Analysis of the mutational status of SIX1/2 and microRNA processing genes in paired primary and relapsed Wilms tumors and association with relapse.

Whereas 90% of patients with Wilms tumor (WT) reach cure, approximately half of patients developing a recurrent tumor die of the disease. Therefore, to disclose events leading to recurrence represents a clinical need. To study paired primary/recurrent tumor samples, being aware of the intra-tumoral heterogeneity, might help finding these answers. We previously suggested that mutations in SIX1 and DROSHA underlie WT recurrence. With the aim to better investigate this scenario, we collected 19 paired primary/recurrent tumors and 10 primary tumors from relapsing patients and searched for mutations in the SIX1/2 genes and microRNA processing genes (miRNAPGs). We found SIX1 mutation in one case, miRNAPGs mutations in seven cases, and the co-occurrence of SIX1 and miRNAPG mutations in one case. We could observe that, whereas in primary tumors the mutations could be heterogeneously present, in all cases they were positively selected and homogeneously present in the recurrent disease, as also indicated by a "moderate" and "almost perfect" agreement (according to the Landis and Koch classification criteria) between paired samples. Analysis of SIX1/2 genes and miRNAPGs in 50 non-relapsing WTs disclosed SIX2 mutation in one case and miRNAPGs mutations in seven. A borderline statistically significant association was observed between miRNAPGs mutations and the occurrence of relapse (p value: 0.05). These data suggest that SIX1 and miRNAPGs mutations may provide an advantage during tumor progression to recurrence and can represent oncogenic drivers in WT development.

Genetic and epigenetic analyses guided by high resolution whole-genome SNP array reveals a possible role of CHEK2 in Wilms tumour susceptibility.

Wilms tumour (WT), the most frequent malignant childhood renal tumour, shows a high degree of genetic and epigenetic heterogeneity. Loss of imprinting on chromosome 11p15 is found in a large fraction of cases and mutations in a few genes, including WT1, CTNNB1, WTX, TP53 and, more recently, SIX1, SIX2 and micro RNA processing genes (miRNAPGs), have been observed. However, these alterations are not sufficient to describe the entire spectrum of genetic defects underlying WT development. We inspected data obtained from a previously performed genome-wide single nucleotide polymorphism (SNP) array analysis on 96 WT samples. By selecting focal regions commonly involved in chromosomal anomalies, we identified genes with a possible role in WT development, based on the prior knowledge of their biological relevance, including MYCN, DIS3L2, MIR562, HACE1, GLI3, CDKN2A and CDKN2B, PALB2, and CHEK2. The MYCN hotspot mutation c.131C>T was detected in seven cases (7.3%). Full sequencing of the remaining genes disclosed 16 rare missense variants and a splicing mutation. Most of these were present at the germline level. Promoter analysis of HACE1, CDKN2A and CDKN2B disclosed partial methylation affecting HACE1 in a consistent fraction of cases (85%). Interestingly, of the four missense variants identified in CHEK2, three were predicted to be deleterious by in silico analyses, while an additional variant was observed to alter mRNA splicing, generating a functionally defective protein. Our study adds additional information on putative WT genes, and adds evidences involving CHEK2 in WT susceptibility.

Factors possibly affecting prognosis in children with Wilms' tumor diagnosed before 24 months of age: A report from the Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) Wilms Tumor Working Group.

BACKGROUND: Children with Wilms' tumor (WT) aged under 24 months (infants) have a better prognosis than older patients. Our aim was to study the epidemiology of this age group, with focus on the modality of diagnosis, tumor size, and association with malformations/syndromes, seeking to understand if any of these factors might be related to prognosis. PATIENTS AND METHODS: Infants diagnosed with WT between 2003 and February 2010 were evaluated. A query form was used to collect data on the modality of WT diagnosis (symptomatic or incidental), tumor volume, maximum diameter, site, and stage. RESULTS: Data were collected for 117 of 124 WT infants registered. Twenty-four cases had an incidental diagnosis (ID) of renal mass, usually arising from an abdominal ultrasound performed for other reasons, and 93 had been diagnosed based on clinical signs/symptoms. The incidental cohort displayed unifocal disease, mean tumor diameter 5.52 cm, mean tumor volume 84.30 ml, and 14 patients showed associated malformations. Symptomatic patients had mean maximum tumor diameter of 10.18 cm, mean tumor volume of 451.18 ml, and six had associated malformations. CONCLUSIONS: Our study showed that 20% of the infants had an ID of WT; they had a relatively smaller nonmetastatic tumor and a higher rate of malformations than infants of the symptomatically diagnosed group, but we did not detect any difference in age at diagnosis between the two groups. Conversely, we found a significant difference in the 5-year event-free survival rate (P = 0.018) between infants under 1 year (96%), more frequently associated with congenital malformations, and infants 1-2 years (80%).

Results of the Third AIEOP Cooperative Protocol on Wilms Tumor (TW2003) and Related Considerations.

PURPOSE: TW2003, the third Italian prospective study on Wilms tumor, aimed to improve survival in patients with stage III-IV tumors, de-escalate therapy for stage I-II nonanaplastic tumors, refine the risk stratification of therapy, and develop a national infrastructure for biobanking and central pathology review. MATERIALS AND METHODS: TW2003 recruited children 18 years old or younger with primary intrarenal tumors. Local physicians chose nephrectomy with or without preoperative chemotherapy as the initial treatment based on the risk of unsafe and/or incomplete immediate surgery. The main drivers for adjuvant therapy were tumor stage and diffuse anaplasia. A new risk stratification schema was investigated, incorporating patient age, reason for stage III designation and completeness of lung nodule response in stage IV disease. RESULTS: We report on 453 patients with unilateral Wilms tumor. Preoperative chemotherapy was administered to 42% of patients. The 5-year event-free survival and overall survival rates were 89.1% (95% CI 83.6-94.9) and 97.0% (93.7-100) for stage I; 85.1% (79.6-91.1) and 94.0% (90.1-98.1) for stage II (160); 82.7% (75.3-90.8) and 90.9% (85.0-97.1) for stage III (101); and 72.1% (61.9-84.0) and 82.5% (73.1-93.1) for stage IV (69), respectively. On multivariable analysis only anaplasia was significant for event-free survival (HR 2.68, 95% CI 1.48-4.86, p=0.001; bias corrected c-index 0.580) and overall survival (HR 5.29, 95% CI 2.52-11.12, p <0.001; bias corrected c-index 0.697). CONCLUSIONS: The survival rates achieved and the proposed risk stratification schema provide a basis for future comparisons of Wilms tumor treatment burden and patient outcome.

Neuroblastoma presenting with symptoms of epidural compression at birth: a case report.

BACKGROUND: Five to 10 % of children with neuroblastoma present with symptoms of epidural compression (EC). More than half these patients are diagnosed in the first year of life. The case of a neuroblastoma presenting symptoms of EC at birth is exceptional and deserves to be reported. CASE PRESENTATION: We describe a case of female born at the 36(th) week of pregnancy by caesarian section decided following ultrasonographic discovery of oligohydramnios. At birth, she was noted to have motor deficit involving both legs and continuous urinary dripping. These symptoms were found to be secondary to a paraspinal neuroblastoma infiltrating the spinal canal. Tumor responded well to chemotherapy, but neurologic deficit only slightly improved and bladder dysfunction remained unchanged. At 2 years of age, patient is able to walk with help of leg orthoses, suffers chronic constipation requiring daily medications, and has neurologic bladder necessitating multiple daily catheterizations. CONCLUSIONS: The finding of a newborn presenting with symptoms of EC secondary to a neuroblastoma invading the spinal canal is quite uncommon. The case described herewith confirms that these rare patients have an excellent survival probability, but almost always develop severe functional sequelae.

Whole transcriptome sequencing identifies BCOR internal tandem duplication as a common feature of clear cell sarcoma of the kidney.

PURPOSE: Clear cell sarcoma of the kidney (CCSK) is a rare pediatric renal tumor that is frequently difficult to distinguish among other childhood renal tumors due to its histological heterogeneity. This work evaluates genetic abnormalities carried by a series of CCSK samples by whole transcriptome sequencing (WTS), to identify molecular biomarkers that could improve the diagnostic process. METHODS: WTS was performed on tumor RNA from 8 patients with CCSK. Bioinformatic analysis, with implementation of a pipeline for detection of intragenic rearrangements, was executed. Sanger sequencing and gene expression were evaluated to validate BCOR internal tandem duplication (ITD). RESULTS: WTS did not identify any shared SNVs, Ins/Del or fusion event. Conversely, analysis of intragenic rearrangements enabled the detection of a breakpoint within BCOR transcript recurrent in all samples. Three different in-frame ITD in exon15 of BCOR, were detected. The presence of the ITD was confirmed on tumor DNA and cDNA, and resulted in overexpression of BCOR. CONCLUSIONS: WTS coupled with specific bioinformatic analysis is able to detect rare genetic events, as intragenic rearrangements. ITD in the last exon of BCOR is recurrent in all CCSK samples analyzed, representing a valuable molecular marker to improve diagnosis of this rare childhood renal tumor.

Loss of heterozygosity analysis at different chromosome regions in Wilms tumor confirms 1p allelic loss as a marker of worse prognosis: a study from the Italian Association of Pediatric Hematology and Oncology.

PURPOSE: The specific aims of the AIEOP-TW-2003 protocol included prospectively investigating a possible association of tumor loss of heterozygosity with outcomes in children treated for Wilms tumor. MATERIALS AND METHODS: We analyzed 125 unilateral favorable histology Wilms tumors registered between 2003 and 2008 in the Italian cooperative protocol for microsatellite markers mapped to chromosomes 1p, 7p, 11q, 16q and 22q. RESULTS: The 3-year disease-free survival and overall survival probabilities were 0.87 (95% CI 0.81-0.93) and 0.98 (95% CI 0.96-1.0), respectively. Loss of heterozygosity at 1p was significantly associated with a worse disease-free survival (probability 0.67 for patients with and 0.92 for those without 1p loss of heterozygosity, p = 0.0009), as confirmed also by multivariate analysis adjusting for tumor stage and patient age at diagnosis. There was no difference in disease-free survival probability among children with loss of heterozygosity in the other chromosomal regions tested. The worse outlook for children older than 2 years at diagnosis did not seem to be influenced by the loss of heterozygosity patterns considered. CONCLUSIONS: Chromosome 1p loss of heterozygosity seems to be a risk factor for nonanaplastic Wilms tumor, possibly regardless of other clinical factors. Our findings were uninformative regarding loss of heterozygosity in the other chromosomal regions tested.

Genomic profiling by whole-genome single nucleotide polymorphism arrays in Wilms tumor and association with relapse.

Despite the excellent survival rate of Wilms tumor (WT) patients, only approximately one-half of children who suffer tumor recurrence reach second durable remission. This underlines the need for novel markers to optimize initial treatment. We investigated 77 tumors using Illumina 370CNV-QUAD genotyping BeadChip arrays and compared their genomic profiles to detect copy number (CN) abnormalities and allelic ratio anomalies associated with the following clinicopathological variables: relapse (yes vs. no), age at diagnosis (≤ 24 months vs. >24 months), and disease stage (low stage, I and II, vs. high stage, III and IV). We found that CN gains at chromosome region 1q21.1-q31.3 were significantly associated with relapse. Additional genetic events, including allelic imbalances at chromosome arms 1p, 1q, 3p, 3q, and 14q were also found to occur at higher frequency in relapsing tumors. Interestingly, allelic imbalances at 1p and 14q also showed a borderline association with higher tumor stages. No genetic events were found to be associated with age at diagnosis. This is the first genome wide analysis with single nucleotide polymorphism (SNP) arrays specifically investigating the role of genetic anomalies in predicting WT relapse on cases prospectively enrolled in the same clinical trial. Our study, besides confirming the role of 1q gains, identified a number of additional candidate genetic markers, warranting further molecular investigations.

Heterogeneity of disease classified as stage III in Wilms tumor: a report from the Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP).

PURPOSE: We analyzed whether the prognosis can differ among Wilms tumors (WT) labeled as Stage III according to currently adopted classification systems. METHODS AND MATERIALS: Patients with nonanaplastic Stage III WT consecutively registered in two Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) trials (CNR-92, TW-2003) were the subjects in the present analysis. The steady mainstay of therapy was primary nephrectomy, followed by three-drug chemotherapy with vincristine, dactinomycin, doxorubicin, and abdominal radiotherapy (RT). RESULTS: Ninety-nine WT patients met the criteria for classification as Stage III according to a revised version of the National Wilms Tumor Study-3 staging system (51 patients in CNR-92, 48 patients in TW-2003). Regional lymph nodes (LN) were not biopsied in 16 patients. After a median follow-up of 66 months, the 4-year disease-free survival (DFS) and overall survival (OS) rates were 85% ± 4% and 92% ± 3%, respectively, for the whole group. For 38 children with positive LN, the 4-year DFS rate was 73% ± 7%, as opposed to 98% ± 2% for the 45 children with Stage III WT according to the other criteria but with negative biopsied LN (p = 0.001). The subgroup with the worst prognosis consisted of children more than 2 years old with positive LN (DFS 67% ± 8%). A delay between surgery and RT > 30 days had an adverse impact on the abdominal tumor relapse rate. CONCLUSIONS: This study provides further evidence that Stage III tumors with LN metastases might be distinguished from WTs meeting the other criteria for classification as Stage III. The worse outcome of the former may warrant a prospective study on the effects of intensified therapy. A subclassification of Stage III tumors is discussed.

Clostridium difficile-associated disease in children with solid tumors.

GOALS OF WORK: The goal of this study was to describe the incidence of Clostridium difficile-associated disease (CDAD) in children with solid tumours. PATIENTS AND METHODS: After documentation of a case of C. difficile-associated pseudomembranous colitis in a patient with neuroblastoma, the presence of C. difficile toxins A and B was prospectively tested in all children undergoing antineoplastic chemotherapy for solid tumours or lymphomas at the "G. Gaslini" Children Hospital in Genoa who presented abdominal pain. MAIN RESULTS: From January 2005 to December 2006, nine (6%) out of 141 patients treated for solid tumours had C. difficile toxin A detected in their stools in the presence of abdominal symptoms including vomit, abdominal pain and diarrhoea. The majority of patients had a normal neutrophil count at onset of gastrointestinal disease No patient developed pseudomembranous colitis, and none died. All patients received antibiotics and/or antineoplastic drugs previously associated with CDAD. CONCLUSIONS: CDAD may be a complication of children with solid tumours. Since this disease may be life threatening and cause epidemic clusters, this possibility must be kept in mind for the differential diagnosis of abdominal diseases in children with cancer, especially in absence of neutropenia.