Head and neck cancer (HNC) is one of the most common malignancies worldwide, with more than 900,000 new cases and approximately 450,000 deaths reported each year. Among these, head and neck squamous cell carcinoma (HNSCC) accounts for over 90% of all head and neck malignancies and has long been associated with high recurrence rates, poor survival outcomes, and limited treatment options.

With the rapid advancement of precision medicine, the epidermal growth factor receptor (EGFR) has emerged as one of the most well-established and extensively studied molecular targets in the treatment of head and neck cancer. From the successful clinical application of cetuximab to the development of antibody-drug conjugates (ADCs), bispecific antibodies, and next-generation EGFR inhibitors, EGFR-targeted therapies are ushering in a new era of precision oncology for patients with HNSCC.

So, why has EGFR become a cornerstone therapeutic target in head and neck cancer? What are the latest developments shaping its future? Hong Kong Dengyue Pharma provides a comprehensive overview.

What Is EGFR?

EGFR (ERBB1/HER1) is a member of the human epidermal growth factor receptor (HER) family and belongs to the receptor tyrosine kinase (RTK) superfamily.

Under physiological conditions, EGFR regulates numerous essential biological processes, including:

●  Cell proliferation

●  Cell differentiation

●  Tissue repair

●  Angiogenesis

●  Cell survival

Upon binding to ligands such as epidermal growth factor (EGF) or transforming growth factor-α (TGF-α), EGFR undergoes receptor dimerization and tyrosine kinase activation, triggering several major intracellular signaling pathways, including:

●  RAS/RAF/MEK/ERK (MAPK) pathway

●  PI3K/AKT/mTOR pathway

●  JAK/STAT pathway

●  PLCγ/PKC pathway

Together, these signaling cascades regulate cell growth, proliferation, and survival.

Why Is EGFR an Important Therapeutic Target in Head and Neck Cancer?

Unlike non-small cell lung cancer (NSCLC), activating EGFR mutations are relatively uncommon in head and neck cancer, whereas EGFR overexpression is highly prevalent.

Numerous studies have shown that:

●  More than 80%–90% of HNSCC tumors overexpress EGFR.

●  Higher EGFR expression is generally associated with poorer overall prognosis.

●  EGFR overexpression is closely linked to local recurrence, distant metastasis, and resistance to radiotherapy.

Therefore, even in the absence of driver mutations, aberrant EGFR activation can continuously promote tumor progression.

Dysregulated EGFR signaling contributes to:

●  Sustained tumor cell proliferation

●  Inhibition of apoptosis

●  Enhanced invasion and metastasis

●  Increased tumor angiogenesis

●  Resistance to chemotherapy and radiotherapy

For these reasons, EGFR has become one of the most important therapeutic targets in head and neck cancer.

What Types of EGFR-Targeted Therapies Are Available?

As research continues to evolve, several therapeutic strategies targeting EGFR have emerged.

1. EGFR Monoclonal Antibodies

Monoclonal antibodies remain the most established and widely used EGFR-targeted therapy.

Representative agents include:

●  Cetuximab

●  Panitumumab (investigational in HNSCC)

●  Nimotuzumab

Their primary mechanisms of action include:

●  Blocking the binding of EGF to EGFR

●  Inhibiting receptor activation

●  Promoting EGFR internalization and degradation

●  Inducing antibody-dependent cellular cytotoxicity (ADCC)

Currently, cetuximab combined with radiotherapy is an established standard treatment option for selected patients with locally advanced HNSCC.

2. EGFR Tyrosine Kinase Inhibitors (TKIs)

Although EGFR TKIs have achieved remarkable success in lung cancer, their efficacy in head and neck cancer has been relatively limited.

Agents investigated include:

●  Erlotinib

●  Gefitinib

●  Afatinib

●  Dacomitinib

Several factors contribute to their limited activity:

●  Low frequency of activating EGFR kinase mutations

●  Activation of bypass signaling pathways

●  Significant tumor heterogeneity

Consequently, EGFR TKIs have not become standard therapy for HNSCC.

3. EGFR Antibody-Drug Conjugates (ADCs)

EGFR ADCs have become one of the most promising areas of current research.

These therapies combine:

An EGFR-targeting antibody + a potent cytotoxic payload + a linker

This design enables:

●  Precise drug delivery to tumor cells

●  Enhanced antitumor efficacy

●  Reduced systemic toxicity

Multiple EGFR ADC candidates are currently undergoing clinical development worldwide.

4. EGFR Bispecific Antibodies

Bispecific antibodies are designed to simultaneously target EGFR and additional molecules, including:

●  CD3

●  PD-1

●  c-MET

●  HER3

Potential advantages include:

●  Activating T cells

●  Overcoming therapeutic resistance

●  Enhancing antitumor immune responses

These agents are expected to become an important direction for future EGFR-targeted therapy.

Why Does Resistance to EGFR Therapy Occur?

Although EGFR-targeted therapies have demonstrated clinical benefits, drug resistance remains a major challenge.

Common resistance mechanisms include:

Activation of Bypass Signaling Pathways

Examples include activation of:

●  MET

●  HER2

●  HER3

●  FGFR

●  PI3K

These alternative pathways allow tumors to continue growing independently of EGFR signaling.

Alterations in EGFR Itself

Resistance may also result from:

●  Changes in EGFR gene amplification

●  Increased ligand expression

●  Persistent activation of downstream signaling pathways

These alterations reduce the effectiveness of anti-EGFR therapies.

Influence of the Tumor Microenvironment

Increasing evidence suggests that components of the tumor microenvironment can compromise EGFR-targeted treatment, including:

●  Cancer-associated fibroblasts (CAFs)

●  Tumor-associated macrophages (TAMs)

●  Regulatory T cells (Tregs)

These cells contribute to immune suppression and therapeutic resistance.

Tumor Heterogeneity

Different patients—and even different lesions within the same patient—may exhibit:

●  Variable EGFR expression

●  Distinct molecular subtypes

●  Different immune microenvironments

These differences highlight the need for more precise patient stratification and personalized treatment strategies.

Global Innovation in EGFR Drug Development Continues to Accelerate

In recent years, EGFR has remained one of the most active targets in oncology drug development worldwide.

Beyond conventional monoclonal antibodies, rapid advances are being made in:

●  Antibody-drug conjugates (ADCs)

●  Bispecific and multispecific antibodies

●  Radiopharmaceutical conjugates

●  Combination therapeutic strategies

Numerous multinational pharmaceutical and biotechnology companies are actively developing next-generation EGFR-targeted therapies.

At the same time, advances in biomarker testing and molecular diagnostics are expected to enable more precise patient selection, optimize treatment decisions, improve clinical outcomes, and minimize unnecessary toxicity.

Conclusion

EGFR has become a cornerstone therapeutic target in head and neck cancer not only because of its exceptionally high expression in HNSCC but also because of its central role in regulating tumor proliferation, invasion, metastasis, therapeutic resistance, and the tumor microenvironment.

Although challenges such as acquired resistance and variable clinical responses remain, continuous advances in ADCs, bispecific antibodies, combination immunotherapy, and AI-assisted precision medicine are expanding the therapeutic potential of EGFR-targeted strategies. As these innovations continue to evolve, EGFR is expected to remain one of the most important targets driving the next generation of drug development for head and neck cancer.