Race disparities in peptide profiles of North American and Kenyan Wilms tumor specimens

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.

Race and Ethnic Group Enrollment and Outcomes for Wilms Tumor: Analysis of the Current Era Children's Oncology Group Study, AREN03B2

BACKGROUND

To review race and ethnic group enrollment and outcomes for Wilms tumor (WT) across all 4 risk-assigned therapeutic trials from the current era Children's Oncology Group Renal Tumor Biology and Risk Stratification Protocol, AREN03B2.

STUDY DESIGN

For patients with WT enrolled in AREN03B2 (2006 to 2019), disease and biologic features, therapeutic study-specific enrollment, and event-free (EFS) and overall (OS) 4-year survival were compared between institutionally reported race and ethnic groups.

RESULTS

Among 5,146 patients with WT, no statistically significant differences were detected between race and ethnic groups regarding subsequent risk-assigned therapeutic study enrollment, disease stage, histology, biologic factors, or overall EFS or OS, except the following variables: Black children were older and had larger tumors at enrollment, whereas Hispanic children had lower rates of diffuse anaplasia WT and loss of heterozygosity at 1p. The only significant difference in EFS or OS between race and ethnic groups was observed among the few children treated for diffuse anaplasia WT with regimen UH-1 and -2 on high-risk protocol, AREN0321. On this therapeutic arm only, Black children showed worse EFS (hazard ratio = 3.18) and OS (hazard ratio = 3.42). However, this finding was not replicated for patients treated with regimen UH-1 and -2 under AREN03B2 but not on AREN0321.

CONCLUSIONS

Race and ethnic group enrollment appeared constant across AREN03B2 risk-assigned therapeutic trials. EFS and OS on these therapeutic trials when analyzed together were comparable regarding race and ethnicity. Black children may have experienced worse stage-specific survival when treated with regimen UH-1 and -2 on AREN0321, but this survival gap was not confirmed when analyzing additional high-risk AREN03B2 patients.

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.

Exploiting embryonic niche conditions to grow Wilms tumor blastema in culture

Introduction

Wilms Tumor (WT), or nephroblastoma, is the most common pediatric kidney cancer. Most WTs display a “favorable” triphasic histology, in which the tumor is comprised of blastemal, stromal, and epithelial cell types. Blastemal predominance after neoadjuvant chemotherapy or diffuse anaplasia (“unfavorable” histology; 5-8%) portend a worse prognosis. Blastema likely provide the putative cancer stem cells (CSCs), which retain molecular and histologic features characteristic of nephron progenitor cells (NPCs), within WTs. NPCs arise in the metanephric mesenchyme (MM) and populate the cap mesenchyme (CM) in the developing kidney. WT blastemal cells, like NPCs, similarly express markers, SIX2 and CITED1. Tumor xenotransplantation is currently the only dependable method to propagate tumor tissue for research or therapeutic screening, since efforts to culture tumors in vitro as monolayers have invariably failed. Therefore, a critical need exists to propagate WT stem cells rapidly and efficiently for high-throughput, real-time drug screening.

Methods

Previously, our lab developed niche conditions that support the propagation of murine NPCs in culture. Applying similar conditions to WTs, we assessed our ability to maintain key NPC "stemness" markers, SIX2, NCAM, and YAP1, and CSC marker ALDHI in cells from five distinct untreated patient tumors.

Results

Accordingly, our culture conditions maintained the expression of these markers in cultured WT cells through multiple passages of rapidly dividing cells.

Discussion

These findings suggest that our culture conditions sustain the WT blastemal population, as previously shown for normal NPCs. As a result, we have developed new WT cell lines and a multi-passage in vitro model for studying the blastemal lineage/CSCs in WTs. Furthermore, this system supports growth of heterogeneous WT cells, upon which potential drug therapies could be tested for efficacy and resistance.

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.

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.

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.

Associations of Socioeconomic Status, Public vs Private Insurance, and Race/Ethnicity With Metastatic Sarcoma at Diagnosis

IMPORTANCE

Approximately 10% to 30% of patients with sarcoma present with detectable metastases at diagnosis. However, the extent to which presentation with metastases is due to delayed diagnosis vs other factors remains unclear.

OBJECTIVE

To evaluate whether socioeconomic status, insurance status, or race/ethnicity were associated with the presence of metastases at diagnosis of sarcoma.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from the population-based Surveillance, Epidemiology, and End Results program. Adult and pediatric patients with an initial diagnosis of soft-tissue and bone sarcoma between 2001 and 2015 were stratified by age group (pediatric, <20 years; adult, 20-65 years; older adult, >65 years) and sarcoma subtype. Statistical analyses were performed between August 2019 and January 2020.

EXPOSURES

Surveillance, Epidemiology, and End Results Census tract-level socioeconomic status index, insurance status, and race/ethnicity.

MAIN OUTCOMES AND MEASURES

The odds of presenting with metastases at diagnosis were calculated.

RESULTS

A total of 47 337 patients with first primary malignant sarcoma were included (24 343 male patients [51.4%]), with 29 975 non-Hispanic White patients (63.3%), 5673 non-Hispanic Black patients (12.0%), 7504 Hispanic patients (15.8%), and 4185 American Indian-Alaskan Native and Asian Pacific Islander patients (8.8%). Liposarcoma in adults was the only subtype and age group combination that demonstrated a significant trend in incidence across socioeconomic status levels (odds ratio, 0.85; 99% CI, 0.76-0.96; P = .001). However, compared with having non-Medicaid insurance, having Medicaid or no insurance in adults was associated with an increased odds of metastases at diagnosis for 6 of the 8 sarcoma subtypes evaluated; osteosarcoma and Ewing sarcoma were the only 2 subtypes in adults for which metastases were not associated with insurance status. In addition, there was an increased risk of presenting with metastases among non-Hispanic Black adults diagnosed with leiomyosarcoma (odds ratio, 1.87; 99% CI, 1.41-2.48) and unclassified sarcomas (odds ratio, 1.65; 99% CI, 1.01-2.67) compared with non-Hispanic White adults that was independent of socioeconomic and insurance status.

CONCLUSIONS AND RELEVANCE

These findings suggest that delayed access to care is associated with advanced stage at diagnosis for several soft-tissue sarcoma subtypes in adults, whereas other factors may be associated with the metastatic progression of osteosarcoma and Ewing sarcoma, as well as the racial disparities observed with metastatic leiomyosarcoma and unclassified sarcomas.

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.

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.

Pediatric solid tumors in Africa: different biology?

PURPOSE OF REVIEW

To review the recent literature regarding biologic characteristics of pediatric solid tumors in African children.

RECENT FINDINGS

Data regarding pediatric solid tumors in Africa, while increasing, remain sparse when considering the ethnic and geographic diversity of the continent. Recent work, especially regarding nephroblastoma in Kenya, has identified some biologic variability among local tribes but also when compared with North American tumors. In general, reports from across the continent reveal markedly poorer survival for pediatric patients with solid tumors when compared with high-resourced regions.

SUMMARY

Multiple resource-related and infrastructure-related challenges contribute to poorer outcomes, and these require systematic, multidisciplinary, and structured solutions. Socioeconomic factors and limited access to care currently seem to drive the survival outcomes in children with solid cancers in Africa.

Resolving the etiology of atopic disorders by using genetic analysis of racial ancestry

Atopic dermatitis (AD), food allergy, allergic rhinitis, and asthma are common atopic disorders of complex etiology. The frequently observed atopic march from early AD to asthma, allergic rhinitis, or both later in life and the extensive comorbidity of atopic disorders suggest common causal mechanisms in addition to distinct ones. Indeed, both disease-specific and shared genomic regions exist for atopic disorders. Their prevalence also varies among races; for example, AD and asthma have a higher prevalence in African Americans when compared with European Americans. Whether this disparity stems from true genetic or race-specific environmental risk factors or both is unknown. Thus far, the majority of the genetic studies on atopic diseases have used populations of European ancestry, limiting their generalizability. Large-cohort initiatives and new analytic methods, such as admixture mapping, are currently being used to address this knowledge gap. Here we discuss the unique and shared genetic risk factors for atopic disorders in the context of ancestry variations and the promise of high-throughput "-omics"-based systems biology approach in providing greater insight to deconstruct their genetic and nongenetic etiologies. Future research will also focus on deep phenotyping and genotyping of diverse racial ancestry, gene-environment, and gene-gene interactions.

Proteomic Upregulation of Fatty Acid Synthase and Fatty Acid Binding Protein 5 and Identification of Cancer- and Race-Specific Pathway Associations in Human Prostate Cancer Tissues

Protein profiling studies of prostate cancer have been widely used to characterize molecular differences between diseased and non-diseased tissues. When combined with pathway analysis, profiling approaches are able to identify molecular mechanisms of prostate cancer, group patients by cancer subtype, and predict prognosis. This strategy can also be implemented to study prostate cancer in very specific populations, such as African Americans who have higher rates of prostate cancer incidence and mortality than other racial groups in the United States. In this study, age-, stage-, and Gleason score-matched prostate tumor specimen from African American and Caucasian American men, along with non-malignant adjacent prostate tissue from these same patients, were compared. Protein expression changes and altered pathway associations were identified in prostate cancer generally and in African American prostate cancer specifically. In comparing tumor to non-malignant samples, 45 proteins were significantly cancer-associated and 3 proteins were significantly downregulated in tumor samples. Notably, fatty acid synthase (FASN) and epidermal fatty acid-binding protein (FABP5) were upregulated in human prostate cancer tissues, consistent with their known functions in prostate cancer progression. Aldehyde dehydrogenase family 1 member A3 (ALDH1A3) was also upregulated in tumor samples. The Metastasis Associated Protein 3 (MTA3) pathway was significantly enriched in tumor samples compared to non-malignant samples. While the current experiment was unable to detect statistically significant differences in protein expression between African American and Caucasian American samples, differences in overrepresentation and pathway enrichment were found. Structural components (Cytoskeletal Proteins and Extracellular Matrix Protein protein classes, and Biological Adhesion Gene Ontology (GO) annotation) were overrepresented in African American but not Caucasian American tumors. Additionally, 5 pathways were enriched in African American prostate tumors: the Small Cell Lung Cancer, Platelet-Amyloid Precursor Protein, Agrin, Neuroactive Ligand-Receptor Interaction, and Intrinsic pathways. The protein components of these pathways were either basement membrane proteins or coagulation proteins.

MALDI mass spectrometry imaging: A cutting-edge tool for fundamental and clinical histopathology

Histopathological diagnoses have been done in the last century based on hematoxylin and eosin staining. These methods were complemented by histochemistry, electron microscopy, immunohistochemistry (IHC), and molecular techniques. Mass spectrometry (MS) methods allow the thorough examination of various biocompounds in extracts and tissue sections. Today, mass spectrometry imaging (MSI), and especially matrix-assisted laser desorption ionization (MALDI) imaging links classical histology and molecular analyses. Direct mapping is a major advantage of the combination of molecular profiling and imaging. MSI can be considered as a cutting edge approach for molecular detection of proteins, peptides, carbohydrates, lipids, and small molecules in tissues. This review covers the detection of various biomolecules in histopathological sections by MSI. Proteomic methods will be introduced into clinical histopathology within the next few years.

Pathology interface for the molecular analysis of tissue by mass spectrometry

Background:

Imaging mass spectrometry (IMS) generates molecular images directly from tissue sections to provide better diagnostic insights and expand the capabilities of clinical anatomic pathology. Although IMS technology has matured over recent years, the link between microscopy imaging currently used by pathologists and MS-based molecular imaging has not been established.

Methods:

We adapted the Vanderbilt University Tissue Core workflow for IMS into a web-based system that facilitates remote collaboration. The platform was designed to perform within acceptable web response times for viewing, annotating, and processing high resolution microscopy images.

Results:

We describe a microscopy-driven approach to tissue analysis by IMS.

Conclusion:

The Pathology Interface for Mass Spectrometry is designed to provide clinical access to IMS technology and deliver enhanced diagnostic value.

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.

Genetic and chromosomal alterations in Kenyan Wilms Tumor

Wilms tumor (WT) is the most common childhood kidney cancer worldwide and poses a cancer health disparity to black children of sub-Saharan African ancestry. Although overall survival from WT at 5 years exceeds 90% in developed countries, this pediatric cancer is alarmingly lethal in sub-Saharan Africa and specifically in Kenya (36% survival at 2 years). Although multiple barriers to adequate WT therapy contribute to this dismal outcome, we hypothesized that a uniquely aggressive and treatment-resistant biology compromises survival further. To explore the biologic composition of Kenyan WT (KWT), we completed a next generation sequencing analysis targeting 10 WT-associated genes and evaluated whole-genome copy number variation. The study cohort was comprised of 44 KWT patients and their specimens. Fourteen children are confirmed dead at 2 years and 11 remain lost to follow-up despite multiple tracing attempts. TP53 was mutated most commonly in 11 KWT specimens (25%), CTNNB1 in 10 (23%), MYCN in 8 (18%), AMER1 in 5 (11%), WT1 and TOP2A in 4 (9%), and IGF2 in 3 (7%). Loss of heterozygosity (LOH) at 17p, which covers TP53, was detected in 18% of specimens examined. Copy number gain at 1q, a poor prognostic indicator of WT biology in developed countries, was detected in 32% of KWT analyzed, and 89% of these children are deceased. Similarly, LOH at 11q was detected in 32% of KWT, and 80% of these patients are deceased. From this genomic analysis, KWT biology appears uniquely aggressive and treatment-resistant.

Peptide spectra in Wilms tumor that associate with adverse outcomes

BACKGROUND

The 2013 Children's Oncology Group (COG) blueprint for renal tumor research challenges investigators to develop new, risk-specific biological therapies for unfavorable histology and higher-risk Wilms tumor (WT) in an effort to close a persistent survival gap and to reduce treatment toxicities. As an initial response to this call from the COG, we used imaging mass spectrometry to determine peptide profiles of WT associated with adverse outcomes.

MATERIALS AND METHODS

We created a WT tissue microarray containing 2-mm punches of formalin-fixed, paraffin-embedded specimens archived from 48 sequentially treated WT patients at our institutions. Imaging mass spectrometry was performed to compare peptide spectra between three patient groups as follows: unfavorable versus favorable histology, treatment success versus failure, and COG higher- versus lower-risk disease. Statistically significant peptide peaks differentiating groups were identified and incorporated into a predictive model using a genetic algorithm.

RESULTS

One hundred thirty-one peptide peaks were differentially expressed in unfavorable versus favorable histology WT (P < 0.05). Two hundred three peaks differentiated treatment failure from success (P < 0.05). Seventy-one peaks differentiated COG higher-risk disease from the very-low, low, and standard-risk groups (P < 0.05). These peaks were used to develop predictive models that could differentiate among patient groups 98.49%, 94.46%, and 98.55% of the time, respectively. Spectral patterns were internally cross-validated using a leave-20% out model.

CONCLUSIONS

Peptide spectra can discriminate adverse behavior of WT. After future external validation and refinement, these models could be used to predict WT behavior and to stratify intensity of chemotherapy regimens. Furthermore, peptides discovered in the model could be sequenced to identify potential risk-specific drug targets.