Susanne J. Rogers

Biological significance of c-erbB family oncogenes in head and neck cancer.

Squamous cell carcinoma of the head and neck (SCCHN) tends to run an aggressive course and the prognosis has remained virtually unchanged in recent decades. The development of novel therapeutic strategies to improve patient outcome centres on the biology of the disease, namely the pivotal c-erbB family of growth factor receptors. c-erbB1 (or epidermal growth factor receptor, EGFR), is key to the pathogenesis of SCCHN and plays a central role in a complex network of downstream integrated signalling pathways. EGFR overexpression, detected in up to 90% of SCCHN, correlates with an increased risk of locoregional tumour relapse following primary therapy and relative resistance to treatment. The biological sequelae of erbB receptor activation are not simply cell proliferation, but also inhibition of apoptosis, enhanced migration, invasion, angiogenesis and metastasis: the ‘hallmarks of cancer’ [1]. As EGFR overexpression is associated with a poor clinical outcome in SCCHN, this receptor is attractive as a therapeutic target and the successful development of targeted therapies represents a paradigm shift in the medical approach to head and neck cancer. However, the extensive cross talk between signalling pathways, the multiple molecular aberrations and genetic plasticity in SCCHN all contribute to inherent and acquired resistance to both conventional and novel therapies. Understanding the cancer cell biology, in particular the significance of co-expression of c-erbB (and other) receptors, and the cell survival stimuli from (for example) activation of the phosphoinositide 3-kinase (PI3-kinase) cascade is fundamental to overcome current limitations in biologically targeted therapies.

Gefitinib (ZD1839, Iressa™) as palliative treatment in recurrent or metastatic head and neck cancer

To assess the level of activity and toxicity of gefitinib (ZD1839, Iressa™) in a population of patients with locally recurrent and/or metastatic head and neck cancer. Patients were recruited into an expanded access programme through the multidisciplinary head and neck clinics at the Royal Marsden and St Georges Hospitals. Patients were required to have received at least one course of standard systemic chemotherapy or radiation therapy, or be medically unfit for chemotherapy. Patients were commenced on single-agent gefitinib at a dose of 500 mg day−1. Clinical, symptomatic and radiological response, time to progression (TTP), survival and toxicity were recorded. A total of 47 patients were enrolled (35 male and 12 female) with a median age of 62 years (range 18–93 years). The observed clinical response rate was 8% with a disease control rate (complete response, partial response, stable disease) of 36%. In all, 34% of patients experienced an improvement in their symptoms. The median TTP and survival were 2.6 and 4.3 months, respectively. Acneiform folliculitis was the most frequent toxicity observed (76%) but the majority of cases were grade 1 or 2. Only four patients experienced grade 3 toxicity of any type (all cases of folliculitis). Gefitinib was well tolerated and yielded symptomatic improvement in one-third of patients. However, this agent appeared to possess limited antitumour activity in this group of patients with head and neck cancer in whom the objective response rate, median TTP and survival were all lower than has been reported in a previous study.

Tumour-microenvironmental interactions: paths to progression and targets for treatment.

Primary human tumours can often be eradicated by surgery if detected early; however metastatic disease renders complete cure less likely and the development of resistance to therapy results in tumour escape and increased risk of death. Interactions of tumour cells with each other, surrounding normal cells and extracellular matrix or basement membrane components are crucial to all stages of cancer progression. Changes in both cell-cell and cell-substrate proteins are linked to tumour cell migratory and invasive ability, induction of angiogenesis (on which sustained tumour growth and dissemination depends) and apoptosis resistance in response to drugs or radiotherapy. Hypoxia within solid tumours is a key driver of many aspects of progression, and may also nurture cancer stem-like cells which are increasingly linked to relapse and treatment failure. This review will briefly outline the cellular and molecular mechanisms underlying tumour progression, focussing on the acquisition of metastatic capacity and resistance to therapy.

Determinants of response to epidermal growth factor receptor tyrosine kinase inhibition in squamous cell carcinoma of the head and neck.

Dramatic responses to epidermal growth factor receptor (EGFR) tyrosine kinase (TK) inhibitors may be seen in non‐small cell lung cancers (NSCLCs) with a sensitizing mutation of the EGFR TK domain. It is not known how to predict response in patients with squamous cell carcinoma of the head and neck (SCCHN), where EGFR TK mutations are less frequent and where response rates in unselected patients are disappointing. We have characterized the intrinsic sensitivity of a panel of 18 SCCHN cell lines to gefitinib, an EGFR TK inhibitor, and have investigated correlations between putative markers of response and intrinsic sensitivity. Induction of G1 arrest was only seen in cell lines with GI50 < 1 µM. Expression of EGFR, by three techniques, correlated with sensitivity to gefitinib. ERB‐B2 expression appeared to influence sensitivity to gefitinib but ERB‐B3 expression did not. While EGFR tyrosine kinase mutations were not detected, EGFR gene amplification was confirmed by fluorescence in situ hybridization in the most sensitive cell line. The number of cytosine adenine dinucleotide repeats in intron 1 of the EGFR gene did not correlate with sensitivity. E‐cadherin expression was detected in cell lines with a range of sensitivities, whereas amphiregulin was secreted predominantly by sensitive cell lines. MET expression was an independent predictor of sensitivity to gefitinib, although neither expression nor phosphorylation of insulin‐like growth factor 1 receptor correlated with intrinsic resistance. Breast receptor kinase (BRK) was more highly expressed in the sensitive cell lines, but siRNA knockdown of neither BRK nor MET affected sensitivity. Our data suggest that overexpression of EGFR and multiple related cell surface receptors may be associated with sensitivity to gefitinib and that differences between our data and the literature highlight that biomarkers of response are tumour type‐ and cell line‐dependent. Copyright

The phosphoinositide 3-kinase signalling pathway as a therapeutic target in squamous cell carcinoma of the head and neck

Squamous cell carcinoma of the head and neck (SCCHN) is associated with high morbidity and mortality. Despite significant surgical advances and refinement in the delivery of chemotherapy and radiotherapy, prognosis has improved little in recent decades. Better local control has led to the late presentation of distant metastases and novel therapeutic agents are urgently required to prevent relapse, control disseminated disease and thus improve survival. PIK3CA encodes the p110α isoform of phosphoinositide 3-kinase (PI3-K) and is important in SCCHN, aberrations in its activity occurring early in the oncogenic process. PI3-K signalling promotes cell survival, proliferation, invasion and angiogenesis, all contributing to tumour progression. Activation of the PI3-K pathway may also mediate resistance to chemotherapy, radiotherapy and novel therapeutic agents such as epidermal growth factor receptor inhibitors. Elements of this signalling matrix, therefore, offer attractive therapeutic targets in SCCHN as inhibition of many malignant characteristics, as well as sensitisation to multiple treatment modalities, could be anticipated.

Combination epidermal growth factor receptor inhibition and radical radiotherapy for NSCLC.

Non-small cell lung cancer (NSCLC) remains the most common cause of cancer-related death in the developed world. Despite advances in therapy with conventional modalities, over 85% of patients will die from their disease within 5 years of diagnosis. For patients with inoperable lung cancer, the addition of chemotherapy to radical radiotherapy yields a small but significant 10% survival benefit at 3 years. However, the systemic toxicity of chemotherapy is common and may be severe. Over the past 20 years, dramatic improvements in our understanding of the molecular etiology of cancer have enabled the development of novel targeted therapies. Overexpression of the epidermal growth factor receptor (EGFR) in lung cancer correlates with an aggressive disease course and poor tumor response to radiotherapy. Strategies to inhibit this molecular switch have become a focus for drug development. Preclinical efficacy has been repeatedly demonstrated with anti-EGFR monoclonal antibodies and small molecule tyrosine kinase inhibitors, and responses have been documented in the clinic with acceptable toxicity. Phase III trials combining EGFR tyrosine kinase inhibitors with radical chemoradiation are recruiting at present. This review addresses the current challenges of discovering how best to use these new anticancer therapies, with particular emphasis on the enhancement of existing therapeutic strategies such as radical radiotherapy, factors relating to patient selection and prediction of clinical response.

Comparison of permanent hair loss in children with standard risk PNETS of the posterior fossa following radiotherapy alone or chemotherapy and radiotherapy after surgical resection

Hair loss was compared between surgery followed by craniospinal radiotherapy (CSRT) or chemotherapy then CSRT (C‐CSRT) for medulloblastoma. The proportion of patients exhibiting hair loss in the cranial field was 70.0% (C‐CSRT) versus 30.0% (CSRT) (95% CI: 14.7% to 58.9%; P = 0.002). The C‐CSRT group also experienced more virtual/complete hair loss over the posterior fossa boost. Age was a significant contributor to hair loss in the cranial field. Persistent significant hair loss is an under‐reported late effect of treatment that could influence quality of survival and should be considered in future trial design. Pediatr Blood Cancer 2011; 57: 1074–1076.

EGFR signaling in invasion, angiogenesis and metastasis

Tumor invasion and metastasis are the hallmarks of advanced stage cancer and are associated with poor patient prognosis. EGFR is overexpressed in a variety of tumor types and this frequently correlates with a more aggressive tumor phenotype. In this chapter, we discuss the cellular and molecular mechanisms by which EGFR contributes to tumor progression and present evidence from experimental and clinical observations that reinforce the notion that EGFR actively contributes to the onset of metastatic disease. EGFR plays a key role in the regulation of processes central to tumor invasion including cell adhesion and motility through its interactions with molecules such as integrins, cadherins, phospholipase Cγ1 and phosphoinositide 3-kinase. In addition, EGFR signaling can contribute to both proteolysis and angiogenesis through up-regulated expression of matrix metalloproteinases (MMPs) and angiogenic cytokines e.g. VEGF-A and IL-8. The significance of these contributions to tumor invasion and metastasis is highlighted by the fact that a mutant, constitutively active receptor (EGFRvIII) associated with human cancers can induce these behaviors when transfected into fibroblasts. Finally, we discuss the use of EGFR antagonists to stem metastatic disease and their potential, in combination with additional novel agents, to improve treatment for cancer patients.