Genetic and chromosomal alterations in Kenyan Wilms Tumor

Current Realities of Wilms Tumor Burden and Therapy in Ghana

BACKGROUND

Between 2005 and 2014, Ghana's Wilms tumor (WT) 2-year disease-free survival of 44% trailed behind that of high-income countries. This study aimed to uncover social determinants of health leading to preventable WT death in Ghana.

METHODS

WT patient records (2014-2022) at Korle-Bu Teaching Hospital (KBTH; Ghana) were reviewed retrospectively. Demographics, clinical course, tumor characteristics, and survival were evaluated using t-tests, Pearson Chi-square, and multivariate Cox logistic regression.

RESULTS

Of 127 patients identified, 65 were female. Median age was 44 months [IQR 25-66]. Forty-eight patients (38%) presented with distant metastasis (75% lung, 25% liver), which associated with hypoalbuminemia (p = 0.009), caregiver informal employment (p = 0.04), and larger tumors (p = 0.002). Despite neoadjuvant chemotherapy shrinking 84% of tumors, larger initial size associated with incomplete resection (p = 0.046). Of 110 nephrectomies, 31 patients had residual disease, negatively impacting survival (p = 2.7 × 10-5). Twenty-two patients (17%) abandoned treatment (45% before nephrectomy; 55% after nephrectomy), with seven patients ultimately lost to follow-up (LTFU). Decedents represented 43% of stage IV patients compared to 28% in other stages. Event-free survival (EFS) was 60% at 4 years with overall survival (OS) at 67%.

CONCLUSIONS

Although Ghana's WT survival has improved, informal employment and distance from KBTH predisposed patients to delayed referral, greater tumor burden, hypoalbuminemia, and lower survival.

TYPE OF STUDY

Prognosis Study.

LEVEL OF EVIDENCE

II.

Pediatric renal tumor epidemiology: Global perspectives, progress, and challenges

Pediatric renal tumors account for 3%-11% of childhood cancers, the most common of which is Wilms tumor or nephroblastoma. Epidemiology plays a key role in cancer prevention and control by describing the distribution of cancer and discovering risk factors for cancer. Large pediatric research consortium trials have led to a clearer understanding of pediatric renal tumors, identification of risk factors, and development of more risk-adapted therapies. These therapies have improved event-free and overall survival for children. However, several challenges remain and not all children have benefited from the improved outcomes. In this article, we review the global epidemiology of pediatric renal tumors, including key consortium and global studies. We identify current knowledge gaps and challenges facing both high and low middle-incomes countries.

Pediatric renal tumor epidemiology: Global perspectives, progress, and challenges

Pediatric renal tumors account for 3%-11% of childhood cancers, the most common of which is Wilms tumor or nephroblastoma. Epidemiology plays a key role in cancer prevention and control by describing the distribution of cancer and discovering risk factors for cancer. Large pediatric research consortium trials have led to a clearer understanding of pediatric renal tumors, identification of risk factors, and development of more risk-adapted therapies. These therapies have improved event-free and overall survival for children. However, several challenges remain and not all children have benefited from the improved outcomes. In this article, we review the global epidemiology of pediatric renal tumors, including key consortium and global studies. We identify current knowledge gaps and challenges facing both high and low middle-incomes countries.

Association Between TP53 Mutation and Prognosis in Wilms Tumor: A Meta-Analysis

BackgroundTP53 mutation has been suggested to have prognostic value for patients with Wilms tumor (WT), but the results are still controversial. Methods: Relevant studies published until August 1, 2019 were identified by searching PubMed, EMBASE and Cochrane Library. A random-effect model was performed to assess pooled data. Begg's and Egger's test were used to evaluate the potential publication bias. Sensitivity analysis was used to evaluate the stability of results. Results: A total of seven eligible articles were included. There was no significant difference in the risk of death among patients with WT with different TP53 mutation status (odds ratio [OR] = 3.09, 95% confidence interval[CI]: 0.81-11.84). Combined hazard ratio (HR) suggested that TP53 mutation had an unfavorable impact on overall survival (OS) (HR = 4.17, 95% CI: 1.97-6.36) and disease-free survival (DFS) (HR = 2.23, 95% CI: 1.29-3.17) in WT. Conclusions: This meta-analysis demonstrates that TP53 mutations are associated with poorer prognosis in WT.

Race disparities in genetic alterations within Wilms tumor specimens

BACKGROUND

Wilms tumor (WT) affects Black children disproportionately. Genetic aberrations within WT specimens that contribute to this disparity have not been reported.

METHODS

The Therapeutically Applied Research to Generate Effective Treatments (TARGET) database was queried for WT patient and genomic features. Clinical and genetic variables were compared by race.

RESULTS

Within the discovery set (enriched for adverse events; N = 94 White, 19 Black, 14 Other/unreported patients), Black children were more likely to present with advanced stage disease (p = 0.019). Within the validation set (primarily a random sampling of NWTS-5; N = 360 White, 92 Black, 72 Other/Unreported), Black children appeared older at diagnosis (p = 0.050), had decreased median follow-up time (p<0.0005) and were over-represented (17.4%) relative to the concurrent U.S. Census (12.8%). Among the 37 target genes sequenced, ACTB (p = 0.030) and DICER1 (p = 0.026) mutations were more common in Black patient specimens, whereas DGCR8 (p = 0.041) mutations were more common in White patient specimens. White patient specimens were more likely to contain one or multiple targeted mutations (p = 0.026).

CONCLUSION

Within the TARGET database, Black children were over-represented and harbored WT specimens containing more frequent ACTB and DICER1 mutations. In contrast, WT from White children contained overall more mutations in targeted genes and specifically in DGCR8.

LEVEL OF EVIDENCE

III.

Authorship Patterns in Cancer Genomics Publications Across Africa

PURPOSE

Authorship is a proxy indicator of research capacity. Understanding the research capacity is imperative for developing population-specific cancer control strategies. This is particularly apropos for African nations, where mortality from cancer is projected to surpass that from infectious disease and the populations are critically under-represented in cancer and genomics studies. Here, we present an analysis and discussion of the patterns of authorship in Africa as they pertain to cancer genomics research across African countries.

METHODS

PubMed metadata of relevant cancer genomics peer-reviewed publications on African populations, published between January 1, 1990, and December 31, 2019, were retrieved and analyzed for patterns of authorship affiliation using R packages, RISmed, and Pubmed.mineR.

RESULTS

The data showed that only 0.016% (n = 375) of cancer publications globally were on cancer genomics of African people. More than 50% of the first and last authors of these publications originated from the North African countries of Tunisia, Morocco, Egypt, and Algeria. South Africa (13.6% and 12.7%) and Nigeria (2.2% and 1.9%) were the Sub-Saharan African countries most represented by first and last authorship positions, respectively. The United States contributed 12.6% of first and last authored papers, and nearly 50% of all African countries had no contributing author for the publications we reviewed.

CONCLUSION

This study highlights and brings awareness to the paucity of cancer genomics research on African populations and by African authors and identifies a need for concerted efforts to encourage and enable more research in Africa, needed for achieving global equity in cancer outcomes.

A Review of Cancer Genetics and Genomics Studies in Africa

Cancer is the second leading cause of death globally and is projected to overtake infectious disease as the leading cause of mortality in Africa within the next two decades. Cancer is a group of genomic diseases that presents with intra- and inter-population unique phenotypes, with Black populations having the burden of morbidity and mortality for most types. At large, the prevention and treatment of cancers have been propelled by the understanding of the genetic make-up of the disease of mostly non-African populations. By the same token, there is a wide knowledge gap in understanding the underlying genetic causes of, and genomic alterations associated with, cancer among black Africans. Accordingly, we performed a review of the literature to survey existing studies on cancer genetics/genomics and curated findings pertaining to publications across multiple cancer types conducted on African populations. We used PubMed MeSH terms to retrieve the relevant publications from 1990 to December 2019. The metadata of these publications were extracted using R text mining packages: RISmed and Pubmed.mineR. The data showed that only 0.329% of cancer publications globally were on Africa, and only 0.016% were on cancer genetics/genomics from Africa. Although the most prevalent cancers in Africa are cancers of the breast, cervix, uterus, and prostate, publications representing breast, colorectal, liver, and blood cancers were the most frequent in our review. The most frequently reported cancer genes were BRCA1, BRCA2, and TP53. Next, the genes reported in the reviewed publications’ abstracts were extracted and annotated into three gene ontology classes. Genes in the cellular component class were mostly associated with cell part and organelle part, while those in biological process and molecular function classes were mainly associated with cell process, biological regulation, and binding, and catalytic activity, respectively. Overall, this review highlights the paucity of research on cancer genomics on African populations, identified gaps, and discussed the need for concerted efforts to encourage more research on cancer genomics in Africa.

Wilms Tumor in Sub-Saharan Africa: Molecular and Social Determinants of a Global Pediatric Health Disparity

Wilms tumor (WT) is the most common renal malignancy of childhood. Global disparities in WT have been reported with the highest incidence and lowest overall survival occurring in sub-Saharan African nations. After a detailed search of PubMed, we reviewed available literature on WT in sub-Saharan Africa and summarized findings that explore biologic and social factors contributing to this alarming cancer health disparity. Access to care and treatment abandonment are the most frequently reported factors associated with decreased outcomes. Implementation of multidisciplinary teams, collaborative networks, and financial support has improved overall survival in some nations. However, treatment abandonment remains a challenge. In high-income countries globally, WT therapy now is risk-stratified according to biology and histology. To a significantly lesser extent, biologic features have been studied only recently in sub-Saharan African WT, yet unique molecular and genetic signatures, including congenital anomaly-associated syndromes and biomarkers associated with treatment-resistance and poor prognosis have been identified. Together, challenges with access to and delivery of health care in addition to adverse biologic features likely contribute to increased burden of disease in sub-Saharan African children having WT. Publications on biologic features of WT that inform treatment stratification and personalized therapy in resource-limited regions of sub-Saharan Africa have lagged in comparison to publications that discuss social determinants of health. Further efforts to understand both WT biology and social factors relevant to appropriate treatment delivery should be prioritized in order to reduce health disparities for children residing in resource-limited areas of sub-Saharan Africa battling this lethal childhood cancer.

FXR1 expression domain in Wilms tumor

BACKGROUND/PURPOSE

Wilms tumor (WT) is the most common childhood kidney cancer globally. Our prior unbiased proteomic screen of WT disparities revealed increased expression of Fragile X-Related 1 (FXR1) in Kenyan specimens where survival is dismal. FXR1 is an RNA-binding protein that associates with poor outcomes in multiple adult cancers. The aim of this study therefore was to validate and characterize the FXR1 expression domain in WT.

METHODS

Quantitative FXR1 gene expression was compared between WT, adjacent, adult, and fetal kidney specimens. The cellular and subcellular expression domain of FXR1 was characterized across these tissues using immunoperoxidase staining. RNA-sequencing of FXR1 was performed from WT and other pediatric malignancies to examine its broader target potential.

RESULTS

FXR1 was detected in all clinical WT specimens evaluated (n = 82), and as a result appeared independent of demographic, histology, or adverse event. Specific cytosolic staining was strongest in blastema, intermediate and variable in epithelia, and weakest in stroma. When present, areas of skeletal muscle differentiation stained strongly for FXR1. qPCR revealed increased FXR1 expression in WT compared to adult and adjacent kidney (p < 0.0002) but was similar to fetal kidney (p = 0.648). RNA-sequencing revealed expression of FXR1 in multiple pediatric tumors, greatest in rhabdomyosarcoma and WT.

CONCLUSIONS

FXR1 was expressed consistently across this broad sampling of WT and most robustly in the primitive blastema. Notably, FXR1 labeled a specific self-renewing progenitor population of the fetal kidney.

Origins of DNA methylation defects in Wilms tumors

Wilms tumor is an embryonic renal cancer that typically presents in early childhood and accounts for 7% of all paediatric cancers. Different genetic alterations have been described in this malignancy, however, only a few of them are associated with a majority of Wilms tumors. Alterations in DNA methylation, in contrast, are frequent molecular defects observed in most cases of Wilms tumors. How these epimutations are established in this tumor is not yet completely clear. The recent identification of the molecular actors required for the epigenetic reprogramming during embryogenesis suggests novel possible mechanisms responsible for the DNA methylation defects in Wilms tumor. Here, we provide an overview of the DNA methylation alterations observed in this malignancy and discuss the distinct molecular mechanisms by which these epimutations can arise.

Molecular and epidemiologic characterization of Wilms tumor from Baghdad, Iraq

BACKGROUND

Wilms tumor (WT) is the most common childhood kidney cancer worldwide, yet its incidence and clinical behavior vary according to race and access to adequate healthcare resources. To guide and streamline therapy in the war-torn and resource-constrained city of Baghdad, Iraq, we conducted a first-ever molecular analysis of 20 WT specimens to characterize the biological features of this lethal disease within this challenged population.

METHODS

Next-generation sequencing of ten target genes associated with WT development and treatment resistance (WT1, CTNNB1, WTX, IGF2, CITED1, SIX2, p53, N-MYC, CRABP2, and TOP2A) was completed. Immunohistochemistry was performed for 6 marker proteins of WT (WT1, CTNNB1, NCAM, CITED1, SIX2, and p53). Patient outcomes were compiled.

RESULTS

Mutations were detected in previously described WT "hot spots" (e.g., WT1 and CTNNB1) as well as novel loci that may be unique to the Iraqi population. Immunohistochemistry showed expression domains most typical of blastemal-predominant WT. Remarkably, despite the challenges facing families and care providers, only one child, with combined WT1 and CTNNB1 mutations, was confirmed dead from disease. Median clinical follow-up was 40.5 months (range 6-78 months).

CONCLUSIONS

These data suggest that WT biology within a population of Iraqi children manifests features both similar to and unique from disease variants in other regions of the world. These observations will help to risk stratify WT patients living in this difficult environment to more or less intensive therapies and to focus treatment on cell-specific targets.

Pediatric Solid Tumors in Resource-Constrained Settings: A Review of Available Evidence on Management, Outcomes, and Barriers to Care

International disparities in outcomes from pediatric solid tumors remain striking. Herein, we review the current literature regarding management, outcomes, and barriers to care for pediatric solid tumors in low- and middle-income countries (LMICs). In sub-Saharan Africa, Wilms Tumor represents the most commonly encountered solid tumor of childhood and has been the primary target of recent efforts to improve outcomes in low-resource settings. Aggressive and treatment-resistant tumor biology may play a role in poor outcomes within certain populations, but socioeconomic barriers remain the principal drivers of preventable mortality. Management protocols that include measures to address socioeconomic barriers have demonstrated early success in reducing abandonment of therapy. Further work is required to improve infrastructure and general pediatric care to address disparities.

Functional KRAS mutations and a potential role for PI3K/AKT activation in Wilms tumors

Wilms tumor (WT) is the most common renal neoplasm of childhood and affects 1 in 10 000 children aged less than 15 years. These embryonal tumors are thought to arise from primitive nephrogenic rests that derive from the metanephric mesenchyme during kidney development and are characterized partly by increased Wnt/β-catenin signaling. We previously showed that coordinate activation of Ras and β-catenin accelerates the growth and metastatic progression of a murine WT model. Here, we show that activating KRAS mutations can be found in human WT. In addition, high levels of phosphorylated AKT are present in the majority of WT. We further show in a mouse model and in renal epithelial cells that Ras cooperates with β-catenin to drive metastatic disease progression and promotes in vitro tumor cell growth, migration, and colony formation in soft agar. Cellular transformation and metastatic disease progression of WT cells are in part dependent on PI3K/AKT activation and are inhibited via pharmacological inhibition of this pathway. Our studies suggest both KRAS mutations and AKT activation are present in WT and may represent novel therapeutic targets for this disease.

Senescence Process in Primary Wilms' Tumor Cell Culture Induced by p53 Independent p21 Expression

Wilms tumor (WT) is an embryonal tumor occurring in developing kidney tissue. WT cells showing invasive cancer characteristics, also retain renal stem cell behaviours. In-vitro culture of WT is hampered by limited replicative potential. This study aimed to establish a longterm culture of WT cells to enable the study of molecular events to attempt to explain its cellular senescence. Methods: Primary cell cultures from fresh WT tumor specimen were established. Of 5 cultures tried, only 1 could be propagated for more than 7 passages. One culture, identified as PSU-SK-1, could be maintained > 35 passages and was then subjected to molecular characterization and evaluation for cancer characteristics. The cells consistently harbored concomitant mutations of CTNNB1 (Ser45Pro) and WT1 (Arg413Stop) thorough the cultivation. On Transwell invasion assays, the cells exhibited migration and invasion at 55% and 27% capability of the lung cancer cells, A549. On gelatin zymography, PSU-SK-1 showed high expression of the matrix metaloproteinase. The cells exhibited continuous proliferation with 24-hour doubling time until passages 28-30 when the growth slowed, showing increased cell size, retention of cells in G1/S proportion and positive β-galactosidase staining. As with those evidence of senescence in advanced cell passages, expression of p21 and cyclin D1 increased when the expression of β-catenin and its downstream protein, TCF, declined. There was also loss-of-expression of p53 in this cell line. In conclusion, cellular senescence was responsible for limited proliferation in the primary culture of WT, which was also associated with increased expression of p21 and was independent of p53 expression. Decreased activation of the Wnt signalling might explain the induction of p21 expression.

International cancer seminars: a focus on kidney cancer

Recent years have seen important advances in our understanding of the etiology, biology and genetics of kidney cancer. To summarize important achievements and identify prominent research questions that remain, a workshop was organized by IARC and the US NCI. A series of 'difficult questions' were formulated, which should be given future priority in the areas of population, genomic and clinical research.

A practical guide for short-term pediatric surgery global volunteers

INTRODUCTION

The tremendous need for increasing the quantity and quality of global pediatric surgical care in underserved areas has been well documented. Concomitantly there has been a significant increase in interest by pediatric surgeons in helping to relieve this problem through surgical volunteerism. The intent of the article is to serve as a practical guide for pediatric surgeons contemplating or planning a short-term global volunteer endeavor.

METHODS

The article is based on the authors' personal experiences and on the published experiences of other volunteers.

FINDINGS

The following aspects of volunteerism are discussed: ethical considerations, where and how to go, what and whom to take with you, what to expect in your volunteer locale, and what to do and what to avoid in order to enhance the volunteer experience.

CONCLUSIONS

The points discussed in this guide will hopefully make the volunteer activity one that results in greatly improved immediate and long term surgical care for children and improves the chances that the activity will be a meaningful, pleasant, and productive experience for both the volunteer and the host physician.

Genetic variation frequencies in Wilms' tumor: A meta-analysis and systematic review

Over the last few decades, numerous biomarkers in Wilms' tumor have been confirmed and shown variations in prevalence. Most of these studies were based on small sample sizes. We carried out a meta-analysis of the research published from 1992 to 2015 to obtain more precise and comprehensive outcomes for genetic tests. In the present study, 70 out of 5175 published reports were eligible for the meta-analysis, which was carried out using Stata 12.0 software. Pooled prevalence for gene mutations WT1, WTX, CTNNB1, TP53, MYCN, DROSHA, and DGCR8 was 0.141 (0.104, 0.178), 0.147 (0.110, 0.184), 0.140 (0.100, 0.190), 0.410 (0.214, 0.605), 0.071 (0.041, 0.100), 0.082 (0.048, 0.116), and 0.036 (0.026, 0.046), respectively. Pooled prevalence of loss of heterozygosity at 1p, 11p, 11q, 16q, and 22q was 0.109 (0.084, 0.133), 0.334 (0.295, 0.373), 0.199 (0.146, 0.252), 0.151 (0.129, 0.172), and 0.148 (0.108, 0.189), respectively. Pooled prevalence of 1q and chromosome 12 gain was 0.218 (0.161, 0.275) and 0.273 (0.195, 0.350), respectively. The limited prevalence of currently known genetic alterations in Wilms' tumors indicates that significant drivers of initiation and progression remain to be discovered. Subgroup analyses indicated that ethnicity may be one of the sources of heterogeneity. However, in meta-regression analyses, no study-level characteristics of indicators were found to be significant. In addition, the findings of our sensitivity analysis and possible publication bias remind us to interpret results with caution.