BACKGROUND:Sonic hedgehog (SHH) medulloblastoma is the most common molecular group of infant and early childhood medulloblastoma (iMB) and has no standard of care at relapse. This work aimed to evaluate the post-relapse survival (PRS) and explore prognostic factors of patients with nodular desmoplastic (ND) and/or SHH iMB. METHODS:This international retrospective study included 147 subjects diagnosed with relapsed ND/SHH iMB between 1995 and 2017, <6 years old at original diagnosis, and treated without initial craniospinal irradiation (CSI). Univariable and multivariable Cox models with propensity score analyses were used to assess PRS for those in the curative intent cohort. RESULTS:The 3-year PRS was 61.6% (95% confidence interval [CI], 52.2-69.6). The median age at relapse was 3.4 years (interquartile range [IQR], 2.6-4.1). Those with local relapse (40.8%) more often received salvage treatment with surgery (P < .001), low-dose CSI (≤24 Gy; P < .001), or focal radiotherapy (P = .008). Patients not receiving CSI (40.5%) more often received salvage marrow-ablative chemotherapy (HDC + AuHCR [P < .001]). On multivariable analysis, CSI was associated with improved survival (hazard ratio [HR] 0.33 [95% CI, 0.13-0.86], P = .04). Salvage HDC + AuHCR, while clinically important, did not reach statistical significance (HR 0.24 [95% CI, 0.0054-1.025], P = .065). CONCLUSIONS:Survival of patients with relapsed SHH iMB is not satisfactory and relies on treatments associated with toxicities including CSI and/or HDC + AuHCR. Cure at initial diagnosis to avoid relapse is crucial. For patients with localized relapse undergoing resection, alternative salvage regimens that avoid high-dose CSI (>24 Gy) can be considered.

BACKGROUND:While international consensus and the 2021 WHO classification recognize multiple molecular medulloblastoma subgroups, these are difficult to identify in clinical practice utilizing routine approaches. As a result, biology-driven risk stratification and therapy assignment for medulloblastoma remains a major clinical challenge. Here, we report mass spectrometry-based analysis of clinical samples for medulloblastoma subgroup discovery, highlighting a MYC-driven prognostic signature and MYC immunohistochemistry (IHC) as a clinically tractable method for improved risk stratification. METHODS:We analyzed 56 formalin fixed paraffin embedded (FFPE) medulloblastoma samples by data-independent acquisition mass spectrometry identifying a MYC proteome signature in therapy-resistant group 3 medulloblastoma. We validated MYC IHC prognostic and predictive value across 2 groups of 3/4 medulloblastoma clinical cohorts (n = 362) treated with standard therapies. RESULTS:After the exclusion of WNT tumors, MYC IHC was an independent predictor of therapy resistance and death [HRs 23.6 and 3.23; 95% confidence interval (CI) 1.04-536.18 and 1.84-5.66; P = .047 and <.001]. Notably, only ~50% of the MYC IHC-positive tumors harbored MYC amplification. Accordingly, cross-validated survival models incorporating MYC IHC outperformed current risk stratification schemes including MYC amplification, and reclassified ~20% of patients into a more appropriate very high-risk category. CONCLUSIONS:This study provides a high-resolution proteomic dataset that can be used as a reference for future biomarker discovery. Biology-driven clinical trials should consider MYC IHC status in their design. Integration of MYC IHC in classification algorithms for non-WNT tumors could be rapidly adopted on a global scale, independently of advanced but technically challenging molecular profiling techniques.

PURPOSE:Tropomyosin receptor kinase (TRK) fusions are detected in less than 2% of central nervous system tumors. There are limited data on the clinical course of affected patients. EXPERIMENTAL DESIGN:We conducted an international retrospective cohort study of patients with TRK fusion-driven central nervous system tumors. RESULTS:A total of 119 patients were identified. The median age at the time of diagnosis was 4.5 years. The majority were reported to have a histology consistent with a diagnosis of high-grade glioma (HGG; 57.1%) followed by low-grade glioma (LGG; 27.7%). Pediatric patients had a better prognosis, with a median overall survival of 185.5 months compared with 24.8 months in adults (P < 0.0001). Patients with LGG also had a better outcome when compared with HGG (P = 0.0012). The objective response was 68.8% with larotrectinib compared with 38.1% for nontargeted treatment. CONCLUSIONS:Children with LGG had a favorable outcome compared with adult glioma and HGG. TRK inhibitors seem to improve tumor control.

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a heterogeneous group of malignancies with poor outcome. Here, we identify a subgroup, PTCL-NOSSMARCB1-, which is characterized by the lack of the SMARCB1 protein and occurs more frequently in young patients. Human and murine PTCL-NOSSMARCB1- show similar DNA methylation profiles, with hypermethylation of T-cell-related genes and hypomethylation of genes involved in myeloid development. Single-cell analyses of human and murine tumors revealed a rich and complex network of interactions between tumor cells and an immunosuppressive and exhausted tumor microenvironment (TME). In a drug screen, we identified histone deacetylase inhibitors (HDACi) as a class of drugs effective against PTCL-NOSSmarcb1-. In vivo treatment of mouse tumors with SAHA, a pan-HDACi, triggered remodeling of the TME, promoting replenishment of lymphoid compartments and reversal of the exhaustion phenotype. These results provide a rationale for further exploration of HDACi combination therapies targeting PTCL-NOSSMARCB1- within the TME. Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a heterogeneous and aggressive type of T-cell lymphoma. Here, the authors perform single-cell analyses of human and murine PTCL-NOS tumors, and identify a subtype defined by the loss of SMARCB1 that could be targeted with HDAC-inhibitor combination therapies.

Abstract In precision medicine, molecular profiling of pediatric tumors is crucial for diagnosis, prognosis, and therapeutic decision-making. Traditional biopsy methods, often invasive, have inherent risks and may not capture a tumor’s heterogeneity. Liquid biopsy, however, offers a minimally invasive and comprehensive alternative. We demonstrate its utility in diagnosing and monitoring brain tumors using cell-free DNA (cfDNA) from cerebrospinal fluid (CSF), where conventional cfDNA plasma analysis has shown low sensitivity. Through digital droplet PCR, we analyzed 23 plasma samples from patients with BRAFV600E or H3K27M gliomas, detecting H3K27M in a single case. Conversely, CSF samples revealed 8 positives out of 9 for these mutations, underscoring CSF’s diagnostic value. We advanced our methodology by developing a 21-gene hybrid-capture panel paired with low-pass whole-genome sequencing to pinpoint copy number variations. In our reference sample set, the panel achieved a detection limit with variant allele frequencies as low as 0.5%. With 10ng of cfDNA, we reached 83% sensitivity and 100% specificity, which increased to 100% sensitivity with a 30ng input. Using this assay, we profiled 141 CSF samples from 119 patients, achieving 70% positivity rate in active disease cases in a validation cohort—ranging from 50% in low-grade gliomas to 84% in high-grade gliomas and 75% in medulloblastomas. Intriguingly, of 14 queried tumor samples lacking biopsy confirmation, half showed positive ctDNA results using the panel and/or low-pass whole-genome sequencing. This approach allowed for differential diagnoses in suspected medulloblastoma relapses, tailored therapeutic interventions based on CSF profiles, and effective treatment response monitoring. In summary, our integrated liquid biopsy strategy showcases a powerful, clinically applicable tool that significantly enhances patient care in pediatric neuro-oncology.

Successful treatment of acute lymphoblastic leukemia (ALL) requires multiagent chemotherapy regimens and central nervous system prophylaxis, including intrathecal methotrexate. Although acute symptomatic seizures can occur during ALL treatment, epilepsy is less common. Furthermore, drug resistant epilepsy (DRE) is rare, presenting with two phenotypes: focal epilepsy, such as temporal lobe, or epileptic encephalopathies (EE), such as Lennox-Gastaut syndrome (LGS). For ALL survivors, the development of DRE has significant impact on morbidity, mortality, and quality of life. We describe four patients with ALL remission, who developed EEs, of which 3 had LGS. Mean age at ALL diagnosis was 1.9 years; range 1.1-2.5 years. All, but one, had normal development prior to ALL. No patient had CNS leukemic involvement. All patients received CNS prophylaxis with intrathecal methotrexate, without cranial radiotherapy. Three had symptomatic methotrexate neurotoxicity during treatment. The mean age at first seizure was 5.6 years; range 3.9-7.5 years, with a mean latency of 3.7 years from ALL diagnosis. All patients developed drug resistant EEs, moderate intellectual disability, and neuropsychiatric co-morbidities. Two patients had a minimal response to corpus callosotomy (CC), and one did not respond the ketogenic diet. Successful treatment of childhood ALL is rarely associated with the development of DRE and EEs. Young age at ALL diagnosis (<3 years) may be a predisposing factor. Palliative treatments, including ketogenic diet and CC have limited benefit in these patients. Individual genetic susceptibility to MTX toxicity is likely related to epileptogenesis, and further research is required for epilepsy biomarkers.

Abstract BACKGROUND WNT and group 4 medulloblastoma (MB) are rare in young children and their outcome when treated with radiation avoidance infant strategies is unknown. METHOD This retrospective international cohort included children less than 7 years of age, with molecularly characterized group 4 or WNT MB, treated with high-dose chemotherapy(HDC) and CSI sparing approach. RESULTS The current cohort includes 29 patients (19M/10F). For the 26 patients with group 4 MB (median age at diagnosis 45.9 months), 16 (61.5%) were M0 and 17 (65.3%) underwent initial gross total resection (GTR). The most common consolidation regimen used was three cycles of high dose carboplatin and thiotepa (65.5%) or a single cycle of high dose of carboplatin, etoposide and thiotepa (31%).Two received adjuvant focal radiotherapy. Sixteen patients (61.5%) relapsed at a median time of 21.4 months from diagnosis (median age of 5.2 years). Relapse was local for 50% of the patients. One patient underwent palliative management and 15 received radiation-based salvage therapy (2 focal, 13 CSI+/- boost).The median dose of CSI was 36Gy (18-36). Five of the 15 died of disease. Overall, at a median follow-up of 37.9 months from diagnosis, 17/26 (65.3%) patients were alive, six had died of disease and two of toxicity. All 3 WNT patients (median age at diagnosis 57.8 months) underwent GTR and two were M0. Two received sequential high dose carboplatin and thiotepa. One patient with initial partial response, progressed 2 months after treatment completion and received salvaged CSI (18Gy). All of them were alive at a median follow up of 88 months from diagnosis. CONCLUSIONS HDC and CSI sparing approaches led to a high rate of relapse for young patient with group 4 (61.5%). However, 2/3 were salvaged with radiation-based therapy given at a median age 5.2 yrs. Additional WNT patients are needed to better describe their management.

Abstract Pediatric low-grade gliomas (PLGG) have excellent outcomes overall but are a major clinical challenge when disseminated. Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a recognised entity both clinically and pathologically, however many disseminated LGG (DLGG) fall outside this diagnosis. To better understand the clinical and molecular features of DLGG as well as risk factors for dissemination, we assembled an international consortium of 30 sites, contributing over 200 patients with clinical annotation, along with genomic and methylation profiling. DLGG have worse progression-free (PFS) and overall survival (OS) than PLGG overall (p<0.0001). Seventy (35%) presented with a localized mass and secondary dissemination, including some with initial gross-total resection. The most common growth pattern observed (n=77, 40%) is a dominant suprasellar/optic pathway tumor with leptomeningeal drop-metastases involving the brainstem and spinal cord. Only 27 (14%) patients had diffuse tumors (without an identifiable dominant mass), and these had significantly worse OS (p=0.03). The most common pathologic diagnosis was pilocytic/pilomyxoid astrocytoma (n=92; 53%). DLGNT comprised a minority of cases (n=23, 14%), with a trend (p=0.056) towards worse survival compared to other diagnoses. The most frequent molecular alteration was BRAF fusion (78/151 with molecular testing; 52%), followed by FGFR mutations or fusions (18/151; 12%). BRAF V600E was underrepresented (14/151; 9%). 1p deletion was rare (17 patients) but highly associated with DLGNT. Methylation classification (n=70) was highly concordant with histologic diagnoses rather than clinical behavior. Importantly, patients who received upfront targeted therapies (TT; BRAF and/or MEK inhibition, n=9) had better PFS compared to those receiving chemotherapy (n=146, p=0.05). Furthermore, patients who were treated sequentially with chemo then TT had longer PFS on TT (p=0.011). This study presents the largest cohort of DLGG to date, expanding our understanding of the clinical, pathologic, and molecular features of this disease and supports the use of upfront targeted therapy.

Radiotherapy is important for treating pediatric CNS tumours. The main modalities include photon therapy and PBT. PBT offers potential advantages over photon therapy in children since its precise dose control can limit long-term side effects. However, Canadian patients needing PBT are referred to the United States (US) because PBT is unavailable in Canada. We aimed to describe PBT use and outcomes over time for Canadian pediatric patients with CNS tumours. Patient demographics, treatment characteristics, and outcomes were extracted from medical records of patients from 10/13 Canadian provinces/territories. Patients diagnosed with a CNS tumour at ≤20 years old between 2001-2021 who received curative-intent PBT were included. PBT plans were compared using Fisher’s exact or Kruskal-Wallis rank sum tests. Overall survival (OS) was estimated using the Kaplan-Meier method. Of 195 patients (59.0% male) included in the study, majority were from Alberta (28.7%), Quebec (26.7%), British Columbia (22.6%), and Ontario (20.5%). Median age at diagnosis was 8.0 years. Most tumours (77.9%) were non-metastatic. Medulloblastoma was the most common diagnosis (30.8%). Provinces/territories referred patients to proton centres in the same geographical regions, except Alberta (74.5% referred to Florida). Referral numbers have increased ~180%/year since 2011. Median time from diagnosis to PBT was 126 days [11-5236] for all patients, and 36 days [21-1313] for medulloblastoma. Radiation doses, irradiation site, therapy duration, and time to treatment were not different (p≥0.2) across all PBT facilities for medulloblastoma. 5-year OS were 86.8% and 73.0% for the PBT study population and the Cancer in Young People-Canada reference population, respectively, in those aged <15 years. Given the unavailability of PBT in Canada, pediatric CNS tumour patients were referred to US PBT facilities close in proximity. Further studies are needed to better understand provincial referral patterns and barriers to equitable PBT access across Canada.

Abstract BACKGROUND High-grade gliomas (HGG) in children are a heterogeneous group of central nervous system (CNS) tumors that are very aggressive and highly malignant. Few patients achieve long-term survival despite decades of clinical trials. International collaborations have sought to better describe and understand the genetic underpinnings of pediatric HGG in hopes to uncover more effective treatment options. We report two HGG cases of young children with a YAP1-MAML2 fusion. METHODS Clinical data was collected retrospectively, and pathology was reviewed to confirm the diagnosis. RNA sequencing was performed using the Illumina TruSight RNA Pan-cancer Next Generation Sequencing Panel. Methylation profiling was completed using the HumanMethylation450 BeadChip platform (Illumina, San Diego, CA). RESULTS Two children ages less than 5 years with HGG were identified to have the YAP1-MAML2 fusion. One child was diagnosed at age 4 years and had an additional somatic BRAF V600D mutation. The child was treated initially with surgical debulking and cisplatin-based chemotherapy but had rapid clinical and radiologic progression. Due to the BRAF V600D mutation, the child started Dabrafenib and Trametinib but continued to have rapid craniospinal dissemination and died within 8 weeks of presentation. The second child was diagnosed at age 2 years and had an additional oncogenic PTENpF341V mutation. DNA methylation profiling on this tumor did not show evidence of clustering with any known CNS tumor entity. This child was treated with surgical debulking, chemotherapy (Baby POG), focal radiation 5400cGy, and maintenance chemotherapy (lomustine and temozolomide as per COG ACNS 0423). This child continues to have stable residual disease 29 months from presentation. CONCLUSION We present two cases of HGG in young children with a unique YAP1-MAML2 fusion. Future studies are needed to further characterize the significance of how this new molecular alteration impacts treatment and long-term outcomes in pediatric HGG.

Abstract BACKGROUND Diffuse hemispheric glioma, H3 G34-mutant (G34-DHG) is generally associated with very poor outcome. Little is known, however, regarding long-term survivors and associated prognostic factors. METHODS This retrospective, multicentre study was designed to investigate clinical, molecular, and imaging variables that may impact the survival of patients with G34-DHG. Patients of any age diagnosed with G34-DHG after January 1, 1995, with at least one measure of survival or progression were eligible. RESULTS 69 patients with G34-DHG (62 G34R, 5 G34V, 2 diagnosed by methylation profiling only) have been included to date. Median age at diagnosis was 16.0 years (range: 2–38). 75% of patients were under the age of 18. 52% of patients were male. 8% of patients had multifocal/disseminated disease at diagnosis. Upfront therapy included gross/near total resection in 47% of patients, radiation therapy in 88% (89% focal, 6% CSI), and maintenance chemotherapy in 85% (62% TMZ-based, 33% TMZ/CCNU, 5% non-TMZ). Median follow-up time was 20.0 months (IQR=12.0–30.0). 86% of patients had progressive disease with a median time-to-progression of 14.0 months (IQR=6.6-22.5). At last follow-up, 70% of patients had died from disease, 23% were alive with disease, and 7% were alive without disease. Median overall survival was 24.7 months (IQR=18.8–30.6). Median time from progression to death was 6.0 months (IQR=2.0–10.8). Six patients were found to be long-term survivors > 5 years (four dead of disease, one alive with disease, one alive without disease). Log-rank assessment revealed improved survival to be associated with upfront gross/near-total resection (p=0.002) and age at diagnosis ≥ 18 years (p=0.012). CONCLUSIONS Surprisingly, we found that nearly 10% of G34-DHG patients survive 5 years or longer. Radical surgical resection and older age at diagnosis appear to be associated with longer survival. Imaging and molecular prognostic factors are being further investigated.

Background: The treatment of BRAF V600E gliomas with BRAF inhibitors (BRAFis) and MEK inhibitors (MEKis) has been increasingly integrated into clinical practice for pediatric low-grade gliomas (PLGGs) and pediatric high-grade gliomas (HGGs). However, some questions remain unanswered, such as the best time to start targeted therapy, duration of treatment, and discontinuation of therapy. Given that no clinical trial has been able to address these critical questions, we developed a Canadian Consensus statement for the treatment of BRAF V600E mutated pediatric as well as adolescent and young adult (AYA) gliomas. Methods: Canadian neuro-oncologists were invited to participate in the development of this consensus. The consensus was discussed during monthly web-based national meetings, and the algorithms were revised until a consensus was achieved. Results: A total of 26 participants were involved in the development of the algorithms. Two treatment algorithms are proposed, one for the initiation of treatment and one for the discontinuation of treatment. We suggest that most patients with BRAF V600E gliomas should be treated with BRAFis ± MEKis upfront. Discontinuation of treatment can be considered in certain circumstances, and we suggest a slow wean. Conclusions: Based on expert consensus in Canada, we developed algorithms for treatment initiation of children and AYA with BRAF V600E gliomas as well as a discontinuation algorithm.

Abstract BACKGROUND Given that radiation therapy is the only treatment modality demonstrated to result in any clinical benefit for children with DIPG, re-irradiation therapy has been explored as a treatment option for progressive DIPG. Several studies suggest re-irradiation is feasible, and may lengthen survival for children with progressive DIPG. However, any re-irradiation benefits are unclear and no standard of care (dose, fractionation, volume, timing, clinical status) has been defined. The aims of this study are to evaluate re-radiation therapy practices for children with progressive DIPG/DMG and to define a historical cohort of children with DIPG/DMG who have received re-radiation (re-XRT) for progressive DIPG/DMG. METHODS Data was extracted from the International DIPG Registry, and analyzed with descriptive statistics. RESULTS Of 1214 patients in the iDIPG Registry, 113 receiving re-XRT. Patients were diagnosed between 2002-2022, with the majority of patients diagnosed over the last decade. Of those 113 patients with specified data, at re-irradiation, n=68 (60%) received photon and n= 4 (4%) were treated with proton radiation. The median dose at re-XRT was 25 Gy (20-30 IQR) in 10 fractions (10-14 IQR). Time between initial XRT and re-XRT was 41.5 weeks (29.5-54 weeks). OS from diagnosis was 18 months (range, 15-23 mo); OS from re-XRT was 6 months (range, 4-10 mo). CONCLUSIONS Re-radiation therapy for children with DIPG/DMG is becoming a more common practice and appears to have OS benefit, with post-progression OS of 6 mo comparing favorably to historical data of 2.3 mo. [Cooney T et al, Neuro Oncol 2017] Efforts are underway to define patient selection and tolerability. Data extraction from the SIOPE DIPG/DMG Registry is also ongoing; data from both registries will be collated and uniformly presented.

Objective To describe disease outcomes including overall survival and relapse patterns by subgroup in young pediatric patients treated for medulloblastoma with a radiation-sparing approach. Methods Retrospective analysis of clinical outcomes includes treatment, relapse, and salvage therapy and late effects in children treated for medulloblastoma with a radiation-sparing approach at British Columbia Children’s Hospital (BCCH) between 2000 and 2020. Results There were 30 patients (median age 2.8 years, 60% male) treated for medulloblastoma with a radiation-sparing approach at BCCH. Subgroups included Sonic Hedgehog (SHH) ( n = 14), group 3 ( n = 7), group 4 ( n = 6), and indeterminate status ( n = 3). Three- and 5-year event-free survival (EFS) were 49.0% (30.2–65.4%) and 42.0% (24.2–58.9%) and overall survival (OS) 66.0% (95% CI 46.0–80.1%) and 62.5% (95% CI 42.5 and 77.2%), respectively, with a median follow-up of 9.5 years. Relapse occurred in 12/25 patients following a complete response, of whom six (group 4: n = 4; group 3: n = 1; unknown: n = 1) were successfully salvaged with craniospinal axis (CSA) RT and remain alive at a median follow-up of 7 years. Disease/treatment-related morbidity included endocrinopathies ( n = 8), hearing loss n = 16), and neurocognitive abnormalities ( n = 9). Conclusions This radiation sparing treatment approach for young patients with medulloblastoma resulted in a durable cure in most patients with SHH subgroup medulloblastoma. In those patients with groups 3 and 4 medulloblastoma, relapse rates were high; however, most group 4 patients were salvaged with RT.

Question Headache, vomiting, lethargy, and seizures are common symptoms in healthy children with benign viral illnesses, but they are also signs that could represent a central nervous system (CNS) tumour. Primary care providers and guardians are hesitant to expose children to radiation associated with computed tomography scans or take on risks associated with the sedation frequently needed for magnetic resonance imaging. When should primary care providers order radiologic head imaging for children with common symptoms to identify those with a CNS tumour? Answer Central nervous system tumours have no pathognomonic features, which often results in delays in diagnosis. Owing to the high prevalence of infratentorial tumours, children commonly present with symptoms of increased intracranial pressure, making a detailed history and a comprehensive physical examination, including ophthalmoscopy for papilledema, especially important. Magnetic resonance imaging is the criterion standard test but it may take time to access, and young children may need sedation. Hence, computed tomography may be a preferable first option. The HeadSmart initiative in the United Kingdom provides guidance to obtain brain imaging within 4 weeks of onset of persistent symptoms that are associated with CNS tumours. We advocate applying the same criteria in Canada in order to reduce delay in diagnosis of CNS tumours in children.

Journal Article Reviewer Lists Get access Neuro-Oncology, Volume 25, Issue 1, January 2023, Pages 214–216, https://doi.org/10.1093/neuonc/noac277 Published: 05 January 2023 Article history Corrected and typeset: 05 January 2023 Published: 05 January 2023