Solid Tumor In Children Research Articles

The emerging field of viroimmunotherapy for pediatric brain tumors.

Pediatric brain tumors are the most common solid tumors in children. Even to date, with the advances in multimodality therapeutic management, survival outcomes remain dismal in some types of tumors, such as pediatric-type diffuse high-grade gliomas or central nervous system embryonal tumors. Failure to understand the complex molecular heterogeneity and the elusive tumor and microenvironment interplay continues to undermine therapeutic efficacy. Developing a strategy that would improve survival for these fatal tumors remains unmet in pediatric neuro-oncology. Oncolytic viruses (OVs) are emerging as a feasible, safe, and promising therapy for brain tumors. The new paradigm in virotherapy implies that the direct cytopathic effect is followed, under certain circumstances, by an antitumor immune response responsible for the partial or complete debulking of the tumor mass. OVs alone or combined with other therapeutic modalities have been primarily used in adult neuro-oncology. A surge in encouraging preclinical studies in pediatric brain tumor models recently led to the clinical translation of OVs with encouraging results in these tumors. In this review, we summarize the different virotherapy tested in preclinical and clinical studies in pediatric brain tumors, and we discuss the limitations and future avenues necessary to improve the response of these tumors to this type of therapy.

Comprehensive analysis identifies ubiquitin ligase FBXO42 as a tumor-promoting factor in neuroblastoma

Neuroblastoma, the deadliest solid tumor in children, exhibits alarming mortality rates, particularly among high-risk cases. To enhance survival rates, a more precise risk stratification for patients is imperative. Utilizing proteomic data from 34 cases with or without N-Myc amplification, we identified 28 differentially expressed ubiquitination-related proteins (URGs). From these, a prognostic signature comprising 6 URGs was constructed. A nomogram incorporating clinical-pathological parameters yielded impressive AUC values of 0.88, 0.93, and 0.95 at 1, 3, and 5 years, respectively. Functional experiments targeting the E3 ubiquitin ligase FBXO42, a component of the prognostic signature, revealed its TP53-dependent promotion of neuroblastoma cell proliferation. In conclusion, our ubiquitination-related prognostic model robustly predicts patient outcomes, guiding clinical decisions. Additionally, the newfound pro-proliferative role of FBXO42 offers a novel foundation for understanding the molecular mechanisms of neuroblastoma.

Patterns of Childhood Solid Malignant Tumours in Paediatric Surgery Department of Mymensingh Medical College Hospital

Patterns of Childhood Solid Malignant Tumours in Paediatric Surgery Department of Mymensingh Medical College Hospital

Cell state plasticity in neuroblastoma

Evolving evidence indicates that tumor cells can transdifferentiate between distinct transcriptionally-determined cell states with changes in resultant phenotypes, a phenomenon known as cellular plasticity. These transitions are not driven by genetic mutations and typically in contrast to normal developmental processes, may proceed bidirectionally. Here, we review the role of cellular plasticity in the aggressive childhood solid tumor, neuroblastoma. We discuss the detection of two cell states, termed mesenchymal (MES) and adrenergic (ADRN), their properties and the transcriptional circuitries that control them, their relation to the normal embryogenesis of the sympathetic nervous system and their potential role in drug resistance, escape from therapy and development of relapse.

Cadaveric analysis of surgical techniques and working space for retroperitoneal tumors as model for improving resection of neuroblastoma

PurposeNeuroblastoma, the most common extracranial solid tumor in children under 5 years, often surrounds visceral arteries. This study aimed to analyze the working space provided by standardized surgical techniques at key arterial landmarks in adult cadavers.MethodsWe assessed in eight adult cadavers the mobilization of the left colon, spleen and pancreas, right colon, duodenum and mesenteric root, access to the bursa omentalis. The average working space score (AWSS) was evaluated at the left and right renal artery, left and right side of the coeliac trunk, superior mesenteric and common hepatic artery. The score was defined as: (0) vessel not visible, (1) working space at the vessel ≤ 1x diameter of the aorta, (2) < 3x the diameter of the aorta, (3) ≥ 3x diameter of the aorta.ResultsThe maximum AWSS of 3 was achieved at key vascular landmarks through specific mobilization techniques.ConclusionAdditional mobilization of spleen, pancreas and mesenteric root and access to the bursa omentalis increase surgical working space at major visceral arteries. The results of our investigation provide surgeons with a useful guide to prepare for abdominal neuroblastoma resection.

The role of surgery in the treatment of childhood solid tumors

The role of surgery in the treatment of childhood solid tumors

131I-mIBG Therapy in the Management of High-Risk Neuroblastoma: A Retrospective Study from a Tertiary Level Hospital in South India

Abstract Introduction Neuroblastoma is the most common extracranial solid tumor in childhood. The data on the treatment experience with 131iodine-meta-iodo-benzyl-guanidine (131I-mIBG) and clinical outcome data are meager from India. Objectives This article studies the efficacy and treatment outcomes in patients treated with 131I-mIBG in high-risk neuroblastoma. Materials and Methods The study group consisted of 201 consecutive patients (aged between 1 and 15 years) with biopsy-proven neuroblastoma who underwent 131I-mIBG scans from 2012 to 2022. The majority of these children had a disease that was inoperable or had poor response to chemotherapy. Patients with positive scintigraphy were considered for therapy with 131I-mIBG. The findings were analyzed and correlated with the final diagnosis and outcomes obtained from survival during follow-up and reviewing patient records. Results Thirty-nine children, 22 males and 17 females, with a median age of 4 years had positive 131I-mIBG scintigraphy. Intra-abdominal primary lesions and osseous lesions were the most common sites of uptake on 131I-mIBG scan. Of these, 13 had upfront chemotherapy and 26 had surgery followed by chemotherapy. All the patients underwent therapy with 131I-mIBG. Fourteen patients had multiple therapies while the remaining 25 had only one therapy. Eight patients had no follow-up, and 13 had disease relapse. The remaining 18 had regression of disease which was confirmed by follow-up 131I-mIBG scintigraphy and with bone scintigraphy in patients with osseous metastases. Conclusion 131I-mIBG scintigraphy should be preferred in intermediate and high-risk neuroblastoma to know the extent of the disease and also for patient selection for early therapy with 131I-mIBG. It holds significant utility in the management of metastatic neuroblastoma, facilitating palliative pain relief and tumor size reduction in inoperable or metastatic disease.

Brain Tumors in Pediatric Patients

Pediatric brain tumors are the most common solid tumors in children, comprising a diverse group of neoplasms that vary in histology, location, and behavior. Common types include astrocytomas, medulloblastomas, ependymomas, and brainstem gliomas. Symptoms often depend on the tumor's location and may include headaches, nausea, vomiting, balance issues, and cognitive or behavioral changes. Advances in imaging, surgical techniques, and therapies, including radiation and chemotherapy, have improved outcomes. However, treatment can have long-term effects on cognitive and physical development, making comprehensive care and follow-up essential for pediatric patients. Early published reviews on pediatric brain tumors may have several lacunae, such as limited data on long-term outcomes, emerging treatment modalities, and the genetic and molecular underpinnings of various tumor types. They might also inadequately address the psychosocial impacts on patients and families. Therefore, a comprehensive review is needed to synthesize the latest research on pediatric brain tumors, encompassing advancements in diagnosis, treatment, and survivorship care. This updated review will provide valuable insights for clinicians, researchers, and policymakers to improve managing and supporting children with brain tumors. The review covers various aspects of pediatric brain tumors, focusing on choroid plexus tumors and spinal cord tumors. It discusses treatment strategies, highlighting surgical, radiotherapy, and chemotherapy options. The review also details presenting signs and symptoms of brain tumors in children, such as headaches, nausea, vomiting, balance issues, and changes in behavior or cognition. These insights aim to enhance early diagnosis and effective management, improving outcomes for affected children. This review addresses gaps in earlier studies on pediatric brain tumors by providing comprehensive insights into choroid plexus and spinal cord tumors, updated treatment strategies, and detailed symptoms. It synthesizes recent research to enhance early diagnosis and management, meeting current needs for effective, tailored treatment and improving patient outcomes.

Oncological background of non-specific abdominal pain in children and adolescents – case report of a girl with ovarian teratoma

Abdominal pain in children is a common, atypical symptom. The vast majority of abdominal pain is functional, non-life threatening and does not require extensive diagnostics. However, it should be remembered that the abdominal cavity is one of the most common locations of solid tumours in children. Carefully collected information and physical examination with oncological vigilance allow for the identification of alarming symptoms accompanying abdominal pain. These include: pain waking up from sleep, palpable mass in the abdominal cavity, vomiting, change in the rhythm of bowel movements, weight loss, fever, dysphagia, weakness, anaemia. The article presents a case report of a teenager with ovarian teratoma. It aims to illustrate the pitfalls and diagnostic difficulties associated with determining the causes of abdominal pain in children and adolescents. The discussion also summarises information on the epidemiology, aetiology and clinical symptoms of teratoma.

Application of the FISH method and high-density SNP arrays to assess genetic changes in neuroblastoma-research by one institute.

Neuroblastoma is the most common extracranial solid tumor in children. Amplification of the MYCN gene has been observed in approximately 20%-30% of tumors. It is strongly correlated with advanced-stage disease, rapid tumor progression, resistance to chemotherapy and poor outcomes independent of patient age and stage of advanced disease. MYCN amplification identifies high-risk patients. To assess neuroblastoma tumors with MYCN amplification we used paraffin-embedded tissue sections in 57 patients and intraoperative tumor imprints in 10 patients by fluorescence in situ hybridization (FISH). Positive results for MYCN amplification have been observed in twelve patients' paraffin-embedded tissue sections and in three patients' intraoperative tumor imprints, which represents 22.4% of all patients tested in the analysis. Fluorescence in situ hybridization is a highly sensitive and useful technique for detecting MYCN amplification on paraffin-embedded tissue sections of neuroblastoma tumors and intraoperative tumor imprints thus facilitating therapeutic decisions based on the presence or absence of this important biologic marker. The presence of structural changes, regardless of MYCN gene amplification status, influences the clinical behavior of neuroblastoma. High-Density SNP Arrays have emerged as the perfect tools for detecting these changes due to their exceptional accuracy, sensitivity and ability to analyze copy number and allele information. Consequently, they are proven to be highly valuable in the genomic diagnosis of immature neuroectodermal tumors.

Effects and mechanisms of puerarin against neuroblastoma: insights from bioinformatics and in vitro experiments

BackgroundNeuroblastoma, a prevalent solid tumor in children, often manifests with hidden onset sites, rapid growth, and high metastatic potential. The prognosis for children with high-risk neuroblastoma remains poor, highlighting the urgent need for novel prognostic models and therapeutic avenues. In recent years, puerarin, as a kind of small molecule drug extracted from Chinese medicine Pueraria lobata, has demonstrated significant anticancer effects on various cancer cell types. In this study, through bioinformatics analysis and in vitro experiments, the potential and mechanism of puerarin in the treatment of neuroblastoma were investigated, and a prognostic model was established.MethodsA total of 9 drug-disease related targets were observed by constructing a database of drug targets and disease genes. Besides, GO and KEGG enrichment analysis was performed to explore the potential mechanism of its therapeutic effect. To construct the prognostic model, risk regression analysis and LASSO analysis were carried out for validation. Finally, the prognostic genes were identified. Parachute test and immunofluorescence staining were performed to verify the potential mechanism of puerarin in neuroblastoma treatment.ResultsThree prognostic genes, i.e., BIRC5, TIMP2 and CASP9, were identified. In vitro studies verified puerarin's impact on BIRC5, TIMP2, and CASP9 expression, inhibiting proliferation in neuroblastoma SH-SY5Y cells. Puerarin disrupts the cytoskeleton, boosts gap junctional communication, curtailing invasion and migration, and induces mitochondrial damage in SH-SY5Y cells.ConclusionsBased on network pharmacology and bioinformatics analysis, combined with in vitro experimental verification, puerarin was hereby observed to enhance GJIC in neuroblastoma, destroy cytoskeleton and thus inhibit cell invasion and migration, cause mitochondrial damage of tumor cells, and inhibit cell proliferation. Overall, puerarin, as a natural medicinal compound, does hold potential as a novel therapy for neuroblastoma.

Irinotecan and temozolomide in combination with dasatinib and rapamycin versus irinotecan and temozolomide for patients with relapsed or refractory neuroblastoma (RIST-rNB-2011): a multicentre, open-label, randomised, controlled, phase 2 trial

Neuroblastoma is the most common extracranial solid tumour in children. Relapsed or refractory neuroblastoma is associated with a poor outcome. We assessed the combination of irinotecan-temozolomide and dasatinib-rapamycin (RIST) in patients with relapsed or refractory neuroblastoma. The multicentre, open-label, randomised, controlled, phase 2, RIST-rNB-2011 trial recruited from 40 paediatric oncology centres in Germany and Austria. Patients aged 1-25 years with high-risk relapsed (defined as recurrence of all stage IV and MYCN amplification stages, after response to treatment) or refractory (progressive disease during primary treatment) neuroblastoma, with Lansky and Karnofsky performance status at least 50%, were assigned (1:1) to RIST (RIST group) or irinotecan-temozolomide (control group) by block randomisation, stratified by MYCN status. We compared RIST (oral rapamycin [loading 3 mg/m2 on day 1, maintenance 1 mg/m2 on days 2-4] and oral dasatinib [2 mg/kg per day] for 4 days with 3 days off, followed by intravenous irinotecan [50 mg/m2 per day] and oral temozolomide [150 mg/m2 per day] for 5 days with 2 days off; one course each of rapamycin-dasatinib and irinotecan-temozolomide for four cycles over 8 weeks, then two courses of rapamycin-dasatinib followed by one course of irinotecan-temozolomide for 12 weeks) with irinotecan-temozolomide alone (with identical dosing as experimental group). The primary endpoint of progression-free survival was analysed in all eligible patients who received at least one course of therapy. The safety population consisted of all patients who received at least one course of therapy and had at least one post-baseline safety assessment. This trial is registered at ClinicalTrials.gov, NCT01467986, and is closed to accrual. Between Aug 26, 2013, and Sept 21, 2020, 129 patients were randomly assigned to the RIST group (n=63) or control group (n=66). Median age was 5·4 years (IQR 3·7-8·1). 124 patients (78 [63%] male and 46 [37%] female) were included in the efficacy analysis. At a median follow-up of 72 months (IQR 31-88), the median progression-free survival was 11 months (95% CI 7-17) in the RIST group and 5 months (2-8) in the control group (hazard ratio 0·62, one-sided 90% CI 0·81; p=0·019). Median progression-free survival in patients with amplified MYCN (n=48) was 6 months (95% CI 4-24) in the RIST group versus 2 months (2-5) in the control group (HR 0·45 [95% CI 0·24-0·84], p=0·012); median progression-free survival in patients without amplified MYCN (n=76) was 14 months (95% CI 9-7) in the RIST group versus 8 months (4-15) in the control group (HR 0·84 [95% CI 0·51-1·38], p=0·49). The most common grade 3 or worse adverse events were neutropenia (54 [81%] of 67 patients given RIST vs 49 [82%] of 60 patients given control), thrombocytopenia (45 [67%] vs 41 [68%]), and anaemia (39 [58%] vs 38 [63%]). Nine serious treatment-related adverse events were reported (five patients given control and four patients given RIST). There were no treatment-related deaths in the control group and one in the RIST group (multiorgan failure). RIST-rNB-2011 demonstrated that targeting of MYCN-amplified relapsed or refractory neuroblastoma with a pathway-directed metronomic combination of a multkinase inhibitor and an mTOR inhibitor can improve progression-free survival and overall survival. This exclusive efficacy in MYCN-amplified, relapsed neuroblastoma warrants further investigation in the first-line setting. Deutsche Krebshilfe.

A mitochondria-related genes associated neuroblastoma signature - based on bulk and single-cell transcriptome sequencing data analysis, and experimental validation.

Neuroblastoma (NB), characterized by its marked heterogeneity, is the most common extracranial solid tumor in children. The status and functionality of mitochondria are crucial in regulating NB cell behavior. While the significance of mitochondria-related genes (MRGs) in NB is still missing in key knowledge. This study leverages consensus clustering and machine learning algorithms to construct and validate an MRGs-related signature in NB. Single-cell data analysis and experimental validation were employed to characterize the pivotal role of FEN1 within NB cells. MRGs facilitated the classification of NB patients into 2 distinct clusters with considerable differences. The constructed MRGs-related signature and its quantitative indicators, mtScore and mtRisk, effectively characterize the MRGs-related patient clusters. Notably, the MRGs-related signature outperformed MYCN in predicting NB patient prognosis and was adept at representing the tumor microenvironment (TME), tumor cell stemness, and sensitivity to the chemotherapeutic agents Cisplatin, Topotecan, and Irinotecan. FEN1, identified as the most contributory gene within the MRGs-related signature, was found to play a crucial role in the communication between NB cells and the TME, and in the developmental trajectory of NB cells. Experimental validations confirmed FEN1's significant influence on NB cell proliferation, apoptosis, cell cycle, and invasiveness. The MRGs-related signature developed in this study offers a novel predictive tool for assessing NB patient prognosis, immune infiltration, stemness, and chemotherapeutic sensitivity. Our findings unveil the critical function of FEN1 in NB, suggesting its potential as a therapeutic target.

IMMU-21. B7-H3 NANOBODY CAR-T CELL THERAPY IN PEDIATRIC GLIOBLASTOMA

Abstract BACKGROUND Immunotherapy is a developing but challenging field of research for the treatment of central nervous system malignancies. Chimeric antigen receptor (CAR)-T cell therapy has been effective in treating hematologic malignancies, but that success has not been clinically translated to solid tumors in children. B7-H3 has been identified as a promising immunotherapy target as it is highly expressed in pediatric glioblastoma and correlates with tumor progression and poor prognosis. We aim to evaluate a nanobody-based CAR-T cell therapy that binds B7-H3 with high affinity and hypothesize that anti-B7-H3 nanobody CAR-T cells can effectively kill B7-H3-expressing tumor cells. METHODS B7-H3 nanobodies were isolated from camel phage libraries and cloned into lentiviral CAR-T cell constructs. Human T cells were transduced by lentivirus to express CAR on the surface. Nanobody CAR-T cell functionality was evaluated by an impedance-based cytotoxicity assay and cytokine release was measured by ELISA. CAR-T avidity was quantified by the Lumicks z-Movi assay. In vivo studies are evaluating the efficacy of B7-H3 CAR-T cells in an orthotopic glioblastoma model in immunodeficient mice. Mice were treated with B7-H3 CAR-T cells by intracerebroventricular or intravenous delivery. RESULTS We confirmed high expression of B7-H3 on the surface of three pediatric glioblastoma cell lines by flow cytometry and Quantibrite staining. We confirmed effective killing of B7-H3-expressing tumor cells and the release of high levels of cytokines. B7-H3 nanobody CAR-T cells were observed to have high avidity compared to control CAR-T cells. In vivo studies are currently ongoing and treatment response will be evaluated by luminescence imaging and endpoint histologic analysis. CONCLUSION We have shown that B7-H3 nanobody CAR-T cells demonstrate significant preclinical efficacy. It is critical to study CAR-T cell therapy in immunocompetent in vivo models for further development and clinical application.

LGG-46. MEKI WITH MIRDAMETINIB: EXPLORING ADAPTIVE SIGNALING PATHWAY DYNAMICS AND IMMUNE MODULATION IN PEDIATRIC GLIOMAS

Abstract INTRODUCTION Glial neoplasms are among the most common types of solid tumors in children. The mitogen-activated protein kinase (MAPK) pathway is implicated in glioma tumorigenesis. Drugs targeting this pathway hold promise as novel therapy for this disease. Vertical inhibition of the MAPK pathway has been linked to increased inflammation in several other cancers but similar exploration in pediatric brain tumors is limited. Within the MAPK pathway, MEK plays a significant role as a modulator of ERK phosphorylation. This study investigates the therapeutic potential of the MEK inhibitor, Mirdametinib, and evaluates the drugs’ capacity to induce tumor-intrinsic inflammation by characterizing changes in PD-L1 expression and proliferation in a panel of pediatric glial neoplasms. METHODS Three cell lines were included in the panel (Res186, Res259, SF188) and were treated with Mirdametinib for 3, 5, or 7 days. P-ERK expression, analyzed by western blot, verified successful inhibition of MEK by Mirdametinib. The CCK8 cytotoxic assay was utilized to determine the drug’s 50% inhibitory concentration as well as its direct effects on cell viability. Changes in Ki67 expression assessed by flow cytometry further characterized Mirdametinib’s effects on cell proliferation. Flow cytometry was also utilized to measure changes in PD-L1 expression following treatment. RESULTS Despite minimal effects on proliferation as measured by Ki67 and CCK8, expression of P-ERK verifies successful inhibition of MEK. Western blot data also reveals increased Pi3K/AKT pathway activity in SF188 groups treated with Mirdametinib. FACS data for SF188 also demonstrates increased PD-L1 expression in response to treatment. CONCLUSIONS Data suggests that, in response to MEKi, gliomas utilize compensatory growth mechanisms through Pi3K/AKT signaling. Findings also point to immune-modulatory effects of MEKi. Supporting results in ongoing experiments are expected to further our understanding of these mechanisms and may help inform effective combination treatment strategies for pediatric gliomas.

BIOM-04. ALTERED IMMUNE ACTIVATION AND REDUCED LYMPHOPOIESIS IN TREATMENT NAÏVE PEDIATRIC BRAIN TUMOUR PATIENTS

Abstract Pediatric central nervous system (CNS) tumors are the most common solid tumor in children. Despite improvements in diagnostic and therapeutic approaches over time, treatment effectiveness remains unsatisfactory. Optimal immune function is critical to protect against development and dissemination of cancer and to offer the ideal conditions for the success of anticancer treatment. Here we analyzed the peripheral immunological features of patients affected by pediatric brain tumors, the process of de novo T- and B-cell development and its association with the lymphopenia often observed in these patients. Eighty-six steroids-naïve pediatric patients with CNS tumors at the onset of the disease were included in the study. Brain tumors were classified into low-grade gliomas (LGG: n=44, 51%), pediatric-type diffuse high-grade gliomas (pHGG: n=16, 19%), medulloblastoma (n =9, 10%), and other CNS tumors (n =17, 20%). Patient’s peripheral immunological status was analyzed by flow-cytometry and by evaluating T-cell receptor excision circles (TRECs) and kappa-deleting excision circles (KREC) to quantify T- and B-cell neogenesis. Although all patients showed tendencies towards low lymphocyte counts, this effect was particularly evident in pHGG patients. T-cells of pHGG patients displayed a shift from naïve to effector memory phenotype compared to age-matched controls. On the other hand, LGG patients were characterized by an expansion of the T-central memory pool and higher expression of T-cell activation markers. Both patient cohorts exhibited decreased frequency of B-cells with activated phenotype. Interestingly, pHGG patients exhibited reduced thymic function as revealed by reduced levels of the recent thymic emigrant population and TRECs. In addition, LGG and pHGG patients were characterized by lower KREC values, suggesting suboptimal B-cell formation. At diagnosis, pediatric patients with brain tumor show alterations in their immunological status and reduced thymic and medullary lymphopoiesis, particularly pronounced in pHGG, which may contribute to explain the systemic lymphopenia characterizing these patients.

Preliminary experience of ex-vivo expanded allogeneic universal donor TGFβi NK cell infusions in combination with irinotecan, temozolomide, and dinutuximab in patients with relapsed or refractory neuroblastoma: The Allo - STING trial.

10005 Background: Neuroblastoma (NBL) is the most common extra-cranial solid tumor in children and outcomes for children with relapsed/refractory (RR) NBL remain dismal. While the combination of chemoimmunotherapy (CIT) with the anti-GD2 antibody dinutuximab as per COG protocol ANBL1221 has improved responses, this regimen is still not curative. Dinutuximab can recruit NK cells for anticancer activity, however, NK cells are depleted in NBL patients undergoing chemotherapy. We devised a method to expand allogeneic NK cells ex vivo to improve effector function and render the NK cells resistant to TGFβ-induced suppression (TGFβi). These TGFβi NK cells are expanded from a universal donor (UD) pool, enabling multiple cycles of “off-the-shelf” high-dose therapy. We hypothesize that adoptive transfer of UD-TGFβi NK cells to patients with RR NBL sequentially following CIT is safe and improves outcomes compared to CIT alone. Methods: This Phase I/II study evaluates the safety and tolerability of UD-TGFβi NK cells in combination with CIT and compares anti-cancer efficacy to CIT alone. Eligibility includes age &lt; 30 years, RR or progressive NBL, and prior treatment with at least 4 cycles of induction chemotherapy. The treatment protocol consists of 21-day cycles of CIT as per COG protocol ANBL1221 with UD-TGFβi NK cells (1x108 cells/kg) infused on day 8. Up to six cycles of treatment are permitted. Overall response rates are defined using the Revised International NBL Response Criteria, with 95% confidence intervals compared to the results from ANBL1221. Progression-free and overall survival will be estimated by the Kaplan Meier method. Results: Four subjects (7 – 11 years) have been enrolled. All patients presented with high risk NBL: three with relapsed disease and one with refractory disease. All received at least one prior salvage therapy. Three patients have completed all 6 cycles of protocol therapy, and one remains on treatment. 20 NK cell infusions have been administered to date. All NK cell infusions occurred within the protocol specified window. One subject experienced grade 1 fever with two NK cell infusions. There have been no other adverse events attributable to the NK cells. Adverse events attributable to CIT were similar to those described in COG ANBL 1221. Treatment delays for cytopenias due to CIT occurred in two patients. Three patients achieved a partial response. A fourth patient attained prolonged stable disease (9 months) but experienced a skeletal recurrence. Conclusions: UD allo-TGFβi NK cells can be safely and feasibly administered to children with RR NBL after treatment with CIT, with early objective responses observed in the preliminary cohort of patients. Ongoing studies will assess markers of response, NK cell persistence, pharmacokinetics and pharmacodynamics. Clinical trial information: NCT04211675 .

PP2A activation as a new therapeutic strategy in neuroblastoma: Making sense out of senescence.

10055 Background: Neuroblastoma (NBL) is the most common extracranial solid tumor in children, accounting for 15% of all pediatric cancer deaths. The five-year survival rate for children with high-risk disease is less than 50%, with the primary reasons for mortality being refractory and relapsed disease. One hypothesis for the poor response to therapy and propensity for recurrent disease in high-risk patients is treatment-induced senescence (TIS). Protein phosphatase 2A (PP2A) is a known tumor suppressor that is downregulated in NBL. PP2A activation has been shown to reverse cellular senescence in non-cancerous pathologies, therefore we hypothesized that reactivation of PP2A using novel small molecule activators would function as a novel senotherapeutic in NBL. Methods: We employed MYCNamplified, SK-N-BE(2), and non-amplified, SK-N-AS, established human NBL cell lines. Topotecan, a common NBL chemotherapeutic, known to induce senescence, and ATUX-1215, a small molecule PP2A activator, were utilized. NBL cells were treated with topotecan and ATUX-1215 alone, as well as in combination. Colorimetric assays detected cell viability and proliferation. Immunoblotting identified proteins of interest including γ-H2AX and CCL2. TIS was detected by S-β galactosidase (Sβgal) assay. Results: We found increased expression of the senescence marker, histone γ-H2AX, and increased Sβgal-positive tumor cells supporting the ability of topotecan to generate TIS in NBL. Following treatment with PP2A activator in combination with topotecan, markers of TIS are decreased in both MYCN amplified and non-amplified NBL cells. Further, and importantly, PP2A activation reversed the effects of topotecan TIS and acted in a synergistic fashion to decrease NBL cell viability. Conclusions: Activation of PP2A with a novel small molecule ameliorates topotecan-induced TIS in NBL cells irrespective of MYCN status. These results are promising, providing a potential novel therapeutic adjunct to children who are most in need of innovative interventions.

A multi-assay liquid biopsy approach to improve detection of bone and soft tissue sarcomas.

10019 Background: Bone and soft tissue sarcomas are among the most common extra-cranial solid tumors of childhood, yet advances in liquid biopsies lag behind what has been achieved across adult cancers. Solid tumors that lack recurrent genetic mutations or translocations, such as bone and soft tissue sarcomas, are more difficult to detect in circulation using established assays, such as ddPCR. We have developed a pipeline to analyze cell-free DNA (cfDNA) using two molecular profiling techniques that we hypothesized would improve detection of circulating tumor DNA at diagnosis for patients with bone and soft tissue sarcomas. Methods: cfDNA was isolated from plasma of patients with osteosarcoma (OS) (n = 36) and fusion-negative rhabdomyosarcoma (FN-RMS) (n = 7) at multiple timepoints. Methods for detecting tumor DNA in cfDNA included ultra-low coverage whole genome sequencing (ULC-WGS, 0.5x) and ultra-deep targeted sequencing (UDP, ~1000x) using a panel of 11 and 22 tumor-associated genes for OS and FN-RMS, respectively. ULC-WGS data underwent ichorCNA analysis to define percent tumor content of each sample. UDP analysis identified somatic variants through variant callers, Mutect2, Lancet, strelka, and DELLY2, with ClinVar to annotate and define tumor-specific variants in each sample. Combining ULC-WGS and UDP data, an integrated tumor score was developed and assessed in diagnostic samples. Results: 136 OS and 30 FN-RMS cfDNA samples were collected during the patients’ disease courses. Circulating tumor material was detected in 18/23 (78%) OS and7/7 (100%) FN-RMS samples at diagnosis. The most frequent copy number aberrations were seen in the region of chromosome 8q containing the cMYC gene. cMYC amplification was found in 11/23 (48%) of diagnostic OS samples and 2/7 (29%) of diagnostic FN-RMS samples. UDP analysis identified variants in 17/23 (73%) and 7/7 (100%) of diagnostic OS and FN-RMS samples respectively. The most commonly detected variants included TP53, BRCA2, MET, and BRAF. Of the 23 diagnostic OS samples, four had TP53 translocations. The integrated tumor score detected the presence of tumor associated material within diagnostic samples with a sensitivity of 25/30 (83%), compared to the sensitivity of ULC-WGS or UDP alone, which was 15/30 (50%) and 24/30 (80%) respectively. Conclusions: A multi-assay liquid biopsy has promise to improve disease detection and monitoring for patients with solid tumors that lack recurrent driver mutations. We plan to integrate additional molecular profiling technologies to improve the sensitivity and specificity of our cfDNA assays and aim to adapt our pipeline across additional cancers.

Overview of European standard clinical practice recommendations for multidiscplinary teams involved in the treatment of central nervous system tumours in children and adolescents – SIOPE Brain Tumour Group

Tumours of the central nervous system (CNS) represent the most common group of solid tumours in children and adolescents up to the age of 18 years. They comprise several biological entities, subgroups, and subtypes. These subtypes and additional factors, including age at diagnosis, location, stage, or genetic characteristics of the tumours result in a very heterogeneous spectrum of treatment-relevant strata for risk-adapted multimodal treatment recommendations, clinical courses, and long-term outcomes. Multidisciplinary teams with highly experienced members are needed to treat these children and adolescents to achieve the best possible outcome in the short and long-term. This is particularly important for the new CNS tumour entities with no established standard of care. On behalf of the Brain Tumour Group of the European Society for Paediatric Oncology, we summarize the key statements of the involved disciplines that need to cooperate in the diagnosis and risk-adapted treatment of children with CNS tumours: neuroradiology, neurosurgery, neuropathology, radiotherapy, endocrinology, neuro-ophthalmology, and quality of survival professionals, covering what should be considered standard clinical practice for diagnostic assessments, treatment modalities, and follow-up of children with CNS-tumours.