The prognostic value of epidermal growth factor receptor is related to tumor differentiation and the overall treatment time of radiotherapy in squamous cell carcinomas of the head and neck

Gene expression profiling to predict outcome after chemoradiation in head and neck cancer

PURPOSE

The goal of the present study was to improve prediction of outcome after chemoradiation in advanced head and neck cancer using gene expression analysis.

MATERIALS AND METHODS

We collected 92 biopsies from untreated head and neck cancer patients subsequently given cisplatin-based chemoradiation (RADPLAT) for advanced squamous cell carcinomas (HNSCC). After RNA extraction and labeling, we performed dye swap experiments using 35k oligo-microarrays. Supervised analyses were performed to create classifiers to predict locoregional control and disease recurrence. Published gene sets with prognostic value in other studies were also tested.

RESULTS

Using supervised classification on the whole series, gene sets separating good and poor outcome could be found for all end points. However, when splitting tumors into training and validation groups, no robust classifiers could be found. Using Gene Set Enrichment analysis, several gene sets were found to be enriched in locoregional recurrences, although with high false-discovery rates. Previously published signatures for radiosensitivity, hypoxia, proliferation, "wound," stem cells, and chromosomal instability were not significantly correlated with outcome. However, a recently published signature for HNSCC defining a "high-risk" group was shown to be predictive for locoregional control in our dataset.

CONCLUSION

Gene sets can be found with predictive potential for locoregional control after combined radiation and chemotherapy in HNSCC. How treatment-specific these gene sets are needs further study.

Phase I/II clinical and pharmacokinetic study evaluating a fully human monoclonal antibody against EGFr (HuMax-EGFr) in patients with advanced squamous cell carcinoma of the head and neck

PURPOSE

To assess safety, tolerability, pharmacokinetics and clinical activity of HuMax-EGFr in patients with SCCHN.

PATIENTS AND METHODS

Twenty-eight patients with SCCHN were enrolled. The study comprised a single-dose escalation part for assessment of safety issues followed by a repeat dose extension including 4 weekly infusions at the same doses. Efficacy and metabolic response were evaluated according to RECIST by CT and FDG-PET.

RESULTS

Most frequently reported adverse event was rash. All but one event were CTC grade 1 or 2 and a dose-dependent relationship was indicated. Duration of skin reactions varied from few days to 2 months. No DLTs were observed and MTD was not reached. In the two highest dose groups, 7 of 11 patients obtained a PR or SD and 9 patients obtained metabolic PR or SD.

CONCLUSIONS

HuMax-EGFr can be safely administered in doses up to 8 mg/kg, and preliminary data on tumour response are encouraging.

Use of Molecular Biomarkers for Predicting the Response to Radiotherapy With or Without Chemotherapy

Radiotherapy (RT), particularly when combined with chemotherapy, has progressively become the nonsurgical standard of care in the primary treatment of a variety of cancers. Likewise, hormonal therapy is routinely combined with RT for the treatment of hormone-sensitive tumors. In addition, the clinical efficacy of combining an epidermal growth factor receptor (EGFR) antagonist with RT was recently validated. In view of cancer heterogeneity and the availability of an increasing number of therapy options, identification of biomarkers that can predict tumor response to a given therapy is crucial in streamlining treatment and sparing patients from receiving often toxic and expensive therapies that are not likely to be effective. Well-established biomarkers for response to hormonal therapy and/or RT are tumor estrogen receptor and the receptor tyrosine kinase HER-2 for breast cancer and serum prostate-specific antigen for prostate carcinoma. Some markers of tumor hypoxia and the level of tumor EGFR expression have been shown to be independent predictors of tumor response to RT. The use of biomarkers for predicting tumor response to the combination of RT and chemotherapy has thus far been limited to the methylation status of O-6-methylguanine-DNA methyltransferase in patients with glioblastoma multiforme treated with the combination of RT plus temozolomide. No validated biomarkers for predicting the response to molecular therapeutics are currently available. In this review, we call for standardization and simplification of assay methods and stress the importance of conducting confirmatory prospective studies. Integrated plans for identifying molecular markers built into many ongoing trials will hopefully generate more insights in the near future.

Is EGFR a moving target during radiotherapy of carcinoma of the uterine cervix?

BACKGROUND

The epidermal growth factor receptor (EGFR) is frequently overexpressed in uterine cervix carcinoma. The role of the pre-treatment EGFR expression levels and the changes of expression induced by ionizing radiation (IR) have not been conclusively defined.

PATIENTS AND METHODS

The staining intensity (SI) and labeling index (LI) of EGFR were determined in 38 patients by immunohistochemistry (IHC). Biopsies were taken before after 1 week of RT. EGFR expression was correlated with cell cycle, apoptosis and angiogenesis.

RESULTS

Before RT, 87% and after 1 week of RT, 95% of samples were positive for EGFR (p=0.2). Two patterns were observed, either increasing or decreasing expression after initiating RT. An increase of the EGFR SI was seen in 63% of patients from a mean of 57 SI (SD+/-60) before RT to 142 SI (SD+/-80.8) (p=0.001) during RT. In 32% of cases, EGFR decreased from 165 SI before (SD+/-83.0) to 75 SI (SD+/-73.0) (p< or =0.001) during RT. Two of five (5%) patients negative for EGFR before RT remained negative. An increase of the RT-induced EGFR LI was associated with reduced microvessel density (MVD) (p=0.02). Changes of the EGFR LI did neither correlate with cell cycle arrest nor apoptosis.

CONCLUSIONS

EGFR expression changes unpredictably during RT. The implications of changing EGFR during RT remain to defined. Repeated biopsies and EGFR reassessment during RT may help to better define EGFR-targeted treatment.

Pre-treatment number of clonogenic cells and their radiosensitivity are major determinants of local tumour control after fractionated irradiation

OBJECTIVE

The response of tumours to fractionated radiotherapy is determined by many factors including repopulation, reoxygenation, the number of clonogenic cells, and their intrinsic radiosensitivity. However, after single radiation doses given under conditions of clamp hypoxia, the dose to control a tumour locally is dependent only on the number of clonogenic cells and their cellular radiosensitivity. Therefore, these parameters were investigated using local control after single doses given under hypoxia, to predict the outcome of fractionated irradiation.

MATERIALS AND METHODS

Ten hSCC cell lines (FaDu, UT-SCC-15, UT-SCC-14, XF354, UT-SCC-5, UT-SCC-45, SAS, CAL-33, UT-SCC-8, and HSC-4) were transplanted subcutaneously into the right hind-leg of NMRI nude mice. At 7mm in diameter, tumours were irradiated either with graded single doses under clamp blood flow conditions (n=873) or with 30 graded fractions within 6 weeks (n=905) under ambient conditions. Local tumour control was determined 120 days after irradiation. Radiation response was quantified in terms of TCD(50), i.e. the dose required to control 50% of tumours locally.

RESULTS

Ten tumour lines investigated showed a pronounced heterogeneity in both TCD(50(30fx/6w)) after fractionated irradiation and TCD(50(SDclamp)) after single dose irradiation. TCD(50(30fx/6w)) varied between 45Gy for UT-SCC-45 and 127Gy for SAS; TCD(50(SDclamp)) varied between 42Gy for UT-SCC-14 and 66Gy for CAL-33. Two tumours were excluded from further analysis due to immunogenicity or non-defined TCD(50). Linear regression analysis revealed a significant positive correlation between TCD(50(SDclamp)) and TCD(50(30fx/6w)) (R(2)=0.82, p=0.002).

CONCLUSIONS

Significant association between TCD(50(SDclamp)) and TCD(50(30fx/6w)) suggests that the pre-treatment number of clonogenic tumour cells and their cellular radiosensitivity have a major impact on local control after fractionated radiotherapy.

Combination of radiotherapy with EGFR antagonists for head and neck carcinoma

The introduction of biologically sound radiation fractionation regimens and combinations of radiotherapy with chemotherapy have gradually improved both the survival of patients with locally advanced head and neck squamous cell carcinoma (HNSCC) and the prospect of organ preservation. Long-term follow-up, however, has shown that some of the radiation-chemotherapy combinations are associated with increased late toxicity. This observation, in conjunction with advances in tumor biology, has led to the launch of investigations into molecular markers and targets for therapeutic interventions. Research on the epidermal growth factor receptor (EGFR)-mediated signaling pathway has enriched our understanding of the biology of HNSCC, in terms of carcinogenesis and cellular processes governing tumor response to therapy. The finding that the addition of an antibody-based inhibitor of the EGFR pathway to radiotherapy significantly improves locoregional control and overall survival rates in patients with locally advanced HNSCC, without increasing radiation-induced toxicity, has resulted in the growing acceptance of such combined regimens as a frontline therapy option for locally advanced HNSCC. Because such therapy has benefited only an additional 10%-15% of patients, studies are being undertaken to identify markers and mechanisms of resistance to EGFR antagonists that are essential for the further refinement of therapy. Overall, preclinical and clinical studies on EGFR have validated the concept that selective tumor radiation sensitization can be achieved by modulating a specific perturbed signaling pathway, and these studies have increased the enthusiasm for developing and investigating other novel agents targeting other cellular processes.

Cellular responses to EGFR inhibitors and their relevance to cancer therapy

EGFR is a trans-membrane receptor tyrosine kinase that belongs to the HER family of receptors. The EGFR family plays an essential role in normal organ development by mediating morphogenesis and differentiation. Unlike normal cells that have tight regulatory mechanisms controlling EGFR pathways, tumor cells often have dysregulated EGFR signaling through receptor overexpression and/or mutation. This leads to proliferation under adverse conditions, invasion of surrounding tissues, and increased angiogenesis as well as resistance to radiation and chemotherapy. Therefore, EGFR is a legitimate therapeutic target. Numerous EGFR inhibitors are under development, but to date only four of them are FDA-approved, including two that inhibit the receptor's intracellular tyrosine kinase activity (gefitinib and erlotinib) and two that block extracellular ligand binding (cetuximab, and most recently panitumumab). In this review, we focus on how these different inhibitors affect EGFR signaling and the mechanisms by which they potentiate the effects of chemotherapy and radiation therapy. Numerous clinical trials have been conducted with these agents either as monotherapy, in combination with chemotherapy, or concurrently with radiation. Unfortunately, many of the clinical trials reported so far have shown at best limited gains; therefore, understanding the actions of these agents is essential to improving their efficacy in the treatment of cancers.

Effects of MnSOD-Plasmid Liposome Gene Therapy on Antioxidant Levels in Irradiated Murine Oral Cavity Orthotopic Tumors

Intraoral manganese superoxide dismutase (SOD2)-plasmid liposome (PL) radioprotective gene therapy prolongs the survival of mice with orthotopic oral cavity tumors within the irradiated field. To determine whether the mechanism involved effects in antioxidant pool, C57BL/6J mice bearing orthotopic oral cavity squamous cell carcinoma SCC-VII tumors received intraoral or intravenous MnSOD-PL gene therapy 24 h prior to 18 Gy irradiation to the head and neck region. Glutathione (GSH) levels and levels of radiation-generated nitric oxide and peroxynitrite were measured in orthotopic tumors and in adjacent oral mucosa. MnSOD-PL transfection of the SCC-VII tumor cells, but not normal embryo fibroblasts, produced acute radiosensitization. Furthermore, SCC-VII tumor cells demonstrated increased relative hydrogen peroxide (the product of MnSOD superoxide dismutation)-induced apoptosis in vitro. Radiation decreased levels of GSH and increased GPX in both tumor and normal cells in vitro, effects that were blunted by MnSOD-PL treatment. In vivo irradiation decreased GSH and GPX more effectively in tumors, and the decrease was not reversed by MnSOD-PL therapy. Intravenous but not intraoral administration of epitope-tagged hemagglutinin MnSOD-PL resulted in significant uptake in orthotopic tumors and decreased the levels of radiation-induced nitric oxide and peroxynitrite. Thus normal tissue radioprotective MnSOD-PL gene therapy radiosensitizes tumor cell lines in vitro and has a therapeutic effect on orthotopic tumors in part through its effects on tumor antioxidants.

A simple and reproducible scoring system for EGFR in colorectal cancer: application to prognosis and prediction of response to preoperative brachytherapy

The aim of this study was to determine the predictive and prognostic value of epidermal growth factor receptor (EGFR) expression in rectal cancers treated with preoperative high-dose rate brachytherapy and in mismatch-repair (MMR)-proficient colorectal cancers (CRCs), respectively. We validate the use of receiver operating characteristic (ROC) curve analysis to select cutoff scores for EGFR overexpression for the end points studied. Immunohistochemistry (IHC) for EGFR was performed on 82 rectal tumour biopsies and 1197 MMR-proficient CRCs using a tissue microarray. Immunoreactivity was scored as the percentage of positive tumour cells by three pathologists and the inter-observer reliability was assessed. ROC curve-derived cutoffs were used to analyse the association of EGFR overexpression, tumour response and several clinicopathological features including survival. The scoring method was found to be reproducible in rectal cancer biopsies and CRCs. The selected cutoff scores from ROC curve analysis for each clinicopathological feature were highly consistent among pathologists. EGFR overexpression was associated with response to radiotherapy (P-value <0.001) and with worse survival time (P-value <0.001). In multivariate analysis, EGFR overexpression was independently associated with adverse prognosis (P-value <0.001). Epidermal growth factor receptor is a predictive marker of response to preoperative radiotherapy and an independent adverse prognostic factor CRC.

Treatment of Advanced Head and Neck Cancer with Cetuximab

Cetuximab is a monoclonal antibody targeting the transmembrane receptor HER-1 (epidermal growth factor receptor, EGFR). In theory, inhibition of EGFR may influence tumor behavior since the receptor regulates many important tumor cell activities including tumor growth, angiogenesis, and inhibition of the apoptotic response to chemotherapy and radiotherapy. Available experimental data suggest that cetuximab may enhance the activity of chemotherapy and radiotherapy, reverse resistance to some anticancer drugs, and has itself anticancer activity. Early clinical data support the experimental results. This paper reviews the published findings on cetuximab in the treatment of advanced head and neck cancer and points out the future objectives of the clinical research on this drug.

Les thérapeutiques ciblées en association avec la radiothérapie dans le cancer bronchique

Targeted therapies are now more often used in lung cancer. Inhibitors of EGFR and of angiogenesis have demonstrated a certain activity in this disease. Some experimental in vitro or in vivo studies are in favour of combined targeted therapies and radiation. For example, additive or supra-additive effects have been shown when inhibitors of the EGFR tyrosine kinase were given with radiation. In advanced lung cancer, the combination of bevacizumab with chemotherapy was demonstrated to produce better survival outcomes. But a high rate of fatal hemoptysis was reported with this drug, particularly for central and squamous tumors. This could be a limitation for its use in combination with radiation. Drugs with multiple targets are becoming available; their association with radiation seems to be promising.

Prediction of response to chemoradiation in rectal cancer by a gene polymorphism in the epidermal growth factor receptor promoter region

PURPOSE

Epidermal growth factor receptor (EGFR) has been associated with radioresistance in solid tumors. Recently a polymorphism in the Sp1 recognition site of the EGFR promoter region was identified. The present study investigated the predictive value of this polymorphism for the outcome of chemoradiation in locally advanced rectal cancer.

METHODS AND MATERIALS

The study included 77 patients with locally advanced T3 rectal tumors. Treatment consisted of preoperative radiation therapy at a total tumor dose of 65 Gy and concomitant chemotherapy with Uftoral. Blood samples from 63 patients were evaluated for Sp1 -216 G/T polymorphism by polymerase chain reaction analysis. Forty-eight primary tumor biopsies were available for EGFR immunostaining. Patients underwent surgery 8 weeks after treatment. Pathologic response evaluation was performed according to the tumor regression grade (TRG) system.

RESULTS

Forty-nine percent had major response (TRG1-2) and 51% moderate response (TRG 3-4) to chemoradiation. The rates of major response were 34% (10/29) in GG homozygote patients compared with 65% (22/34) in patients with T containing variants (p=0.023). Fifty-eight percent of biopsies were positive for EGFR expression (28/48). The major response rates with regard to EGFR immunostaining were not significantly different. EGFR-positive tumors were found in 83% of the GG homozygote patients compared with 38% of patients with TT or GT variants (p=0.008).

CONCLUSIONS

There was a significant correlation between EGFR Sp1 -216 G/T polymorphism and treatment response to chemoradiation in locally advanced rectal cancer. Further investigations of a second set of patient and other treatment schedules are warranted.

Preclinical evaluation of molecular-targeted anticancer agents for radiotherapy

The combination of molecular-targeted agents with irradiation is a highly promising avenue for cancer research and patient care. Molecular-targeted agents are in themselves not curative in solid tumours, whereas radiotherapy is highly efficient in eradicating tumour stem cells. Recurrences after high-dose radiotherapy are caused by only one or few surviving tumour stem cells. Thus, even if a novel agent has the potential to kill only few tumour stem cells, or if it interferes in mechanisms of radioresistance of tumours, combination with radiotherapy may lead to an important improvement in local tumour control and survival. To evaluate the effects of novel agents combined with radiotherapy, it is therefore necessary to use experimental endpoints which reflect the killing of tumour stem cells, in particular tumour control assays. Such endpoints often do not correlate with volume-based parameters of tumour response such as tumour regression and growth delay. This calls for radiotherapy specific research strategies in the preclinical testing of novel anti-cancer drugs, which in many aspects are different from research approaches for medical oncology.

Blockage of Epidermal Growth Factor Receptor-Phosphatidylinositol 3-Kinase-AKT Signaling Increases Radiosensitivity of K-RAS Mutated Human Tumor Cells In vitro by Affecting DNA Repair

PURPOSE

It is known that blockage of epidermal growth factor receptor (EGFR)/phosphatidylinositol 3-kinase (PI3K) activity enhances radiation sensitivity of human tumor cells presenting a K-RAS mutation. In the present study, we investigated whether impaired repair of DNA double-strand breaks (DSB) is responsible for the radiosensitizing effect of EGFR and PI3K inhibition in K-RAS mutated (K-RAS(mt)) cells.

EXPERIMENTAL DESIGN

The effect of the EGFR tyrosine kinase inhibitor BIBX1382BS (BIBX) on cellular radiosensitivity was determined in K-RAS(mt) (A549) and K-RAS(wt) (FaDu) cell lines by clonogenic survival assay. Radiation-induced phosphorylation of H2AX (Ser139), ATM (Ser1981), and DNA-dependent protein kinase catalytic subunit (DNA-PKcs; Thr2609) was analyzed by immunoblotting. Twenty-four hours after irradiation, residual DSBs were quantified by identification of gammaH2AX foci and frequency of micronuclei.

RESULTS

BIBX reduced clonogenic survival of K-RAS(mt)-A549 cells, but not of K-RAS(wt)-FaDu cells, after single-dose irradiation. Analysis of the radiation-induced H2AX phosphorylation revealed that BIBX, as well as the PI3K inhibitor LY294002, leads to a marked reduction of P-H2AX in K-RAS(mt)-A549 and MDA-MB-231 cells, but not in K-RAS(wt)-FaDu and HH4ded cells. Likewise, radiation-induced autophosphorylation of DNA-PKcs at Thr2609 was only blocked in A549 cells by these two inhibitors and AKT1 small interfering RNA transfection. However, neither in K-RAS(mt) nor in K-RAS(wt) cells the inhibitors did affect radiation-induced ATM phosphorylation. As a consequence of inhibitor treatment, a significant enhancement of both residual DSBs and frequency of micronuclei was apparent only in A549 but not in FaDu cells following radiation.

CONCLUSION

Targeting of the EGFR-dependent PI3K-AKT pathway in K-RAS-mutated A549 cells significantly affects postradiation survival by affecting the activation of DNA-PKcs, resulting in a decreased DSB repair capacity.

Radiotherapy plus cetuximab for squamous-cell carcinoma of the head and neck

BACKGROUND

We conducted a multinational, randomized study to compare radiotherapy alone with radiotherapy plus cetuximab, a monoclonal antibody against the epidermal growth factor receptor, in the treatment of locoregionally advanced squamous-cell carcinoma of the head and neck.

METHODS

Patients with locoregionally advanced head and neck cancer were randomly assigned to treatment with high-dose radiotherapy alone (213 patients) or high-dose radiotherapy plus weekly cetuximab (211 patients) at an initial dose of 400 mg per square meter of body-surface area, followed by 250 mg per square meter weekly for the duration of radiotherapy. The primary end point was the duration of control of locoregional disease; secondary end points were overall survival, progression-free survival, the response rate, and safety.

RESULTS

The median duration of locoregional control was 24.4 months among patients treated with cetuximab plus radiotherapy and 14.9 months among those given radiotherapy alone (hazard ratio for locoregional progression or death, 0.68; P=0.005). With a median follow-up of 54.0 months, the median duration of overall survival was 49.0 months among patients treated with combined therapy and 29.3 months among those treated with radiotherapy alone (hazard ratio for death, 0.74; P=0.03). Radiotherapy plus cetuximab significantly prolonged progression-free survival (hazard ratio for disease progression or death, 0.70; P=0.006). With the exception of acneiform rash and infusion reactions, the incidence of grade 3 or greater toxic effects, including mucositis, did not differ significantly between the two groups.

CONCLUSIONS

Treatment of locoregionally advanced head and neck cancer with concomitant high-dose radiotherapy plus cetuximab improves locoregional control and reduces mortality without increasing the common toxic effects associated with radiotherapy to the head and neck. (ClinicalTrials.gov number, NCT00004227.)

Radioresistance of K-Ras mutated human tumor cells is mediated through EGFR-dependent activation of PI3K-AKT pathway

BACKGROUND AND PURPOSE

In the context of EGFR-targeting strategies we investigated autocrine/paracrine factors leading to in vitro radioresistance of K-Ras mutated tumor cells through activation of EGFR mediated signal transduction.

PATIENTS AND METHODS

Ras mutated (Rasmt) and normal Ras (Raswt) presenting human tumor cell lines were used to analyze the potential of conditioned media (CM) of both cell types to mediate radioresistance and to activate EGFR-signaling cascades. Therefore, clonogenic assays as well as SDS-PAGE combined with immunoblotting was performed. Additionally, Ras-mutated cells were transfected with K-Ras-siRNA to investigate, how downregulation of mutated K-Ras affects secretion of EGFR-ligands, stimulation of EGFR-signaling and modulation of radiation response.

RESULTS

TGFalpha, Amphiregulin (ARG) and CM from Rasmt cells (Rasmt-CM) resulted in an increased clonogenic survival of irradiated Raswt cells. Both, EGFR ligands as well as Rasmt-CM led to a strong phosphorylation of EGFR and activation of downstream pathways, i.e. PI3K-AKT. However, neutralization of TGFalpha or ARG in Rasmt-CM led to a marked reduction of P-AKT. Furthermore, Rasmt-CM from K-Ras-siRNA transfected Rasmt-cells markedly inhibited phosphorylation of AKT in Raswt cells and enhanced radiation sensitivity of A549 cells transfected with the siRNA.

CONCLUSION

The data suggest that constitutively upregulated autocrine/paracrine secretion of EGF receptor ligands, especially ARG from K-Ras mutated cells, mediates radioresistance in Rasmt-cells through stimulation of EGFR-PI3K-AKT pathway.

Pre-treatment proliferation and the outcome of conventional and accelerated radiotherapy

This study investigated the influence of pre-treatment proliferation characteristics, assessed by Ki-67 staining, in patients treated in the CHART trial of accelerated radiotherapy in head and neck cancer. Histological material from 402 patients was collected and stained for the presence and pattern of Ki-67 staining. Locoregional control and overall survival were the main clinical endpoints. Increasing Ki-67 positivity was associated with decreasing differentiation (P < 0.001) and increasing N-stage (P < 0.004). Increasing N-stage was also associated with the progression of proliferation pattern from marginal to random (P < 0.001). Using a multivariate model, a trend was seen towards a greater benefit from CHART in the lower Ki-67 tumours (P = 0.08); this became significant by pooling the low and intermediate Ki-67 groups in comparison with the high Ki-67 group (P = 0.032). Tumours with marginal proliferation pattern showed a lower hazard ratio with CHART versus conventional for locoregional control (P = 0.005). The data presented in this study do not support that a high pre-treatment Ki-67 is associated with a therapeutic benefit from accelerated radiotherapy.

Mechanisms of disease: Radiosensitization by epidermal growth factor receptor inhibitors

The epidermal growth factor receptor (EGFR) inhibitors are among the most intensely studied new molecular therapeutic agents. Although response rates have been somewhat disappointing when EGFR inhibitors are used as single-agent therapy for advanced disease, these inhibitors may be more effective as chemo- and radiosensitizers. The first phase III randomized trial evaluating EGFR inhibitors as radiosensitizers in patients with locally advanced head and neck cancer was strongly positive, indicating significant potential of this class of agents to improve outcome with radiotherapy. However, optimal implementation of EGFR inhibitors as radiosensitizers depends, in part, on a better understanding of the mechanisms of radiosensitization. Preclinical studies provide important observations with regard to potential mechanisms. The phenotypic cellular changes associated with EGFR inhibition are impressively consistent between different model systems, with almost all studies showing that EGFR inhibitors affect proliferation, angiogenesis, and cell survival. Whether EGFR inhibitors influence response to radiation directly, or whether the improved response is a result of additive effects of the two modalities, remains unclear. However, cell-cycle arrest, endothelial cell sensitivity, and apoptotic potential are all important factors in radiation response of epithelial tumors. Furthermore, less-studied effects of EGFR inhibitors on DNA repair suggest that modulation of DNA damage response to cytotoxic injury might result in radio- or chemosensitization. This review will explore potential mechanisms of radiosensitization by EGFR inhibitors.

Epidermal growth factor receptor expression in pretreatment biopsies from head and neck squamous cell carcinoma as a predictive factor for a benefit from accelerated radiation therapy in a randomized controlled trial

PURPOSE

Accelerated repopulation is a main reason for locoregional failure after fractionated radiotherapy for head and neck squamous cell carcinoma (HNSCC). Epidermal growth factor receptor (EGFR) is a key controller of cellular proliferation in HNSCC, which stimulated the current study to look for a direct link between EGFR status and a possible clinical advantage of accelerated radiotherapy.

PATIENTS AND METHODS

Immunohistochemical staining for EGFR was performed in 304 patients with available pretreatment tumor biopsy material among 918 patients randomized to receive continuous hyperfractionated accelerated radiotherapy versus conventionally fractionated radiotherapy. The EGFR index was estimated as the proportion of tumor cells with EGFR membrane staining.

RESULTS

Significant benefit in locoregional tumor control from continuous hyperfractionated accelerated radiotherapy was seen in patients with HNSCC with high EGFR expression (2P = .010) but not in those with low EGFR expression (2P = .85). EGFR status had no significant effect on survival or rate of distant metastases. The EGFR index was significantly associated with histologic grade and microvessel density. There was moderate support for an association between EGFR status and subsite within the head and neck region but no significant association with Ki-67 index, Ki-67 pattern, p53 index, p53 intensity, bcl-2 expression, or cyclin D1 index.

CONCLUSION

This study indicates a key role for the EGFR receptor in determining the proliferative cellular response to fractionated radiotherapy in HNSCC. It also shows that we can select the dose-fractionation regime that has the greatest chance of benefiting the patient. These results also encourage further development of EGFR targeting combined with fractionated radiotherapy in HNSCC.

The possible role of TP53 mutation status in the treatment of squamous cell carcinomas of the head and neck (HNSCC) with radiotherapy with different overall treatment times

BACKGROUND AND PURPOSE

TP53-mutations have been shown to influence the radiosensitivity of HNSCC. Furthermore, HNSCC with mutated TP53, may have a higher proliferative potential caused by a lack of control in G1 checkpoint. Our aim of the study was to identify the role of TP53 mutations for the outcome of radiotherapy.

PATIENTS AND METHODS

DNA extracted from 180 paraffin-embedded formalin-fixed pretreatment biopsies of HNSCC was screened for mutations in exon 4C-10 by denaturing high-pressure liquid chromatography (DHPLC) followed by sequencing. Treatment was 66-68Gy, 2Gy/fx with overall treatment times of 6.5 and 5.5 weeks according to the DAHANCA-guidelines. Endpoints were local control at T-site, disease-specific and crude survival.

RESULTS

125 of 180 carcinomas (69%) carried in total 176 mutations. 72 carcinomas were WT (40%) and 108 carcinomas (60%) carried mutations giving dysfunctional p53. Overall, mutations in TP53 were not associated with the endpoints. However, when dichotomising according to TP53 status and evaluating the effect of the overall treatment time then tumours with mutant TP53 did benefit from 6 instead of 5fx/wk regarding local control, P=0.005; RR: 0.33 (C.I 95%:0.15-0.75) whereas WT-tumours did not (P=0.9). These observations were also reflected in the disease-specific and crude survival.

CONCLUSIONS

If all patients were considered regardless of treatment schedule, then TP53-mutations were not related to local control or survival. However, mutations in TP53 may be associated with HNSCC that benefit of a reduced overall treatment time of radiotherapy.

Kinetics of EGFR expression during fractionated irradiation varies between different human squamous cell carcinoma lines in nude mice

BACKGROUND AND PURPOSE

Preclinical and clinical data indicate that high pretherapeutic EGFR expression is associated with poor local tumour control, possibly caused by a high repopulation rate of clonogenic cells during radiotherapy in these tumours. Previous data reported from our laboratory showed a correlation between EGFR expression and acceleration of repopulation in poorly differentiated FaDu human squamous cell carcinoma (SCC) during fractionated irradiation. To test whether this is a general phenomenon, two further SCC were investigated in the present study.

PATIENTS AND METHODS

GL and UT-SCC-14, two moderately well differentiated and keratinising hSCC, were grown as xenografts in nude mice. Functional data on the repopulation kinetics during fractionated irradiation for these tumour models have been previously determined. The expression of EGFR during fractionation was analysed by immunohistochemistry. Endpoints were the membrane-staining score and the proportion of EGFR-positive cells (EGFR labelling index).

RESULTS

Different kinetics of EGFR expression during fractionated RT were found. In UT-SCC-14, EGFR staining score and labelling index increased significantly during radiotherapy. In GL SCC, the EGFR expression was unchanged. Both tumours are characterized by a small but significant repopulation rate during radiotherapy.

CONCLUSIONS

The expression of EGFR may change significantly during fractionated irradiation. No clear correlation between EGFR expression and the repopulation kinetics of clonogenic tumour cells during fractionated irradiation was found. The changes in EGFR expression during irradiation warrant further investigation on their prognostic implications and on their importance for therapeutic interventions.

Repopulation of cancer cells during therapy: an important cause of treatment failure

Radiotherapy and chemotherapy are given in multiple doses, which are spaced out to allow the recovery of normal tissues between treatments. However, surviving cancer cells also proliferate during the intervals between treatments and this process of repopulation is an important cause of treatment failure. Strategies developed to overcome repopulation have improved clinical outcomes, and now new strategies to inhibit repopulation are emerging in parallel with advances in the understanding of underlying biological mechanisms.

The influence of epidermal growth factor receptor and tumor differentiation on the response to accelerated radiotherapy of squamous cell carcinomas of the head and neck in the randomized DAHANCA 6 and 7 study

BACKGROUND AND PURPOSE

Reduction of the overall treatment time of radiotherapy has increased locoregional control and disease specific survival in squamous cell carcinomas of the head and neck (HNSCC), but the response is heterogeneous. EGFr is often overexpressed in HNSCC and has been related to the repopulation taking place during radiotherapy. The aim of the current study was to address the influence of EGFr and histopathological differentiation when the overall treatment time of radiotherapy was moderately reduced.

PATIENTS AND METHODS

Eight hundred and three patients with representative pretreatment tissue samples from the randomized DAHANCA 6 and 7 study of 5 vs. 6 fx/wk of radiotherapy. EGFr was visualized using immunohistochemistry and separated into high and low expression before correlation with clinical data.

RESULTS

Tumors with high EGFr (84%) responded better to moderately accelerated radiotherapy, than carcinomas with low EGFr, using locoregional control as endpoint and a similar pattern was seen, stratifying by well/moderate vs. poor tumor differentiation. Therefore, a combined parameter was constructed showing a more prominent separation of response: tumors with high EGFr and well/moderate differentiation did benefit from moderate acceleration of treatment regarding locoregional control, HR 0.54 (0.37-0.78), whereas such an effect was not seen in tumors with low EGFr and/or poor differentiation, HR 0.8 (0.51-1.25). These results reflected the disease specific survival as well and were confirmed in multivariable analyses.

CONCLUSIONS

Moderately accelerated fractionation is superior to conventional treatment in HNSCC but the response is heterogeneous and may be predicted by high expression of EGFr and well/moderate tumor differentiation.

LRIG-1 provides a novel prognostic predictor in squamous cell carcinoma of the skin: immunohistochemical analysis for 38 cases

BACKGROUND

The LRIG-1 gene (formerly LIG-1) encodes a type 1 transmembrane glycoprotein with an extracellular region of 15 leucine-rich repeats and 3 immunoglobulin-like domains. LRIG-1 interacts with ErbB receptors, down-regulating the downstream signals. Because ErbB signaling is disrupted in cutaneous squamous cell carcinoma (SCC), we examined LRIG-1 expression in cutaneous SCC.

OBJECTIVE

To analyze the differential expression of LRIG-1 and to investigate whether LRIG-1 is useful as a prognostic indicator in SCC of the skin.

METHODS

LRIG-1 expression in 38 cases of cutaneous SCC patients was examined by immunohistochemistry.

RESULTS

LRIG-1 expression was highest in well-differentiated lesions of cutaneous SCC. The cases studied here were categorized into 23 cases (60.5%) of high expression and 15 cases (39.5%) of low expression of LRIG-1. There was a significant correlation (p = .000018) of LRIG-1 expression intensity of tumor cells with histologic differentiation of SCC. Furthermore, we found a significant inverse correlation with metastatic rate (p = .02). When the overall survival of SCC patients was statistically compared between high and low LRIG-1 expression groups, a significant survival benefit for the patients in the former group was found (p = .03).

CONCLUSION

LRIG-1 expression is an excellent candidate for a prognostic indicator of cutaneous SCC.

The role of epidermal growth factor receptor and E-cadherin for the outcome of reduction in the overall treatment time of radiotherapy of supraglottic larynx squamous cell carcinoma

Reduction of the overall treatment time (OTT) of radiotherapy results in increased T-site control in squamous cell carcinomas of the head and neck (HNSCC). However, the response is heterogeneous and accelerated repopulation of clonogenic tumour cells during therapy may be one of the factors determining this response. The aim of the present study was to identify the influence of the epidermal growth factor receptor (EGFr) and E-cadherin for T-site control when the OTT was reduced and whether the markers add information to the histopathological grading in selecting patients for accelerated radiotherapy. A total of 209 patients from randomized DAHANCA-trials with supraglottic larynx squamous cell carcinomas treated with primary radiotherapy with different OTT of 9(1/2), 6(1/2), and 5(1/2) weeks. Available formalin-fixed paraffin embedded tumour tissues were re-evaluated for histopathological characteristics and stained for EGFr and E-cadherin. Data were correlated with patient and tumour characteristics and 5-year T-site control. EGFr and E-cadherin were not associated with patient or tumour characteristics except that EGFr correlated to carcinomas with a well to moderate histopathological feature. Tumours with high EGFr or low E-cadherin did benefit from reduced OTT, and the combination of the two (high EGFr and low E-cadherin) had the most significant acceleration of treatment effect, compared with tumours with other combinations of EGFr and E-cadherin expression. Tumours with high expression of EGFr and low expression of E-cadherin showed the most significant increase in T-site control when the overall treatment time of radiotherapy was reduced, and the markers may be useful for selecting patients who will benefit from accelerated radiotherapy.

Targeting the epidermal growth factor receptor in radiotherapy: radiobiological mechanisms, preclinical and clinical results

BACKGROUND AND PURPOSE

Inhibition of the epidermal growth factor receptor (EGFR) is a fastly developing field in preclinical and clinical cancer research. This review presents the current status of knowledge and discusses radiobiological mechanisms which may underly the efficacy of EGFR inhibitors combined with irradiation.

MATERIALS AND METHODS

Preclinical and clinical results on combined targeting of the EGFR and irradiation from the literature and from this laboratory are reviewed. Focus is given to the radiobiological rationale of this approach and to endpoints of experimental radiotherapy.

RESULTS

Overexpression of the EGFR is associated with decreased local tumour control after radiotherapy, especially when the overall treatment time is long. Inhibition of the EGFR either alone or in combination with irradiation decreases the growth rate of tumours expressing this receptor. Preclinical data provide proof-of-principle that local tumour control may be improved by combining irradiation with C225 mAb. In a randomised phase III clinical trial, simultaneous irradiation and treatment with the EGFR antibody Cetuximab (Erbitux; C225) in head and neck cancer patients resulted in significantly improved locoregional tumour control and survival compared to curative irradiation alone. Acute skin reactions increased in the experimental arm. The underlying mechanisms of enhanced radiation effects of combined EGFR inhibition with irradiation and of the partly conflicting results in different studies are poorly understood. There is increasing evidence, that important intertumoral heterogeneity in the response to EGFR inhibition alone and combined with irradiation exists, which appears to be at least partly dependent on specific mutations of the receptor as well as of molecules that are involved in the intracellular signal transduction pathway.

CONCLUSIONS AND OUTLOOK

Further investigations at all levels of the translational research chain exploring the mechanisms of EGFR inhibition in the context of radiotherapy are needed to fully exploit the potential of such combinations and to develop predictive tests that direct their use.

Theragnostic imaging for radiation oncology: dose-painting by numbers

Theragnostic imaging for radiation oncology is the use of molecular and functional imaging to prescribe the distribution of radiation in four dimensions-the three dimensions of space plus time-of radiotherapy alone or combined with other treatment modalities in an individual patient. Several new imaging targets for positron-emission tomography, single-photon-emission CT, and magnetic resonance spectroscopy allow variations in microenvironmental or cellular phenotypes that modulate the effect of radiation to be mapped in three dimensions. Dose-painting by numbers is a strategy by which the dose distribution delivered by inverse planned intensity-modulated radiotherapy is prescribed in four dimensions. This approach will revolutionise the way that radiotherapy is prescribed and planned and, at least in theory, will improve the therapeutic outcome in terms of local tumour control and side-effects to unaffected tissue.

Molecular profiles as predictive marker for the effect of overall treatment time of radiotherapy in supraglottic larynx squamous cell carcinomas

BACKGROUND AND PURPOSE

Reduction of the overall treatment time of radiotherapy increases the probability of local tumour control, but it does not benefit all patients. Identification of molecular marker profiles may aid in the selection of patients likely to benefit from accelerated radiotherapy.

PATIENTS AND METHODS

Two hundred and nine patients with SCC of the supraglottic larynx received primary radiotherapy in the randomised DAHANCA trials to 66-68 Gy, 2 Gy/fx but with different overall treatment times of 9.5 week, 6.5 week and 5.5 week. Formalin-fixed paraffin embedded tumour slides were assessed by immunohistochemistry for expression of EGFr, E-cadherin, KI-67 and Bcl-2 and the TP53 mutation profile was determined using PCR-amplification, DHPLC and sequencing. The profiles were established using a hierarchical clustering algorithm with a Bayesian information criterion for cluster number optimisation.

RESULTS

Full data-set were available for 158 patients and four almost equally sized clusters were identified. One of these clusters differed significantly with respect to local control compared to the other clusters: the cluster (n=36) characterised by wild type TP53, low expression of E-cadherin and Bcl-2, moderate KI-67 and EGFr, was not influenced by a reduction in the overall treatment time (P=0.6) whereas the other clusters showed an increase in local control when the overall treatment time of radiotherapy was reduced. This was also partially seen with disease specific survival as the endpoint.

CONCLUSIONS

Molecular marker profiling may aid in the selection of patients that will benefit of a reduction in overall treatment time of radiotherapy in SCC of the supraglottic larynx.

Clinicopathologic analysis of esophageal and cardiac cancers and survey of molecular expression on tissue arrays in Chaoshan littoral of China

AIM: To investigate clinical and pathologic data of esophageal carcinoma (EC) and cardiac carcinoma (CC) among residents in Chaoshan region of China.

METHODS: Clinical and pathologic data of 9 650 patients with EC and 4 173 patients with CC in the Chaoshan population were collected and analyzed. Moreover, Chaoshan esophageal carcinoma tissue arrays were made for high-throughput study.

RESULTS: Male to female ratio was 3:1 in patients with EC and 4.75:1 in CC. The average age of the occurrence of EC was 54.6 years, and of CC was 58.1 years. For both EC and CC, age at diagnosis was a little younger in Chaoshan region than in most other areas. The most commonly affected site of esophageal carcinoma was the middle third of esophagus (72.0%); the second was the lower third (15.3%). The main gross type of esophageal carcinoma was ulcerative type (41.50%); the medullary type was the second (39.6%). Squamous cell carcinoma accounted for the overwhelming majority of esophageal cancer (96.4%); adenocarcinoma accounted for the overwhelming majority of cardiac carcinoma (94.5%). Chaoshan esophageal carcinoma tissue arrays were easily for high-throughput study, and tissue cores with a diameter of 1.5 mm could better keep more structure for molecular expression study.

CONCLUSION: Both EC and CC are common in males. The average occurrence age of EC and CC is younger in Chaoshan than in most other regions of China. The most commonly affected site of esophageal carcinoma was the middle third of esophagus (72.0%). Squamous cell carcinoma accounted for the overwhelming majority of esophageal cancer; adenocarcinoma accounted for the overwhelming majority of cardiac carcinoma. Tissue arrays technology is applicable for rapid molecular profiling of large numbers of cancers in a single experiment.