Expression and prognostic value of epidermal growth factor receptor, transforming growth factor-alpha, and c-erb B-2 in nephroblastoma

The first investigation of Wilms' tumour atomic structure-nitrogen and carbon isotopic composition as a novel biomarker for the most individual approach in cancer disease

The paper describes a novel approach to investigating Wilms' tumour (nephroblastoma) biology at the atomic level. Isotope Ratio Mass Spectrometry (IRMS) was used to directly assess the isotope ratios of nitrogen and carbon in 84 Wilms' tumour tissue samples from 28 cases representing the histological spectrum of nephroblastoma. Marked differences in nitrogen and carbon isotope ratios were found between nephroblastoma histological types and along the course of cancer disease, with a breakout in isotope ratio of the examined elements in tumour tissue found between stages 2 and 3. Different isotopic compositions with regard to nitrogen and carbon content were observed in blastemal Wilms' tumour, with and without focal anaplasia, and in poorly- and well-differentiated epithelial nephroblastoma. This first assessment of nitrogen and carbon isotope ratio reveals the previously unknown part of Wilms' tumour biology and represents a potential novel biomarker, allowing for a highly individual approach to treating cancer. Furthermore, this method of estimating isotopic composition appears to be the most sensitive tool yet for cancer tissue evaluation, and a valuable complement to established cancer study methods with prospective clinical impact.

Biomarkers for Wilms Tumor: A Systematic Review

PURPOSE

Wilms tumor is the most common childhood renal malignancy and the fourth most common childhood cancer. Many biomarkers have been studied but there has been no comprehensive summary. We systematically reviewed the literature on biomarkers in Wilms tumor to quantify the prognostic implications of the presence of individual tumor markers.

MATERIALS AND METHODS

We searched for English language studies from 1980 to 2015 performed in patients younger than 18 years with Wilms tumor and prognostic data. The protocol was conducted per PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Two reviewers abstracted data in duplicate using a standard evaluation form. We performed descriptive statistics, then calculated relative risks and 95% confidence intervals for markers appearing in multiple level II or III studies.

RESULTS

A total of 40 studies were included examining 32 biomarkers in 7,381 patients with Wilms tumor. Studies had a median of 61 patients, 24 biomarker positive patients per series and a median followup of 68.4 months. Median percentages of patients with stages 1, 2, 3, 4 and 5 tumors were 28.5%, 26.4%, 24.5%, 14.1% and 1.7%, respectively, and 10.2% had anaplasia. The strongest negative prognostic association was loss of heterozygosity at 11p15, with a risk of recurrence of 5.00, although loss of heterozygosity at 1p and gain of function at 1q were also strongly linked to increased recurrence (2.93 and 2.86, respectively).

CONCLUSIONS

Several tumor markers are associated with an increased risk of recurrence or a decreased risk of overall survival in patients with Wilms tumor. These data suggest targets for development of diagnostic tests and potential therapies.

Expression of TGF-β1 in Wilms' tumor was associated with invasiveness and disease progression

OBJECTIVE

To detect the expression of TGF-β1 in Wilms' tumor and association with disease progression.

METHODS

Immunohistochemistry was used to examine TGF-β1 expression in 51 primary tumors and 17 invasions/metastases. Transient transfection was performed to establish Wilms' tumor cells with high TGF-β1 expression (TGF-β1-WT), and the expression level of TGF-β1 was detected by Western blot analysis. Invasive capacity of the transfected cells was evaluated by transwell analysis.

RESULTS

The positive expression rate of TGF-β1 was 50.98% (26/51) and 82.35% (14/17) in primary WT tissues and associated invasive/metastatic tissues, respectively. The higher level of TGF-β1 expression in primary WT tumors was relative to invasion/metastasis (p = 0.048). The expression of TGF-β1 between primary WT and matched invasive/metastatic tissues was concordant (p = 0.219). TGF-β1-WT cells showed more invasive capacity than GFP-WT and WT cells. TGF-β1 expression status was associated with disease-free survival (DFS) (50.2 months vs. 75.4 months, p = 0.022) but not overall survival (OS) (62.3 months vs. 75.8 months, p = 0.141).

CONCLUSIONS

Positive expression of TGF-β1 in WT was correlated with tumor invasion and disease progression, which might be useful in identifying patients at high risk of unfavorable outcomes.

β-Catenin and K-RAS synergize to form primitive renal epithelial tumors with features of epithelial Wilms' tumors

Wilms' tumor (WT) is the most common childhood renal cancer. Although mutations in known tumor-associated genes (WT1, WTX, and CATNB) occur only in a third of tumors, many tumors show evidence of activated β-catenin-dependent Wnt signaling, but the molecular mechanism by which this occurs is unknown. A key obstacle to understanding the pathogenesis of WT is the paucity of mouse models that recapitulate its features in humans. Herein, we describe a transgenic mouse model of primitive renal epithelial neoplasms that have high penetrance and mimic the epithelial component of human WT. Introduction of a stabilizing β-catenin mutation restricted to the kidney is sufficient to induce primitive renal epithelial tumors; however, when compounded with activation of K-RAS, the mice develop large, bilateral, metastatic, multifocal primitive renal epithelial tumors that have the histologic and staining characteristics of the epithelial component of human WT. These highly malignant tumors have increased activation of the phosphatidylinositol 3-kinase-AKT and extracellular signal-regulated kinase pathways, increased expression of total and nuclear β-catenin, and increased downstream targets of this pathway, such as c-Myc and survivin. Thus, we developed a novel mouse model in which activated K-RAS synergizes with canonical Wnt/β-catenin signaling to form metastatic primitive renal epithelial tumors that mimic the epithelial component of human WT.

Overexpression of carbonic anhydrase and HIF-1α in Wilms tumours

Background

Overexpression of carbonic anhydrase (CA IX) is associated with poor survival in several adult-type cancers but its expression is undocumented in Wilms tumour (WT), the most common tumour of the paediatric kidney.

Methods

CA9 expression was measured using polymerase chain reaction (PCR) in 13 WTs and matched-paired non-neoplastic kidneys (NKs). CA IX and hypoxia-inducible factor-1 α-subunit (HIF-1α) protein were quantified in 15 matched-paired WTs and NKs using enzyme-linked immunosorbent assays. CA IX and HIF-1α were localised by immunostaining tissue sections of 70 WTs (untreated WTs, n = 22; chemotherapy-treated WTs, n = 40; relapsed/metastatic WTs, n = 8). CA IX-positive untreated WTs (n = 14) were immunostained for vascular endothelial growth factor (VEGF), glucose transporter-1 (GLUT1) and CD31. Double staining for CA IX and CD31 was performed in WTs (n = 14).

Results

CA9 full length (FL) was significantly up-regulated in WTs compared to NKs (p = 0.009) by real-time PCR. Conventional PCR showed expression of alternative splice variant in all NKs and WTs but FL in WTs only. WTs showed a 2-fold increase in CA IX protein over NKs (p = 0.01). HIF-1α levels were up-regulated in WTs compared to NKs, although the difference was not statistically significant (p = 0.09). CA IX and HIF-1α immunolocalisation were observed in 63% and 93% of WTs, respectively. The median fraction of cells staining positively for CA IX and HIF-1α was 5% and 22%, respectively. There was no significant association between the expression of either CA IX or HIF-1α and clinicopathological variables in WTs resected following chemotherapy. VEGF and GLUT1 immunoreactivity was seen in 94% and 100% with the median fraction of 10% and 60% respectively. Co-expression and co-localisation of all four hypoxia markers was seen in 7/14 and 6/14 cases respectively. CA IX was seen in well vascularised areas as well as in the peri-necrotic areas.

Conclusions

Carbonic anhydrase 9 (mRNA and protein), and HIF-1α protein are overexpressed in a significant portion of WTs. No significant association was detected between the expression of either CA IX or HIF-1α and clinicopathological variables in WTs resected following chemotherapy. Cellular localisation studies in untreated WTs suggest that CA IX and HIF-1α are regulated by hypoxia and non-hypoxia mechanisms.

The predictive value of immunohistochemical markers in untreated Wilms' tumour: are they useful?

Purpose

This study reevaluates the potential role of different tumour markers as prognostic indicators in untreated nephroblastoma.

Methods

Expression of a broad panel of tumour markers was investigated by means of immunohistochemical analysis in 43 WT patients. Patients were treated by radical nephrectomy and had a mean follow-up of 11.9 years.

Results

Generally, all the tumour markers studied were expressed in normal kidney tissue and at variable levels in the three cell types of WT (blastema, epithelium and stroma). Immunoreactive blastemal (Bcl-X, Bcl-2 and CD44s) and epithelial (Bcl-X, Bcl-2 and MIB-1) cells were present in the majority of tumours. No correlation was found between their expression and pathological stages. Univariate analysis showed that blastemal WT-1, TGF-α, VEGF, MIB-1 and p27 Kip1 were indicative for clinical progression. In a multivariate analysis, WT-1 protein expression by blastemal cells was an independent prognostic marker for clinical progression.

Conclusions

The blastemal WT-1, TGF-α, VEGF, MIB-1 and p27Kip1 expression correlate with clinical progression in untreated nephroblastoma. Therefore, their expression may be of value in identifying patients with a high propensity to develop distant metastases.

Phase I and pharmacokinetic study of cetuximab and irinotecan in children with refractory solid tumors: a study of the pediatric oncology experimental therapeutic investigators' consortium

PURPOSE

To determine the dose of cetuximab that can be safely combined with irinotecan for treatment of pediatric and adolescent patients with refractory solid tumors.

PATIENTS AND METHODS

This open-label, phase I study enrolled patients ages 1 to 18 years with advanced refractory solid tumors, including tumors of the CNS. Patient cohorts by age group (children, ages 1 to 12 years; adolescents, ages 13 to 18 years) received escalating weekly doses of cetuximab (75, 150, 250 mg/m(2)) in a 3 + 3 design, plus irinotecan (16 or 20 mg/m(2)/d) for 5 days for 2 consecutive weeks every 21 days. The primary end points were establishing the maximum-tolerated dose (MTD), recommended phase II dose (RPIID), and pharmacokinetics of the combination. Preliminary safety and efficacy data were also collected.

RESULTS

Twenty-seven children and 19 adolescents received a median of 7.1 and 6.0 weeks of cetuximab therapy, respectively. Cetuximab 250 mg/m(2) weekly plus irinotecan 16 mg/m(2)/d (pediatric) or 20 mg/m(2)/d (adolescent) have been established as the MTD/RPIID. Dose-limiting toxicities included diarrhea and neutropenia. Mild to moderate (grade 1 to 2) acneiform rash occurred in a majority of patients; no grade 3 to 4 rashes were observed. Cetuximab demonstrated dose-dependent clearance in both children and adolescents, similar to that in adults. There were two confirmed partial responses, both in patients with CNS tumors. Stable disease was achieved in 18 patients overall, including 10 patients with CNS tumors (38.5%).

CONCLUSION

The cetuximab/irinotecan combination can be given safely to children and adolescents with cancer. Promising activity, particularly in CNS tumors, warrants phase II evaluation of this regimen.

Amplification and expression of EGFR and ERBB2 in Wilms tumor

Wilms tumor is one of the most common solid tumors in children. We evaluated expression and amplification of a number of genes and their prognostic significance in 45 patients with Wilms tumor, using tissue microarray technology. The expression of EGFR, ERBB2, MDM2, CCND1, MLH1, MSH2, TP53, and ABCB1 (alias MDR1) was studied by immunohistochemistry. Amplification of the EGFR, ERBB2, MDM2, CCND1, CTTN (previously EMS1), RAF1, MYC, FGF3 (previously INT2), WNT1, GLI1, CDK4, and NCOA3 (alias AIB1) genes was assessed by fluorescence in situ hybridization. Expression of EGFR was seen in 17 of the 45 cases (38%) but was not associated with gene amplification. The ERBB2 gene was neither overexpressed nor amplified in any case. Tissue microarray and immunohistochemistry analyses for ERBB2 in whole-tumor sections were also negative in all cases. Strong p53 reactivity was noted in blastemal cells in two cases with an unfavorable outcome. ABCB1 reactivity was seen in five cases with favorable histology and outcome. Only one case showed nuclear cyclin D1 positivity. All tumors showed MLH1 and MSH2 expression. All examined genes showed normal copy numbers. Unfavorable histology correlated with poor prognosis (P=0.03). There was no significant association between gene expression and prognosis. Overexpression of the EGFR gene in many Wilms tumor cases warrants further study to determine the therapeutic benefit of EGFR inhibitors in combination with other therapies in Wilms tumor patients.

HER2/neu expression: a predictor for differentiation and survival in children with Wilms tumor

Wilms tumor is a mixed embroynal neoplasm of the kidney . HER2 is an onco-protein. Its over-expression could be implicated in the development of many tumors. The clinico-demographic and pathological data of 28 Wilms tumor patients were , reviewed. The tissue samples were examined by light Microscopy then immunohistochemical staining for HER2/neu expression. Additional 28 normal surrounding renal tissue specimens were included. There was significant differences between HER2/neu positive and HER2/neu negative Wilms tumors in relation to stage, histological phase and epithelial differentiation (P > 0.05 for all). The overall survival advantage was noticed if Wilms tumor was at early stages (I and II) (Log-rank = 13.23 and P > 0.001), homologous epithelial differentiation (Log-rank = 6.01 and P = 0.04), as well as HER2/neu positive tumors (Log-rank = 6.14 and P = 0.013). A statistical significant trend toward a longer recurrence free survival was, noticed if Wilms tumor was at early stages (Log-rank = 21.22, P > 0.0000) and if HER2/neu positive (Log-rank = 8.53, P = 0.004). HER2/neu expression in Wilms tumor could be a marker for epithelial and homologous differentiation and its expression could be a good predictor for overall survival and longer recurrence free survival.

Inheritance of susceptibility to induction of nephroblastomas in the Noble rat

Noble (Nb) strain rats are susceptible to nephroblastoma induction with transplacental exposure to direct-acting alkylating agent N-nitrosoethylurea (ENU), while F344 strain rats are highly resistant. To study the inheritance of susceptibility to induction of these embryonal renal tumors, fetal Nb and F344 rats and F1, F2 and reciprocal backcross hybrids were exposed transplacentally to ENU once on day 18 of gestation. Nephroblastomas developed in 53% of Nb offspring with no apparent gender difference, while no nephroblastomas developed in inbred F344 offspring. F1 and F2 hybrid offspring had intermediate responses, 28% and 30%, respectively. Nephroblastoma incidence in the offspring of F1 hybrids backcrossed to the susceptible strain Nb was 46%, while that in F1 hybrids backcrossed to resistant strain F344 was much lower (16%). Carcinogenic susceptibility is therefore consistent with the involvement of one major autosomal locus; the operation of a gene dosage effect; and a lack of simple Mendelian dominance for either susceptibility or resistance. Since established Wilms tumor-associated suppressor genes, Wt1 and Wtx, were not mutated in normal or neoplastic tissues, genomic profiling was performed on isolated Nb and F344 metanephric progenitors to identify possible predisposing factors to nephroblastoma induction. Genes preferentially elevated in expression in Nb rat progenitors included Wnt target genes Epidermal growth factor receptor, Inhibitor of DNA binding 2, and Jagged1, which were further increased in nephroblastomas. These studies demonstrate the value of this model for genetic analysis of nephroblastoma development and implicate both the Wnt and Notch pathways in its pathogenesis.

Copy number gains in EGFR and copy number losses in PTEN are common events in osteosarcoma tumors

BACKGROUND

Osteosarcoma cell lines and tumors have been shown to express epidermal growth factor receptor (EGFR) and harbor amplifications at the EGFR locus. In this study, the authors further analyzed the genomic features of EGFR in osteosarcoma tumors and investigated whether they correlate with phosphatase and tensin homolog (PTEN) expression and copy number status.

METHODS

EGFR and PTEN expression was assessed by immunohistochemistry (n = 28), and copy number alterations at the EGFR and PTEN loci were surveyed using Affymetrix (Santa Clara, Calif) 50K single nucleotide polymorphism (SNP) arrays (n = 31) and fluorescence in situ hybridization (FISH) (n = 27). The EGFR tyrosine kinase domain was sequenced to survey for activating mutations (n = 34). In addition, EGFRvIII expression was assessed using reverse transcriptase polymerase chain reaction (n = 24). Results were correlated with available clinical information on 59 patients, with a median age of 14.1 years (range, 5-23 years) and median follow-up of 4.4 years.

RESULTS

EGFR expression was detected in the majority of osteosarcoma tumors surveyed (23 of 28; 82%). SNP arrays revealed evidence of frequent copy number gains at 7p11.2 and losses at 10q23.21. A sizeable subset (16 of 27 cases; 59%) showed gains at the EGFR locus using FISH (amplification in 4 of 27 [15%] and balanced chromosome 7 polysomy in 12 of 27 [44%]), and 12 cases showed deletions at the PTEN locus (biallelic deletions in 4 of 27 [15%] and monoallelic deletion in 9 of 27 [33%]). No activating mutations in the EGFR tyrosine kinase domain, EGFRvIII expression, or association with clinical findings were detected.

CONCLUSIONS

EGFR expression and genomic gains at the EGFR locus are prevalent in osteosarcoma tumors, which also commonly harbor deletions at the PTEN locus.

High cyclin E staining index in blastemal, stromal or epithelial cells is correlated with tumor aggressiveness in patients with nephroblastoma

Purpose

Identifying among nephroblastoma those with a high propensity for distant metastases using cell cycle markers: cyclin E as a regulator of progression through the cell cycle and Ki-67 as a tumor proliferation marker, since both are often deregulated in many human malignancies.

Methodology/Principal Findings

A staining index (SI) was obtained by immunohistochemistry using anti-cyclin E and anti-Ki-67 antibodies in paraffin sections of 54 postchemotherapy nephroblastoma including 42 nephroblastoma without metastasis and 12 with metastases. Median cyclin E and Ki-67 SI were 46% and 33% in blastemal cells, 30% and 10% in stromal cells, 37% and 29.5% in epithelial cells. The highest values were found for anaplastic nephroblastoma. A correlation between cyclin E and Ki-67 SI was found for the blastemal component and for the epithelial component. Univariate analysis showed prognostic significance for metastases with cyclin E SI in stromal cells, epithelial cells and blastemal cells (p = 0.03, p = 0.01 and p = 0.002, respectively) as well as with Ki-67 SI in blastema (p<10⁻⁴). The most striking data were that both cyclin E SI and blastemal Ki-67 SI discriminated between patients with metastases and patients without metastasis among intermediate-risk nephroblastoma.

Conclusions

Our findings show that a high cyclin E SI in all components of nephroblastoma is correlated with tumor aggressiveness and metastases, and that assessment of its expression may have prognostic value in the categorization of nephroblastoma.

KIT, PDGFRalpha and EGFR analysis in nephroblastoma

Nephroblastoma prognosis has dramatically improved, but an unfavourable prognostic subgroup warrants development of novel therapeutic strategies. Selective KIT, PDGFRalpha and epidermal growth factor receptor (EGFR) tyrosine kinase inhibition evolved as powerful targeted therapy for gastrointestinal stromal tumours and non-small-cell lung cancer. To investigate a potential role for tyrosine kinase inhibition, we analyzed 209 nephroblastomas for immunohistochemical KIT and EGFR expression, 63 nephroblastomas for mutations in KIT exons 9, 11, 13, EGFR exons 18, 19, 20 and 21, and all 209 nephroblastomas for PDGFRalpha exons 12, 14 and 18. Twenty-two tumours (10.5%) expressed KIT, 31 (14.8%) EGFR, and 10 (4.8%) both KIT and EGFR, respectively. KIT expression was relatively more common among high-risk tumours (6/27; 22.3%) compared to low-/intermediate-risk tumours (26/181; 14.4%). Nine patients deceased, four of which had high-risk tumours with KIT expression in two of four and EGFR expression in one of four. There were no KIT, PDGFRalpha or EGFR mutations. Our results suggest no significant contribution of KIT, EGFR or PDGFRalpha mutations to nephroblastoma pathogenesis. Despite a trend towards association of immunohistochemical KIT and EGFR expression with poor outcome in high-risk nephroblastomas, statistical analysis did not yield significant correlations in this subgroup. Therefore, it remains open if KIT, PDGFRalpha or EGFR tyrosine kinase inhibition constitute a therapeutic target in nephroblastoma in the absence of KIT, PDGFRalpha or EGFR mutations.

Analysis of biologic surrogate markers from a Children's Oncology Group Phase I trial of gefitinib in pediatric patients with solid tumors

This trial evaluated the effect of gefitinib on the plasma circulating levels of epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP)-2 and -9 of patients treated on a pediatric Phase I trial. Complete plasma correlative studies were obtained from 16 of the 25 enrolled patients. There was a trend for lower MMP-2 baseline levels in patients with partial response or stable disease. The Ewing sarcoma from the only patient with partial response lacked egfr mutations. Gefitinib did not induce any significant variation in the levels of the assessed parameters, and none of these determinations showed significant predictive or prognostic value.

Immunohistochemical analysis with multiple antibodies in search of prognostic markers for clear cell renal cell carcinoma

OBJECTIVES

To simultaneously analyze multiple biologic markers to identify strong prognostic markers for disease-specific survival of patients with clear cell renal cell carcinoma (ccRCC).

METHODS

The expression of Ki-67, p53, bcl-2, cyclin-D1, caveolin-1, vascular endothelial growth factor, and HER-2 was evaluated in 119 paraffin-embedded ccRCC specimens using immunohistochemistry. The clinical significance of these markers in relation to disease-specific survival was analyzed.

RESULTS

On univariate analysis, high-level staining for Ki-67 (P <0.0001), p53 (P = 0.0029), vascular endothelial growth factor (P = 0.0062), and caveolin-1 (P = 0.0396) was associated with decreased survival, but high-level staining for bcl-2 (P <0.0001) and cyclin-D1 (P = 0.0002) was associated with increased survival. Only HER-2 expression was not related to survival (P = 0.1131). Multivariate analysis revealed the following independent predictors of disease-specific survival: expression of p53 (P = 0.0059) or bcl-2 (P = 0.0413) in all cases of ccRCC; expression of p53 (P = 0.0043) or bcl-2 (P = 0.0227) in cases of grade 1-2 disease; and expression of p53 (P = 0.0207) in cases with metastasis at surgery.

CONCLUSIONS

Of the seven markers reviewed, p53 and bcl-2 were strong prognostic factors in all cases and in cases of grade 1-2 ccRCC. Only p53 attained independent prognostic significance in metastatic ccRCC. This information could prove useful in selecting markers to predict for survival and plan therapy for patients with ccRCC.

Association between the HER2 expression and histological differentiation in Wilms tumor

Human epidermal growth factor receptors (HER) play a critical role in the branching morphogenesis of renal tubules. In the current study, we analyzed the expression of HER2 in Wilms tumor and assessed the role of this gene in the tumorgenesis of Wilms tumor. During the period from 1960 to 2005, 40 patients with Wilms tumor were treated in our department. Twenty-four of those patients (except those with clear cell sarcoma of the kidney and malignant rhabdoid tumor of the kidney) were collected and assessed. The histological component of each Wilms tumor was divided into three categories (epithelial, blastemal, and mesenchymal) and the extent of HER2 protein expression was analyzed immunohistochemically. The normal kidney tissue accompanied with 12 cases of Wilms tumor was also examined. In the normal kidney, HER2 showed a strong immunoreactivity in the cell membranes of the collecting tubules and in the endothelial cells. Of 24 cases, 15 cases showed an epithelial component, while 24 cases had a blastemal component and 21 cases had a mesenchymal component, respectively. Among the 15 specimens with epithelial cell differentiation, eight (53.3%) showed HER2 immunoreactive epithelial cells. HER2 immunoreactive blastemal cells were present in 11 (45.8%) of 24 specimens with blastemal cells. On the other hand, only 3 (14.3%) of 21 specimens containing mesenchymal cells showed HER2 immunoreactivity. These results suggest that the extent of HER2 expression is associated with epithelial differentiation in Wilms tumor. These histological findings may therefore help to explain the development of Wilms tumor from the standpoint of histological differentiation.

Evaluation of gefitinib for treatment of refractory solid tumors and central nervous system malignancies in pediatric patients

Gefitinib (ZD1839, Iressa), a member of the 4-anilinoquinazoline class of compounds, has the chemical name 4-quinazolinamine, N-(3-chloro-4-flurophenyl)-7-methoxy-6-[3-(4-morpholinyl)propoxy]. Gefitinib often is referred to as a "specific" or "selective" inhibitor of epidermal growth factor receptor (EGFR). EGFR expression has been noted in neuroblastoma and rhabdomyosarcoma cell lines and in tumor specimens from children with Wilms tumor, osteosarcoma, and glioma. Thus, gefitinib, the first marketed EGFR tyrosine kinase inhibitor, was chosen for study in children with refractory solid tumors and central nervous system (CNS) malignancies. This review discusses findings from 3 clinical trials of gefitinib in children with refractory solid tumors and CNS malignancies, focusing on the clinical pharmacology of the compound. To date, gefitinib has been studied in children as a single agent and in combination with irinotecan. Overall, the compound has been well tolerated in children and has a safety profile similar to that observed in adults. The clinical pharmacokinetics of gefitinib in children are similar to those observed in adults. Finally, the future for the use of gefitinib in pediatrics is similar to that of other molecularly targeted agents and awaits definition of tumors and patient populations in which it will be most advantageous.

Immunohistochemical Study of Porcine Nephroblastoma

Nephroblastoma, a relatively common renal neoplasm of young swine, represents the animal counterpart of Wilms' tumour of children. Five porcine nephroblastomas were examined histologically, and immunohistochemically with antibodies against vimentin (VIM), cytokeratins (CKs), smooth-muscle actin, Factor VIII, and laminin. Histologically all showed the three components typical of this tumour: mesenchymal blastema, epithelium (tubuli, and glomeruloid bodies) and stroma. The only antibody recognizing mesenchymal cells was VIM. One-third of tubular structures were positive for VIM. All of the tubules were positive for CK19, two-thirds expressed CK AE1/AE3, and only one-third expressed CKs 8-18. Small round tubuli, located in the stromal septa, were positive for CK7 (ureteric branches). Stromal cells expressed both VIM and actin, demonstrating myofibroblastic differentiation. The kidney originates from mesenchymal blastema, which changes to epithelium, losing VIM and acquiring CK expression. In the adult mammalian kidney, CK 19 is expressed only by the parietal epithelium of Bowman's capsule and the distal tubules. Nevertheless, CK19 is also considered a "transient" CK, expressed by different kinds of epithelia during differentiation. CK 19 was also detected in several undifferentiated neoplasms. This finding, together with the co-expression of VIM detected in some tubules, demonstrates the embryonic origin of nephroblastoma.

New approaches to drug development in pediatric oncology

This article reviews the changing paradigm of new drug development for childhood cancer. Although there have been dramatic improvements in the treatment and outcome for childhood cancer over the past 50 years, in some cancers, only limited progress has been made. New strategies to improve the outcome for poor-prognosis tumors and to minimize the long-term sequelae associated with therapy are required. Such strategies include a new pediatric-specific initiative for the preclinical testing of anticancer drugs for childhood malignancies, and ongoing research into the molecular heterogeneity of childhood tumors to facilitate the evaluation of molecularly targeted drugs. In addition, continued investigation into the genetic basis underlying interpatient variability in drug exposure and response is a priority. The goal of these initiatives is to improve the overall outcome for childhood cancer while minimizing the short and long-term sequelae associated with current treatment strategies.

ERBB2 in pediatric cancer: innocent until proven guilty

Adult oncologists and their research colleagues have "led the charge" in the war on cancer. Their efforts have generated effective new chemotherapies that target cancer causing molecular alterations. It is hoped that these successes will be repeated within the pediatric oncology community. Testing whether molecular targeted therapies of adult cancers are also effective against childhood cancers might allow the rapid introduction of these exciting new agents into the pediatric clinic. However, it is imperative that we do not introduce blindly these agents into the pediatric population. We must ensure that molecular targets in adult cancers also fulfill a number of important criteria within the pediatric disease. This review addresses the issues surrounding the identification of molecular targets in pediatric cancers by focusing on studies of the ERBB2 oncogene.

Phase I and pharmacokinetic study of gefitinib in children with refractory solid tumors: a Children's Oncology Group Study

PURPOSE

Epidermal growth factor receptor is expressed in pediatric malignant solid tumors. We conducted a phase I trial of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in children with refractory solid tumors.

PATIENTS AND METHODS

Gefitinib (150, 300, 400, or 500 mg/m2) was administered orally to cohorts of three to six patients once daily continuously until disease progression or significant toxicity. Pharmacokinetic studies were performed during course one (day 1 through 28).

RESULTS

Of the 25 enrolled patients, 19 (median age, 15 years) were fully evaluable for toxicity and received 54 courses. Dose-limiting toxicity was rash in two patients treated with 500 mg/m2 and elevated ALT and AST in one patient treated with 400 mg/m2. The maximum-tolerated dose was 400 mg/m2/d. The most frequent non-dose-limiting toxicities were grade 1 or 2 dry skin, anemia, diarrhea, nausea, and vomiting. One patient with Ewing's sarcoma had a partial response. Disease stabilized for 8 to > or = 60 weeks in two patients with Wilms' tumor and two with brainstem glioma (one exophytic). At 400 mg/m2, the median peak gefitinib plasma concentration was 2.2 microg/mL (range, 1.2 to 3.6 microg/mL) and occurred at a median of 2.3 hours (range, 2.0 to 8.3 hours) after drug administration. The median apparent clearance and median half-life were 14.8 L/h/m2 (range, 3.8 to 24.8 L/h/m2) and 11.7 hours (range, 5.6 to 22.8 hours), respectively. Gefitinib systemic exposures were comparable with those associated with antitumor activity in adults.

CONCLUSION

Oral gefitinib is well tolerated in children. Development of the drug in combination with cytotoxic chemotherapy will be pursued.

ErbB2 is a tumor associated antigen and a suitable therapeutic target in Wilms tumor

PURPOSE

The modern multimodality therapeutic approach to Wilms tumor (WT), combining surgery with radiotherapy and chemotherapy results in high cure rates even for high stage disease. However, the combination of radiotherapy and chemotherapy is associated with severe early and late complications such as neutropenic sepsis, growth retardation and secondary malignancies. Therefore, novel therapeutic strategies, which would decrease the treatment burden, are required. We studied the expression of erbB2 growth factor receptor in WT cells as well as its role as a tumor therapeutic target in an in vivo xenograft model of Wilms tumor.

MATERIALS AND METHODS

Paraffin embedded pathological samples from 14 different WT cases as well as xenografts derived thereof were immunostained with anti-erbB2 monoclonal antibody. The immunostaining was graded in comparison to a known positive control (breast cancer) and was scored by the intensity of staining (0 to +3) multiplied by the percentage of cells expressing the antigen. The expression of erbB2 in the human WT xenograft was verified also by fluorescence activated cell sorter analysis. In addition, nude mice bearing established subcutaneous human WT xenografts were treated with either 3 intraperitoneal injections of N29 anti-erbB2 monoclonal antibody or irrelevant antibody.

RESULTS

All of the authentic human pathological samples, except 1 anaplastic WT as well the WT xenografts (at different stages), expressed erbB2. Expression was also observed in WT metastasis and in tumors which out grew chemotherapy. Systemic administration of anti-erbB2 monoclonal antibody inhibited and even prevented the growth of WT xenograft in vivo.

CONCLUSIONS

ErbB2 is a tumor associated antigen in WT. Being expressed in almost all tumor stages, our in vivo model suggests that erbB2 may serve as a WT therapeutic target. Further work is needed to establish the role of erbB2 in the disease and its potential use in decreasing current treatment burden.

Prognostic classification of relapsing favorable histology Wilms tumor using cDNA microarray expression profiling and support vector machines

Treatment of Wilms tumor has a high success rate, with some 85% of patients achieving long-term survival. However, late effects of treatment and management of relapse remain significant clinical problems. If accurate prognostic methods were available, effective risk-adapted therapies could be tailored to individual patients at diagnosis. Few molecular prognostic markers for Wilms tumor are currently defined, though previous studies have linked allele loss on 1p or 16q, genomic gain of 1q, and overexpression from 1q with an increased risk of relapse. To identify specific patterns of gene expression that are predictive of relapse, we used high-density (30 k) cDNA microarrays to analyze RNA samples from 27 favorable histology Wilms tumors taken from primary nephrectomies at the time of initial diagnosis. Thirteen of these tumors relapsed within 2 years. Genes differentially expressed between the relapsing and nonrelapsing tumor classes were identified by statistical scoring (t test). These genes encode proteins with diverse molecular functions, including transcription factors, developmental regulators, apoptotic factors, and signaling molecules. Use of a support vector machine classifier, feature selection, and test evaluation using cross-validation led to identification of a generalizable expression signature, a small subset of genes whose expression potentially can be used to predict tumor outcome in new samples. Similar methods were used to identify genes that are differentially expressed between tumors with and without genomic 1q gain. This set of discriminators was highly enriched in genes on 1q, indicating close agreement between data obtained from expression profiling with data from genomic copy number analyses.

Multiple G-protein-coupled receptor signals converge on the epidermal growth factor receptor to promote migration and invasion

Signalling through G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTK) is involved in the regulation of essential cellular processes and its deregulation is associated with tumorigenesis in vitro and in vivo. We investigated pathophysiological processes that are regulated by GPCR pathways in human kidney and bladder cancer cell lines. Our results show that GPCR ligands induce tyrosine phosphorylation of the epidermal growth factor receptor (EGFR) as well as downstream signalling events such as recruitment of the adapter protein Shc and activation of the mitogen-activated protein kinases (MAPK) ERK1/2, JNK and p38. Moreover, we report that the EGFR transactivation signal involves the EGFR ligands amphiregulin, HB-EGF and TGFalpha as well as the metalloproteinases ADAM 10, 15 and 17, depending on the cellular system. Finally, we demonstrate that EGFR transactivation is part of a regulatory system that modulates the migratory and invasive behaviour of kidney and bladder cancer cells. In conclusion, our findings demonstrate that metalloproteinase-mediated transactivation of the EGFR is a key mechanism of the cellular signalling network that promotes MAPK activation as well as tumour cell migration and invasion in response to a variety of physiologically relevant GPCR ligands, and therefore represents a novel target for cancer intervention strategies.

Expression of tumor related genes NGX6, NAG-7, BRD7 in gastric and colorectal cancer

AIM: NGX6, NAG-7 and BRD7 genes are tumor related genes, which have been newly cloned by positional candidate cloning strategy. This study was designed to investigate the expression levels of NGX6, NAG-7 and BRD7 genes in human gastric and colorectal cancer tissues, and their corresponding normal tissues, and to investigate whether these genes play a role in the pathogenesis of gastric and colorectal cancers.

METHODS: Reverse transcription-polymerase chain reaction (RT-PCR), dot hybridization and Northern blot analysis were used to compare the expression levels of NGX6, NAG-7 and BRD7 genes in 34 gastric cancer tissues and 34 colorectal cancer tissues with their corresponding normal tissues of the same patients, respectively.

RESULTS: Among the 34 colorectal cancer specimens and the 34 gastric cancer specimens, the expression of NGX6 in 25 colorectal cancer tissues was absent or very weak (73.5%) by RT-PCR analysis. The down-regulation rate of NGX6 in colorectal cancer tissues was significantly higher than that in corresponding normal tissues (26.5%,9/34) (P < 0.005). Moreover, the down-regulation of NGX6 was significantly correlated with lymph node and/or distance metastases. Patients with lymph node and/or distance metastasis had much higher down-regulation rate of NGX6 than patients without metastases (93.8% vs 55.6%, P < 0.05). However no correlation was found between the expression of NGX6 and pathologic type of colorectal cancer in this study, and also the expression of NGX6 did not display any difference between gastric cancer and corresponding normal tissues (58.8% vs 70.6%, P > 0.25). Dot hybridization and Northern blot analysis confirmed the results of RT-PCR. Furthermore, NAG-7 and BRD7 mRNA was not up- or down-regulated in gastric and colorectal cancers compared with their corresponding normal tissues in our study.

CONCLUSION: The down-regulation of NGX6 may be closely associated with tumorigenesis and metastasis of colorectal carcinoma. However, it may not contribute to the development and progression of gastric carcinoma. In addition, the expression levels of NAG-7, and BRD7 did not alter in gastric and colorectal cancers. This seems to suggest that NAG-7 and BRD7 genes may not play a role in gastric and colorectal carcinogenesis.

Expression of transforming growth factor-alpha, epidermal growth factor receptor and platelet-derived growth factors A and B in oropharyngeal cancers treated by curative radiation therapy

BACKGROUND AND PURPOSE

Epidermal growth factor receptor (EGFR) has been implicated in cellular responses to ionizing radiation and represents a major target for current radiosensitizing strategies. We wished to ascertain whether a correlation existed between the expression of EGFR, transforming growth factor-alpha (TGFalpha) and platelet-derived growth factors A and B (PDGF-A and PDGF-B) and treatment outcome in a group of patients with oropharyngeal cancer who had undergone curative radiation therapy. We also assessed the relationship existing between each of the aforementioned proteins and intratumoral microvessel densities (IMD) which have been previously reported (Int J Radiat Oncol Biol Phys 2000;48:17-25.

MATERIALS AND METHODS

Pretherapeutic tumor biopsies from 95 patients were immunohistochemically stained and their immunoreactivities evaluated semi-quantitatively. The statistical analyses included Cox regression for calculating risk ratios of survival endpoints and logistic regression for determining odds ratios for the development of distant metastasis.

RESULTS

Local tumor control as well as disease-free and overall survival were independent of protein expression levels, whereas combined TGFalpha and EGFR immunoreactivities were closely related to IMD (P = 0.003). The expression levels of these two proteins were also correlated to each other (P = 0.015). Expression of PDGF-B occurred in 54% of cases and was associated with an increase in the risk of developing distant metastasis (P = 0.011).

CONCLUSIONS

Tumoral levels of TGFalpha, EGFR and PDGF-A/B are not predictive of radioresponsiveness in oropharyngeal cancers. The association between IMD and immunoreactivity for TGFalpha and EGFR indicates the involvement of these proteins in the promotion of angiogenesis in these tumors. PDGF-B should be further evaluated as a prognostic marker for squamous cell cancer of the head and neck.

Emerging new therapies for chemotherapy-resistant cancer using adenoviral vectors

The treatment of cancer by genetic manipulation of either the tumor itself or the patient as a whole offers new avenues for the treatment of otherwise refractory cancers. Gene therapy seeks to correct underlying genetic defects in malignant tissue or to augment the host defense response or to promote selectivity of other therapies. Many innovative and exciting genetic targets have been recently identified. However, the field as a whole is still constrained by limitations of gene delivery. The most common vector for gene delivery is modified adenovirus. In this review, we survey a sampling of current therapeutic approaches that depend upon adenoviral delivery vehicles and outline the advantages and disadvantages of this vector system.