Cetuximab Resistance in Head and Neck Cancer Is Mediated by EGFR-K₅₂₁ Polymorphism

Area of Science:

• Oncology
• Molecular Biology
• Cancer Genetics

Background:

• Head and neck squamous cell carcinomas (HNSCC) often develop resistance to cetuximab, an EGFR-targeting drug.
• This resistance poses a significant challenge to effective clinical management and treatment outcomes.

Purpose of the Study:

• To investigate a specific mechanism of cetuximab resistance in HNSCC.
• To identify the role of EGFR-K521 polymorphism in treatment response.
• To explore alternative therapeutic strategies for resistant HNSCC.

Main Methods:

• Analysis of EGFR-K521 polymorphism in HNSCC patient samples.
• Assessment of cetuximab efficacy in cancer models with varying K-allele frequencies.
• Evaluation of cetuximab binding affinity and downstream signaling.
• Characterization of EGFR-K521 protein stability and glycosylation.
• Testing of an optimized antibody (CetuGEX) in preclinical models.

Main Results:

• The EGFR-K521 polymorphism (K-allele), present in over 40% of HNSCC cases, is linked to shorter progression-free survival with cetuximab treatment.
• Cetuximab showed reduced efficacy in inhibiting signaling and killing cancer cells with high K-allele frequency.
• EGFR-K521 exhibited reduced stability and altered glycosylation, impacting cetuximab efficacy.
• CetuGEX restored sensitivity in HNSCC models via antibody-dependent cellular cytotoxicity (ADCC).

Conclusions:

• EGFR-K521 expression is a key mechanism of cetuximab resistance in HNSCC and a potential predictive biomarker.
• Optimized antibodies like CetuGEX show promise for treating HNSCC harboring the EGFR-K521 isoform.
• Further clinical evaluation of EGFR-K521 and ADCC-optimized antibodies is warranted.