Classification of malignant pediatric renal tumors by gene expression

Dynamic network curvature analysis of gene expression reveals novel potential therapeutic targets in sarcoma

Network properties account for the complex relationship between genes, making it easier to identify complex patterns in their interactions. In this work, we leveraged these network properties for dual purposes. First, we clustered pediatric sarcoma tumors using network information flow as a similarity metric, computed by the Wasserstein distance. We demonstrate that this approach yields the best concordance with histological subtypes, validated against three state-of-the-art methods. Second, to identify molecular targets that would be missed by more conventional methods of analysis, we applied a novel unsupervised method to cluster gene interactomes represented as networks in pediatric sarcoma. RNA-Seq data were mapped to protein-level interactomes to construct weighted networks that were then subjected to a non-Euclidean, multi-scale geometric approach centered on a discrete notion of curvature. This provides a measure of the functional association among genes in the context of their connectivity. In confirmation of the validity of this method, hierarchical clustering revealed the characteristic EWSR1-FLI1 fusion in Ewing sarcoma. Furthermore, assessing the effects of in silico edge perturbations and simulated gene knockouts as quantified by changes in curvature, we found non-trivial gene associations not previously identified.

Molecular Signature of Biological Aggressiveness in Clear Cell Sarcoma of the Kidney (CCSK)

Clear cell sarcoma of the kidney (CCSK) is a rare pediatric renal tumor with a worse prognosis than Wilms' tumor. Although recently, BCOR internal tandem duplication (ITD) has been found as a driver mutation in more than 80% of cases, a deep molecular characterization of this tumor is still lacking, as well as its correlation with the clinical course. The aim of this study was to investigate the differential molecular signature between metastatic and localized BCOR-ITD-positive CCSK at diagnosis. Whole-exome sequencing (WES) and whole-transcriptome sequencing (WTS) were performed on six localized and three metastatic BCOR-ITD-positive CCSKs, confirming that this tumor carries a low mutational burden. No significant recurrences of somatic or germline mutations other than BCOR-ITD were identified among the evaluated samples. Supervised analysis of gene expression data showed enrichment of hundreds of genes, with a significant overrepresentation of the MAPK signaling pathway in metastatic cases (p < 0.0001). Within the molecular signature of metastatic CCSK, five genes were highly and significantly over-expressed: FGF3, VEGFA, SPP1, ADM, and JUND. The role of FGF3 in the acquisition of a more aggressive phenotype was investigated in a cell model system obtained by introducing the ITD into the last exon of BCOR by Crispr/Cas9 gene editing of the HEK-293 cell line. Treatment with FGF3 of BCOR-ITD HEK-293 cell line induced a significant increase in cell migration versus both untreated and scramble cell clone. The identification of over-expressed genes in metastatic CCSKs, with a particular focus on FGF3, could offer new prognostic and therapeutic targets in more aggressive cases.

Incidence patterns of childhood non-Wilms renal tumors: Comparing data of the Nationwide Registry of Childhood Hematological Malignancies and Solid Tumors (NARECHEM-ST), Greece, and the Surveillance, Epidemiology, and End Results Program (SEER), USA

BACKGROUND

We used, for the first time, data registered in the Nationwide Registry for Childhood Hematological Malignancies and Solid Tumors (NARECHEM-ST)-Greece to estimate incidence/time trends of the rare childhood (0-14 years) non-Wilms tumors (non-WT), and compared the results of malignant non-WT to those from the Surveillance, Epidemiology, and End Results Program (SEER)-USA.

METHODS

Fifty-five cases (n = 33 malignant-only) were extracted from NARECHEM-ST (2001-2020) and 332 malignant cases from SEER (1990-2017). To allow between-country comparisons, age-standardized incidence rates (AIR) of malignant-only non-WT were calculated, and temporal trends were evaluated using Poisson and joinpoint regressions.

RESULTS

In NARECHEM-ST, malignant and non-malignant non-WT accounted for 22.6% of all renal tumors. Among malignant tumors, the AIR was 1.0/106 children in Greece, similar to that calculated for SEER, USA (AIR=0.9/106). The proportion of infant malignant and non-malignant non-WT was 27% (20% before 6 months) in NARECHEM-ST. Most common non-WT in Greece were congenital mesoblastic nephromas (CMN) diagnosed mainly in infancy (CIR=7.2/106). The proportion of infant malignant non-WT was 20% in SEER (AIRinfancy=2.5/106), mainly attributed to rhabdoid tumors (CIR=1.6/106). The male-to-female (M:F) ratio of malignant non-WT was 0.9 in NARECHEM-ST vs. 1.2 in SEER, whereas boys outnumbered girls with clear cell sarcoma in NARECHEM-ST (M:F=4.0). Lastly, significantly increasing trends in incidence rates were noted in NARECHEM-ST [+ 6.8%, 95% confidence intervals (CI): 0.5, 13.3] and in SEER (+7.3%, 95%CI: 5.6, 9.0).

CONCLUSIONS

Observed incidence, time trends and sociodemographic variations of non-WT may reflect differential registration practices and healthcare delivery patterns including differences regarding surveillance, coding and treatment practices.

Techniques to avoid hypothermic circulatory arrest in the management of renal tumor with right atrium extension in children

Clear cell sarcoma of the kidney is a rare variety of renal tumor accounting for less than 5% of all pediatric renal tumors. Cardiopulmonary bypass along with hypothermic circulatory arrest is frequently used for management of tumor thrombus extending into supra-hepatic inferior vena cava and right atrium. In this paper, we present a strategy of avoiding circulatory arrest and hypothermia and thereby fast-tracking the recovery in managing a case of clear cell sarcoma of the kidney in a 3.5-year-old child with tumor thrombus extending into the right atrium.

Exosomal miR-214-3p as a potential novel biomarker for rhabdoid tumor of the kidney

PURPOSE

Rhabdoid tumor of the kidney (RTK) is a rare, highly aggressive pediatric renal tumor. No specific biomarkers are available for detection of RTK, and the initial differential diagnosis from other pediatric abdominal tumors, including neuroblastoma (NB), is difficult. Exosomal miRNAs are novel cancer biomarkers that can be detected in biological fluids. We explored candidate RTK-specific exosomal miRNAs as novel biomarkers of RTK.

METHODS

Exosomal miRNAs were collected from conditioned media of human RTK-derived cell lines, a human embryonic renal cell line, and human NB-derived cell lines. miRNA sequencing (miRNA-Seq) was performed to detect candidate RTK-specific exosomal miRNAs. The exosomal miRNA expression in conditioned media of tumor cell lines and serum from RTK xenograft-bearing mice was analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

RESULTS

The expression of exosomal miR-214-3p detected by miRNA-Seq was highest in RTK-derived cell lines. Exosomal miR-214-3p expression level determined by qRT-PCR was significantly higher in RTK-derived cell lines than in the human embryonic renal cell line or NB-derived cell lines. Furthermore, the serum exosomal miR-214-3p expression level was significantly higher in RTK xenograft mice than controls.

CONCLUSION

Our data indicated that exosomal miR-214-3p has potential as a novel biomarker of RTK.

Clear Cell Sarcoma of the Kidney

Clear cell sarcoma of the kidney is the second most common primary renal malignancy in childhood. It is histologically diverse, making accurate diagnosis challenging in some cases. Recent molecular studies have uncovered BCOR exon 15 internal tandem duplications in most cases, and YWHAE-NUTM2 fusion in a few cases, with the remaining cases having other genetic mutations, including BCOR-CCNB3 fusion and EGFR mutations. Although clear cell sarcoma of the kidney has no specific immunophenotype, several markers including cyclin D1, nerve growth factor receptor, and BCOR (BCL6 corepressor) have emerged as potential diagnostic aides. This review provides a concise account of recent advances in our understanding of clear cell sarcoma of the kidney to serve as a practical update for the practicing pathologist.

Congenital Mesoblastic Nephroma Presenting with Hematuria in a Neonate

Congenital mesoblastic nephroma (CMN) is a rare tumor of infancy. CMNs can be histologically divided into classic, cellular, and mixed subtypes. Cellular CMNs are difficult to differentiate from Wilms tumors. Herein, a neonate with cellular CMN accompanied by macroscopic hematuria, is described. The clinical, pathological, and imaging features of the disease are discussed.

TLE1 Positive Clear Cell Sarcoma of the Kidney: A Case Report and Review of the Literature

Clear cell sarcoma of the kidney (CCSK) is an uncommon malignant tumor of uncertain histogenesis that occurs most commonly in childhood. Histologically, CCSK can mimic myxoid variant of synovial sarcoma (SS); however, the double positivity for CD99 and TLE1 in SS helps in excluding CCSK. Herein, we report a rare case of CCSK arising in the left kidney of a 3-year-old girl. The mass grossly measured 9.5 cm in maximum dimension and histologically showed the classic arborizing fibrovascular septae and background myxoid matrix that is usually seen in CCSK. The tumor however was double positive for CD99 and TLE1 which made it difficult to discriminate it from the myxoid variant of SS based on histopathological examination and immunophenotype alone, and genetic analysis for SYT gene rearrangement was required to reach a definitive diagnosis. Although there have been previous case reports of CCSK with positive expression of CD99 and negative TLE1, to our knowledge, this is the first case of CCSK expressing both CD99 and TLE1.

Sarcoma With CIC-DUX4 Gene Fusion: Case Report of Kidney Tumor Location in a 12-year-old Boy

Recent molecular advances have identified a novel sarcoma defined molecularly by oncogenic fusion of the genes CIC and DUX4 termed CIC-DUX4 sarcomas. The most common site of involvement was the trunk but some cases have been described in the head and neck and extremities. We report one of the first cases of primitive renal CIC-DUX4 sarcoma: a 12-year-old boy who presented a renal tumor, a vena cava thrombus, and lung metastases. The morphological and immunohistochemical analysis showed an undifferentiated sarcoma. Molecular analysis demonstrated a CIC-DUX4 translocation, confirmed by fluorescence in situ hybridization. Despite treatment with chemotherapy, the evolution was unfavorable and the patient died 17 months after the diagnosis in a context of brain metastases. The diagnosis of sarcoma with CIC-DUX4 gene fusion is difficult in lack of specific pathological characteristics emphasizing the need for molecular analysis. Treatment has not yet been codified for these very aggressive tumors.

Identification of a gene signature associated with radiotherapy and prognosis in gliomas

Glioma is one of the most common primary brain tumors with poor prognosis. Although radiotherapy is an important treatment method for gliomas, the efficacy is still limited by the high occurrence of radioresistance and the underlying molecular mechanism is unclear. Here, we performed a data mining work based on four glioma expression datasets. These datasets were classified into training set and validation set. Radiotherapy-induced differential expressed genes and prognosis-associated genes were screened using different classifiers. The Kaplan-Meier curves along with the two-sided Log Rank (Mantel-Cox) test were used to evaluate overall survival. We found the gene expression profiles of gliomas between those patients received radiotherapy and those patients without received radiotherapy were quite different. A 20-gene signature was identified, which was associated with radiotherapy.Furthermore, a novel 5-gene signature (HOXC10, LOC101928747, CYB561D2, RPL36A and RPS4XP2) as an independent predictor of glioma patients’ prognosis was further derived from the 20-gene signature. These findings provided a new insight into the molecular mechanism of radioresistance in gliomas. The 5-gene signature might represent therapeutic target for gliomas.

Bladder Recurrence of Clear Cell Sarcoma of the Kidney Seven Years After Initial Presentation

Clear cell sarcoma of the kidney (CCSK) is the second most common pediatric renal malignancy after Wilms tumor. CCSK has the potential to metastasize to distant sites and was historically known as the bone metastasizing renal tumor. We report an exceedingly rare case of a bladder recurrence of CCSK. Our patient presented with gross hematuria 7 years after initial complete response. He was found to have a large sessile bladder tumor and underwent a partial cystectomy with right pelvic lymph node dissection. Final pathology was metastatic CCSK.

[Clear cell sarcoma of kidney in children]

Clear cell sarcoma of the kidney (CCSK) is a rare tumor that is diagnosed most often in children between 2- and 4-years-old of age. Usually, patients with CCSK are treated in international study for intrarenal tumors, preferentially Wilms tumor, according to bad histopronostic group. The purpose of this paper is to review the most important features in 2015 about epidemiology, radiology, anatomopathology and genetic of CCSK, and above all a synthesis about successive treatment strategies with their results. Second most common pediatric renal tumor in children less than 5-years-old, its prognosis has improved dramatically in recent years with the use of anthracyclines.

[Not Available]

Le sarcome à cellules claires du rein (SCCR) se voit très rarement chez les jeunes. Il est caractérisé par une évolution agressive marquée par un taux élevé de récidive et de mortalité. Nous rapportons le cas d’un SCCR chez un patient de 17 ans et nous discutons de son apport et de son intérêt médical en vue d’une bonne prise en charge thérapeutique. L’agressivité du SCCR et la prolifération de métastases surtout osseuses impliquent qu’il ne faut pas méconnaître ce diagnostic afin de mettre en place un traitement adapté.

Clinically relevant subsets identified by gene expression patterns support a revised ontogenic model of Wilms tumor: a Children's Oncology Group Study

Wilms tumors (WT) have provided broad insights into the interface between development and tumorigenesis. Further understanding is confounded by their genetic, histologic, and clinical heterogeneity, the basis of which remains largely unknown. We evaluated 224 WT for global gene expression patterns; WT1, CTNNB1, and WTX mutation; and 11p15 copy number and methylation patterns. Five subsets were identified showing distinct differences in their pathologic and clinical features: these findings were validated in 100 additional WT. The gene expression pattern of each subset was compared with published gene expression profiles during normal renal development. A novel subset of epithelial WT in infants lacked WT1, CTNNB1, and WTX mutations and nephrogenic rests and displayed a gene expression pattern of the postinduction nephron, and none recurred. Three subsets were characterized by a low expression of WT1 and intralobar nephrogenic rests. These differed in their frequency of WT1 and CTNNB1 mutations, in their age, in their relapse rate, and in their expression similarities with the intermediate mesoderm versus the metanephric mesenchyme. The largest subset was characterized by biallelic methylation of the imprint control region 1, a gene expression profile of the metanephric mesenchyme, and both interlunar and perilobar nephrogenic rests. These data provide a biologic explanation for the clinical and pathologic heterogeneity seen within WT and enable the future development of subset-specific therapeutic strategies. Further, these data support a revision of the current model of WT ontogeny, which allows for an interplay between the type of initiating event and the developmental stage in which it occurs.

Mediators of receptor tyrosine kinase activation in infantile fibrosarcoma: a Children's Oncology Group study

Infantile fibrosarcoma (IFS; also known as cellular congenital mesoblastic nephroma, CMN, when in the kidney) is a rare, undifferentiated tumour often characterized by the ETV6-NTRK3 fusion transcript. Our goal was to identify downstream pathways, diagnostic markers and potential therapeutic targets for IFS/CMN. Global gene expression, reverse-phase protein array and ETV6-NTRK3 fusion analyses were performed on 14 IFS/CMN and compared with 41 other paediatric renal tumours. These analyses confirm significant receptor tyrosine kinase (RTK) activation, with evidence of PI3-Akt, MAPK and SRC activation. In particular, GAB2 docking protein, STAT5-pTyr-694, STAT3-pSer-729 and YAP-pSer-127 were elevated, and TAZ-pSer-89 was decreased. This provides mRNA and proteomic evidence that GAB2, STAT activation and phosphorylation of the Hippo pathway transcription co-activators YAP and TAZ contribute to the RTK signal transduction in IFS/CMN. All IFS/CMN tumours displayed a distinctive gene expression pattern that may be diagnostically useful. Unexpectedly, abundant ETV6-NTRK3 transcript copies were present in only 7/14 IFS, with very low copy number in 3/14. An additional 4/14 were negative by RT-PCR and absence of ETV6-NTRK3 was confirmed by FISH for both ETV6 and NTRK3. Therefore, molecular mechanisms other than ETV6-NTRK3 fusion are responsible for the development of some IFS/CMNs and the absence of ETV6-NTRK3 fusion products should not exclude IFS/CMN as a diagnosis.

Clear cell sarcoma of the kidney: a review

Clear cell sarcoma of the kidney (CCSK) is a rare renal tumour that is observed most often in children under 3years of age. Only a few large series of CCSK have been reported and patients with CCSK are often included among patients with other types of childhood renal tumours. The purpose of this paper is to review the published series and case reports of CCSK and to create an up-to-date overview of clinical and histological features, genetics, treatment, and outcome.

Malignant rhabdoid tumours of the kidney (MRTKs), registered on recent SIOP protocols from 1993 to 2005: a report of the SIOP renal tumour study group

BACKGROUND

Survival data of malignant rhabdoid tumour of the kidney (MRTK) registered in SIOP trials, advocating preoperative chemotherapy, are not available.

AIM

To evaluate characteristics, response and survival of MRTK patients registered in recent SIOP protocols.

METHODS

An evaluation of all MRTK patients treated from 1993 to 2005 (SIOP trials 93-01 and 2001) was performed. Data were obtained from study specific case record forms and entered centrally in a database.

RESULTS

Hundred and seven patients were identified (57 male), with a median age at diagnosis of 13 months (interquartile range 6-27 months), and a median follow-up time of 60 months. Left and right kidneys were equally affected. Tumour stage distribution was stage I (6%), stage II (22%), stage III (43%), stage IV (22%) and stage V (3%). Stage IV patients included 17 with pulmonary metastasis (8 lung-only) and 12 with multiple organ metastases (bone, brain and liver). Primary surgery was the upfront treatment approach in 22/107 patients (21%), by which 19 patients reached a complete remission (CR). Median difference in tumour volume before and after preoperative chemotherapy was 69 ml (interquartile range: 4.5-158.0, P < 0.0001), indicating marked chemosensitivity. The 5-year event-free survival (EFS) of the total group was 22% (95% CI: 15-33) and overall survival 26% (95% CI: 18-37). Most events (86%) occurred within the first 2 years after diagnosis. Younger age at diagnosis was an important adverse prognostic factors for survival. In contrast, tumour volume at diagnosis, nor volume reduction was associated with outcome.

CONCLUSION

MRTK has a poor outcome especially in young and advanced-stage disease patients. Neither tumour volume at diagnosis, nor pre-operative chemosensitivity are prognostic factors for survival.

[Clear-cell sarcoma of the kidney: about a paediatric case]

Clear-cell sarcoma of the kidney (CCSK) is a rare malignant tumor of childhood, known for its aggressiveness, its tendency to recurrence and to metastasis to bone. We report an observation of a child of 48 months carrying a large abdominal mass. The diagnosis of the SCCR was made on biopsy, since imaging remained uncertain as to the renal origin of the mass. Indeed, our observation underlines the difficulty of its diagnosis. Excepting the morphological aspect, there is no criterion for its recognition. Its prognosis has been improved by the new treatments.

Rhabdoid tumor: gene expression clues to pathogenesis and potential therapeutic targets

Rhabdoid tumors (RT) are aggressive tumors characterized by genetic loss of SMARCB1 (SNF5, INI-1), a component of the SWI/SNF chromatin remodeling complex. No effective treatment is currently available. This study seeks to shed light on the SMARCB1-mediated pathogenesis of RT and to discover potential therapeutic targets. Global gene expression of 10 RT was compared with 12 cellular mesoblastic nephromas, 16 clear cell sarcomas of the kidney, and 15 Wilms tumors. In all, 114 top genes were differentially expressed in RT (P<0.001, fold change >2 or <0.5). Among these were downregulation of SMARCB1 and genes previously associated with SMARCB1 (ATP1B1, PTN, DOCK4, NQO1, PLOD1, PTP4A2, PTPRK); 28/114 top differentially expressed genes were involved with neural or neural crest development and were all sharply downregulated. This was confirmed by Gene Set Enrichment Analysis (GSEA). Neural and neural crest stem cell marker proteins SOX10, ID3, CD133, and Musashi were negative by immunohistochemistry, whereas Nestin was positive. Decreased expression of CDKN1A, CDKN1B, CDKN1C, CDKN2A, and CCND1 was identified, while MYC-C was upregulated. GSEA of independent gene sets associated with bivalent histone modification and polycomb group targets in embryonic stem cells showed significant negative enrichment in RT. Several differentially expressed genes were associated with tumor suppression, invasion, and metastasis, including SPP1 (osteopontin), COL18A1 (endostatin), PTPRK, and DOCK4. We conclude that RTs arise within early progenitor cells during a critical developmental window in which loss of SMARCB1 directly results in repression of neural development, loss of cyclin-dependent kinase inhibition, and trithorax/polycomb dysregulation.

Subsets of very low risk Wilms tumor show distinctive gene expression, histologic, and clinical features

PURPOSE

Recent studies suggest that children <24 months with stage I favorable histology Wilms tumors <550 g [very low risk Wilms tumors (VLRWT)] have an excellent prognosis when treated with nephrectomy only, without adjuvant chemotherapy. The identification of risk categories within VLRWT may enable refinement of their definition and optimization of their therapy.

EXPERIMENTAL DESIGN

To define biologically distinct subsets, global gene expression analysis was done on 39 VLRWT that passed all quality-control parameters and the clusters identified were validated in an independent set of 11 VLRWT. Validation of select differentially expressed genes was done with immunohistochemistry on a tissue microarray from 20 of 39 tumors. Loss of heterozygosity (LOH) for 11p15, 1p, and 16q was analyzed in 52 tumors using PCR.

RESULTS

Two distinctive clusters were identified. One cluster included 9 tumors with epithelial differentiated tubular histology, paucity of nephrogenic rests, lack of LOH for 1p, 16q, and 11p, absence of relapse, and a unique gene expression profile consistent with arrest following mesenchymal-to-epithelial transition. The second cluster included 13 tumors with mixed histology, intralobar nephrogenic rests, and decreased expression of WT1. Three of 6 relapses occurred in this cluster. Of 43 informative tumors, 11p LOH was present in 5 of 5 relapses and 11 of 38 nonrelapses.

CONCLUSIONS

Two subsets comprising a total of 56% of VLRWT are identified that have pathogenetic and molecular differences and apparent differences in risk for relapse. If these predictors can be prospectively validated, this would enable the refinement of clinical stratification and less arbitrary definition of VLRWT.

Vascular characterization of clear cell sarcoma of the kidney in a child: a case report and review

Clear cell sarcoma of the kidney (CCSK) is uncommon pediatric renal tumor and can present a significant therapeutic challenge in those patients whose tumors spread beyond the kidney. Thus, identifying potential novel targets for treatment may be clinically important. Clear cell sarcoma of the kidney is characterized by a unique vascular pattern, in which nests of tumor cells are separated by regularly-spaced, fine fibrovascular septa. This distinctive histopathology raises the possibility that understanding the factors which drive angiogenesis in CCSK tumors may suggest new therapeutic targets. Here, we describe a case of CCSK and present immunohistochemical studies of its vasculature.

Biomarkers for early and late stage chronic allograft nephropathy by proteogenomic profiling of peripheral blood

Background

Despite significant improvements in life expectancy of kidney transplant patients due to advances in surgery and immunosuppression, Chronic Allograft Nephropathy (CAN) remains a daunting problem. A complex network of cellular mechanisms in both graft and peripheral immune compartments complicates the non-invasive diagnosis of CAN, which still requires biopsy histology. This is compounded by non-immunological factors contributing to graft injury. There is a pressing need to identify and validate minimally invasive biomarkers for CAN to serve as early predictors of graft loss and as metrics for managing long-term immunosuppression.

Methods

We used DNA microarrays, tandem mass spectroscopy proteomics and bioinformatics to identify genomic and proteomic markers of mild and moderate/severe CAN in peripheral blood of two distinct cohorts (n = 77 total) of kidney transplant patients with biopsy-documented histology.

Findings

Gene expression profiles reveal over 2400 genes for mild CAN, and over 700 for moderate/severe CAN. A consensus analysis reveals 393 (mild) and 63 (moderate/severe) final candidates as CAN markers with predictive accuracy of 80% (mild) and 92% (moderate/severe). Proteomic profiles show over 500 candidates each, for both stages of CAN including 302 proteins unique to mild and 509 unique to moderate/severe CAN.

Conclusions

This study identifies several unique signatures of transcript and protein biomarkers with high predictive accuracies for mild and moderate/severe CAN, the most common cause of late allograft failure. These biomarkers are the necessary first step to a proteogenomic classification of CAN based on peripheral blood profiling and will be the targets of a prospective clinical validation study.

Molecular Pathology of the Genitourinary Tract: Molecular Pathology of Kidney and Testes

With the advent of newer molecular technologies, our knowledge of cellular mechanisms with tumors of the kidney and testis has grown exponentially. Molecular technologies have led to better understanding of interplay between the von Hippel-Lindau gene and angiogenic cytokines in renal cancer and isochromosome 12p in testicular neoplasms. The result has been development of antiangiogenic-targeted therapy within recent years that has become the mainstay treatment for metastatic renal cell cancer. In the near future, classification and diagnosis of renal and testicular tumors through morphologic analysis will be supplemented by molecular information correlating to prognosis and targeted therapy. This article outlines tumor molecular pathology of the kidney and testis encompassing current genomic, epigenomic, and proteonomic findings.

Predicting relapse in favorable histology Wilms tumor using gene expression analysis: a report from the Renal Tumor Committee of the Children's Oncology Group

PURPOSE

The past two decades has seen significant improvement in the overall survival of patients with favorable histology Wilms tumor (FHWT); however, this progress has reached a plateau. Further improvements may rely on the ability to better stratify patients by risk of relapse. This study determines the feasibility and potential clinical utility of classifiers of relapse based on global gene expression analysis.

EXPERIMENTAL DESIGN

Two hundred fifty FHWT of all stages enriched for relapses treated on National Wilms Tumor Study-5 passed quality variables and were suitable for analysis using oligonucleotide arrays. Relapse risk stratification used support vector machine; 2- and 10-fold cross-validations were applied.

RESULTS

The number of genes associated with relapse was less than that predicted by chance alone for 106 patients (32 relapses) with stages I and II FHWT treated with chemotherapy, and no further analyses were done. This number was greater than expected by chance for 76 local stage III patients. Cross-validation including an additional 68 local stage III patients (total 144 patients, 53 relapses) showed that classifiers for relapse composed of 50 genes were associated with a median sensitivity of 47% and specificity of 70%.

CONCLUSIONS

This study shows the feasibility and modest accuracy of stratifying local stage III FHWT using a classifier of <50 genes. Validation using an independent patient population is needed. Analysis of genes differentially expressed in relapse patients revealed apoptosis, Wnt signaling, insulin-like growth factor pathway, and epigenetic modification to be mechanisms important in relapse. Potential therapeutic targets include FRAP/MTOR and CD40.

Current and emerging chemotherapy treatment strategies for Wilms tumor in North America

Wilms tumor is the most common primary renal malignancy occurring in childhood. Approximately 500 children are diagnosed with Wilms tumor annually in the US alone, most of whom are aged <5 years. Several prognostic factors have been identified, including stage of disease, tumor histology, patient age, tumor weight, and tumor-specific loss of heterozygosity for chromosomes 1p and 16q. During the period from 1969 to 2002, the National Wilms Tumor Study Group coordinated five multicenter Wilms tumor studies. The overall survival rate for Wilms tumor has risen to >90% for patients with tumors of favorable histology. However, the treatment of patients with Wilms tumor with anaplastic histology remains challenging. The optimal treatment strategies for Wilms tumor in relapse will be studied via international collaboration in the near future. Goals of emerging studies include minimizing toxicity while maintaining the outstanding cure rates for patients with a good prognosis and, through advancing biologic understanding and developing novel therapeutic approaches, improving the prognosis for those patients in whom effective cure of their disease continues to elude physicians.

Renal tumours of childhood: an update

The role of the pathologist has been fundamental in the progress of the treatment of paediatric renal tumours. There are different philosophies in the treatment of these tumours, and there have been many recent advances in the areas of chemotherapy, identification of new entities, prognostic histological criteria following treatment and molecular prognostic and diagnostic features. This review discusses the different approaches of the different treatment protocols from Europe and North America, and reviews staging criteria, prognostic criteria and also the different tumour entities.

Treatment of recurrent clear cell sarcoma of the kidney with brain metastasis

BACKGROUND

Clear cell sarcoma of the kidney (CCSK) is known for its propensity to metastasize to bone, but it also spreads to other sites including the brain. This study was undertaken to describe the treatment and outcomes of patients with recurrent CCSK involving the brain.

METHODS

A retrospective records review was conducted on eight patients with CCSK who developed brain metastases after complete responses to initial therapy.

RESULTS

The recurrences occurred at a median of 24.5 months after initial diagnosis (range, 12-53 months). At the time of recurrence, patients were treated with multimodal therapy including biopsy or resection, radiation therapy, and chemotherapy. All patients received a variable number of courses of ifosfamide, carboplatin, and etoposide (ICE), with or without other agents. Four patients received high-dose chemotherapy with autologous stem cell rescue. One patient died from complications of bacteremia 8 weeks after starting chemotherapy. The other seven patients achieved a complete response after either surgery or ICE chemotherapy. Of these, six patients were alive without disease with a median follow-up of 30 months from the time of recurrence (range, 24 to 71 months). All six survivors received radiation therapy and four had gross total resections. Three survivors received high-dose chemotherapy with stem cell rescue.

CONCLUSION

Patients with recurrent CCSK involving the brain can have durable survival after recurrence. ICE chemotherapy, together with radiation therapy and surgery, provides a reasonable salvage regimen for recurrent CCSK. It is unclear whether high-dose chemotherapy confers a benefit compared to conventional-dose chemotherapy.

Part II: Treatment of primary malignant non-Wilms' renal tumours in children

Renal-cell carcinoma, clear-cell sarcoma, (congenital) mesoblastic nephroma, rhabdoid tumour, and renal medullary carcinoma form a heterogeneous group of childhood renal malignancies known as non-Wilms' tumours. Progress has been slow in improving the management of these tumours to decrease morbidity and increase survival. However, greater cooperation between national and international centres should engender specialisation, and an increased knowledge of the molecular biology of these tumours will inevitably lead to substantial progress over the next decade. This review is the second of two parts: the first part provided an updated review of the clinical presentation, imaging, and pathology of non-Wilms' tumours and this second part provides an updated review of the treatment of these tumours.

Pediatric genitourinary tumors

PURPOSE OF REVIEW

We will review the 2005 and 2006 literature on pediatric genitourinary tumors.

RECENT FINDINGS

Survival continues to improve for primary renal, bladder/prostate and testicular tumors in childhood. The addition of more intensive chemotherapy for anaplastic histology disease, recognition of loss of heterozygosity for chromosomes 1p and 16q as an adverse prognostic factor in favorable histology Wilms' tumor, and the utilization of molecular markers to better characterize all renal tumors will better enable individualized therapy. Recognition and treatment of anaplastic histology and bilateral Wilms' tumor remains a challenge. In rhabdomyosarcoma, genitourinary site and embryonal histology confer a relatively favorable prognosis.

SUMMARY

Advances in molecular oncology, diagnostic imaging, surgical approaches and long-term follow-up of childhood cancer survivors drive risk-stratified therapy in pediatric genitourinary tumors.

Update on pediatric genitourinary oncology

PURPOSE OF REVIEW

Results of collaborative studies and advances in our understanding of the molecular biologic events involved in children's genitourinary cancers continue to advance treatment. Simultaneously, newly released reports analyze the long-term risks of treatment. We review the most significant recent developments in the field.

RECENT FINDINGS

New basic research findings are making molecular staging a reality for children with cancer. Patients with adverse biologic features can now be stratified to receive intensified therapy while others may safely be considered for diminished adjunctive treatment. Collaborative trials continue to accrue experience and refine current strategies. Studies of survivors suggest that the long-term risk of adverse effects associated with current chemotherapeutic and radiation regimens are significant.

SUMMARY

Continued progress from collaborative trials along with advancing knowledge of the molecular biology of children's cancers promise to improve outcomes. Novel therapies are needed as emerging data suggest significant treatment-associated morbidity exists from current therapy.