Treatment Of Medulloblastoma Research Articles

Demographic, medical, and neighborhood barriers to clinical neuropsychological services in pediatric medulloblastoma patients treated in the United States.

Medulloblastoma is the most commonly occurring malignant brain tumor of childhood. Treatment includes a combination of surgery, radiation therapy, and chemotherapy, all of which are associated with cognitive impairments. Despite appreciation of the value of neuropsychological evaluations to assess for cognitive impairments, there are barriers to these evaluations. This study aimed to identify potential demographic, medical, or neighborhood factors associated with barriers to neuropsychological evaluations. Retrospective chart review identified pediatric patients with a medulloblastoma diagnosed between 2005 and 2024. Demographic, medical, and neighborhood factors were gleaned from the medical records. Of the 67 identified patients, only 36 (53.73%) completed a clinical neuropsychological evaluation. Patients who obtained a neuropsychological evaluation were more likely to be non-Hispanic [X2 (1,62) = 9.20, p = <.01], diagnosed at younger ages [t(60) = - 8.40, p = < 0.001], treated with photon radiation therapy [X2 (1,62) = 15.24, p = < 0.001], live closer to the hospital [t(60) = 3.19, p = 0.001], and live in communities with higher health-related resources [t(60) = - 2.09, p = 0.02]. The two groups did not differ by any of the medical/clinical factors. Neuropsychological evaluations assess for cognitive changes following cancer directed treatment, clarify other diagnostic possibilities (e.g., learning or attention difficulties), and facilitate access to appropriate accommodations and school- and community- based services. Although neuropsychological evaluations are recommended as standard of care following treatment for medulloblastoma, we identified demographic, medical, and neighborhood-level factors that serve as barriers to clinical neuropsychological evaluations. Implications for clinical care and recommendations to address these barriers are discussed.

STEM-08. LIPID SATURATION HOMEOSTASIS PRESENTS A TARGETABLE VULNERABILITY IN MYC-AMPLIFIED GROUP 3 MEDULLOBLASTOMA

Abstract Medulloblastoma (MB) is the most common malignant pediatric brain cancer, originating from the cerebellum. Despite advancements in standard of care (SoC), MB remains fatal for 30% of patients. Tumor relapse, spinal metastasis and treatment resistance are the most prevalent in MYC-driven Group 3 MB (G3-MB). Patients surviving SoC are faced with life-long neurocognitive and neurodevelopmental deficits. These issues highlight the urgent need for improved treatment modalities. Reprogramming of cellular lipid metabolism is an emerging hallmark of cancer and may yield novel cancer-specific therapeutic options. Here we explore the lipidome of both G3-MB and its proposed cell of origin, human neural stem cells (hNSCs) by comparing untargeted lipidomics using Liquid-Chromatography-Mass Spectrometry (LC-MS). Comparative analyses revealed a differential abundance of distinct lipid species in G3-MB, with an overall reduced saturation level of fatty acids (FAs). These findings implicate the de novo lipid synthesis (DNL) pathway. We identified the enzymes involved in DNL to be essential for MB survival in our genome-wide CRISPR KO screen. Additionally, mRNA expression of the DNL enzymes increases at relapse in our SoC-adapted murine patient-derived xenograft (PDX) model. Pharmacological and genetic targeting of the DNL enzyme Stearoyl-CoA Desaturase 1 (SCD1) selectively targets G3-MB. Furthermore, small molecule treatment of SCD1 demonstrates efficacy against G3-MB PDX models in vivo. We identified SCD expression as a prognostic marker in Group 3 and 4 MB patients and identified possible pathways for MB treatment. Overall, these findings indicate that SCD1 is a potent target for the treatment of G3-MB.

EXTH-50. THYROID HORMONE-INDUCED DIFFERENTIATION: A PROMISING THERAPEUTIC STRATEGY FOR MEDULLOBLASTOMA

Abstract Medulloblastoma (MB) is the most common malignant brain tumor in children, consisting of four major subgroups (WNT, SHH, Group 3, and Group 4) that differ in genetic/epigenetic profiles and prognoses. Despite current therapy, a significant proportion of patients still succumb to MB. Moreover, survivors often suffer severe side effects from aggressive treatments. Therefore, improved strategies to treat MB are urgently needed. MB tumor cells retain the capacity for differentiation and can undergo terminal differentiation, after which they lose their proliferative and tumorigenic capacity. This suggests that MB can potentially be treated by inducing tumor cell differentiation. However, the mechanisms underlying MB tumor cell differentiation remain unclear. Our recent studies reveal that thyroid hormone (TH) plays a critical role in promoting tumor cell differentiation in MB. Reduced TH levels free the TH receptor, TRα1, to bind to EZH2 and repress the expression of NeuroD1, a transcription factor that drives tumor cell differentiation. Increased TH levels reverse the EZH2-mediated repression of NeuroD1 by disrupting the binding between EZH2 and TRα1, thereby stimulating tumor cell differentiation and reducing MB growth. Importantly, triiodothyronine (T3, active form of TH) inhibits the growth of both SHH- and Group 3 tumors, suggesting that the tumor-inhibitory effect of T3 is not restricted by MB subgroups. Additionally, this effect is significantly enhanced by concurrent chemotherapy. These findings establish an unprecedented association between TH signaling and MB pathogenicity, providing solid evidence for TH as a promising therapeutic modality for MB treatment.

NOVEL HETEROCYCLIC COMPOUNDS AS KINASE INHIBITORS WITH ANTICANCER ACTIVITY IN MEDULLOBLASTOMA

Abstract AIMS Medulloblastoma is the most common malignant brain tumor of childhood. Protein kinases are often overexpressed and constitute targets for the development of novel molecularly-targeted therapies in brain tumors. Here, we report the synthesis of new derivatives with kinase inhibitory activity and their anticancer activity in an early screening in medulloblastoma cells. METHOD The synthesis route was performed through six steps using a proper amino acid as starting material. The inhibitory activity of the final derivatives on the protein kinase was measured by fluorescence. Cultured DAOY medulloblastoma cells were used to examine anticancer activity. RESULTS The compounds display potent inhibitory activity on viability of DAOY medulloblastoma cells. The more promising derivative shows IC50 in the μM range in inhibiting the targeted protein kinase. CONCLUSION Further optimization of compounds in this series is currently being carried out. The encouraging preliminary results have revealed potential novel strategies for inhibiting kinase activity for the treatment of medulloblastoma.

Impaired DNA Double-Strand Break Repair in Irradiated Sheep Lung Fibroblasts: Late Effects of Previous Irradiation of the Spinal Thecal Sac.

Children with cancer previously treated with radiotherapy face the likelihood of side effects that can be debilitating or fatal. This study aimed to assess the long-term effect of medulloblastoma radiotherapy on the DNA double-strand break (DSB) repair capability of primary fibroblasts derived from lung biopsies of previously irradiated young sheep. This study included biopsies from three control and five irradiated sheep. The treated sheep had previously received spinal radiotherapy at a total dose of 28 Gy, which is equivalent to pediatric medulloblastoma treatment. Lung biopsies were taken 4 years post-irradiation from high-dose (HD, >18 Gy) and low-dose (LD, <2 Gy) regions. Fifteen cell lines were extracted (six control, four LD and five HD). The cells were irradiated, and DNA DSB repair was analyzed by immunofluorescence. Clonogenic, trypan blue and micronuclei assays were performed. Both the HD and LD cell lines had a significantly higher number of residual γH2AX foci 24 h and a significant decrease in pATM activity post-irradiation compared to the control. There was no statistically significant difference in the clonogenic assay, trypan blue and micronuclei results. Our study showed that a previous irradiation can impair the DNA DSB repair mechanism of ovine lung fibroblasts.

Treatment of Medulloblastoma in the Adolescent and Young Adult Population: A Systematic Review.

Medulloblastoma is the most frequent high-grade tumor of the central nervous system in children but accounts for less than 1% of these tumors in adults. Adolescent and young adult (AYA) patients are between both age groups, and different approaches are used to treat medulloblastoma in this population. We performed a systematic review of studies published between 2007 and 2023 that reported treatment approaches and survival data of AYA patients with medulloblastoma, defined as 15 to 39 years of age at diagnosis. Due to the heterogeneity of data, a meta-analysis was not possible. Except for the omission of chemotherapy after radiotherapy in a few adult studies, the treatment backbone is very similar between studies starting enrolment during childhood and older adolescence or adulthood. Despite indications for a higher rate of early treatment termination due to toxicity in adults, survival data remain comparable between studies starting enrolment earlier or later in life. However, molecular subtyping was missing in most studies, so the survival data must be interpreted cautiously. Nevertheless, pediatric-inspired strategies in the AYA population are feasible, but individual dose adjustments may be necessary during treatment and should be considered upfront. Collaborative studies investigating the best treatment approach for medulloblastoma in the AYA population are needed in the future.

Identification of tumor rejection antigens and the immunologic landscape of medulloblastoma

BackgroundThe current standard of care treatments for medulloblastoma are insufficient as these do not take tumor heterogeneity into account. Newer, safer, patient-specific treatment approaches are required to treat high-risk medulloblastoma patients who are not cured by the standard therapies. Immunotherapy is a promising treatment modality that could be key to improving survival and avoiding morbidity. For an effective immune response, appropriate tumor antigens must be targeted. While medulloblastoma patients with subgroup-specific genetic substitutions have been previously reported, the immunogenicity of these genetic alterations remains unknown. The aim of this study is to identify potential tumor rejection antigens for the development of antigen-directed cellular therapies for medulloblastoma.MethodsWe developed a cancer immunogenomics pipeline and performed a comprehensive analysis of medulloblastoma subgroup-specific transcription profiles (n = 170, 18 WNT, 46 SHH, 41 Group 3, and 65 Group 4 patient tumors) available through International Cancer Genome Consortium (ICGC) and European Genome-Phenome Archive (EGA). We performed in silico antigen prediction across a broad array of antigen classes including neoantigens, tumor-associated antigens (TAAs), and fusion proteins. Furthermore, we evaluated the antigen processing and presentation pathway in tumor cells and the immune infiltrating cell landscape using the latest computational deconvolution methods.ResultsMedulloblastoma patients were found to express multiple private and shared immunogenic antigens. The proportion of predicted TAAs was higher than neoantigens and gene fusions for all molecular subgroups, except for sonic hedgehog (SHH), which had a higher neoantigen burden. Importantly, cancer-testis antigens, as well as previously unappreciated neurodevelopmental antigens, were found to be expressed by most patients across all medulloblastoma subgroups. Despite being immunologically cold, medulloblastoma subgroups were found to have distinct immune cell gene signatures.ConclusionsUsing a custom antigen prediction pipeline, we identified potential tumor rejection antigens with important implications for the development of immunotherapy for medulloblastoma.

Neurocognitive outcomes and functional independence in adult survivors of childhood medulloblastoma diagnosed over 3 decades.

Treatment of childhood medulloblastoma has evolved to reduce neurotoxicity while improving survival. However, the impact of evolving therapies on late neurocognitive outcomes and adult functional independence remains unknown. Adult survivors of childhood medulloblastoma (n = 505; median [minimum-maximum] age, 29 [18-46] years) and sibling controls (n = 727; 32 [18-58] years) from the Childhood Cancer Survivor Study completed surveys assessing neurocognitive problems and chronic health conditions (CHCs). Treatment exposures were categorized as historical (craniospinal irradiation [CSI] ≥ 30 Gy, no chemotherapy), standard-risk (CSI > 0 to <30 Gy + chemotherapy) and high-risk (CSI ≥ 30 Gy + chemotherapy) therapy. Latent class analysis identified patterns of functional independence using employment, independent living, assistance with routine/personal care needs, driver's license, and marital/partner status. Multivariable models estimated the risk of neurocognitive impairment in survivors versus siblings and by treatment exposure group, and associations between neurocognitive impairment, CHCs, and functional independence. Survivors in each treatment exposure group had a 4- to 5-fold elevated risk of impaired memory and task efficiency compared to siblings. Contemporary risk-based therapies did not confer lower risk compared to historical therapy. Survivors treated in the 1990s had a higher risk of memory impairment (relative risk [RR] 2.24, 95% confidence interval 1.39-3.60) compared to survivors treated in the 1970s. Sensorimotor, hearing problems, and seizures were associated with 33-34%, 25-26%, and 21-42% elevated risk of task efficiency and memory impairment, respectively. Treatment-related CHCs and neurocognitive impairment were associated with nonindependence. Despite treatment changes, long-term survivors of childhood medulloblastoma remain at risk for neurocognitive impairment, which was associated with CHCs. Neurocognitive surveillance after contemporary regimens is imperative.

Immunoexpression of Survivin and P53 in the Histological Subtypes of Medulloblastoma: A Cross-Sectional Observational Study.

Medulloblastoma (MB) is a common malignant intracranial neoplasms in children. The treatment and prognosis of this tumor depends on histology and molecular subtypes. Survivin, implicated in various malignancies, may hold prognostic significance. We investigated survivin and p53 immunoreactivity in different histological subtypes in 20 MB cases from January 2018 to June 2021. Immunohistochemistry revealed survivin expression in 75% (15/20) of cases, with cytoplasmic (10 cases), nuclear (four cases), or combined expression (one case). p53 nuclear expression was present in 35% (7/20) of cases. Classical variant MB exhibited predominant p53 and cytoplasmic survivin expression. Given the association of survivin and p53 expression with poor prognosis, especially in the prevalent classical variant, targeted therapies may hold promise for MB treatment advancement.

MDB-36. 22-HDOHE, A PREDICTIVE MARKER IN CSF OF PATIENTS WITH RECURRENT MEDULLOBLASTOMA TREATED WITH MEMMAT

Abstract BACKGROUND With the antiangiogenic metronomic MEMMAT combinatorial regimen, we could achieve sustained responses in a quarter of the patients with previously irradiated recurrent medulloblastoma. There are currently no molecular biomarkers predicting response to MEMMAT treatment for recurrent medulloblastoma. Lipid mediators, including classical arachidonic acid-derived eicosanoids and docosanoids, are locally acting bioactive signaling lipids that regulate a diverse set of homeostatic and inflammatory processes. Before initiation of MEMMAT treatment for relapsed medulloblastoma, we examined the bioactive lipid mediator profile in the cerebrospinal fluid (CSF) of patients and compared it with samples from patients with different neurological disorders, but without cancer. METHODS We analyzed CSF samples from 23 patients with relapsed MBL before initiation of MEMMAT treatment and from 12 controls. Lipid mediators were enriched via solid phase extraction and analyzed using liquid chromatography coupled to a high resolution orbitrap Exploris 480 mass spectrometer. RESULTS Mass spectrometry-based untargeted oxylipin analysis led to the identification of 98 lipid mediators. Several molecules were downregulated in medulloblastoma samples versus control, such as lipoxin A4 and 14(15)-DiHETE. Non-responders had lower levels of these molecules than responders. Glycodeoxycholic acid and deoxycholic acid were up-regulated in medulloblastoma patients, again with higher levels in non-responders. Remarkably, the docosahexaenoic acid (DHA)-derived 22-HDoHE was specifically identified in the CSF samples of medulloblastoma patients but not in control samples. CONCLUSION An oxylipin pattern in CSF might serve as a predictive biomarker signature for response in patients with recurrent medulloblastoma treated with the antiangiogenic metronomic MEMMAT regimen. Our findings advocate for the prospective assessment of CSF-derived lipid markers in future trials for recurrent medulloblastoma.

MDB-37. RAC1 INHIBITION FOR THE TREATMENT OF MEDULLOBLASTOMA

Abstract Despite considerable advances in identifying genetic and epigenetic abnormalities in medulloblastoma, many patients succumb to the disease. In addition, patients who respond to traditional therapy suffer from cognitive and intellectual deficits. Therefore, there is a dire need to identify novel therapies for treating medulloblastoma. Rho family GTPases are targets in multiple cancers including medulloblastoma. Rho, Rac1 and Cdc42 are essential mediators of cell-cell adhesion and cellular motility signaling, which are dysregulated in medulloblastoma. These GTPases are involved in the regulation of the cytoskeleton, cell migration, cellular proliferation, and developmental signaling. The small GTPase Rac1 has recently been reported as a possible therapeutic target in SHH-medulloblastoma due to its regulation of Hedgehog signaling via the GLI1 and GLI2 transcription factors. We have recently reported that GLI1/GLI2 are in a novel complex that contains the epigenetic regulators UHRF1 and DNMT1. Therefore, Rac1 may play a previously unappreciated role in epigenetic regulation of medulloblastoma by controlling the GLI1/GLI2/UHRF1/DNMT1 complex. To test this, we have utilized a novel brain penetrant Rac1 inhibitor termed GYS32661. GYS32661 treatment of medulloblastoma cells inhibits the GLI1-UHRF1 interaction. Importantly this inhibition of the interaction occurs rapidly suggesting that it is disrupting an early event in SHH signaling. GYS32661 also inhibits actin polymerization suggesting that utilizing this compound may provide a dual mechanism of inhibiting Shh signaling and cellular migration concurrently. GYS32661 is not toxic in animal models and is approximately 50% brain penetrant and therefore is an important clinical candidate for the treatment of medulloblastoma. Our studies identify an essential link between Rac1, Shh signaling, epigenetics, and cellular migration in medulloblastoma.

EPID-04. CAUSES AND LONG-TERM COURSE OF OTOTOXICITY IN PEDIATRIC MEDULLOBLASTOMA AND EPENDYMOMA PATIENTS – CUMULATIVE PLATINUM AND COCHLEAR IRRADIATION DOSE MATTER

Abstract BACKGROUND Ototoxicity is a well-known side effect of treatment with platinum-containing chemotherapy and radiotherapy (RT). Nevertheless, precise dose-effect relationships are still lacking. METHODS Patients from the HIT2000 trial receiving first-line treatment for medulloblastoma (MB) or ependymoma (EPN) who were alive at last follow-up and had at least one audiogram prior to and after administration of chemotherapy with cisplatinum and radiotherapy were included into this study. Treatment details (incl. cochlear irradiation dose [CID]) and audiological outcome were analyzed. The ototoxicity was graded using the HIT scoring. RESULTS Courses of 101 patients were analyzed. Median audiology follow-up was 6 years [range: 1.0–18.1 years]. Ototoxicity grade ≥1 was documented for n=66 patients (65.4%). For n=27 this resulted in treatment modification. Univariable analyses revealed different proportions of ototoxicity (grade ≥1) regarding histology (CMB: 50/65, LCAMB: 3/3, DMB/MBEN: 8/12, EPN: 5/21; p&amp;lt;0.001), tumor location (supratentorial: 3/9, infratentorial: 63/92; p&amp;lt;0.001), metastatic status at diagnosis (M0: 46/77, M+: 20/24; p=0.003), radiation field (CSI: 59/75, local RT: 6/21, no RT: 1/5; p&amp;lt;0.001), CID (continuous variable, p=0.001) and cumulative cisplatinum dose (continuous variable, p&amp;lt;0.001). Certainly, disease specific parameters (histology/staging) were related to treatment intensity (cisplatinum/irradiation dose). Multivariable analyses confirmed the impact of cumulative cisplatinum dose (p=0.01) and CID (p=0.04). ROC-analyses allowed the definition of cut-offs for high risk of ototoxicity grade ≥1 (cisplatinum: 70mg/m2 BSA, CID: 37.5 Gy) and ototoxicity risk estimation, when applying doses above the respective cut-offs (cisplatinum dose increase by 1mg/m2 BSA results in 4% higher risk for ototoxicity grade ≥1; CID dose increase by 1 Gy results in 4.6% higher risk for ototoxicity grade ≥1). CONCLUSIONS Ototoxicity affects a majority of children receiving adjuvant treatment for MB and EPN. To avoid disabilities and negative effect on quality of live, dosage of cisplatinum and radiotherapy should be scrutinized and reduced whenever possible.

LMIC-01. SURVIVAL AND PROGNOSTIC FACTORS IN CHILDHOOD MEDULLOBLASTOMA SINGLE TERTIARY CENTER EXPERIENCE FROM KING FAHAD MEDICAL CITY KFMC SAUDI ARABIA

Abstract BACKGROUND Medulloblastoma (MB) is the most common childhood malignant brain tumor treated with intensive multimodalities therapy including Surgery, Craniospinal Radiation, and chemotherapy. Our study aims to document the clinical courses, prognostic factors, and survival outcomes in Saudi children above three years with Medulloblastoma treated in King Fahad Medical City KFMC. METHODS Retrospective analysis of MB patients diagnosed between January 2009 to January 2022 All patients received Risk-adapted Radiation therapy followed by maintenance chemotherapy,3 patients progressed and died after surgery and were excluded from analysis. RESULTS We identified 145 MB patients 65.5 % were male. median age at Diagnosis 7.00 years (range3-14 years), Age less than 5 years did not have a worse outcome in our cohort. Classic histology was predominant (80%), 42.1% of patients had metastatic disease at presentation; the Median time to start radiation therapy after surgery was 35 days. 51.7% were treated as High-Risk HR MB and Average Risk AR MB 48.3%. 65 cases having molecular testing for MB molecular subgroups. 6 patients 4.1% developed a second malignancy with a median time of 6 years post diagnosis. Multivariate survival analysis showed that progression-free survival was significantly reduced by the extent of surgical resection (P=0.021) and Metastatic MB at diagnosis(P=0.014). At Median follow-up of 7 years, Progression-free survival PFS and overall survival OS for the whole cohort were 72.4% and 71.7% respectively. PFS for AR MB and HR MB was 81.4% and 64.0% respectively. PFS analysis based on molecular subgroup: WNT subgroup 92.3%, SHH 69.2%, Group 4:57.7%:and group 3: 46.2%. CONCLUSIONS Our study is the largest analysis of childhood MB treatment outcomes in Saudi Arabia Defining the poor prognostic factor for these patients and will form the baseline for future pediatric Neuro-Oncology studies in KFMC, which may help to improve the outcome of childhood MB in Saudi Arabia.

MDB-51. PHASE II INTERVENTIONAL STUDY TO EVALUATE THE SAFETY AND EFFICACY OF STANDARD AND HIGH-DOSE CHEMOTHERAPY COMBINED WITH CRANIOSPINAL IRRADIATION WITH PROTON THERAPY IN PATIENTS WITH METASTATIC MEDULLOBLASTOMA AND OTHER EMBRYONIC CANCERS: PRELIMINARY RESULTS

Abstract BACKGROUND The high risk medulloblastoma remains a leading cause of cancer-related death in children. METHODS A total of 18 patients have been enrolled from February 2018 to May 2022.The median age was 7,5 years (range; 12 males and 6 female). The protocol predicted the first phase of induction with 4 cycles of chemotherapy. After induction patients with favorable histology without evidence of disease were enrolled to proton therapy (with concomitant vinorelbine biweekly). The maintenance phase with Lomustine repeated every 9 weeks and vinorelbine every 3 weeks for overall 12-18 months (PR). Conversely LC/A MB, were subjected to consolidation phase with high dose of chemotherapy with tiothepa followed by autologous HSC transplant and successive maintenance phase of 6 months. RESULTS At October 2023, the median follow up was 24 months. After the induction phase 14 patients showed CR, 2 PR, 1PD, 1SD. At subsequent re-evaluations two with PR, showed disease control, one CR and the other SD and the patient with PD showed CR. Patient with SD showed an unchanged state of the disease. During the reporting period two patient died for progression of the underlying disease. At 24 months from the start of treatment the PFS was 75,4 % (95% CI: 34.1% - 87.6%) and at 15 months the OS was 86,1% (95% CI: 68.1% - 99.2%). The principal expected side effects of chemotherapy were hematology toxicity and 58% rate of GH deficiency. Among the unexpected side effect was CMV retinopathy with complete blindness and leukoencephalopathy after high dose of thiotepa and proton irradiation. We reported only one case of ototoxicity. CONCLUSIONS The use of proton therapy combined with intensive chemotherapy and myeloablative chemotherapy only in selected cases and always before irradiation has proven feasible and effective in the treatment of high-risk patients medulloblastomas and other embryonic tumors.

MDB-58. REDUCED CRANIOSPINAL DOSE FOR NEWLY DIAGNOSED HIGH-RISK MEDULLOBLASTOMA IN CHILDREN YOUNGER THAN 5 YEARS OLD: RETROSPECTIVE EXPERIENCE FROM SFCE

Abstract BACKGROUND High Risk medulloblastoma (MB) treatment strategy is based on an intensive multimodal treatment including surgery, chemotherapy and radiotherapy. French adapted PNET HR +5 is based on high-dose chemotherapy and age-stratified (18 Gy &amp;lt; 3 yo, 23 for 3-5 yo, 36 Gy for &amp;gt; 5 yo) craniospinal dose irradiation to reduce long-term side-effects of radiotherapy. METHODS To estimate progression-free (PFS) in a national multi-institutional retrospective study, we enrolled children younger than 5 yo with newly diagnosed high-risk MB treated according to adapted PNET HR +5 trial. RESULTS Thirty-seven children from 15 French hospitals (median age, 3.4 yo; range, 0.7-4.8) with confirmed high-risk MB were included. 15 patients (39%) were less than 3 years old. 29 patients (81%) had metastatic disease. Group 3 was the most represented molecular subgroup. 5-year PFS and OS was 59 % and 77 %, respectively. According to dose of craniospinal irradiation, PFS for 18 Gy, 23.4 Gy and 36 Gy patient groups were 100 %, 75 % and 45%, respectively. Treatment was well tolerated. One toxic death was declared. Analysis of longitudinal neurocognitive performance is ongoing. CONCLUSIONS the French strategy comprising high-dose chemotherapy and age-adapted craniospinal irradiation is promising with a high rate of survival in young children and must be confirmed by a prospective trial.

MDB-48. A SINGLE INSTITUTION EXPERIENCE OF CIPN MEASURED BY THE PED-MTNS IN CHILDREN AND ADOLESCENTS WITH MEDULLOBLASTOMA TREATED ON A TRIAL USING SIMILAR DOSING OF VINCRISTINE AND CISPLATIN FOR ALL PATIENTS

Abstract BACKGROUND Standard treatment for medulloblastoma in patients &amp;gt;3 years of age consists of tumor resection, radiation and chemotherapy using vincristine, cisplatin, cyclophosphamide +/- CCNU. Vincristine and Cisplatin are known to cause chemotherapy induced peripheral neuropathy (CIPN). The prevalence of CIPN in children with non-CNS cancers can be measured using the pediatric-modified Total Neuropathy Score (ped-mTNS). The purpose of this observational, retrospective pilot design is twofold: to investigate the prevalence of CIPN in children with medulloblastoma receiving neurotoxic chemotherapy, and to examine the feasibility of using the ped-mTNS as a measurement tool in this population. METHODS Data was manually extracted from medical records and entered into a REDCap database for analysis. The percent of patients successfully tested and clinical inferences made from ped-mTNS testing results were used to determine feasibility and barriers to use. A total of 33 medulloblastoma patients &amp;gt;3 years of age were treated from 6/2013 - 6/2021 at Children’s Minnesota. Of those, 18 received testing using the ped-mTNS during chemotherapy treatment. RESULTS During cancer treatment, 54.5% of the cohort of patients received ped-mTNS testing. The average age of children tested was 10.26 (4.39) years with a majority being male (79%), and non-Hispanic white race/ethnicity (89%). Of the tested participants, 61.1% had more than one measurement. For those patients tested at multiple timepoints, 72.7% demonstrated worsening ped-mTNS scores while on chemotherapy treatment. Therapists recorded inferences relating to neuropathy in 88.1% of testing occurrences with questions of accuracy recorded in 31.3% of testing occurrences. Barriers to use of results included confounding impairments that may occur as a result of the primary tumor, post-surgical changes, and radiation. CONCLUSIONS Using the ped-mTNS is feasible in children and adolescents with medulloblastoma. The ped-mTNS scores indicated that children with medulloblastoma, treated with Vincristine and Cisplatin, experience worsening neuropathy while undergoing chemotherapy treatment.

ETMR-29. PRIMARY CNS SARCOMAS IN CHILDREN AND ADOLESCENTS: EXPERIENCE OF AN INSTITUTION

Abstract BACKGROUND Soft tissue sarcomas represent 6% of childhood cancers, less than 0.2% of CNS tumors are primary intracranial sarcomas. Their origin is pluripotential primitive mesenchymal cells. OBJECTIVE to evaluate clinical and genetic characteristics and report the experience of a rare CNS tumor. METHODS review of CNS tumors database at IOP/GRAACC/UNIFESP for the period 2008-2024, searching for all types of sarcomas that involved the CNS. RESULTS case series included 7 male, 2 female patients; average age at diagnosis 11.3 years. Supratentorial was the most common site of occurrence (66.6%), posterior fossa and intramedulary (2 and 1 cases, respectively) were found. One PF sarcoma presented as a second neoplasm after 2 years finished treatment for medulloblastoma, the other was diagnosed just after metilation. The presenting symptoms varied with tumor location, specially hemiparesis, seizure and headache. Gross total resection was achieved in 7 cases (77.7%), 1 after second look surgery. Histology and immunohistochemistry studies revealed: spinocellular sarcoma, fusocellular and myxoid sarcoma, gliosarcoma, meningeal sarcoma, Ewing sarcoma, condrosarcoma and synovial sarcoma. Work-up excluded other primary tumor origin outside CNS. Analyses for genetic characteristics were performed by Next Generation Sequencing in 6 patients (66.6%) and the following alterations were found: NRAS, TP53, JAK3, NF2, C11orf95-RELA fusion, PDGFRA. Some of these, by now, with no significant meaning for the disease. All patients underwent multimodal treatment. Chemotherapy involved mainly ICE Protocol (55.5%), but also Head Start Protocol and Ewing Sarcoma Protocol. Follow-up ranged from 13 months to 12 years, 90% of patients are alive, 2 (28.5%) dealing with endocrinal issues after focal radiotherapy. The mean overall survival was 61.4 months. CONCLUSION CNS primary sarcomas were mostly observed in the supratentorial region and in older children, with male predilection. Multimodal treatment seems to benefit patients’ outcomes. More patients and longer follow-up periods are needed to further elucidate the biological features of these tumors.

LMIC-03. BRAINSTEM RADIATION NECROSIS IN A PATIENT WITH RECURRENT MEDULLOBLASTOMA. SUCCESFULL TREATMENT OF A HIGHLY FEARED COMPLICATION

Abstract BACKGROUND Medulloblastoma is the most common malignant brain tumor in pediatric population. Standard treatment combines surgery, risk-adapted craniospinal irradiation and chemotherapy. Given the well-known cognitive sequelae in young children associated to radiation, strategies in infants try to avoid upfront radiation. A significant number of patients treated during infancy will ultimately relapse. Re-irradition in relapse setting has proven to be effective in disease control (survival depending on several factors) although there is a concern in exceeding radiation tolerance and risk of toxicity. METHODS Herein, we describe the case of male patient that presented at 1 year of age with a non-metastatic anaplastic medulloblastoma that was completely resected. He received 3 cycles of adjuvant chemotherapy (as per Head Start II), local relapse was detected in tumor bed during evaluation and was completely resected, afterwards he received myeloablative chemotherapy with stem cell rescue and posterior fossa radiation therapy (54 Gy). At 8 months off therapy patient developed spinal relapse in imaging with negative cytology, then treated with spinal irradiation 36Gy without adjuvant chemotherapy. He remained disease free during 12 months, then tumor recur at the right cerebellopontine angle, surgery was complete and there was no evidence of distant disease. Patient received adjuvant local radiation with 30.6Gy followed by chemotherapy (bi weekly bevacizumab + irinotecan). Cumulative maximal dose to brainstem was 84Gy. 2 months after radiation patient presented with extreme sleepiness and imaging findings compatible with brainstem radiation necrosis, symptoms resolved promptly after scheduled bevacizumab. Patient is currently 6-year-old and remains free of disease after 3 years off therapy. CONCLUSION Medulloblastoma treatment in infants is challenging because survival is not the only goal. Future clinical trials will help to better tailored treatment based on molecular biology. Re-irradiation in medulloblastoma has been described as well tolerated but clinician should be aware of its complications and management.

Triptolide and its prodrug Minnelide target high-risk MYC-amplified medulloblastoma in preclinical models.

Most children with medulloblastoma (MB) achieve remission, but some face very aggressive metastatic tumors. Their dismal outcome highlights the critical need to advance therapeutic approaches that benefit such high-risk patients. Minnelide, a clinically relevant analog of the natural product triptolide, has oncostatic activity in both preclinical and early clinical settings. Despite its efficacy and tolerable toxicity, this compound has not been evaluated in MB. Utilizing a bioinformatic data set that integrates cellular drug response data with gene expression, we predicted that Group 3 (G3) MB, which has a poor 5-year survival, would be sensitive to triptolide/Minnelide. We subsequently showed that both triptolide and Minnelide attenuate the viability of G3 MB cells ex vivo. Transcriptomic analyses identified MYC signaling, a pathologically relevant driver of G3 MB, as a downstream target of this class of drugs. We validated this MYC dependency in G3 MB cells and showed that triptolide exerts its efficacy by reducing both MYC transcription and MYC protein stability. Importantly, Minnelide acted on MYC to reduce tumor growth and leptomeningeal spread, which resulted in improved survival of G3 MB animal models. Moreover, Minnelide improved the efficacy of adjuvant chemotherapy, further highlighting its potential for the treatment of MYC-driven G3 MB.

Radiotherapy for Recurrent Medulloblastoma in Children and Adolescents: Survival after Re-Irradiation and First-Time Irradiation.

Radiotherapy (RT) involving craniospinal irradiation (CSI) is important in the initial treatment of medulloblastoma. At recurrence, the re-irradiation options are limited and associated with severe side-effects. For pre-irradiated patients, patients with re-irradiation (RT2) were matched by sex, histology, time to recurrence, disease status and treatment at recurrence to patients without RT2. A total of 42 pre-irradiated patients with RT2 were matched to 42 pre-irradiated controls without RT2. RT2 improved the median PFS [21.0 (CI: 15.7-28.7) vs. 12.0 (CI: 8.1-21.0) months] and OS [31.5 (CI: 27.6-64.8) vs. 20.0 (CI: 14.0-36.7) months]. Concerning long-term survival after ten years, RT2 only lead to small improvements in OS [8% (CI: 1.4-45.3) vs. 0%]. RT2 improved survival most without (re)-resection [PFS: 17.5 (CI: 9.7-41.5) vs. 8.0 (CI: 6.6-12.2)/OS: 31.5 (CI: 27.6-NA) vs. 13.3 (CI: 8.1-20.1) months]. In the RT-naïve patients, CSI at recurrence improved their median PFS [25.0 (CI: 16.8-60.6) vs. 6.6 (CI: 1.5-NA) months] and OS [40.2 (CI: 18.7-NA) vs. 12.4 (CI: 4.4-NA) months]. RT2 could improve the median survival in a matched cohort but offered little benefit regarding long-term survival. In RT-naïve patients, CSI greatly improved their median and long-term survival.