
- Combinatorial targeting of EGFR with antibody mixtures, specifically those engaging distinct epitopes on domain III, represents a highly effective therapeutic strategy.
- The novel anti-EGFR antibody mixture Sym004, composed of two antibodies targeting domain III, was discovered through this approach and is currently in Phase 2 clinical trials.
- Induction of EGFR degradation is a key mechanism underlying the superior anti-tumor activity of these antibody combinations.
