Paul E. Grundy

Frequent Hypomethylation in Wilms Tumors of Pericentromeric DNA in Chromosomes 1 and 16

Rearrangements in the pericentromeric heterochromatin of chromosome 1 or 16 are often found in many types of cancers, including Wilms tumors, and have been suggested to contribute to oncogenesis or tumor progression. The oncogenic potential of these rearrangements has been ascribed to the resulting chromosome arm imbalances affecting the dosage of tumor suppressor genes or protooncogenes. Because DNA hypomethylation has been linked to rearrangements in the pericentromeric regions of chromosome 1 and 16 in two types of non-cancer cell populations, we examined methylation of normally highly methylated satellite DNA sequences in these regions in Wilms tumors. Hypomethylation was found to be frequent in juxtacentromeric (satellite 2) sequences and, especially, in centromeric (satellite alpha) sequences of chromosome 1. Hypomethylation of satellite 2 DNA of chromosome 16 showed a high degree of concordance with that of satellite 2 DNA of chromosome 1. We discuss the relationship of this satellite DNA hypomethylation in Wilms tumors to chromosome aberrations, as determined by assays for loss of heterozygosity.

Array CGH profiling of favourable histology Wilms tumours reveals novel gains and losses associated with relapse

Despite the excellent survival of Wilms tumour patients treated with multimodality therapy, approximately 15% will suffer from tumour relapse, where response rates are markedly reduced. We have carried out microarray‐based comparative genomic hybridisation on a series of 76 Wilms tumour samples, enriched for cases which recurred, to identify changes in DNA copy number associated with clinical outcome. Using 1Mb‐spaced genome‐wide BAC arrays, the most significantly different genomic changes between favourable histology tumours that did (n = 37), and did not (n = 39), subsequently relapse were gains on 1q, and novel deletions at 12q24 and 18q21. Further relapse‐associated loci included losses at 1q32.1, 2q36.3‐2q37.1, and gain at 13q31. 1q gains correlated strongly with loss of 1p and/or 16q. In 3 of 11 cases with concurrent 1p−/1q+, a breakpoint was identified at 1p13. Multiple low‐level sub‐megabase gains along the length of 1q were identified using chromosome 1 tiling‐path arrays. One such recurrent region at 1q22‐q23.1 included candidate genes RAB25, NES, CRABP2, HDGF and NTRK1, which were screened for mRNA expression using quantitative RT‐PCR. These data provide a high‐resolution catalogue of genomic copy number changes in relapsing favourable histology Wilms tumours. Copyright

Treatment of Wilms tumor relapsing after initial treatment with vincristine, actinomycin D, and doxorubicin. A report from the national Wilms tumor study group

We evaluated the use of alternating cycles of cyclophosphamide/etoposide and carboplatin/etoposide in children entered on National Wilms Tumor Study (NWTS)‐5 who were diagnosed between August 1, 1995 and May 31, 2002 and who relapsed after chemotherapy with vincristine, actinomycin D, and doxorubicin (VAD) and radiation therapy (DD‐4A).

Recurrent somatic mutation in DROSHA induces microRNA profile changes in Wilms tumour

Wilms tumour (WT) is an embryonal kidney neoplasia for which very few driver genes have been identified. Here we identify DROSHA mutations in 12% of WT samples (26/222) using whole-exome sequencing and targeted sequencing of 10 microRNA (miRNA)-processing genes. A recurrent mutation (E1147K) affecting a metal-binding residue of the RNase IIIb domain is detected in 81% of the DROSHA-mutated tumours. In addition, we identify non-recurrent mutations in other genes of this pathway (DGCR8, DICER1, XPO5 and TARBP2). By assessing the miRNA expression pattern of the DROSHA-E1147K-mutated tumours and cell lines expressing this mutation, we determine that this variant leads to a predominant downregulation of a subset of miRNAs. We confirm that the downregulation occurs exclusively in mature miRNAs and not in primary miRNA transcripts, suggesting that the DROSHA E1147K mutation affects processing of primary miRNAs. Our data underscore the pivotal role of the miRNA biogenesis pathway in WT tumorigenesis, particularly the major miRNA-processing gene DROSHA.

Treatment of Wilms tumor relapsing after initial treatment with vincristine and actinomycin D: A report from the National Wilms Tumor Study Group

NWTS‐5 was a multi‐institutional clinical trial for patients less than 16 years of age at diagnosis with specific renal neoplasms who were diagnosed between August 1, 1995 and May 31, 2002. A uniform approach to the treatment of patients with relapse was employed.

New policies to address the global burden of childhood cancers

Childhood cancer is a major global health issue. Every year, almost 100 000 children die from cancer before the age of 15 years, more than 90% of them in resource-limited countries. Here, we review the key policy issues for the delivery of better care, research, and education of professionals and patients. We present a key list of time-limited proposals focusing on change to health systems and research and development. These include sector and system reforms to make care affordable to all, policies to promote growth of civil society around both cancer and Millennium Development Goals, major improvements to public health services (particularly the introduction of national cancer plans), improved career development, and increased remuneration of specialist health-care workers and government support for childhood cancer registries. Research and development proposals focus on sustainable funding, the establishment of more research networks, and clinical research specifically targeted at the needs of low-income and middle-income countries. Finally, we present proposals to address the need for clinical trial innovation, the complex dichotomy of regulations, and the threats to the availability of data for childhood cancers.

Characteristics and survival of 750 children diagnosed with a renal tumor in the first seven months of life: A collaborative study by the SIOP/GPOH/SFOP, NWTSG, and UKCCSG Wilms tumor study groups.

To review the clinical characteristics and survival of infants diagnosed with a primary renal tumor in the first 7 months of life.

Gain of 1q is associated with inferior event-free and overall survival in patients with favorable histology Wilms tumor: a report from the Children's Oncology Group.

Wilms tumor is the most common childhood renal tumor. Although the majority of patients with favorable histology Wilms tumor (FHWT) have good outcomes, some patients still experience disease recurrence and death from disease. The goal of the current study was to determine whether tumor‐specific chromosome 1q gain is associated with event‐free survival (EFS) and overall survival (OS) in patients with FHWT.

Long-term outcomes for infants with very low risk wilms tumor treated with surgery alone in national wilms tumor study-5

Objective:To determine the event-free survival (EFS) and overall survival (OS) of children with very low risk Wilms tumor (VLRWT) treated with surgery only. Background:Previous studies suggested that postoperative chemotherapy had not improved the prognosis of children with VLRWT. A total of 77 children <24 months of age with small (<550 g) Stage I favorable histology Wilms tumors were treated with surgery only. This study was closed based on stopping rules to ensure that the 2-year EFS was ≥90%. Methods:A total of 77 children were assessed for EFS and OS. Of these patients, 21 enrolled at the time of closure were recalled, treated with dactinomycin and vincristine (regimen EE4A), and censored for analysis thereafter. About 111 children subsequently treated with EE4A were available for comparison. Results:Median follow-up of surviving patients was 8.2 years for surgery only (range, 1.9–11.8 years) and 5.2 years for the EE4A group (range, 1.6–8.9 years). The estimated 5-year EFS for surgery only was 84% (95% confidence interval [CI]: 73%, 91%); for the EE4A patients it was 97% (95% CI: 92%, 99%, P = 0.002). One death was observed in each treatment group. The estimated 5-year OS was 98% (95% CI: 87%, 99%) for surgery only and 99% (95% CI: 94%, 99%) for EE4A (P = 0.70). Conclusion:The surgery-only EFS was lower than anticipated but, coupled with a much higher than anticipated salvage rate of the chemotherapy naive patients whose disease recurred, led to an observed long-term OS equivalent to that seen with 2-drug chemotherapy. This approach to the treatment of patients with VLRWT eliminates the toxic side-effects of chemotherapy for a large majority of patients. A follow-up study is underway to confirm these findings.

Genetic and genetic expression analyses of clear cell sarcoma of the kidney

Clear cell sarcoma of the kidney (CCSK) represents a significant diagnostic and clinical challenge. In search of diagnostically useful or biologically significant genetic abnormalities, we screened 30 CCSKs from the National Wilms Tumor Study Group. Genetic gains and losses were analyzed using comparative genomic hybridization; loss of heterozygosity at 11p15 was studied using microsatellite analysis. Loss of imprinting (LOI) was studied using allele-specific expression or methylation analysis at the ApaI polymorphic site for IGF2, AluI and RsaI sites for H19, and Cfo I site for SNRPN. Comparative genomic hybridization analysis revealed quantitative abnormalities in only 4 of 30 CCSKs. Two showed gain of 1q, one also showed loss of 10q, and the other also showed loss of terminal 4p. The other two cases demonstrated chromosome 19 loss and chromosome 19p gain, respectively. All 22 cases informative for 11p15 showed retention of both alleles. Of 14 CCSKs informative for IGF2, six showed biallelic expression; all three CCSKs informative for H19 exhibited monoallelic expression. The normal imprint pattern was present in all six CCSKs analyzed for SNRPN methylation. These data demonstrate an absence of consistent genetic gains or losses in CCSKs using these methods. The high frequency of LOI for IGF2 in CCSKs (43%) is comparable to that reported in Wilms tumors. The retention of imprinting at the SNRPN and H19 loci confirm that LOI is not a ubiquitous epigenetic change. This suggests that IGF2, a potent growth factor, may play a role in the development or progression of CCSK.