BACKGROUND:The utility of chemotherapy for childhood ependymoma is uncertain without a prior randomized trial. METHODS:ACNS0831, a multicenter phase 3 randomized study conducted through the Children's Oncology Group (COG), included patients 1-21 years with newly diagnosed intracranial ependymoma. Patients with complete/near-total resections (GTR/NTR) or complete response (CR) to induction therapy were randomized to radiation (RT) alone or RT followed by chemotherapy (RT-CHEMO). Primary outcomes were event-free survival (EFS) and overall survival (OS). Due to anticipated noncompliance with chemotherapy, an "as treated" analysis was planned. Patients with subtotal resection (STR) were non-randomly assigned to RT-CHEMO. Grade 2 supratentorial tumors with GTR or CR to induction therapy were observed. RESULTS:Of 449 eligible patients, 325 with GTR/NTR or CR were randomized. Five-year EFS was 63.7% (95% CI: 55.1%-71.1%) for RT only (n = 161) versus 69.2% (60.8%-76.3%) for RT-CHEMO (n = 164) (1-sided log-rank P = .299, HR = 0.866). Five-year OS was 86.9% (79.8%-91.6%) for RT only versus 88.3% (81.8%-92.6%) for RT-CHEMO (1-sided log-rank P-value = .172, HR = 0.757). The "as treated" and "as randomized" analysis results were similar. Sixty-three subjects with STR were assigned to RT-CHEMO; 5-year EFS was 33.6% (22.1%-45.5%) and OS 74.0% (60.5%-83.5%). Supratentorial grade 2 tumors with GTR or CR were observed with a 5-year EFS of 66.9% (49.0%-79.7%) and OS of 100%. Molecular classification was provided for 94% (n = 422) of all subjects. CONCLUSIONS:Primary analysis showed no benefit for maintenance chemotherapy. Further follow-up is important to assess its effect on late relapses. This is the largest cohort of molecularly classified ependymomas treated on a Phase 3 randomized trial.

BACKGROUND:Ependymoma (EPN) is an aggressive pediatric central nervous system tumor with poor survival and significant morbidity. As immune factors are associated with outcome, the potential for effective immunotherapy in posterior fossa (PF) EPN has been suggested. Based on the success of immune stimulants combined with an anti-GD2 monoclonal antibody in high-risk pediatric neuroblastoma, we hypothesized that a similar approach would be a plausible immunotherapy strategy for recurrent PF EPN. METHODS:A phase 0/1 trial evaluating the safety and dosing of intrathecal (IT) trastuzumab combined with subcutaneous (s.c.) granulocyte-macrophage colony-stimulating factor (GM-CSF) for pediatric patients with relapsed PF EPN was conducted. RESULTS:ErbB2/Her2, targeted by trastuzumab, was identified as a top therapeutic antibody target for EPN by in silico screening. In vitro co-culture assays with GM-CSF-stimulated autologous PBMCs showed trastuzumab antibody-dependent cell cytotoxicity in PFA EPN cell lines. A phase 1 clinical study identified that IT delivery of trastuzumab in combination with s.c. GM-CSF was safe in children at both dose levels tested. Four patients (57%) successfully completed all planned therapy. The median progression-free survival was 2.4 years (95% CI, 0.47, not evaluable). Profiling of biological correlates identified that tumors of patients who did not progress on the study had increased T-cell activity and decreased pro-tumor inflammatory myeloid gene expression compared to patients who progressed on study treatment. CONCLUSION:IT trastuzumab in combination with GM-CSF is safe in recurrent pediatric PF EPN. A larger phase 2 study that includes both recurrent PFA and RELA-ST EPN is needed to determine the long-term efficacy of this immunotherapy strategy.

Pediatric low-grade gliomas (pLGG) comprise 35% of all brain tumors. Despite favorable survival, patients experience significant morbidity from disease and treatments. A deeper understanding of pLGG biology is essential to identify novel, more effective, and less toxic therapies. We utilized single-cell RNA sequencing (scRNA-seq), spatial transcriptomics, and cytokine analyses to characterize and understand tumor and immune cell heterogeneity of pilocytic astrocytoma (PA) and ganglioglioma (GG). scRNA-seq revealed tumor and immune cells within the tumor microenvironment (TME). Tumor cell subsets include both progenitor and mature cell populations. Immune cells included myeloid and lymphocytic cells. There was a significant difference between the prevalence of two major myeloid subclusters between PA and GG. Bulk and single-cell cytokine analyses evaluated the immune cell signaling cascade with distinct immune phenotypes among tumor samples. KIAA1549-BRAF tumors appeared more immunogenic, secreting higher levels of immune cell activators and chemokines, compared to BRAF V600E tumors. Spatial transcriptomics revealed the differential gene expression of these chemokines and their location within the TME. A multi-pronged analysis demonstrated the complexity of the PA and GG TME and differences between genetic drivers that may influence their response to immunotherapy. Further investigation of immune cell infiltration and tumor-immune interactions is warranted.

BACKGROUND:Posterior fossa molecular subtype A (PFA) ependymoma occurs in young children and is the deadliest subtype of pediatric ependymoma. High-risk subtypes with chromosome 1q + and/or 6q- exhibit significantly poorer outcomes compared to wild-type PFA. However, 50% of wild-type PFA patients relapse and there is a high risk of gaining chromosome 1q at recurrence. We previously found constitutively active NF-κB, through loss of LDOC1, led to chronic IL-6 secretion and an overall immunosuppressive tumor microenvironment in the higher-risk wild-type PFA ependymoma subset (PFA1). METHODS:In this study, we delineate the mechanistic consequences of LDOC1 loss in PFA1, using our PFA ependymoma in vitro and in vivo models under normoxia and hypoxia conditions. RESULTS:We noted chromatin compaction by H3K27me3 at the LDOC1 loci results in loss of LDOC1 gene expression. Restoration of LDOC1 was sufficient to reduce proliferation, NF-κB signaling, and a significant decrease in IL-6 secretion. Furthermore, tumors implanted with LDOC1-transduced cells in vivo were out competed by non-transduced cells, suggesting loss of LDOC1 is required for PFA tumor growth. CONCLUSION:These findings shed further light on the biology of PFA1 ependymoma and the role LDOC1 loss has on the tumor and immunobiology of high-risk pediatric ependymoma.

Childhood epilepsy is a common and devastating condition, for which many children still do not have adequate treatment. Some children with drug-resistant epilepsy require surgical excision of epileptogenic brain tissue for seizure control, affording the opportunity to study this tissue ex vivo to interrogate human epileptic neurons for potentially hyperexcitable perturbations in intrinsic electrophysiological properties. In this study, we characterized the diversity of layer L2/3 (L2/3) pyramidal neurons (PNs) in ex vivo brain slices from pediatric patients with epilepsy. We found a remarkable diversity in the firing properties of epileptic L2/3 PNs: five distinct subpopulations were identified. Additionally, we investigated whether the etiology of epilepsy influenced the intrinsic neuronal properties of L2/3 PNs when comparing tissue from patients with epilepsy due to malformations of cortical development (MCDs), other forms of epilepsy (OEs), or with deep-seated tumors. When comparing epileptic with control L2/3 PNs, we observed a decrease in voltage sag and lower maximum firing rates. Moreover, we found that MCD and OE L2/3 PNs were mostly similar indicating that epilepsy etiology may not outweigh the influences of epileptiform activity on L2/3 PN physiology. Lastly, we show that the proconvulsant drug, 4-aminopyridine (4-AP), leads to increased AP half-width, reduced firing rate accommodation, and slower AHPs. These changes imply that 4-AP induces an increase in [K+]o and a resultant increase in AP duration, leading to the release of more excitatory neurotransmitters per action potential, thereby promoting network hyperexcitability.

Epilepsy is one of the most common neurological disorders worldwide. Despite the availability of many anti-seizure medicines (ASMs), about 30 % of patients with epilepsy develop drug-resistant epilepsy. Unfortunately, the mechanisms of ictogenesis in patients with drug-resistant epilepsy remain to be elucidated. Here, we used 4-aminopyridine (4-AP) to study interictal-like oscillations in human epileptic neocortex. 4-AP is a voltage-gated potassium channel blocker commonly used to induce seizure-like activity in ex vivo brain slices. We observed that 4-AP induced neuronal bursting and robust slow, hyperpolarizing oscillations (HypOs) in layer 2/3 (L2/3) pyramidal neurons (PNs). Using paired recordings, we demonstrate that neuronal bursting and HypOs are synchronized between neighboring L2/3 PNs. We also determined that 4-AP-induced HypOs are potassium currents that were not mediated by GABAA/B receptors, NMDA receptors or AMPA receptors, or NKCC1 and KCC2 channels. Instead, HypOs are dependent on network activity and are impacted by gap junction blockade. Interestingly, HypOs were eliminated by activation, but not inactivation, of KCNQ2-5 (Kv7.2-Kv7.5) channels and were reduced via intercellular calcium chelation suggesting a role for calcium in KCNQ channel activation. Our results indicate 4-AP-induced HypOs are due to GABAergic interneuron synchronization, which leads to local extracellular potassium fluctuations without the need for GABA neurotransmission. Moreover, KCNQ2-5 channel activation can help stabilize potassium fluctuations, resulting in cessation of interictal-like events.

Densitometry for apoptosis proteomic array of 1q+ PFA cell lines treated with 5FU and 5Gy radiation.

MAF-811_XC in vivo survival with radiation and chemotherapy.

MAF-928 in vivo mice had more metastatic lesions with radiation alone.

Combination of radiation with 5FU is synergistic in 1q+ PFA cell lines.

Purpose: Oncology advanced practitioners (APs) are on the front line in treating adverse effects. Among children with brain tumors, treatments such as craniospinal irradiation (CSI) cause neurocognitive injury, endocrinopathies, and ototoxicity. High-dose CSI with concurrent chemotherapy allows high-risk embryonal tumors (non-anaplastic) good survival (70%), but significant distressing effects are commonly treated by APs in multidisciplinary long-term follow-up. The aim of this study was to test feasibility of reducing radiation dose with an AP-led protocol. Methods: An interdisciplinary team developed this pilot study with the primary outcome of fewer than two deaths in 10 patients (80% survival). Secondary outcomes were feasibility of an AP-led treatment protocol and acute/late effects of treatment. The AP held a pioneering role as principal investigator of a tumor treatment study. Exclusion criteria included age less than 3 years and anaplasia. The CSI was reduced from 36 to 24 Gy. All other treatment was standard. Results: Survival rate exceeded the primary outcome threshold (88%); the accrual rate (80%) and follow-up neurocognitive testing rate (75%) were acceptable. Eight children ages 3 to 19 years (M = 8) with tumors of varied molecular subtyping were enrolled. The single death occurred 2.5 years from diagnosis of multiorgan failure (without evidence of tumor). The mean survival is 11 years, with two college and one graduate degrees. Acute and late effects were decreased compared with the higher-dose CSI. Conclusion: APs who treat cancer adverse effects can also conduct clinical prospective studies to maintain survival rates and improve quality-of life-outcomes.

Subdural fluid collection is a common neurosurgical condition in the pediatric population. Patients requiring surgical intervention have historically been managed with subdural drains, subdural-subgaleal shunting, subdural-peritoneal shunting, and mini-craniotomies. An alternative procedure for patients with an open anterior fontanelle is bedside transfontanelle drainage. This study aims to evaluate the efficacy of the transfontanelle angiocatheter drain placement including complications and the need for any further surgery. We performed a single-center retrospective review of all patients who underwent placement of transfontanelle drain to treat subdural fluid collections from January 2013 to June 2023. Data points collected included demographics, comorbidities, mechanism of subdural collection, neurologic status on presentation, subdural size, amount of drainage, complications, and need for further intervention. We identified 28 patients who underwent bedside transfontanelle subdural angiocatheter placement between January 2013 and June 2023. The patient age range was 0–11 months (avg 3.96). Twenty-three patients were male (82

BACKGROUND:Tumor invasion of the spinal canal is detected radiographically in approximately 15% of patients with newly diagnosed neuroblastoma (NB). The optimal clinical approach to maintain excellent survival outcomes while minimizing long-term sequelae is yet to be defined. METHODS:Patients with intermediate-risk neuroblastoma (IR-NB) and radiographically identified intraspinal tumors who were treated on the Children's Oncology Group study ANBL0531 were studied prospectively to evaluate neurologic outcomes related to cord compression. Patients were defined as being symptomatic versus asymptomatic based on reporting of neurologic motor deficits at diagnosis. Patient characteristics, tumor biology, chemotherapy treatment, surgical interventions, and neurologic and disease outcomes are reported. RESULTS:Of the 92 patients with intraspinal tumors, 42 (46%) were symptomatic and most (73%) had complete resolution of symptoms. Age, degree of motor deficit, and duration of symptoms at diagnosis were not associated with complete resolution. While symptomatic patients were more likely to undergo upfront laminectomy, laminectomy was not associated with improvement of motor symptoms. Administration of additional chemotherapy beyond initial treatment assigned per protocol to achieve the treatment end point was not associated with achieving symptom resolution. CONCLUSION:Patients presenting with motor deficits due to intraspinal tumor had excellent survival and favorable neurologic outcomes, with the majority reporting complete resolution of motor symptoms regardless of severity and duration of symptoms at diagnosis or neurosurgical intervention. Prompt diagnosis and initiation of first-line chemotherapy treatment remain priority, while neurosurgical intervention should be reserved for patients with rapid neurologic deterioration. Biology-based therapy and tumor response should continue to be used to maintain favorable outcomes.

5FU at 75mg/kg in combination with 10Gy radiation is too toxic in vivo

AbstractPurpose:There are no effective treatment strategies for children with highest-risk posterior fossa group A ependymoma (PFA). Chromosome 1q gains (1q+) are present in approximately 25% of newly diagnosed PFA tumors, and this number doubles at recurrence. Seventy percent of children with chromosome 1q+ PFA will die because of the tumor, highlighting the urgent need to develop new therapeutic strategies for this population.Experimental Design:In this study, we utilize 1q+ PFA in vitro and in vivo models to test the efficacy of combination radiation and chemotherapy in a preclinical setting.Results:5-fluorouracil (5FU) enhances radiotherapy in 1q+ PFA cell lines. Specifically, 5FU increases p53 activity mediated by the extra copy of UCK2 located on chromosome 1q in 1q+ PFA. Experimental downregulation of UCK2 resulted in decreased 5FU sensitivity in 1q+ PFA cells. In in vitro studies, a combination of 5FU, retinoid tretinoin (ATRA), and radiation provided the greatest reduction in cellular proliferation and greatest increase in markers of apoptosis in 1q+ PFA cell lines compared with other treatment arms. Similarly, in vivo experiments demonstrated significant enhancement of survival in mice treated with combination radiation and 5FU and ATRA.Conclusions:These results are the first to identify a chromosome 1q+ specific therapy approach in 1q+ PFA. Existing phase I studies have already established single-agent pediatric safety and dosages of 5FU and ATRA, allowing for expedited clinical application as phase II trials for children with high-risk PFA.

MAF-811_XC in vivo survival with radiation and chemotherapy.

BACKGROUND:We previously reported excellent three-year overall survival (OS) for patients with newly diagnosed intermediate-risk neuroblastoma treated with a biology- and response-based algorithm on the Children's Oncology Group study ANBL0531. We now present the long-term follow-up results. METHODS:All patients who met the age, stage, and tumor biology criteria for intermediate-risk neuroblastoma were eligible. Treatment was based on prognostic biomarkers and overall response. Event-free survival (EFS) and OS were estimated by the Kaplan-Meier method. RESULTS:The 10-year EFS and OS for the entire study cohort (n = 404) were 82.0% (95% confidence interval (CI), 77.2%-86.9%) and 94.7% (95% CI, 91.8%-97.5%), respectively. International Neuroblastoma Staging System stage 4 patients (n = 133) had inferior OS compared with non-stage 4 patients (n = 271; 10-year OS: 90.8% [95% CI, 84.5%-97.0%] vs 96.6% [95% CI, 93.9%-99.4%], p = .02). Infants with stage 4 tumors with ≥1 unfavorable biological feature (n = 47) had inferior EFS compared with those with favorable biology (n = 61; 10-year EFS: 66.8% [95% CI, 50.4%-83.3%] vs 86.9% [95% CI, 76.0%-97.8%], p = .02); OS did not differ (10-year OS: 84.4% [95% CI, 71.8%-97.0%] vs 95.0% [95% CI, 87.7%-100.0%], p = .08). Inferior EFS but not OS was observed among patients with tumors with (n = 26) versus without (n = 314) 11q loss of heterozygosity (10-year EFS: 68.4% [95% CI, 44.5%-92.2%] vs 83.9% [95% CI, 78.7%-89.2%], p = .03; 10-year OS: 88.0% [95% CI, 72.0%-100.0%] vs 95.7% [95% CI, 92.8%-98.6%], p = .09). CONCLUSIONS:The ANBL0531 trial treatment algorithm resulted in excellent long-term survival. More effective treatments are needed for subsets of patients with unfavorable biology tumors.

Abstract BACKGROUND Nearly all children with gain of chromosome 1q (1q+) PFA ependymoma (EPN) will die, highlighting the urgent need to develop new treatment strategies for these patients. It has recently been shown that 1q+ creates a p53 mutant-like phenotype through trisomy expression of MDM4, a repressor of p53 signaling. This same study found toxic uracil analogs could reverse trisomy MDM4 effect on p53 and this was mediated through another 1q-trisomy gene UCK2. We and other have previously identified 5-fluorouracil (5FU) as an ependymoma specific inhibitor. In this study, we present the mechanism for 5FU sensitivity. METHODS In this study we utilize 1q+ PFA in vitro models to test the efficacy of combination radiation and 5FU in a preclinical setting. We measured p53 signaling through proteomic array and qRT-PCR for p21, a p53 response gene. RESULTS 5FU enhances radiotherapy in 1q+ PFA cell lines. Specifically, 5FU increases p53 activity mediated by the extra copy of UCK2 located on chromosome 1q in 1q+ PFA. Experimental down regulation of UCK2 resulted in decreased 5FU sensitivity in 1q+ PFA cells. Though not statistically significant, we did see prolong survival and decreased tumor burden in 1q+ PFA orthotopic patient-derived xenograft models treated with focal 2Gyx5days radiation and 5FU. CONCLUSION These results are the first to identify a 1q+ specific therapy approach in PFA EPN. Existing phase 1 studies in pediatrics have already established safety and dose of 5FU, providing a rapid translation into phase 2 trials for children both up front and at recurrence for 1q+ PFA.

Pediatric low-grade gliomas (pLGG) comprise 35% of all brain tumors. Despite favorable survival, patients experience significant morbidity from disease and treatments. A deeper understanding of pLGG biology is essential to identify novel, more effective, and less toxic therapies. We utilized single cell RNA sequencing (scRNA-seq), spatial transcriptomics, and cytokine analyses to characterize and understand tumor and immune cell heterogeneity across pLGG. scRNA-seq revealed tumor and immune cells within the tumor microenvironment (TME). Tumor cell subsets revealed a developmental hierarchy with progenitor and mature cell populations. Immune cells included myeloid and lymphocytic cells. There was a significant difference between the prevalence of two major myeloid subclusters between pilocytic astrocytoma (PA) and ganglioglioma (GG). Bulk and single-cell cytokine analyses evaluated the immune cell signaling cascade with distinct immune phenotypes among tumor samples. KIAA1549-BRAF tumors appeared more immunogenic, secreting higher levels of immune cell activators and chemokines, compared to BRAF V600E tumors. Spatial transcriptomics revealed the differential gene expression of these chemokines and their location within the TME. A multi-pronged analysis of pLGG demonstrated the complexity of the pLGG TME and differences between genetic drivers that may influence their response to immunotherapy. Further investigation of immune cell infiltration and tumor-immune interactions is warranted. Key points There is a developmental hierarchy in neoplastic population comprising of both progenitor-like and mature cell types in both PA and GG. A more immunogenic, immune activating myeloid population is present in PA compared to GG. Functional analysis and spatial transcriptomics show higher levels of immune mobilizing chemokines in KIAA1549-BRAF fusion PA tumor samples compared to BRAF V600E GG samples. Importance of the Study While scRNA seq provides information on cellular heterogeneity within the tumor microenvironment (TME), it does not provide a complete picture of how these cells are interacting or where they are located. To expand on this, we used a three-pronged approach to better understand the biology of pediatric low-grade glioma (pLGG). By analyzing scRNA-seq, secreted cytokines and spatial orientation of cells within the TME, we strove to gain a more complete picture of the complex interplay between tumor and immune cells within pLGG. Our data revealed a complex heterogeneity in tumor and immune populations and identified an interesting difference in the immune phenotype among different subtypes.