EGFR-targeting monoclonal antibodies in head and neck cancer

The epidermal growth factor (EGFR) and its receptor were discovered nearly 40 years ago. Over the past decade interruption of this pathway has been exploited in the treatment of various solid tumors. Antibodies that interfere with ligand binding to and dimerization of the EGFR (and small molecules that inhibit the EGFR tyrosine kinase) are anti-proliferative, profoundly radiosensitizing, and synergistic with DNA-damaging cytotoxic agents. Proposed mechanisms of radio- and chemosensitization include enhanced apoptosis, interference with DNA repair and angiogenesis, receptor depletion from the cell surface and antibody-dependent cell-mediated cytotoxicity. This article provides a reader with a comprehensive review of EGFR-targeting antibodies under development for the treatment of head and neck squamous cell cancer (HNSCC) and also summarizes relevant clinical data in this disease with small molecule EGFR inhibitors. One of the monoclonal antibodies, cetuximab, recently received full FDA approval for the treatment of patients with locally advanced (with radiation) or metastatic HNSCC (as a single agent). Regulatory approval followed reporting of a large international study in which the addition of cetuximab to definitive radiation therapy in HNSCC resulted in statistically significant improvements in locoregional control and overall survival. Results of the pivotal trial, other clinical data supporting the regulatory approval, and a preview of the next generation of clinical trials are presented. Considerable work remains to be done, particularly to enhance our understanding of factors that may predict for favorable response to EGFR inhibitor therapy and to evaluate the impact of integrating anti-EGFR therapies into complex chemoradiation programs delivered with curative intent.     

Targeting the epidermal growth factor receptor in the treatment of colorectal cancer: state of the art

The epidermal growth factor receptor (EGFR) is an important mediator of normal cellular processes such as growth, survival, differentiation and morphogenesis. Disturbances in the EGFR pathway have been associated with the development and progression of malignancy, including cellular proliferation, angiogenesis, invasion/metastasis and anti-apoptosis, as well as with resistance to chemotherapy and/or radiation therapy. As a result, this is an excellent rationale for treatment with EGFR-specific therapeutic agents. These agents may be EGFR-targeted antibodies or small molecules that inactivate the receptor tyrosine kinase. While only cetuximab has received US FDA approval for the treatment of colorectal cancer, numerous agents are currently in development and in clinical trials and constitute an area of intensive, ongoing research.     

Epidermal growth factor receptor inhibitors in non-small-cell lung cancer

The epidermal growth factor receptor (EGFR) is a cell membrane receptor that plays a key role in cancer development and in the progression of many human malignancies, including non-small-cell lung cancer (NSCLC). EGFR-dependent signaling is involved in cancer cell proliferation, apoptosis, angiogenesis, invasion and metastasis. Targeting the EGFR is a valuable molecular approach in cancer therapy. This receptor is overexpressed in up to 80% of NSCLC cases. Thus, several molecules inhibiting this critical biologic pathway have been synthesized and tested as a single agent or in combination with other anticancer modalities in a wide of clinical trials, including reversible and irreversible small tyrosine kinase inhibitors, such as gefitinib and erlotinib, dual vascular endothelial growth factor receptor EGFR tyrosine kinase inhibitors, such as vandetanib (ZD-6474), and monoclonal antibodies, such as cetuximab, which have shown promising activity in patients with NSCLC. This review focuses on the preclinical and clinical results available with EGFR inhibitors in the treatment of NSCLC patients.     

Pharmacotherapy of head and neck squamous cell carcinoma

Background: The clinical management of locally advanced head and neck squamous cell carcinoma (HNSCC) is a challenging problem and requires a multidisciplinary approach. Historically, locally advanced HNSCC has been primarily managed with surgery and radiation (RT). The integration of pharmacotherapy has rapidly expanded over the years into the multimodality treatment paradigm of locally advanced HNSCC. Objective: The studies leading to the adoption of the current standard of care for locally advanced HNSCC are discussed. In addition, the limitations of these various treatment approaches are presented. Methods: An extensive literature search was conducted using the PubMed database for studies published before January 2009. The keywords used for this search were: head and neck neoplasms, chemoradiation, adjuvant chemotherapy, induction chemotherapy, EGFR inhibitor, cisplatin, carboplatin, paclitaxel, docetaxel, 5-fluorouracil, and cetuximab. Publications of randomized clinical trials and other supporting references leading to the current standard of care were particularly selected and discussed in this review. Conclusions: Various single-agent and multi-agent chemotherapeutic regimens have been examined in the context of randomized clinical trials in locally advanced HNSCC for definitive, induction and adjuvant settings. Results from these clinical trials support the use of cisplatin-based chemoradiation as the standard of care for the definitive and adjuvant settings. Recent evidence indicates that cetuximab, an epidermal growth factor receptor (EGFR) inhibitor, is highly active as a single agent and in combination with standard chemotherapy and/or RT. Future studies should focus to determine the optimal pharmacotherapeutic regimens for use in locally advanced HNSCC.     

The epidermal growth factor receptor in malignant gliomas: pathogenesis and therapeutic implications

Activated epidermal growth factor receptor (EGFR) has emerged as an important therapeutic target for a variety of solid tumors, particularly malignant gliomas. Mutation or amplification of EGFR is commonly observed in malignant gliomas and these modifications are associated with increased cell proliferation and radiation resistance. Small-molecule kinase inhibitors targeting the intracellular kinase domain of the EGFR and monoclonal antibodies against the extracellular domain of the EGFR have demonstrated in vitro efficacy and have spawned clinical trials incorporating EGFR inhibition into the management of malignant gliomas, for example, combining EGFR inhibitors with radiation therapy. This early clinical experience indicates that EGFR inhibitors are well tolerated; however, it remains unclear how best to integrate EGFR inhibition into the management of malignant gliomas. As signaling pathways become better defined, patients may be treated with EGFR inhibitors based on the molecular features of their tumors and treatment efficacy may be improved by combining EGFR inhibition with other small kinase inhibitors and radiation therapy.     

Emerging molecular targeted therapies in the treatment of head and neck cancer

Current development of molecular targeted therapies in oncology is particularly active. The aim of this study is to review recent advances in the field of molecular targeted therapies for head and neck squamous cell carcinoma (HNSCC). As EGFR signaling pathway and angiogenesis play a key role in the growth of HNSCC, EGFR with its downstream effectors and molecular factors implicated in the angiogenesis process, such as VEGF and its receptors, represent the main targets of the new therapeutic agents now in development. Today, cetuximab, an anti-EGFR monoclonal antibody, is the only targeted therapy approved for the treatment of HNSCC in patients with locally advanced tumors, in association with radiotherapy, and in patients with recurrent or metastatic diseases. Future progress is expected with the integration of cetuximab into induction chemotherapeutic regimens or in association with concurrent chemoradiotherapy for locally advanced tumors and with the development and evaluation of other molecular targeted therapies such as antiangiogenic drugs. As these innovative molecules start to be used in clinical practice, the identification of predictive markers for efficacy and toxicity becomes a crucial issue.     

The epidermal growth factor receptor in malignant gliomas: pathogenesis and therapeutic implications

Activated epidermal growth factor receptor (EGFR) has emerged as an important therapeutic target for a variety of solid tumors, particularly malignant gliomas. Mutation or amplification of EGFR is commonly observed in malignant gliomas and these modifications are associated with increased cell proliferation and radiation resistance. Small-molecule kinase inhibitors targeting the intracellular kinase domain of the EGFR and monoclonal antibodies against the extracellular domain of the EGFR have demonstrated in vitro efficacy and have spawned clinical trials incorporating EGFR inhibition into the management of malignant gliomas, for example, combining EGFR inhibitors with radiation therapy. This early clinical experience indicates that EGFR inhibitors are well tolerated; however, it remains unclear how best to integrate EGFR inhibition into the management of malignant gliomas. As signaling pathways become better defined, patients may be treated with EGFR inhibitors based on the molecular features of their tumors and treatment efficacy may be improved by combining EGFR inhibition with other small kinase inhibitors and radiation therapy.     

Epidermal growth factor receptor-targeted molecular therapeutics for head and neck squamous cell carcinoma

Several molecular-targeted therapeutics have been tested in clinical trials for the treatment of head and neck squamous cell carcinoma (HNSCC). Of these, therapeutics targeting the epidermal growth factor receptor (EGFR) have been studied most extensively and some agents have demonstrated measurable clinical effectiveness. However, molecular studies designed to define HNSCC patient subcohorts of likely responders to EGFR-targeted therapy have not identified molecular signatures that correlate with clinical response. Here, the authors summarise the relevant clinical findings and highlight reported molecular correlative studies for EGFR-targeted therapeutics for HNSCC. The authors focus especially on molecular markers evaluated for association with clinical response and include data from EGFR-targeted clinical studies in other cancer sites that they anticipate will be of interest to the head and neck cancer research and treatment communities.     

Epidermal growth factor receptor – targeted molecular therapeutics for head and neck squamous cell carcinoma

Several molecular-targeted therapeutics have been tested in clinical trials for the treatment of head and neck squamous cell carcinoma (HNSCC). Of these, therapeutics targeting the epidermal growth factor receptor (EGFR) have been studied most extensively and some agents have demonstrated measurable clinical effectiveness. However, molecular studies designed to define HNSCC patient subcohorts of likely responders to EGFR-targeted therapy have not identified molecular signatures that correlate with clinical response. Here, the authors summarise the relevant clinical findings and highlight reported molecular correlative studies for EGFR-targeted therapeutics for HNSCC. The authors focus especially on molecular markers evaluated for association with clinical response and include data from EGFR-targeted clinical studies in other cancer sites that they anticipate will be of interest to the head and neck cancer research and treatment communities.     

头颈鳞癌的分子靶向药物治疗

头颈鳞癌（HNSCC）是全球的第六种最常见的恶性肿瘤。尽管极力提高各种治疗方式的水平,但晚期病例死亡率仍高。因此,寻找更有效的分子靶向药物和联合应用不同治疗方法势在必行。抗EGFR单克隆抗体,西妥昔单抗（Cetuximab）是第一个治疗HNSCC的靶向药。现已证明局部晚期HNSCC患者用Cetuximab＋放射治疗（P．T）有生存期益处,并增强局部区域控制。对铂耐药的转移性HNSCC患者单用Cetuximab有临床效果。Ⅲ期试验用Cetuximab和标准的铂为基础的方案第一线治疗复发转移HNSCC患者证明有生存期益处。其他靶向治疗方法也在研究中,正在对各期HNSCC患者进行的临床试验将进一步确定靶向治疗作用     

EGFR targeting drugs in the treatment of head and neck squamous cell carcinoma

Importance of the field: Head and neck cancer is the sixth most common cancer worldwide. Despite intense efforts to improve different treatment modalities, mortality rates in advanced cases remain high.

Areas covered in the review: EGFR targeting mAb cetuximab (Erbitux) has been approved for the treatment of locally advanced head and neck squamous cell carcinoma (HNSCC) in combination with radiotherapy and for recurrent or metastatic HNSCC. Here, we review recent scientific advances, as well as future research goals regarding EGFR inhibitors in the treatment of HNSCC. Information was compiled by searching the PubMed, Web of Knowledge and American Society of Clinical Oncology databases for articles published before October 2009. The search terms included ‘head and neck cancer’, ‘EGFR’, ‘cetuximab’, ‘panitumumab’, ‘zalutumumab’, ‘nimotuzumab’, ‘erlotinib’, ‘gefitinib’ and ‘lapatinib’. The National Institutes of Health registry of clinical trials (www.clinicaltrials.gov) was used to search for clinical trials in HNSCC.

What the reader will gain: The background scientific rationale, clinical efficacy and development of EGFR inhibitors in HNSCC are discussed.

Take home message: Cetuximab significantly improves survival of patients with locally advanced or metastatic HNSCC. Treatment strategies combining EGFR inhibitors with multimodality approaches may eventually increase cure rate in HNSCC.     

An update: emerging drugs to treat squamous cell carcinomas of the head and neck

ABSTRACT

Introduction: Subsequent to the 2006 FDA approval of cetuximab, a variety of molecular targeting agents have been evaluated in head and neck squamous cell carcinoma (HNSCC). The treatment outcomes of recurrent and/or metastatic (R/M) HNSCC, in particular, remain dismal. The 2016 FDA approval of PD-1 immune checkpoint inhibitors has expanded the treatment options for R/M HNSCC and highlights the potential for immune-based therapies.

Areas covered: We will review the clinical application of EGFR-targeted agents, alone and in combination with other drugs. Molecular targeting agents directed against the IL6/PI3K/STAT3 signaling pathway will be covered. In addition, evaluation of immune checkpoint inhibitors in HNSCC, along with ongoing combination trials incorporating these agents, will be discussed. The expanded indications of emerging drugs and the potential clinical benefit of new drugs and treatment combinations will be summarized.

Expert opinion: In recent years, there has been a major shift toward immunotherapy-based approaches for the treatment of HNSCC, leading to significant improvements in outcomes for a subset of patients. Leveraging the increased understanding of the genetic alterations that characterize individual HNSCC tumors will facilitate precision medicine approaches using targeted agents, immunotherapies, as well as standard chemotherapy and radiation.     

Rational combination of targeted therapies as a strategy to overcome the mechanisms of resistance to inhibitors of EGFR signaling

The epidermal growth factor receptor (EGFR) has been widely used as a target for novel anticancer agents, such as blocking antibodies and small molecular weight tyrosine kinase compounds. In spite of recent advances in cancer cell biology, leading to the introduction of clinically active new drugs, such as cetuximab, panitumumab and erlotinib, unfortunately disease control remains unsuccessful due to the presence of constitutive resistance to EGFR inhibitors in most patients and the development of acquired resistance in the responders. A large number of molecular abnormalities in tumor cells seem to partly contribute to their resistance to anti-EGFR therapy: increased angiogenesis, constitutive activation of downstream mediators, overexpression of other tyrosine kinase receptors. Moreover, some mutations in the EGFR receptor kinase domain seem to play a crucial role in determining the sensitivity of cancer cells to specific inhibitors by altering the conformation of the receptor and its activity. The development of rational combinations of anticancer agents and EGFR inhibitors, able to exert synergistic cytotoxic interactions, has been widely accepted and used in both preclinical and clinical studies. Although the failure of large clinical trial based on empirical combination of anti-EGFR and classic chemotherapeutic agents, several preclinical data seems to support the hypothesis that combining EGFR inhibitors and other novel agents could efficiently inhibit tumor growth and overcome intrinsic resistance to a single-agent based therapy. This review focuses on the role of complementary signalling pathways in the development of resistance to EGFR targeting agents and the rationale to combine novel inhibitors as anticancer therapy.     

Investigational multitargeted kinase inhibitors in development for head and neck neoplasms

Introduction: Despite advances in treatment, head and neck squamous cell carcinoma (HNSCC) survival rates remain stagnant. Current treatment is associated with significant toxicities and includes chemotherapy, radiation, surgery, and few targeted treatments. Targeted treatments, epidermal growth factor receptor (EGFR)-targeted agent, cetuximab, and immune checkpoint inhibitors, pembrolizumab and nivolumab, show improved toxicity profiles and modestly improved survival in select patients. An urgent need remains to identify novel targeted treatments for single-agent or combined therapy use.

Areas covered: Multitargeted kinase inhibitors are small molecule inhibitors with limited toxicity. This review will focus on early-stage investigations of multitargeted tyrosine kinase inhibitors (m-TKIs) (those that target at least two tyrosine kinases) for HNSCC. Preclinical and early trials investigating m-TKIs for various disease settings of HNSCC will be evaluated for efficacy, identification of significant biomarkers and potential for combination therapy.

Expert opinion: Few single agent m-TKIs have demonstrated efficacy in unselected HNSCC populations. The most promising clinical results have been obtained when m-TKIs are tested in combination with other therapies, including immunotherapy, or in mutation-defined subgroups of patients. The future success of m-TKIs will rely on identification, in preclinical models and clinical trials, of predictive biomarkers of response and mechanisms of innate and acquired resistance.     

Epidermal growth factor receptor and signal transduction: potential targets for anti-cancer therapy

Agents targeting the epidermal growth factor receptor (EGFR) pathway hold particular promise for the treatment of patients with advanced disease, for whom standard chemotherapy is generally palliative. Expression of EGFR on numerous types of solid tumors, and the association of EGFR activation with tumorigenic processes including proliferation, anti-apoptosis and metastatic spread, make this pathway a particularly compelling target for rational drug design. The two classes of anti-EGFR agents in late-stage clinical testing include antibodies directed toward the extracellular EGFR domain (cetuximab, panitumumab) and small molecule tyrosine kinase inhibitors (gefitinib, erlotinib), which inactivate the receptor enzyme activity. However, important issues remain to be addressed. These include the development of appropriate predictive markers for response, such as improved tests for EGFR activity, correlation of rash with response and potential pharmacogenomic approaches; the sequencing and combination of these agents with chemotherapy and irradiation; and the possible role of these agents in the treatment of patients with earlier stage disease.     

Epidermal growth factor receptor inhibitors for radiotherapy: biological rationale and preclinical results

Blocking the epidermal growth factor receptor (EGFR) represents a role model for a successful biological targeting approach to improving outcomes after radiotherapy. This review summarizes data from several local tumour control experiments in which EGFR inhibitors were combined with radiation in FaDu human squamous cell carcinomas xenografted into nude mice. BIBX1382BS is an oral bioavailable inhibitor of the intracellular tyrosine kinase domain of EGFR. It was administered in different experimental settings: concurrent with fractionated radiotherapy, following completion of irradiation, and in the period between surgery and adjuvant irradiation. Despite beneficial effects on tumour growth, in none of these experimental settings did BIBX1382BS improve local tumour control. In contrast, cetuximab (Erbitux), an IgG1 monoclonal antibody against the extracellular ligand-binding domain of EGFR, improved local tumour control when given concurrently with radiation. Results from a series of local tumour control experiments designed to elucidate the underlying mechanisms of cetuximab suggest that multiple radiobiological mechanisms might contribute to the observed effects: decreased number of clonogenic tumour cells, increased cellular radiation sensitivity, decreased repopulation and improved reoxygenation of clonogenic tumour cells during the combined treatment. In summary, the data suggest that different classes of EGFR inhibitors may have a different potential to improve local tumour control after fractionated irradiation.     

Antiepidermal growth factor receptor radiosensitizers in rectal cancer

The activation of the epidermal growth factor receptor (EGFR) pathway correlates with a worse prognosis in many solid tumours. Hence, EGFR inhibitors have been developed as a treatment for cancer. The EGFR inhibitor cetuximab has been successfully combined with radical radiotherapy in head and neck cancer. In metastatic colorectal cancer, cetuximab and panitumumab have activity as single agents, and increased response rates are achieved when added to standard chemotherapy schedules. This approach of using EGFR inhibitors has also been extrapolated to the preoperative treatment of locally advanced rectal cancer. Counterintuitively, the combination of chemotherapy, EGFR inhibitors and anti-VEGF antibodies seem to show lower response rates, suggesting antagonism. In rectal cancer, disappointingly low pathological complete response (pCR) rates have often been observed in chemoradiation regimens using EGFR inhibitors. In this study, we aimed to examine the rationale for the integration of EGFR inhibitors into chemoradiation schedules for rectal cancer. We have reviewed the clinical evidence and potential mechanisms for an interaction when EGFR inhibitors are added to fluoropyrimidine-based preoperative chemoradiation, the majority of which have used cetuximab. The primary outcome measure used was pCR. The overall pooled pCR for cetuximab-based chemoradiation was 10.71% (38/356). The rate of G3/G4 gastrointestinal toxicity, in terms of diarrhoea, varied from 5 to 30%, with an overall pooled rate of 13.8% (49/353). A better understanding of the mechanisms involved in combining chemotherapy and radiotherapy might allow more effective future scheduling of biological and chemical agents in combination with radiation.     

Monoclonal antibodies targeting the epidermal growth factor receptor

The epidermal growth factor receptor (EGFR, HER1) autocrine pathway contributes to a number of highly relevant processes in cancer development and progression, including cell proliferation, regulation of apoptotic cell death, angiogenesis and metastatic spread. The crucial role that EGFR plays in human cancers has led to an extensive search for selective inhibitors of its signaling pathway. The results of a large body of preclinical studies and clinical trials thus far conducted suggest that targeting the EGFR could bring a significant contribution to cancer therapy. A variety of different approaches are currently being used to target the EGFR. The most promising strategies in clinical development include monoclonal antibodies, to prevent ligand binding, and small molecules inhibitors of the tyrosine kinase enzymatic activity, that inhibit autophosphorylation and downstream intracellular signaling. Several blocking monoclonal antibodies against the EGFR have been developed. Among these, IMC-225 is a chimeric human-mouse monoclonal IgG1 antibody that has been the first anti-EGFR targeted therapy to enter clinical evaluation in cancer patients in Phase II and III studies, alone or in combination with conventional radiotherapy and chemotherapy. However, other antibodies against EGFR have demonstrated antitumor activity in several preclinical models of human cancer and are currently under investigation in the clinical setting, such as ICR62, ABX-EGF and EMD72000. This review will focus on all the preclinical data available on monoclonal antibodies engineered against the EGF receptor.