The prognostic significance of blastemal predominant histology in initially resected Wilms' tumors: a report from the Study Group for Pediatric Solid Tumors in the Kyushu Area, Japan

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.

Importance of COX-2 expression in Wilms' tumour: A preliminary study

OBJECTIVES

In Wilms' tumour (WT), secondary malignancies caused by the side effects of intensive treatments remain one of the important problems. Therefore, there is a need for new studies to identify low- and high-risk groups for WT and to improve the treatment regimens of children in the low-risk group. In our study, we aimed to determine the prognostic significance of the cyclooxygenase-2 (COX-2) biomarker in WT.

MATERIALS AND METHODS

Our study included 24 patients diagnosed with WT between January 2010 and December 2019. The correlation between COX-2 expression and significant prognostic parameters was investigated by studying the COX-2 antibody using the immunohistochemical method.

RESULTS

COX-2 expression was observed in 22 of the patients and it was more evident in the epithelial component. No significant correlation was observed between COX-2 positivity and prognostic parameters. There was also no statistically significant difference between the two groups regarding survival (P = .563).

CONCLUSIONS

In our study, no significant relationship was found between significant prognostic parameters and COX-2 expression. Since COX-2 expression was observed in almost all patients, we consider that the COX-2 pathway is effective during the development phase of WT.

The prognosis of prechemotherapy blastemal predominant histology subtype in Wilms tumor: A retrospective study in China

PURPOSE

This study aimed to retrospectively analyze survival outcomes for Chinese patients with prechemotherapy blastemal predominant histology type Wilms tumors (WTs).

METHODS

We collected and analyzed clinical data concerning patients aged <15 years with favorable histology (FH) WTs treated at the Sun Yat-Sen University Cancer Center from December 2005 to May 2016, based on the Children's Oncology Group protocol. Pathological specimens were collected through biopsy or surgical resection before initiation of chemotherapy. We analyzed survival outcomes involving different prechemotherapy histology subtypes.

RESULTS

We enrolled 97 patients with FH WTs (median follow-up, 71.5 months; range, 22.2-170.7). The total recurrence rate was 17.5%, and the subtype recurrence rates were as follows: blastemal predominant (45.5%), mixed (7.5%), epithelial (14.3%), and mesenchymal (9.5%) (P = .010). Five-year event-free survival (EFS) and overall survival (OS) rates were 84.9% and 81.4%, respectively. Respective 5-year EFS and OS rates for subtypes were as follows: blastemal predominant (54.5% and 68.2%), mixed (90.0% and 88.9%), epithelial (85.7% and 85.1%), and mesenchymal (90.5% and 94.7%). Multivariate survival analyses showed that the blastemal predominant subtype was an independent prognostic factor of EFS (P = .001) and OS (P = .017).

CONCLUSIONS

Our findings showed that prechemotherapy blastemal predominant WTs had higher recurrence and lower EFS and OS rates. Our findings suggested that, albeit with some deficiencies, blastemal predominant histology WT-diagnosed prechemotherapy may have prognostic relevance. Further research into other potential confounding variables are required to determine whether such patients warrant altered risk-stratified therapy.

Factores asociados a la sobrevida en pacientes con tumor de Wilms

Introducción. El tumor de Wilms es el segundo tumor abdominal más frecuente en la edad pediátrica y responde por más del 90 % de los tumores renales en pediatría. A pesar de que la sobrevida descrita es mayor del 90 %, en nuestro medio encontramos que solo alcanza al 70 %, por lo que deseamos evaluar cuáles son los factores asociados con dichos resultados desfavorables, con el fin de implementar medidas para mejorar la sobrevida de nuestros pacientes. Métodos. Se realizó un estudio observacional, transversal, en dos centros de alto nivel de atención, que incluyó una muestra de 84 pacientes menores de 15 años, con diagnóstico de tumor de Wilms. Resultados. Los factores que se asociaron significativamente con un aumento en la probabilidad de morir fueron: no completar el protocolo de quimioterapia, (OR 34; IC95% 3,7-312; p 0,000) y presentar recidiva tumoral (OR 35,7; IC95% 6,9-184; p 0,000). Otros factores que aumentaron esta probabilidad sin alcanzar a ser significativos, pero mostrando una evidente tendencia fueron: presentación bilateral (OR 4,1; IC95% 0,6-5,5; p 0,147), complicaciones quirúrgicas (OR 3,2; IC95% 0,7-14,6; p 0,136), compromiso de ganglios linfáticos en tomografía (OR 2,4; IC95% 0,7-8,4; p 0,139) y las metástasis a distancia (OR 2,5; IC95% 0,7-9; p 0,143). Discusión. La sobrevida de nuestros niños con tumor de Wilms es menor que la reportada en la literatura mundial, siendo la falla en terminar la quimioterapia, la recidiva y la necesidad de cirugía bilateral, los factores asociados con este desenlace.  

Texture Analysis to Differentiate Malignant Renal Tumors in Children Using Gray-Scale Ultrasonography Images

We assessed the feasibility of texture analysis to differentiate Wilms tumor, clear cell sarcoma and rhabdoid tumor of the kidney in children using gray-scale ultrasonography images. Children who had pre-operative renal ultrasonography images of the three tumors from January 2002 to February 2017 were retrospectively included as the test set, and children with the same criteria from March 2017 to December 2018 were included as the validation set. From histogram and second-order statistics, features were compared between the tumors, and diagnostic performances were assessed. Among a total of 32 children (24 children with Wilms tumors, five children with clear cell sarcomas and three children with rhabdoid tumors) from the test set, features from the second-order statistics showed an area under the curve greater than 0.89 for differentiating Wilms tumor from the others. These features aided in the differentiation of tumor type in the two children with Wilms tumors in the validation set. Therefore, texture analysis from gray-scale ultrasonography images can be used to differentiate Wilms tumors from clear cell sarcomas and rhabdoid tumors in children.

Quantitative RT-PCR-based miRNA profiling of blastemal Wilms' tumors from formalin-fixed paraffin-embedded samples

Blastemal Wilms' tumors are associated with poor chemo-responsiveness and an adverse prognosis. Our aim was to contribute to the miRNA profiling of the disease, while demonstrating the value of archived formalin-fixed, paraffin-embedded (FFPE) samples as miRNA sources. MiRNA was extracted from tumor and normal tissues of 8 patients diagnosed with blastemal Wilms' tumor in Hungary. A quantitative real-time PCR-based protocol was used to identify miRNAs of interest and study the expression of selected miRNAs in all samples. Profiling of miRNA expression from FFPE samples turned out to be cost-effective in Wilms' tumor, as most miRNAs (including miRNA-194-5p, which was studied in all patients) showed expression alterations similar to the ones reported in the literature. MiR-184 expression was found to be lower than in previous studies, while the downregulation of miR-203a is a novel finding. MiR-184 may be downregulated in a subset of blastemal and other Wilms' tumors. A loss of miR-203a may or may not be specific to blastemal cells, but available evidence hints at its importance in the pathogenesis of Wilms' tumor. It should be considered for inclusion in future studies of miRNA expression.

Blastemal predominant type Wilms tumor in Japan: Japan Children's Cancer Group

BACKGROUND

Persistence of blastemal components after chemotherapy is a marker of poor outcome in Wilms tumor (WT). Recent reports from local Japanese areas have described pre-chemotherapy blastemal predominant type WT to also be a risk factor for relapse. The significance, however, of blastemal predominant WT remains to be evaluated in a larger study. This study retrospectively evaluated the prognostic significance of pre-chemotherapy blastemal predominant type WT in the Japan Wilms tumor Study (JWiTS) trials.

METHODS

The JWiTS trial (1996-2013) was a prospective, single-arm study. The outcomes of blastemal predominant type WT were retrospectively evaluated compared with non-blastemal type WT excluding anaplasia between 1996 and 2013. Relapse-free survival (RFS) and overall survival (OS) were estimated.

RESULTS

Of 319 primary renal tumors diagnosed by the central pathology review system, advanced stage of pre-chemotherapy blastemal predominant type WT (n = 53; 16.1%) occurred more frequently in older children than non-blastemal type WT (n = 225), and was especially frequent in female patients registered in the JWiTS trials. No significant difference in 10 years RFS and OS (78.8% vs 84.5; P = 0.201) or in 10 years RFS and OS (89.3% vs 93.5; P = 0.45) was seen between pre-chemotherapy blastemal predominant type and non-blastemal type WT.

CONCLUSIONS

Relapse-free survival and OS are not significantly different between pre-chemotherapy blastemal predominant type and non-blastemal type WT.

Higher incidence of surgery-related complications in Wilms tumor nephrectomy from clinical records analysis compared with central database registration

BACKGROUND/OBJECTIVES

Central database registrations are widely used tools for assessment of clinical results, but their reliability is subject to debate. The aim of this study is to evaluate the reliability of central database registration for Wilms tumor (WT) nephrectomy-related complications.

DESIGN/METHODS

All Dutch patients undergoing WT nephrectomy according to the International Society of Paediatric Oncology (SIOP) 2001 protocol between 2001 and 2013 were evaluated. Results from the central database were analyzed and compared with data found via individual medical records analysis (gold standard).

RESULTS

A total of 179 patients were included. Fourteen (7.8%) patients with a total of 17 complications were identified in the central database. The medical records revealed that 33 (18.4%) of patients had undergone a total of 41 complications (P < 0.001). Operative complications were similar between the groups (P = 0.157). Eleven short-term complications were noted in the central database versus 27 in the medical records (P = 0.059). Significantly more long-term complications, namely, adhesive small-bowel obstruction, were noted from the medical records compared with the central database (7 vs 1, respectively, P < 0.001). Postoperative chemotherapy was significantly delayed by on average 6 days (P < 0.0001) in patients with complications. No significant effect of complications on event-free survival, overall survival, or the relapse rate was recorded.

CONCLUSION

Central database registrations underestimate the incidence of surgery-related complications after WT nephrectomy and need to be regarded with caution.

Glypican-3 mRNA expression level in Wilms tumor: correlation with histological type, stage, and outcome

PURPOSE

To correlate expression of Glypican-3 in Wilms tumor with histopathology, stage, and outcome.

METHODS

Glypican-3 mRNA expression by real-time PCR on tumor and normal germline samples from 75 fresh nephrectomies for Wilms tumor with fold change after normalization against GAPDH was compared. Survival analysis for event-free and overall survival (EFS, OS) with 2-year follow-up for Glypican-3 overexpression (>1.5 times) and clinicopathological parameters was performed.

RESULTS

Glypican-3 was overexpressed in 37/75 (49.3%). It was overexpressed in 77% (10/13) cases with blastema predominance or anaplastic histology, as compared to 44% of other histologies (27/62) (p = 0.03). OS was 73 and 93%, respectively (p = 0.016), for those with and without GPC-3 overexpression. EFS was not significantly different with Glypican-3 overexpression (p = 0.11). All 5 deaths among blastema predominant tumors and 4/5 deaths among triphasic tumors had overexpressed Glypican-3. Most deaths in Stage IV, Stage III, and Stage I + II (5/7, 3/3, 1/1) had GPC-3 overexpression. On multivariate analysis, only histology and stage were found to have independent prognostic value.

CONCLUSION

Glypican-3 overexpression in Wilms tumor correlates with poor OS on univariate analysis. However, only histology and stage have independent prognostic value. Glypican-3 levels may help to stratify intermediate outcome histology (triphasic) and Stage III Wilms tumors.

Management of pediatric renal tumor: Past and future trials of the Japan Wilms Tumor Study Group

The Japan Wilms Tumor Study group (JWiTS) was founded in 1996 to improve outcomes for children with renal tumor in Japan, and a nationwide multicenter cooperative study was initiated thereafter. JWiTS-1 (1996-2005) was analyzed, and JWiTS-2 (2005-2014) is now under analysis; the following problems have been identified and used to decide future study protocol: (i) there has been a decline in survival rate for patients with rhabdoid tumor of the kidney (RTK) and new treatment strategies are required; (ii) the survival rate for bilateral Wilms tumors (BWT) has improved, but results for renal preservation are unsatisfactory; (iii) the prognosis of stage IV favorable nephroblastoma is very good, suggesting that the current protocols provide overtreatment, particularly for patients with lung metastasis; and (iv) no effective biological risk factors exist for predicting the outcome of Wilms tumor, and a study of the genetic changes of these tumors is necessary to determine biological markers for use in risk classification. To solve these issues, the development of a new risk classification of pediatric renal tumors is required. In addition, different study protocols should be developed according to the risk-based classification of the patients. Further, a new study protocol for BWT began in 2015, and new study protocols are being prepared for RTK, and for Wilms tumor with lung metastasis. In addition, an analysis of biological markers with regard to risk classification is to be performed. Furthermore, to create new protocols for patients with rare renal tumors, international collaboration with Children's Oncology Group and International Society of Pediatric Oncology is necessary.

A rare occurrence of neonatal nephroblastoma in sub-saharan Africa: a case report and management in a resource-constrained region

Neonatal nephroblastoma has been rarely reported in African neonate. A premature newborn (a 5-day-old male) was transferred with a history of neonatal abdominal mass. Ultrasonography revealed 75×46 mm, well-defined mass with mixed echogenicity replacing the right kidney. The patient underwent right radical nephrectomy and the tumor was confirmed to be a blastemal predominant Wilms’ tumor by the histopathological examination and has an unfavorable prognosis. The child died secondary to multiple organ failure, three days after surgery. Our case report serves to remind us the need to bear in mind the possibility of the diagnosis of neonatal nephroblastoma in neonate with renal mass.

Pathological Features of the Unilateral Favorable Histology Nephroblastoma with Relapse

PURPOSE

To evaluate the pathological features of the primary lesion in patients with relapse of unilateral favorable histology nephroblastoma.

MATERIAL AND METHODS

Fifty-eight patients with unilateral favorable histology nephroblastoma who underwent initial nephrectomy before chemotherapy were categorized into one of two groups: the nonrelapsed group (n = 52) and the relapsed group (n = 6). The histological subtypes of both groups and pathological features of the relapsed group were re-evaluated retrospectively.

RESULTS

The histological subtypes of all relapsed cases were classified as blastemal predominant. In three of six cases with relapse, sheets of spindle-shaped blastemal cells that were histologically reminiscent of synovial sarcoma were predominant (massive sarcomatoid pattern).

CONCLUSIONS

The histological blastemal predominant subtype of nephroblastoma is a strong indicator of relapse. In particular, the blastemal predominant subtype with massive sarcomatoid pattern may have a higher risk of relapse.

Intra- and interobserver variability of whole-tumour apparent diffusion coefficient measurements in nephroblastoma: a pilot study

BACKGROUND

The apparent diffusion coefficient (ADC) is potentially useful for assessing treatment response in nephroblastoma (Wilms tumour). However the precision of ADC measurements in these heterogeneous lesions is unknown.

OBJECTIVE

To assess intra- and interobserver variability of whole-tumour ADC measurements in viable parts of nephroblastomas at diagnosis and after preoperative chemotherapy.

MATERIALS AND METHODS

We included children with histopathologically proven nephroblastoma who had undergone MRI with diffusion-weighted imaging before and after preoperative chemotherapy. Three independent observers performed whole-tumour ADC measurements of all lesions, excluding non-enhancing areas. One observer evaluated all lesions on two occasions. We performed analyses using Bland-Altman plots and concordance correlation coefficient (CCC) calculations with 95% limits of agreement for median ADC, difference between pre- and post-chemotherapy median ADC (ADC shift) and percentage of pixels with ADC values <1.0 × 10(-3) mm(2)/s.

RESULTS

In 22 lesions (13 pretreatment and 9 post-treatment) in 10 children the interobserver variability in median ADC and ADC shift were within the interval of approximately ±0.1 × 10(-3) mm(2)/s (limits of agreement for median ADC ranged -0.08-0.11 × 10(-3) mm(2)/s and for ADC-shift -0.11-0.09 × 10(-3) mm(2)/s). The interobserver variability for percentage of low-ADC pixels was larger and also biased. The calculated CCC confirmed good intra- and interobserver agreement (ρ-c ranging from 0.968 to 0.996).

CONCLUSION

Measurements of whole-tumour ADC values excluding necrotic areas seem to be sufficiently precise for detection of chemotherapy-related change.

SIX2 Effects on Wilms Tumor Biology

Wilms tumor (WT) blastema retains gene expression profiles characteristic of the multipotent nephron progenitor pool, or cap mesenchyme (CM), in the developing kidney. As a result, WT blastema and the CM are believed to represent contextual analogues of one another. Sine oculis homeobox 2 (SIX2) is a transcription factor expressed specifically in the CM, provides a critical mechanism for CM self-renewal, and remains persistently active in WT blastema, although its purpose in this childhood malignancy remains unclear. We hypothesized that SIX2, analogous to its function in development, confers a survival pathway to blastema, the putative WT stem cell. To test its functional significance in WT biology, wild-type SIX2 was overexpressed in the human WT cell line, WiT49. After validating this model, SIX2 effects on anchorage-independent growth, proliferation, invasiveness, canonical WNT pathway signaling, and gene expression of specific WNT pathway participants were evaluated. Relative to controls, WiT49 cells overexpressing SIX2 showed significantly enhanced anchorage-independent growth and early-passage proliferation representing surrogates of cell survival. Interestingly, overexpression of SIX2 generally repressed TCF/LEF-dependent canonical WNT signaling, which activates and coordinates both differentiation and stem pathways, but significantly heightened canonical WNT signaling through the survivin promoter, a mechanism that exclusively maintains the stem state. In summary, when overexpressed in a human WT cell line, SIX2 enhances cell survival and appears to shift the balance in WNT/β-catenin signaling away from a differentiation path and toward a stem cell survival path.

Malignant renal tumors in childhood: report of 54 cases treated at a single institution

BACKGROUND

Wilms tumor is the most common primary renal malignancy occurring in childhood. Significant improvement has been made in the treatment of children with Wilms tumor. However, the treatment of patients with non-Wilms renal tumors remains challenging.

METHODS

Between 1991 and 2010, 70 children with renal tumors were diagnosed at a single institution. Fifty-four patients were histologically confirmed and divided into three groups, including 42 Wilms tumors, seven clear cell sarcomas of kidney, and five malignant rhabdoid tumors. Most patients underwent unilateral nephrectomy and lymph node sampling followed by adjuvant chemotherapy. Twenty-one of these patients subsequently received radiotherapy.

RESULTS

During follow-up, 12 patients died of progressive disease and one died of operative mortality. One patient with unilateral pleural metastases subsequently underwent hematopoietic stem cell transplantation. The median survival time of all patients was 88 months. Children under 2 years of age at diagnosis with Wilms tumor or clear cell sarcoma of kidney had an excellent survival rate of 100% compared to the 0% survival rate of MRT.

CONCLUSION

Younger age at diagnosis bore a better prognosis than did older age, whereas a diagnosis of malignant rhabdoid tumor portended a worse prognosis. Younger patients and appropriate treatment may have contributed to the improved prognosis of clear cell sarcoma of kidney.

Repeat nephron-sparing surgery for children with bilateral Wilms tumor

BACKGROUND

Renal insufficiency is a significant complication of Wilms tumor treatment in the 5% with bilateral disease. Nephron-sparing surgery (NSS) is recommended after neoadjuvant chemotherapy initially. However, the role of NSS in recurrent disease is unknown. We reviewed our experience to assess the feasibility and oncologic and functional outcomes of repeat NSS for children with recurrent disease.

METHODS

A retrospective review was performed of all children treated at our institution for bilateral, favorable histology (FH) Wilms tumor. Patients undergoing repeat NSS for locally recurrent disease were identified. The outcomes evaluated included tumor recurrence, renal function, and patient survival.

RESULTS

Since 2001, 36 children with bilateral FH Wilms tumor have been treated at our institution. Eight patients (22%) underwent repeat NSS for locally recurrent disease. Two patients had a second local recurrence and underwent a third NSS. Six patients are alive without disease (75%) with an average follow-up of 4.5years. Two patients have died, each with blastemal-predominant histology at repeat NSS. The surviving patients have normal renal function, although two patients require medical management of hypertension.

CONCLUSIONS

Our experience suggests that repeat NSS for local recurrence of FH bilateral Wilms tumor is feasible and affords acceptable oncologic outcome with preservation of renal function. However, more aggressive therapy may be required for patients whose recurrence has blastemal-predominant histology, given the poor outcome for these patients in our series.

New risk classification is necessary in the treatment of Wilms tumor

The National Wilms Tumor Group (NWTS) presented the clinicopathological findings predicting relapse in children with stage III favorable-histology (FH) Wilms tumor (WT) treated in the NWTS-5 study. They reported that lymph node involvement and a microscopic residual tumor were highly predictive of the EFS and OS, and concluded that patients with different stage III criteria may receive different therapies. These data suggest that the current risk classification of WT is not satisfactory. Like other pediatric tumors, such as neuroblastoma and rhabdomyosarcoma, more systemic and detailed risk classification for WT should be established using various clinical and biological markers. In the previous therapeutic protocols for WT, no biological marker was used for risk classification. Therefore, it is important to identify effective biological markers related to the prognosis of WT. The presence of LOH at 1p and 16q was associated with a worse EFS and OS, and was used for risk classification to choose the treatment regimens used in the recent COG clinical trials. There are some candidate prognostic factors that can be used in the future risk classification of WT, such as the methylation status of RASSF1A. A worldwide cooperative study should be conducted in the future to confirm whether these factors are useful in the risk classification. The goal of treatment for WT is to identify approaches that provide excellent outcomes for children with low-risk tumors without the need for chemotherapy or XRT. Conversely, more aggressive therapy may be used for children with high-risk tumors in an effort to improve their survival. To meet these goals, a new effective risk classification for WT should be established via collaborative clinical trials.