Molecularly targeted therapy for the treatment of head and neck cancer: a review of the ErbB family inhibitors

Abstract

The majority of patients with head and neck squamous cell carcinoma (HNSCC) present with locally advanced disease, which requires site-specific combinations of surgery, radiation, and chemotherapy. Despite aggressive therapy, survival outcomes remain poor, and treatment-related morbidity is not negligible. For patients with recurrent or metastatic disease, therapeutic options are further limited and prognosis is dismal. With this in mind, molecularly targeted therapy provides a promising approach to optimizing treatment efficacy while minimizing associated toxicity. The ErbB family of receptors (ie, epidermal growth factor receptor [EGFR], ErbB2/human epidermal growth factor receptor [HER]-2, ErbB3/HER3, and ErbB4/HER4) is known to contribute to oncogenic processes, such as cellular proliferation and survival. EGFR, specifically, is upregulated in more than 90% of HNSCC, has been implicated in radiation resistance, and correlates with poorer clinical outcomes. The central role of EGFR in the pathogenesis of HNSCC suggests that inhibition of this pathway represents an attractive treatment strategy. As a result, EGFR inhibition has been extensively studied, with the emergence of two classes of drug therapy: monoclonal antibodies and tyrosine kinase inhibitors. While the monoclonal antibody cetuximab is currently the only US Food and Drug Administration-approved EGFR inhibitor for the treatment of HNSCC, numerous investigational drugs are being evaluated in clinical trials. This paper will review the role of the ErbB family in the pathogenesis of HNSCC, as well as the evidence-based data for the use of ErbB family inhibition in clinical practice.

Keywords: epidermal growth factor receptor; head and neck cancer; monoclonal antibody; tyrosine kinase inhibitor.

Figure 1

ErbB family of receptors and their associated signaling pathways and downstream effects. Abbreviations: Akt, v-akt murine thymoma viral oncogene homologue; EGF, epidermal growth factor; EGFR, epidermal growth factor receptor; Erk, extracellular signal-related kinase; Mek, mitogen-activated protein kinase kinase; PI3K, phosphatidylinositol-3-kinase; PLC-γ, phospholipase-C gamma; PKC, protein kinase C; Ras, rat sarcoma viral oncogene homologue; Raf, Raf proto-oncogene, serine/threonine kinase; STAT, signal transducers and activators of transcription; TGF-α, transforming growth factor alpha.