Background/Objectives: Neuroblastoma cells are phenotypically plastic, transitioning between mesenchymal and adrenergic states. Core functional genes (e.g., YAP1) mark the mesenchymal state, which is linked to unfavorable prognosis. We and others previously demonstrated relapse-specific Hippo-YAP pathway activation in matched primary/relapsed neuroblastomas. Here we explored the role of YAP1 in neuroblastoma aggressiveness and response to therapy. Methods: RT-qPCR and immunoblotting assessed YAP1 expression in neuroblastoma cell lines. RNA-sequencing detected YAP1-dependent gene signatures in Tet-ON SK-N-AS and SH-EP neuroblastoma cell models expressing wildtype YAP1 or constitutively activated YAP1S127A. Data from cell models were compared with our published YAP1 expression data from neuroblastomas. Efficacy of commonly used chemotherapeutics was comparatively analyzed in the cell models. Results: YAP1 expression showed marked variability across a panel of neuroblastoma cell lines, assessed by mRNA analysis in 10 cell lines and protein analysis in a subset of 9 cell lines. RNA sequencing in constitutively activated YAP1S127A mutant and wildtype YAP1 models detected 2162 and 1837 significantly differentially expressed genes in the SK-N-AS and SH-EP backgrounds, respectively. Continuously activating YAP1 in SK-N-AS cells upregulated mesenchymal signature genes and mesenchymal-associated transcription factors. Gene expression influenced by YAP1 activity in the cell models significantly overlapped with YAP1-associated genes (e.g., CYR61 and SPRY4) in published tumor data. Functionally, YAP1S127A expression rendered neuroblastoma cells resistant to chemotherapy. Conclusions: Findings corroborate the idea of a mechanistic role for YAP1 in neuroblastoma adrenergic to mesenchymal reprogramming and therapy resistance. The YAP1-mediated plastic switch towards a mesenchymal expression state in neuroblastoma cells may provide the molecular basis for novel therapeutic avenues.

Accurate detection of macroscopic residual disease after neuroblastoma resection is essential for postoperative treatment decisions, including radiotherapy. Standard imaging follow-up is often performed at a time point when postoperative and therapy-related changes may hamper reliable differentiation between residual disease and reactive findings. To assess inter-reader agreement and the diagnostic accuracy of early postoperative magnetic resonance imaging (MRI) for detecting residual disease after neuroblastoma surgery. This retrospective single-center study included patients with histologically confirmed neuroblastic tumors who underwent surgical resection at a reference center and received standardized early postoperative MRI with adequate preoperative imaging. Two independent pediatric radiologists, blinded to all clinical data, assessed all examinations. A hierarchical multimodal reference standard was established based on surgical reports including expert consensus between a senior pediatric radiologist and a pediatric surgeon, and follow-up imaging (median follow-up 33 months). Thirty-nine patients (median age 46 months), predominantly with International Neuroblastoma Staging System (INSS) stage 4 neuroblastoma, were included; all patients had at least one image-defined risk factor. MRI was performed at a mean of 8±5 days after surgery. Residual disease was identified in 14 patients and confirmed by the reference standard. Five residual diseases were expected by the surgeons (median volume 8 ml), whereas nine were unexpected and small (median volume 1 ml). Diagnostic accuracy were 95

BACKGROUND:The management of clinically apparent single lesions or oligofocal nephroblastomatosis, a facultative precursor of nephroblastoma, remains debated. METHODS:We retrospectively analyzed 37 patients with clinically apparent single or oligofocal nephroblastomatosis (two to three lesions per kidney) among 2347 patients registered between 1993 and 2014 in the SIOP93-01/GPOH and SIOP2001/GPOH renal tumor studies. RESULTS:Of the 37 patients, 23 had a single lesion, and 14 had oligofocal disease; 65% had a clinically apparent and/or molecularly diagnosed cancer predisposition syndrome, and 27% bilateral involvement. Preoperative chemotherapy was administered to 62%, primary surgery to 32%, and chemotherapy without surgery to 5%. Nephron-sparing surgery was performed in 71%. In oligofocal cases, preoperative chemotherapy led to significant tumor volume reduction. Prognosis was favorable: 10-year event-free, nephroblastoma-free, and overall survival rates were 77.4%, 80.7%, and 92.0%, respectively. Of 35 patients who underwent definitive surgery, 26 received short postoperative treatment (≤4 weeks) or a watch-and-wait approach (W&W). Three patients (11.5%) developed nephroblastoma, two of whom were successfully salvaged. Ten-year nephroblastoma-free survival was 74.1%, 90.0%, and 100% for short, W&W, and long postoperative treatment (>4 weeks), respectively. All 12 patients undergoing primary definitive surgery remained nephroblastoma-free. CONCLUSION:Short postoperative chemotherapy or W&W is a safe option for patients with single or oligofocal nephroblastomatosis in complete remission, provided they undergo close ultrasound monitoring. The modest relapse risk, manageable with salvage therapy, must be weighed against the toxicity of prolonged treatment, especially in infants. Both primary and delayed surgery are viable strategies.

PURPOSE:The International Society of Paediatric Oncology-Renal Tumour Study Group (SIOP-RTSG) classifies blastemal-type Wilms tumor (WT) after preoperative chemotherapy as high-risk (HRWT). It remains unresolved whether residual absolute volume of blastema (AVB) functions as an independent prognostic factor across WT subtypes. MATERIALS AND METHODS:AVB was calculated from preoperative tumor volume, necrosis percentage, and viable blastema using prospectively collected data from 3,459 patients with unilateral WT treated in the SIOP WT 2001 study between 2001 and 2018. Martingale residual plots defined AVB thresholds discriminating survival in localized HRWT, intermediate-/low-risk WT (IRWT/LRWT), and metastatic WT (stage IV). Complete AVB data were available for 1,802 patients (51.2%); 298 (16.5%) had stage IV disease. Of 1,504 patients with localized WT, 265 (17.6%) had HRWT, 1,203 (79.9%) had IRWT, and 36 (2.4%) had LRWT. RESULTS:Multivariable Cox regression adjusted for age, sex, and local stage confirmed significantly worse survival for patients exceeding these AVB thresholds: (1) IRWT (≥20 mL): Hazard ratio for event-free survival (EFS) 2.93 (95% CI, 2.08 to 4.12) and overall survival (OS) 2.76 (95% CI, 1.32 to 5.77); (2) HRWT (≥100 mL): EFS 2.89 (95% CI, 1.59 to 5.26) and OS 3.25 (95% CI, 1.45 to 7.27); and (3) stage IV (≥10 mL): EFS 5.78 (95% CI, 3.65 to 9.17) and OS 4.59 (95% CI, 2.57 to 8.17). Patients above these thresholds had significantly lower 2-year EFS (P < .0001). In stage II to III IRWT patients with AVB ≥20 mL, those treated with doxorubicin had superior EFS versus those without (87.6%, 95% CI, 81.5 to 94.1 v 69.2%, 95% CI, 59.8 to 80.1; P = .0064). CONCLUSION:AVB after preoperative chemotherapy is a strong, independent predictor of both EFS and OS in WT across risk groups. An AVB of ≥20 mL identifies a clinically relevant subset of patients with IRWT who may benefit from intensified therapy with doxorubicin. These findings support the use of AVB as a stratification criterion in future SIOP-RTSG protocols.

Surgery is a corner stone of treatment in children with nephroblastoma. Over recent years, the evolution of surgical guidelines has added to the improvement of treatment results in affected children. Minimally invasive surgery (MIS) has been described as part of this evolution. The present article summarises the current recommendations for MIS in nephroblastoma based on the relevant global treatment protocols.

Background/Objectives: In bilateral nephroblastoma and high-risk neuroblastoma in children with extensive tumor involvement of the renal vessels or pedicle, complete tumor resection with preservation of healthy renal tissue is not feasible with in situ nephron-sparing surgery or vascular replacement. The aim of this study was to present our experience with ante situ tumor resection and renal autotransplantation (RATX) in these children. Methods: A retrospective study of children with bilateral nephroblastoma and high-risk neuroblastoma who underwent tumor resection and RATX at an international referral center for pediatric surgical oncology between 2006 and 2024 was performed. RATX was performed by transection of renal vessels, ante situ mobilization, and perfusion of the kidney with Bretschneider’s solution. Tumor resection was performed on a bloodless kidney under hypothermia. Results: Ante situ tumor resection and RATX were performed at a median age of 36 months (range 13–62) in 4 children with bilateral nephroblastoma and 4 children with high-risk neuroblastoma. Complete tumor resection was achieved in all patients. One patient with neuroblastoma died of sepsis after 14 days. The 7 surviving patients showed no evidence of disease and normal to slightly decreased glomerulofiltration rates at a median follow-up of 20 months (range 3–155). Limitations include the retrospective design, small sample size, and heterogeneity of the study population due to very rare indication. Conclusions: Ante situ tumor resection and RATX is a feasible surgical approach for children with multifocal bilateral nephroblastoma or high-risk neuroblastoma who are ineligible for in situ nephron-sparing surgery or vascular reconstruction.

Non-invasive differentiation of paediatric kidney tumours is particularly important in the SIOP-RTSG protocols, which recommend pre-operative chemotherapy without histological confirmation. The identification of clinical and tumour-related parameters may enhance diagnostic accuracy. Age, metastases, and tumour volume (TV) were retrospectively analysed in 3306 patients enrolled in SIOP/GPOH 9, 93-01, and 2001 including Wilms tumour (WT), congenital mesoblastic nephroma (CMN), clear cell sarcoma (CCSK), malignant rhabdoid tumour of the kidney (MRTK), and renal cell carcinoma (RCC). WT was diagnosed in 2927 (88.5%) patients followed by CMN 138 (4.2%), CCSK 126 (3.8%), MRTK 58 (1.8%) and RCC 57 (1.7%). CMN, the most common localized tumour (71.6%) in patients younger than 3 months of age, was diagnosed earliest and RCC the latest (median age [months]: 0 and 154, respectively) both associated with significantly smaller TV (median TV [mL]: 67.2 and 45.0, respectively). RCC occurred in >14% of patients older than 120 months or older than 84 months with TV <100 mL. Receiver operating characteristic analyses discriminated WT from CMN, RCC and MRTK regarding age (AUC = 0.976, 0.929 and 0.791) and TV (AUC = 0.768, 0.813 and 0.622). MRTK had the highest risk of metastasis (37.9%) despite young age, whereas the risk of metastasis increased significantly with age in WT. Age and TV at diagnosis can differentiate WT from CMN and RCC. MRTK must be considered for metastatic tumours at young age. Identification of CCSK without histology remains challenging. Combined with MRI-characteristics, including diffusion-weighted imaging, and radiomics and liquid biopsies in the future, our approach allows optimization of biopsy recommendations and prevention of misdiagnosis-based neoadjuvant treatment.

Background & AimsChildren with chronic intestinal failure (IF) require a long-term central venous catheter (CVC) for provision of parenteral nutrition. Vascular, mechanical and infectious complications such as central line-associated bloodstream infections (CLABSI) may lead to progressive loss of venous access sites. Handling and management of CVCs therefore play an important role. Our vascular rehabilitation concept (VRC) is a core component of our intestinal rehabilitation program (IRP) and consists of an education program, optimization of skin care, catheter fixation and lock solution, and the use of hybrid technique for catheter placement.Aim of this study is to analyse the effectiveness of our VRC on CLABSI rates and need for CVC replacements.MethodsRetrospective analysis of all children treated in our IRP that were followed up between 2018 and 2023.ResultsA total of 117 children with chronic IF could be included for analysis of 248864 catheter days (CD). 91 patients were referred from other hospitals (127117 CD before and 89359 CD after entry into our IRP). Children receiving primary care at our IRP (32388 CD) showed a significantly lower CLABSI and line replacement rate than patients referred from external centers (p<0.001). After entering our IRP, CLABSI rates and need for CVC replacements per 1000 CD decreased significantly in referred patients: 1.17 to 0.26 and 1.75 to 0.59, respectively (p<0.001).ConclusionManagement of paediatric chronic IF patients by an IRP with a vascular rehabilitation concept significantly lowers the rate of CLABSI episodes and the need for catheter replacements.

Objective: This study aimed to identify parameters that allow the estimation of tumor-infiltrated lymph nodes (LN) after pretreatment for unilateral Wilms tumor (WT). Summary Background Data: Complete tumor resection with removal of regional LN is always necessary. Positive LNs require local irradiation influencing benefits in case of NSS in long-term follow-up. Clinical and tumor-related data available at the time of surgery in combination with intraoperative findings (IAF) were used to estimate the LN status during surgery. Methods: Altogether, 2115 patients with unilateral WT were prospectively enrolled in SIOP-93-01 / GPOH and SIOP-2001 / GPOH over a period of 30 years (1993–2023). LN infiltration by tumor was calculated for age, sex, metastases at diagnosis, tumor volume (TV), TV shrinkage, and intraoperative findings (IAF) using logistic regression models. Results: Age ≥48 months (P<0.001, OR 2.17, CI 1.57 – 3.00), TV at diagnosis ≥300 (P<0.001, OR 3.72, CI 2.37 – 5.85), metastasis at diagnosis (P<0.001, OR 6.21, CI 4.47 – 8.62) and IAF (>1: P<0.001, OR 3.54, CI 2.13 – 5.88) correlated with positive LNs. TV shrinkage was not predictive of positive LN. Three flow charts were developed based on age, TV at diagnosis, metastasis, and IAF. These flowcharts defined risks between 0% and 41.5% for LN infiltration by tumor. Conclusions: The combination of age, TV at diagnosis, and metastasis with IAF allows the estimation of the frequency of positive LNs, which may help surgeons deciding about NSS.

Solid tumors of the cervicothoracic junction, the posterior mediastinum, or bilateral dorsal thoracic tumors represent a challenge in pediatric surgical oncology. The aim of this study was to evaluate trap-door thoracotomy and clamshell thoracotomy as surgical approaches. A single-center retrospective study of children with solid tumors in these specific localizations was performed. From 2015 to 2023, 26 children (17 girls; 9 boys) were treated at a median age of 54 months (range 8–229). Tumor resection was performed for neuroblastoma (n = 11); metastatic disease (n = 7); malignant rhabdoid tumor (n = 4); Ewing sarcoma (n = 1); inflammatory myofibroblastic tumor (n = 1); rhabdomyosarcoma (n = 1); and neurofibroma (n = 1). The surgical goal of macroscopic complete excision was achieved in all of the 14 children who underwent trap-door thoracotomy and in 11 of the 12 children who underwent clamshell thoracotomy. There were no major complications. At a median follow-up of 8 months (range 0–60), the disease was under local control or in complete remission in 66.7% of the children. In conclusion, surgical resection of solid tumors of the cervicothoracic junction in children can be performed safely and successfully with trap-door thoracotomy and with clamshell thoracotomy for posterior mediastinal or bilateral dorsal thoracic tumors.

OBJECTIVES:Paediatric patients with intestinal failure (IF) are at risk for both gastrointestinal (GI) and systemic complications, thus depending on a functioning network of multidisciplinary care. Data on the clinical impact of coronavirus disease 2019 (COVID-19) or the pandemic-related restrictions are limited. We aimed to analyse the clinical course of COVID-19 in children with IF, and to evaluate the perceived impact of the COVID-19 pandemic on IF patients and their caregivers by analysing quality of life (QoL), health-related QoL (HRQoL) and health care. METHODS:Children with IF presenting at our intestinal rehabilitation centre were enrolled and interviewed about test-proven COVID-19 infection. A standardised questionnaire was offered to all caregivers of IF patients and to two control groups (children with inflammatory bowel disease and gastrointestinal healthy children). RESULTS:Between December 2020 and November 2022, 25 out of 127 patients with IF contracted COVID-19. Forty-eight per cent had GI symptoms, 32% required additional intravenous fluids and 20% were hospitalized. Only 25% of vaccinated children showed signs of GI dysfunction, compared to 52% of unvaccinated children. Analysis of 93 questionnaires showed a negative impact on QoL and HRQoL (>66.7% and >27.8%, respectively). IF patients frequently experienced restrictions in health care, including appointments, services and supply of parenteral nutrition or medications. Caregiver burden increased significantly more often in caregivers of children with IF (p = 0.007). CONCLUSIONS:Paediatric patients with IF contracting COVID-19 have an increased risk for GI dysfunction which may be alleviated by vaccination. Children and their caregivers were highly burdened by pandemic-related restrictions and reductions in health care provision.

The pretreatment International Neuroblastoma Risk Group Staging System (INRGSS) discriminates localized tumors L1/L2 depending on the absence/presence of image‐defined risk factors (IDRFs) at diagnosis. Referring to this new staging system, we assessed initial imaging of localized thoracic neuroblastoma (NB) and ganglioneuroma (GN) and the extent of initial tumor resection.

Purpose: The purpose of our study was to evaluate the association between the [18F]FDG standard uptake value (SUV) and the apparent diffusion coefficient (ADC) in neuroblastoma (NB) by voxel-wise analysis. Methods: From our prospective observational PET/MRI study, a subcohort of patients diagnosed with NB with both baseline imaging and post-chemotherapy imaging was further investigated. After registration and tumor segmentation, metabolic and functional tumor volumes were calculated from the ADC and SUV values using dedicated software allowing for voxel-wise analysis. Under the mean of thresholds, each voxel was assigned to one of three virtual tissue groups: highly vital (v) (low ADC and high SUV), possibly low vital (lv) (high ADC and low SUV), and equivocal (e) with high ADC and high SUV or low ADC and low SUV. Moreover, three clusters were generated from the total tumor volumes using the method of multiple Gaussian distributions. The Pearson’s correlation coefficient between the ADC and the SUV was calculated for each group. Results: Out of 43 PET/MRIs in 21 patients with NB, 16 MRIs in 8 patients met the inclusion criteria (PET/MRIs before and after chemotherapy). The proportion of tumor volumes were 26%, 36%, and 38% (v, lv, e) at baseline, 0.03%, 66%, and 34% after treatment in patients with response, and 42%, 25%, and 33% with progressive disease, respectively. In all clusters, the ADC and the SUV correlated negatively. In the cluster that corresponded to highly vital tissue, the ADC and the SUV showed a moderate negative correlation before treatment (R = −0.18; p < 0.0001) and the strongest negative correlation after treatment (R = −0.45; p < 0.0001). Interestingly, only patients with progression (n = 2) under therapy had a relevant part in this cluster post-treatment. Conclusion: Our results indicate that voxel-wise analysis of the ADC and the SUV is feasible and can quantify the different quality of tissue in neuroblastic tumors. Monitoring ADCs as well as SUV levels can quantify tumor dynamics during therapy.

detailed information to material and Methods

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(1) Background: The study aimed to investigate the influence of MRI-defined residual disease on local tumor control after resection of neuroblastic tumors in patients without routine adjuvant radiotherapy. (2) Methods: Patients, who underwent tumor resection between 2009 and 2019 and received a pre- and postoperative MRI, were included in this retrospective single-center study. Measurement of residual disease (RD) was performed using standardized criteria. Primary endpoint was the local or combined (local and metastatic) event free survival (EFS). (3) Results: Forty-one patients (20 female) with median age of 39 months were analyzed. Risk group analysis showed eleven low-, eight intermediate-, and twenty-two high-risk patients (LR, IR, HR). RD was found in 16 cases by MRI. A local or combined relapse or progression was found in nine patients of whom eight patients had RD (p = 0.0004). From the six patients with local or combined relapse in the HR group, five had RD (p = 0.005). Only one of 25 patients without RD had a local event. Mean EFS (month) was significantly higher if MRI showed no residual tumor (81 ± 5 vs. 43 ± 9; p = 0.0014) for the total cohort and the HR subgroup (62 ± 7 vs. 31 ± 11; p = 0.016). (4) Conclusions: In our series, evidence of residual tumor, detectable by MRI, was associated with insufficient local control, resulting in relapses or local progression in 50% of patients. Only one of the patients without residual tumor had a local relapse.

PURPOSE Patients with relapsed high-risk neuroblastoma (rHR-NB) have a poor prognosis. We hypothesized that graft-versus-neuroblastoma effects could be elicited by transplantation of haploidentical stem cells (haplo-SCT) exploiting cytotoxic functions of natural killer cells and their activation by the anti-GD2 antibody dinutuximab beta (DB). This phase I/II trial assessed safety, feasibility, and outcomes of immunotherapy with DB plus subcutaneous interleukin-2 (scIL2) after haplo-SCT in patients with rHR-NB. METHODS Patients age 1-21 years underwent T-/B-cell–depleted haplo-SCT followed by DB and scIL2. The primary end point ‘success of treatment’ encompassed patients receiving six cycles, being alive 180 days after end of trial treatment without progressive disease, unacceptable toxicity, acute graft-versus-host-disease (GvHD) ≥grade 3, or extensive chronic GvHD. RESULTS Seventy patients were screened, and 68 were eligible for immunotherapy. Median number of DB cycles was 6 (range, 1-9). Median number of scIL2 cycles was 3 (1−6). The primary end point was met by 37 patients (54.4%). Median observation time was 7.8 years. Five-year event-free survival (EFS) and overall survival from start of trial treatment were 43% (95% CI, 31 to 55) and 53% (95% CI, 41 to 65), respectively. Five-year EFS among patients in complete remission (CR; 52%; 95% CI, 31 to 69) or partial remission (44%; 95% CI, 27 to 60) before immunotherapy were significantly better compared with patients with nonresponse/mixed response/progressive disease (13%; 95% CI, 1 to 42; P = .026). Overall response rate in 43 patients with evidence of disease after haplo-SCT was 51% (22 patients), with 15 achieving CR (35%). Two patients developed GvHD grade 2 and 3 each. No unexpected adverse events occurred. CONCLUSION DB therapy after haplo-SCT in patients with rHR-NB is feasible, with low risk of inducing GvHD, and results in long-term remissions likely attributable to increased antineuroblastoma activity by donor-derived effector cells.

Purpose: In pediatric bladder/prostate-rhabdomyosarcoma, the rate of bladder preservation after neoadjuvant chemotherapy is high, with an excellent oncological outcome. Information about functional urological long-term outcomes is rare. Methods: Data of all patients who had undergone bladder-preserving surgery with or without brachytherapy at our institution between 2009 and 2020 were analyzed retrospectively.Detailed urological function was assessed focusing on age-related continence, bladder capacity and urodynamic findings. Results: We identified 40 patients, median age at surgery of 27 months (range 9-191), and 32 patients additionally received postoperative high-dose-rate brachytherapy. The median follow-up was 32.5 months (range 6-125). The bladder capacity increased from median 66.7% (21.1-180) of expected bladder capacity related to age 3 months after surgery to 87.4% (58.1-181.8) 9 months after surgery. In the group of aged >6-year-old, continence was 94% (83% with brachytherapy, 100% without brachytherapy). Erectile function was normal in 92% (90 % with brachytherapy, 100% without brachytherapy). Bladder capacity was more than 65% expected bladder capacity related to age in 70% (60% with brachytherapy, 86% without brachytherapy). 65% of all patients need neither anticholinergic drugs nor low-dose antibiotics (63% with brachytherapy, 71% without brachytherapy). Conclusions: Bladder preservation with good functional outcome can be achieved in localized bladder/prostate-rhabdomyosarcoma. In selected cases, supportive brachytherapy additionally contributes to an improvement in the oncological outcome with calculable risks for bladder and erectile function. Careful urological aftercare should be a fixed priority after oncological follow-ups.

Resection of lung metastases in children with solid tumors is regularly hampered by limited intraoperative detectability and relevant operative trauma of the open surgical access. The aim of this study was to analyze thoracoscopic resection of lung metastases in children following CT-guided labeling with coil wires. We retrospectively analyzed data of children and adolescents undergoing this approach at our institution between 2010 and 2022 with regard to technical aspects as well as surgical and oncological data. Within this period, we performed this procedure on 12 patients wherein we resected 18 lesions (1-5 per patient). The median age of patients was 178 months (51-265). The median duration of coil wire placement was 41 min (30-173) and the median surgery time was 53 min (11-157). No conversions were necessary and no intraoperative complications occurred. Complete microscopic resection (R0) was achieved in all labeled lesions and malignant tumor components were found in 5/12 patients. Our study shows that with a careful patient selection, thoracoscopic resection of lung metastases after coil wire labeling is a safe and reproducible procedure in children. Using this approach, lesions that are expected to have a reduced intraoperative detectability during open surgery become resectable. Patients benefit from the minimally invasive surgical access and reduced operative trauma.