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BACKGROUND: The outcome for pediatric patients with high-grade glioma (HGG) remains poor. Veliparib, a potent oral PARP1/2 inhibitor, enhances the activity of radiotherapy and DNA-damaging chemotherapy. Preclinical data indicates that veliparib crosses the blood-brain-barrier and enhances the efficacy of radiotherapy and temozolomide in IDH mutant and wild-type HGG models. ACNS1721 was a single-arm, non-randomized phase 2 clinical trial designed to determine whether treatment with veliparib and radiotherapy, followed by the poly (ADP-ribose) polymerase (PARP) inhibitor veliparib and temozolomide, improves progression-free survival (PFS) in pediatric patients with newly diagnosed HGG without H3 K27M or BRAF mutations compared to patient level data from historical cohorts with closely matching clinical and molecular features. METHODS: Following surgical resection, newly diagnosed children with non-metastatic HGG were screened by rapid central pathology review and molecular testing. Eligible patients without somatic H3 K27M or BRAF mutations were enrolled on Stratum 1 (IDH wild-type) or Stratum 2 (IDH mutant). Protocol radiochemotherapy consisted of involved field radiotherapy with concurrent veliparib at 65 mg/m2 twice daily. Adjuvant chemotherapy consisted of up to 10 cycles of veliparib 25 mg/m2 twice daily and temozolomide 135 mg/m2 once daily for 5 days every 4 weeks. RESULTS: Both strata were closed to accrual for futility after planned interim analyses. Among the 23 eligible patients who enrolled on Stratum 1 and received protocol therapy, the 1-year progression-free survival (PFS) was 0.29 (SE = 0.09) and 1-year overall survival (OS) was 0.67 (SE = 0.10). Among the 14 eligible patients who enrolled on Stratum 2 and received protocol therapy, the 1-year PFS was 0.57 (SE = 0.15) and 1-year OS was 0.90 (SE = 0.09). CONCLUSION: Rapid central pathology review and molecular testing was feasible. The protocol therapy was well tolerated but failed to improve outcome compared to clinically and molecularly matched historical control cohorts.

BACKGROUND The outcome for pediatric patients with high-grade glioma (HGG) remains poor. Veliparib, a potent oral PARP1/2 inhibitor, enhances the activity of radiotherapy and DNA-damaging chemotherapy. Preclinical data indicates that veliparib crosses the blood-brain-barrier and enhances the efficacy of radiotherapy and temozolomide in IDH mutant and wild-type HGG models. ACNS1721 was a single-arm, non-randomized phase 2 clinical trial designed to determine whether treatment with veliparib and radiotherapy, followed by the poly (ADP-ribose) polymerase (PARP) inhibitor veliparib and temozolomide, improves progression-free survival (PFS) in pediatric patients with newly diagnosed HGG without H3 K27M or BRAF mutations compared to patient level data from historical cohorts with closely matching clinical and molecular features. METHODS Following surgical resection, newly diagnosed children with non-metastatic HGG were screened by rapid central pathology review and molecular testing. Eligible patients without somatic H3 K27M or BRAF mutations were enrolled on Stratum 1 (IDH wild-type) or Stratum 2 (IDH mutant). Protocol radiochemotherapy consisted of involved field radiotherapy with concurrent veliparib at 65 mg/m2 twice daily. Adjuvant chemotherapy consisted of up to 10 cycles of veliparib 25 mg/m2 twice daily and temozolomide 135 mg/m2 once daily for 5 days every 4 weeks. RESULTS Both strata were closed to accrual for futility after planned interim analyses. Among the 23 eligible patients who enrolled on Stratum 1 and received protocol therapy, the 1-year progression-free survival (PFS) was 0.29 (SE = 0.09) and 1-year overall survival (OS) was 0.67 (SE = 0.10). Among the 14 eligible patients who enrolled on Stratum 2 and received protocol therapy, the 1-year PFS was 0.57 (SE = 0.15) and 1-year OS was 0.90 (SE = 0.09). CONCLUSION Rapid central pathology review and molecular testing was feasible. The protocol therapy was well tolerated but failed to improve outcome compared to clinically and molecularly matched historical control cohorts.

BACKGROUND Primary spinal high-grade gliomas(S-HGG) are rare, aggressive tumors and radiation therapy(RT) plays a dominant role in the management given their infiltrative nature. We conducted a single-institution retrospective review to study the clinicopathological features and management of S-HGGs. METHODS Patients with biopsy-proven S-HGG who received RT from 2001-2020 were analyzed for patient, tumor, and treatment characteristics. Kaplan-Meier estimate and Cox proportional hazard regression method were used for survival analyses. RESULTS Twenty-nine patients were identified with a median age of 25.9 years (range 1-74y). Four patients had gross total resection(GTR) while 25 underwent subtotal resection or biopsy. Nineteen patients had WHO grade 4 tumor. IDH1 mutation and MGMT promoter methylation were analyzed in 14 and four patients respectively; all were IDH wildtype and MGMT-promoter unmethylated. H3K27M mutation was present in five out of 10 patients tested. Twenty-two patients received photon-based radiation and 7 received proton therapy. Median RT dose was 50.4 Gy (range 39.6-54Gy) with 79% receiving >45Gy. 65% patients received concurrent chemotherapy, most commonly temozolomide. Twenty-three (79%) patients had documented recurrence. Overall, 16 patients relapsed locally, 10 relapsed in the brain and 8 developed leptomeningeal disease; only 8(35%) had isolated local relapse. Median OS from diagnosis was 21.3 months and median PFS after RT was 9.7 months. On univariate analysis, age, sex, GTR, grade, RT modality, RT dose and concurrent chemotherapy did not predict for survival. Patients with H3K27M mutation had a poorer median PFS after RT compared to those without the mutation but the difference did not reach statistical significance (p = 0.26). CONCLUSIONS Although 86% of patients had gross disease at RT and received a lower median RT dose than typically used in cerebral high-grade gliomas, only 55% of patients failed locally. H3K27M mutation may portend worse survival; future studies to improve the therapeutic approach in these patients are warranted.

BACKGROUND/PURPOSE: Stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) deliver highly conformal, ablative doses of radiation over 1–5 treatments, while minimizing dose to surrounding normal tissues. To document toxicities and outcomes of these treatments in children, our updated institutional experience with SRS or SRT for intracranial targets in pediatric patients was reviewed. METHODS: On an IRB approved study, institutional databases were reviewed to identify pediatric patients with intracranial lesions treated with SRS or SRT from October 2009 to July 2021. Medical records were retrospectively reviewed for patient and treatment characteristics. Outcomes were analyzed for symptomatic radionecrosis and CNS progression. RESULTS: Thirty SRS or SRT treatment courses in 26 patients age 3.2 to 17.8y (median, 15.6y) at the time of SRS or SRT were identified. Twenty-two patients had one treatment and four had two treatments. Sixteen patients had brain metastases from extracranial primary disease; 10 had recurrence of a primary CNS tumor. Fifteen patients had prior fractionated radiation to the brain. Nineteen treatments used Gamma Knife (GK) with Leksell frame, three used GK ICON with mask, and eight used linear accelerator with volumetric modulated arc therapy with thermoplastic mask. All patients (10 treatments in nine patients) treated since July 2016 received mask-based radiation. Twelve of 26 (46%) patients were treated with anesthesia. With 9.6-month median follow up (range, 0.1-96.2m), five patients had progression of treated lesions, eight had distant CNS failure, and one had both local and distant failure, for a crude local failure rate of 6/26 (23%) and a crude distant failure rate of 9/26 (35%). There were no skull fractures or other complications from Leksell frame placement. One patient developed symptomatic radionecrosis requiring surgery. CONCLUSION: SRS and SRT can be safely performed in pediatric patients with intracranial lesions. Mask-based immobilization provides an alternative to frame-based treatments.

Case Presentation A 3-year-old female with insignificant past medical history presented with 6 weeks of headaches, emesis, and lethargy. MR imaging identified a heterogeneously enhancing right cerebellar hemispheric mass and obstructive hydrocephalus. Gross total resection was performed without complications; pathology revealed classical WHO grade 4 medulloblastoma (MB). MR imaging of the spine and cerebrospinal fluid testing were negative for disseminated disease. Treatment for standard risk medulloblastoma was initiated, comprising proton craniospinal irradiation with posterior fossa boost and concurrent vincristine, followed by adjuvant chemotherapy with vincristine, lomustine, cisplatin, and cyclophosphamide as standard of care. Next generation sequencing of the tumor tissue performed using a high-multiplex PCR-based NGS panel was negative for alteration of the SMO, PTCH1 and CTBNN1 genes. Further molecular characterization via methylation profiling demonstrated the sonic hedgehog (SHH) molecular subtype. Prior to initiation of chemotherapy, renal ultrasound was performed and identified congenitally absent right kidney; audiology evaluation was unremarkable. Discussion In patients with Gorlin syndrome, cases of unilateral renal agenesis in association with germline SHH-pathway mutations have been reported [1]. SHH signaling is implicated in multiple steps in the development of the urinary system [2]. Outside Gorlin syndrome, however, to the best of our knowledge unilateral renal agenesis coinciding with SHH-driven MB has not been reported. Our patient notably lacks any clinical stigmata of Gorlin syndrome (skeletal abnormalities, skin pits, macrocephaly) and does not exhibit the characteristic germline genetic abnormalities that define GS (PTCH1 mutation or 9q22.3 microdeletion). There are important treatment implications for patients with the constellation of abnormalities we describe here, particularly regarding the requisite frequent monitoring of renal function during multi-agent chemotherapy courses. Our patient tolerated chemoradiation well, and is currently on maintenance chemotherapy with favorable course to date.

ONC201, an anti-cancer DRD2 antagonist and ClpP agonist, is in Phase II trials for adult H3 K27M-mutant diffuse midline gliomas. The recommended phase 2 dose (RP2D) of 625mg ONC201 once a week has been established as a biologically active dose that is well tolerated in adult and pediatric populations. Radiographic regressions with single agent ONC201 have been reported in recurrent H3 K27M-mutant glioma patients. In another study, twice/week dosing was explored in adult patients and deemed to be safe (no DLTs observed). This warranted exploration of twice/week dosing in pediatric patients and will be discussed in this presentation. This multi-arm, dose-escalation and dose-expansion trial (ONC014; NCT03416530) determined the pediatric RP2D of ONC201 administered once per week and twice per week on two consecutive days. ONC201 was orally administered and scaled by body weight. Dose escalation was performed by a 3 + 3 design beginning with two 125mg capsules less than the adult RP2D equivalent. Twelve children (8 females; 4 males) with H3 K27M-mutant gliomas (pons: 8; thalamus: 2; spinal cord: 2) aged 4-19 years have been treated post-radiation: 3 at dose level -1; 3 at dose level 1; 6 as part of the dose expansion cohort on dose level 2. Median KPS was 90 (range 70-100). One treatment cycle was 21 days (6 doses), which also defined the DLT window. Patients were on-treatment for a median length of 4 cycles (range: 2-11). Twice weekly dosing of ONC201 was tolerated well, as observed with weekly dosing, with no instance of DLT. A total of 4 SAEs were reported, none of which were related to the study drug. The most common AEs (regardless of relatedness) included headache, facial nerve disorder, abducens nerve disorder, nausea, fatigue and ataxia. Additional safety data, PK, and clinical outcomes from this arm will be reported.

Neurocognitive late effects are unfortunately common following treatment for pediatric medulloblastoma. While radiation therapy is an essential component of treatment for most pediatric medulloblastoma patients, it is associated with neurocognitive compromise. Effects include deficits in cognitive speed and performance efficiency, aspects of attention, as well as working memory. Yet long after treatment it is difficult to tease apart relative contributions of other risk factors to neurocognitive functioning beyond radiation. We examined neurocognitive functioning in a sample of pediatric medulloblastoma patients prior to radiation therapy, including investigation of neurocognitive risk factors such as hydrocephalus, presence of posterior fossa syndrome, and duration of neurological symptoms prior to diagnosis. Results indicated that the sample functioned in the average range in terms of overall IQ (n=34, X̅=103). Patients also functioned in the normal range in terms of language-based ability (X̅=106), nonverbal ability (X̅=104), and working memory (X̅=103). However, the sample performed statistically significantly lower than the general population in terms of cognitive speed and efficiency (z=-2.026, p=.043). The sample was also rated by parents as exhibiting more attention problems relative to the general population (z=1.988, p=.047). There was no specific association with hydrocephalus, duration of symptoms, or history of posterior fossa syndrome. Results suggest weaknesses in attention and processing speed may exist in some pediatric medulloblastoma patients prior to radiation therapy secondary to tumor and related complications. Implications for future research are presented, along with difficulties inherent to “baseline” assessment with pediatric brain tumor survivors.

INTRODUCTION Spinal myxopapillary ependymoma (MPE) is a rare histological variant of ependymoma, classified as WHO grade I tumor. Further interrogation of the molecular and clinical profile is warranted, to better understand the biology and clinical phenotype. We summarize our institutional experience with spinal MPE including methylation-profiling. METHODS A retrospective analysis of charts during the period of 2001 to 2019 of histologically proven MPE was done. We performed methylation profiling for 12 patients by Infinium MethylationEPIC Kit. RESULTS 26 patients with spinal MPE were identified, median age of diagnosis was 34.2 years with a range of 11 to 59.9 years. Ten patients were below 30 years of age, lumbar spine location was commonest and 6 had leptomeningeal spread at diagnosis. All the patients underwent surgery and 11 received radiation following surgery. Eight patients below the age of 30 received radiation due to residual disease or metastases. Methylation profiling revealed 11,752 CpGs differentially methylated between the younger and older patients (p < 0.05), however only one CpG cg22496254 associated with gene NCAPG/DCAF16 (role in promoting mitosis) was detectable with FDR < 0.25 that overly methylated in the younger age group. This is a new finding in MPE. CONCLUSIONS Spinal MPE is a rare spinal tumor. Our study though limited by numbers, showed younger patients had aggressive phenotype, most requiring radiation. Methylation profiling reaffirmed this finding and trend in the younger patients. Prospective studies in a larger cohort of patients with methylation profiling are needed to identify prognostic variables and new targets for treatment.

INTRODUCTION We report the first known cases of pediatric glioblastoma (GBM) with prior clinical NF1 diagnoses, one with concurrent germline Lynch syndrome (LS) and NF1, and the other with somatic NF1 mutation and germline constitutional mismatch repair deficiency (CMMRD). METHODS Two pediatric GBM cases with prior NF1 clinical diagnoses based on neurocutaneous criteria were reviewed. Next generation sequencing and immunohistochemical staining were used for somatic and germline NF1 and MMR gene mutation detection, and for MMR protein expression, respectively. RESULTS Sixteen year old male with prior NF1 clinical diagnosis had resection of right frontal GBM revealing somatic mutations of POLE and PMS2, but not NF1. His father had confirmed LS with MSH2 mutation and no neurocutaneous stigmata. Patient’s germline testing revealed both pathogenic MSH2 plus NF1 mutations confirming LS and NF1. Treatment consisted of chemoradiation with temozolomide followed by adjuvant temozolomide with stable disease at 8 cycles. Nineteen year old male with former NF1 clinical diagnosis had 2 GBMs, first in left midbrain biopsied revealing somatic PMS2 and NF1 mutations underwent radiation then 7 cycles of temozolomide, then new left frontal GBM underwent resection followed by radiation and 5 cycles of pembrolizumab stable at 5th cycle. CONCLUSION Children with NF1 stigmata and GBM can have concurrent NF1 and LS, or CMMRD with NF1 somatic mutations. Our patients tolerated alkylating agents, despite risk for secondary malignancies as upfront therapy and at recurrence checkpoint inhibitors. Upfront therapy in GBM with mismatch repair syndrome with checkpoint inhibitors should be studied.

BACKGROUND Diffuse intrinsic pontine glioma (DIPG) constitutes 80% of pediatric brain stem tumors with a median survival of 12 months. The PI3K/AKT/mTOR pathway is a key oncogenic driver of this tumor. Targeting the chromatin dysregulation through HDAC inhibition, demonstrated benefit in vivo and vitro studies. We completed the first study as a multi-targeted therapy using SAHA and temsirolimus in pediatric DIPG. METHODS After receiving institutional IRB approval, we enrolled 6 patients on this phase I study using a 3 + 3 statistical design. Patients were divided into stratum 1 and stratum 2, based on newly diagnosed or relapsed DIPG respectively. Stratum I patients received radiation therapy concurrently with vorinostat, followed by maintenance therapy with vorinostat and temsirolimus for 10 cycles (28 day cycle), while in stratum II patients received vorinostat and temsirolimus for 12 cycles. Neuroimaging including diffusion tensor imaging were evaluated where feasible. RESULTS Three patients were enrolled in each of the stratum. One patient in stratum 1 completed therapy, 2 other demonstrated progressive disease (PD) after 4th and 1st cycle of maintenance therapy respectively. In stratum 2 all patients progressed 2 months after the start of therapy. However no dose-limiting toxicity (DLT) was noted. The patient in stratum 1 who completed therapy, remained free of PD 21 months after diagnosis with continued improvements in the volume of enhancing and T2 hyperintense disease. CONCLUSION Although no significant benefit was seen as compared to historical controls during this study, no dose limiting toxicity was noticed with this treatment.

BACKGROUND Predicting neurocognitive outcomes in pediatric brain tumor (PBT) patients is challenging. Rarity of PBT makes inclusion of detailed risk factors (e.g., treatment modality, intensity, individual complications) difficult when sample sizes are small. The Neurological Predictor Scale (NPS) summarizes complications and treatment factors associated with neurocognitive risks and has modest validation. Recently, the Pediatric Neuro-Oncology Rating of Treatment Intensity (PNORTI) was developed to evaluate the impact of treatment intensity on psychosocial outcomes but has not been compared to neurocognitive outcomes. This study compared the NPS and PNORTI in terms of relationship to neurocognitive outcomes known to be at risk in PBT survivors. METHODS 88 PBT survivors’ neuropsychological outcomes were retrospectively analyzed in relation to the NPS and PNORTI. Variables of interest included IQ, working memory, and processing speed. RESULTS NPS associated with lower IQ (rs=-.476, p=.001), lower working memory (rs=-.323, p=.010), and lower processing speed (rs=-.389, p=.007) in patients diagnosed at a younger age, but only processing speed for children diagnosed after age 7 years (rs=-.262, p=.036). PNORTI was not correlated with neurocognitive variables for either group. CONCLUSION NPS has value in predicting neurocognitive outcomes, though much more in a younger age at diagnosis group compared to older patients. The PNORTI did not demonstrate predictive value for these neurocognitive domains in our sample. Given the potential clinical and research value of a summary rating of treatment burden relating to long-term outcome, future research should include relationship to psychosocial outcomes and quality of life.

Background Recurrent pediatric medulloblastoma and ependymoma have a grim prognosis. We report a first-in-human, phase I study of intraventricular infusions of ex vivo expanded autologous natural killer (NK) cells in these tumors, with correlative studies. Methods Twelve patients were enrolled, 9 received protocol therapy up to 3 infusions weekly, in escalating doses from 3 × 106 to 3 × 108 NK cells/m2/infusion, for up to 3 cycles. Cerebrospinal fluid (CSF) was obtained for cellular profile, persistence, and phenotypic analysis of NK cells. Radiomic characterization on pretreatment MRI scans was performed in 7 patients, to develop a non-invasive imaging-based signature. Results Primary objectives of NK cell harvest, expansion, release, and safety of 112 intraventricular infusions of NK cells were achieved in all 9 patients. There were no dose-limiting toxicities. All patients showed progressive disease (PD), except 1 patient showed stable disease for one month at end of study follow-up. Another patient had transient radiographic response of the intraventricular tumor after 5 infusions of NK cell before progressing to PD. At higher dose levels, NK cells increased in the CSF during treatment with repetitive infusions (mean 11.6-fold). Frequent infusions of NK cells resulted in CSF pleocytosis. Radiomic signatures were profiled in 7 patients, evaluating ability to predict upfront radiographic changes, although they did not attain statistical significance. Conclusions This study demonstrated feasibility of production and safety of intraventricular infusions of autologous NK cells. These findings support further investigation of locoregional NK cell infusions in children with brain malignancies.

Introduction Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare diagnosis first incorporated into the WHO Classification of Tumors of the Central Nervous System in 2016. Though historically considered indolent, emerging evidence suggests that the biological behavior of these tumors may be further classified by molecular features of prognostic significance. Methods A retrospective review was conducted in accordance with IRB approval of patients with the histologic diagnosis of DLGNT. Demographic, clinical, and molecular data where abstracted from the medical record when available. Results 10 patients were identified (M = 8, F = 2). Median age at diagnosis was 6 years (range 0.3–21 years), and the most common symptoms at diagnosis were related to obstructive hydrocephalus, for which 3 patients required CSF diversion. MRI findings included diffuse leptomeningeal thickening, nodularity, or coating of the subarachnoid or ependymal surfaces. Histologically, these tumors expressed variable features of neuronal and/or glial differentiation. Four patients (40%) were treated with radiation therapy (all craniospinal), which was upfront for 2 patients. Chemotherapy regimens used included temozolomide, carboplatin and vincristine and vinblastine. NTRK or BRAF-targeted therapy were used upon progression. At follow-up, 6/10 had stable disease (4/6 of whom were on second line therapy), 1 had partial response, 1 passed away from sepsis and 2 were lost to follow-up. The median progression-free survival for the four patients who developed disease progression was 26 months (range 12–34 months). Next generation sequencing of the tumor tissue performed using a high-multiplex PCR-based NGS panel detected BRAF-KIAA1549 (4 patients) and NTRK (1 patient) fusions. Conclusions DLGNT are rare tumors with scarce data about imaging characteristic and standard of care treatment. Our case series reinforces current literature that although these tumors appear low-grade, they can be clinically aggressive. Further study is needed regarding molecular diagnosis and profiling treatment strategies.

BACKGROUND Despite its increasing use, circulating tumor cells (CTCs) have not been studied in pediatric brain tumors. METHODS Cell surface vimentin (CSV) is a marker for CTC detection. We developed an automated CSV-based CTC capture method for pediatric brain tumor using the Abnova Cytoquest platform. PBMCs isolated from blood samples from 52 brain tumor patients were processed to isolate CSV+ CTCs. Captured cells were then stained for CSV and CD45 and scanned to determine the number of CTCs. DIPG samples were additionally examined for H3K27M expression on CSV+ cells. Long term cancer survivors were used as a control cohort. RESULTS 86.4% of all the samples exhibited between 1–13 CSV+ CTCs, with a median of 2 CSV+ CTCs per sample. Using a value of ≥ 1 CTC as a positive result, the sensitivity and specificity of this test was 83.05% and 60.0% respectively. 19 DIPG samples were analyzed and 70% (13 samples) were positive for 1–5 CTCs. Five of these 7 positive CSV+ CTCs DIPG samples were also positive for H3K27M mutations by immunohistochemistry (71%). Mean survival in days for the CTC positive and negative DIPG samples were 114 and 211 days, respectively (p= 0.13). CONCLUSION This is the first study of CTCs in pediatric CNS tumors using an automated approach. Patients with brain tumors can exhibit CSV+ CTCs within peripheral blood. The use of specific molecular markers such as H3K27M can improve the diagnostic capability of liquid biopsies and may enable future disease assessment for personalized therapy.

BACKGROUND Embryonal Tumor with Multilayered Rosettes (ETMR) are rare tumors that are molecularly diagnosed by C19MC amplification. Rarity of this tumor has precluded profiling uniform therapeutic strategy. METHODS Retrospective review after institutional approval, identified 10 pediatric case of ETMR, treated at MD Anderson Cancer Center during the period of 2005 to 2019. RESULTS Median age of at diagnosis was 4.6 years. Tumor sites include frontal or parietal lobes (3), spine (3) and posterior fossa involving the brainstem (4). All patients received a combination of chemotherapy and radiation. 4 patients had metastasis at the presentation. 9 patients received focal radiation but only 6 of them received Craniospinal irradiation (CSI). Average dose of radiation was 50 Gy. Surgical resection was performed in all cases except the brainstem tumors. 7 children had recurrence including all the patients with metastasis at diagnosis (median time: 9.4 months), 1 passed away secondary to hemorrhage in brainstem and data was not available for 2 patients. 5/6 patients who received CSI had recurrence. CONCLUSIONS To-date no well-defined treatment regimens exists for these neoplasms, resulting in poor overall survival. Preclinical drug screen have shown the efficacy of topotecan, actinomycin D, and volasertib as potential new therapeutic candidates, though this has not translated successfully into the clinical arena. Given the limited success with current conventional therapeutic methods, molecular interrogation in addition to histopathological diagnosis are essential upfront, as it could provide clues to targeted therapy. Defining molecularly-based treatment with less toxicities and increased survival are warranted.

BACKGROUND Pseudoprogression after proton therapy of CNS tumors is a challenging clinical situation. The rate of pseudoprogression after proton therapy of pediatric spinal tumors is unknown. METHODS Records of pediatric patients with spinal pilocytic astrocytoma (sPA; n = 9) or myxopapillary ependymoma (MPE; n = 6) with gross disease treated with proton therapy with at least 6 months of follow up from completion of proton therapy were retrospectively reviewed for demographics, treatment characteristics, and occurrence of pseudoprogression. Pseudoprogression was defined as a post-radiation increase in tumor size with subsequent decrease in size without additional tumor-directed therapy. RESULTS The median age at radiation for sPA patients was 10.1y (range, 7.0 – 16.2y) and 12.7y (range, 7.9 – 14.4y) for MPE patients. The median prescribed dose was 45 GyRBE (range, 39.6 – 50.4 GyRBE) for sPA patients and 50.4 GyRBE (range, 45 – 54 GyRBE) for MPE patients. One sPA patient received concurrent vincristine. Median follow up after proton therapy was 44 months (range, 9 – 99 months). Six of nine sPA patients (67%) had pseudoprogression occurring at a median of 81 days (range, 34 – 136 days) after proton therapy; no MPE patients developed pseudoprogression (0%; p < 0.03). Two sPA patients with pseudoprogression were symptomatic and improved with medical therapy. CONCLUSION Preliminary analysis suggests that pseudoprogression occurs frequently within 6 months after proton therapy for sPA and infrequently after proton therapy for MPE.

H3 K27M-mutant gliomas often manifest as midline gliomas, have a dismal prognosis, and have no effective treatments. ONC201 efficacy has been shown in high-grade glioma preclinical models and durable responses with single agent ONC201 have been reported in adults with recurrent H3 K27M-mutant gliomas. These observations led to a Phase I pediatric clinical trial of ONC201 dosed by body weight. This multi-center, open-label, 3 + 3 dose-escalation and dose-expansion clinical trial (NCT03416530) for H3 K27M-mutant glioma or non-biopsied DIPG has 6 arms: arms A and E determine the RP2D in pediatric post-radiation (recurrent or not-recurrent) H3 K27M-mutant glioma patients with ONC201 administered as an oral capsule as well as a liquid formulation, respectively. Both arms have completed accrual. The study is currently enrolling newly diagnosed DIPG patients to determine the RP2D for ONC201 in combination with radiation (arm B). Dedicated assessment of intratumoral ONC201 concentrations in midline gliomas patients (arm C) and the effects of ONC201 in H3K27M DNA levels in circulating CSF (arm D) are currently enrolling patients. ONC201 as a single agent in patients with progressive H3K27M mutant tumors following irradiation (excluding DIPG/spinal cord tumors) was recently opened (arm F). Once the RP2D is confirmed, there is a dose-expansion cohort to confirm the safety, radiographic efficacy and survival with ONC201. The primary endpoints of arms A, B, and E have been established with the RP2D of 625mg scaled by body weight as a capsule or liquid formulation administered alone or in combination with radiation without incidence of dose-limiting toxicity.

Pediatric low-grade gliomas (pLGG) account for one third of all central nervous system (CNS) tumors. MRI is the preferred imaging modality for diagnosis and response evaluation. This study aims to evaluate if radiographic characteristics of pLGG at diagnosis are prognostic. Medical records of 700 pLGG patients were reviewed who were seen between 1998- 2019 at our institution. Summary statistics were provided to describe patient demographic and clinical characteristics. 603 patients were not eligible because incomplete records, 97 patients were identified and eligible for the review. There were 45 females and 52 males with the mean age of 6.5 years at diagnosis. Patients were categorized based on contrast enhancement to 2 groups; none/mild versus moderate/high with 65 and 32 patients respectively. 31 patients had infiltrative glioma (32.3%) with more than one lobe involved at diagnosis. Fifteen patients (15.46%) had hydrocephalous at initial diagnosis. 32 patients (32.9%) did not have any treatment and remained stable while 65(67.0%) had either surgery, chemotherapy or radiation or combination. 21 patients had neurofibromatosis type-1(NF-1) with better outcome comparing to non-NF1 as previously reported. No statistically significant difference in outcome was found based on the imaging characteristics at diagnosis including contrast enhancement, hydrocephalus, tumor size, presence of cyst or infiltrative tumors. The 5 years PFS rate for the entire cohort was 47%. Our study results are limited by low patient number, hence collaborative multi-institutional studies are warranted to delineate consensus and investigate prognostic factors to improve the outcome of pLGG.

Diffuse Intrinsic Pontine Glioma (DIPG) is an incurable pediatric brain tumor. Current standard of care has shown no improvements in survival. Here, we report our study of ONC201, a first-in-class small molecule developed by Oncoceutics, Inc., against a panel of DIPG cells in vitro and in mouse orthotopic models. ONC201 inhibits signaling through dopamine receptor D2 (DRD2), a G protein-coupled receptor (GPCR). MTT assays revealed a delayed but more robust response to ONC201, as measured by IC50 values, in DIPGs with histone H3.3-K27M expression compared to cells expressing wildtype (WT) or K27M mutant histone H3.1. Interestingly, transcriptomic profiling identified an association of this response delay with an elevation of genes controlling the cellular unfolded protein response, lysosomal and vacuole organization, and a decline in nucleic acid biosynthetic genes. These cells were also more committed to neuronal and oligodendrocytic lineage specification. By contrast, WT-H3 DIPGs that survived ONC201 treatment were stem-like and exhibited altered expression of genes controlling cell proliferation and apoptosis induction, respectively. Single cell proteomics validated the increase in anti-apoptotic proteins in these cells. Intraperitoneal administration of ONC201 for 7-weeks in mice bearing pontine xenografts of histone H3.1-K27M mutant DIPGs, caused a complete blockade of tumor growth relative to untreated controls. However, identical treatment of animals with forebrain tumors resulted only in a partial reduction in tumor burden, suggesting that the tumor microenvironment may be involved in the differential effect. These data indicate that tumor intrinsic and extrinsic factors may contribute to the response of DIPG tumors to ONC201.

DNA mismatch repair machinery is an integral part of the human genome and its defect has been involved in tumorigenesis and treatment resistance. Heterozygous monoallelic germline loss of function in MLH-1, MSH-2, MSH-6 or PMS-2 is involved in Lynch syndrome, whereas biallelic mutations cause constitutional mismatch repair deficiency (CMMRD) which is associated with hematologic malignancies and glioblastoma. We report here the clinical characterization and molecular analyses of 7 patients who presented with gliomas and MMR machinery aberrations. Two patients had a clinical diagnosis of NF-1 with dermatologic stigmata, of whom one patient has CMMRD and the other has Lynch syndrome. Two patients had a known family history of Lynch syndrome upon their diagnosis of glioma. Three patients with high-grade glioma and negative family history, 2 had germline mutations in MMR genes, and one had numerous mutations including MMR genes with microsatellite instability. Patients were initially treated with chemotherapy and radiation for high-grade gliomas (HGG); 5/7 had progression. Median time to progression was 12 months (range: 5–52), and median time from progression to death was 7 months (range: 2–25). One patient had low-grade glioma initially but progressed to HGG and is currently on therapy. Another patient treated with temozolomide and radiation is currently receiving maintenance therapy without any disease recurrence. Although the literature data on brain tumors with MMR deficiency is limited, these consistently show that MMRD-associated gliomas are treatment-resistant and have a dismal outcome. Collaborative efforts are needed to better understand this subgroup of pediatric HGG and to define optimal treatment strategy.

BACKGROUND Pediatric GBMs are rare, accounting for 3% of all pediatric CNS tumors. Despite advances in treatment, the outcomes for pediatric glioblastomas (GBM) have not significantly improved. Research suggests a link between enhancement patterns and survival in adult patients with glial tumors. We sought to study this relationship in a cohort of pediatric GBMs. METHODS A radiology database was searched for cases < 22 years, pathology proven brain glioblastoma, and pre-surgical MR imaging available for review. Based on pre-treatment, T1-contrast enhanced MR images, size, and contrast enhancement patterns were characterized as focal, diffuse, or ring-like. The extent of resection was assessed by comparing pre- and post-surgery T2 hyperintensity and contrast enhancement. RESULTS 64 eligible patients (age 2-21y, 14.6 + 5.4) were identified. The majority of lesions demonstrated enhancement on gadolinium-enhanced T1 imaging. (n=58/64; 90%). The lesions were categorized into six (9.4%) cases with focal enhancement, 37 (57.8%) cases with diffuse enhancement, and 15 (23.4%) with ring-like enhancement. Patients who received GTR/subtotal resection (STR) and had focal-enhanced GBMs had a significantly longer progression-free survival (PFS) – 14.1 months (p = 0.0308), comparing to diffuse and ring-like enhancing glioblastomas which had respectively 13.9 and 5.5 months of PFS. DISCUSSION Our data suggests that the contrast enhancement pattern is a significant prognostic factor for survival in pediatric GBM. Patients with GTR/STR who had focal-enhancing GBMs had a significantly longer progression-free survival (p=0.03) comparing to other enhancement patterns.

An 11 y.o. female presented to a GI specialist with complaints of morning vomiting and periumbilical abdominal pain for several months. Had progressing symptoms with GI work-up for ~1 year. She developed diplopia and worsening headaches. Imaging revealed a T2/FLAIR hyperintense mass in the 4th ventricle with heterogeneous enhancement and obstructive hydrocephalus. Three T2 bright, non-enhancing, subcentimeter masses identified in the right cerebellum. Due to poor differentiation between tumor and normal tissue at brainstem, only partial resection (PR) was feasible. Pathology initially called pilocytic astrocytoma (PA). All symptoms resolved after PR. Slow progression in the tumor and “satellite” lesions noted over two years. Second opinion and molecular typing reclassified the tumor as rosette-forming glioneuronal tumor (RFGNT) with a mutation in PIK3CA. Therapy started with vinblastine and carboplatin with stable disease x 7 months, discontinued due to allergic reaction to carboplatin. Initiated therapy with everolimus, an mTOR inhibitor. The tumor’s characteristics on imaging changed with initial growth and increase in peripheral enhancement in one satellite and the primary tumor. Nevertheless, we persevered. When comparing pre-treatment MRI to most recent 7 months later, there has been an overall decrease in volume of expansile heterogenous tumor along the margins of the fourth ventricle. The degree of peripheral enhancement associated with the mass has increased. RFGNT is a rare tumor included in WHO classification since 2007. Ellezam et al identified recurrent PIK3CA mutations. To our knowledge, this is the only report of treatment targeting the mutation. We report a radiographic response despite initial growth.

Pediatric chordomas are exceedingly rare and there are limited data to guide treatment decisions. We report a retrospective analysis of 19 patients with chordomas who received treatment at our institution from 2001–2020. Of the 19 patients, 15 had clival (79%), 3 cervical and 1 sacral chordoma. There were 9 males (47%). Median age at diagnosis of 10.6 years. Eight patients had gross total (42%) and 11 (58%) had sub-total resection. As front line therapy 15 patients (79%) underwent surgery followed by radiation (1 photon and 14 proton), 3 patients (16%) received surgery and chemotherapy (anaplastic histology) and 1 patient received only surgery. For patients treated with radiation therapy the average prescribed dose was 70 Gy (range: 52–74). Post-surgery and radiation, 14 of 15 patients remained in remission. Five (26%) patients had progressive disease (PD) with median time to progression of 13 months of whom 3 died of disease at median of 18 months. Treatment of PD consisted of chemotherapy and radiation for 3, re-resection with radiation for 1 and chemotherapy alone for 1 patient. The patients with metastatic and anaplastic disease mean survival is 21 month versus 45 for the rest of the cohort. In summary, post-operative adjuvant radiation provided an overall good outcome in majority of patients. Patients with anaplastic pathology and metastasis at diagnosis had worse outcome. Those who relapsed, subsequent treatment was palliative at best with short survival. Molecular analysis is warranted in future for better disease stratification.

ONC201, an anti-cancer DRD2 antagonist and ClpP agonist, is in Phase II trials for adult H3 K27M-mutant diffuse midline gliomas. In adults, the recommended phase 2 dose (RP2D) of 625mg ONC201 once a week has been established as a biologically active dose that is well tolerated. Radiographic regressions with single agent ONC201 have been reported in adult recurrent H3 K27M-mutant glioma patients. This multi-arm, dose-escalation and dose-expansion trial determined the pediatric RP2D of ONC201 administered as an oral capsule (Arm A) or liquid formulation (Arm E) in post-radiation H3 K27M-mutant glioma (Arm A) or in newly diagnosed DIPG (Arm B) patients. Molecular assessments include intratumoral ONC201 concentrations (Arm C) and CSF H3 K27M DNA levels (Arm D). Enrollment as of April 30, 2020 is complete in Arm A (22) and Arm E (26) and continues in Arm B (18/24), Arm C (5/12), and Arm D (22/24). The RP2D of weekly 625mg ONC201 scaled by body weight was confirmed when administered as a capsule or a liquid formulation as a single agent or in combination with radiation without dose-limiting toxicity. The most frequent adverse events regardless of attribution to the drug were predominantly low grade: ONC201 capsule alone was headache (54.5%), nausea (36.4%), and fatigue (36.4%); ONC201 liquid formulation was vomiting (31.8%), headache (22.7%), VIth nerve disorder (22.7%); ONC201 capsules in combination with radiation (Arm B) was headache (47.1%), vomiting (52.9%), nausea (41.2%). Pharmacokinetic analysis in plasma of Arm A patients revealed T1/2: 8.4h; Tmax: 2.1h; Cmax: 2.3ug/mL; AUC0-tlast: 16.4ug/mL, with similar exposure across body weights. In conclusion, when scaled by body weight the ONC201 capsule or liquid formulation alone or in combination with radiation were associated with safety and pharmacokinetic profiles in pediatric H3 K27M-mutant diffuse midline glioma patients that are similar to the experience in adults.

Diffuse intrinsic pontine glioma (DIPG) in children remains essentially incurable with a median survival of 12 months. Radiation therapy is currently the standard treatment modality. To date chemotherapy or biologic agents have had no meaningful increase in survival. Data from biopsied DIPG showed the PI3K/AKT/mTOR pathway as a major oncogenic player. Thus targeting these pathways with mTOR inhibitors could hold promise. Genomic and epigenetic insights have shown the role of histone deacetylase (HDAC) in these tumors. Both temsirolimus (mTOR inhibitor) and SAHA (HDAC inhibitor) are well described in pediatric clinical trials with an established maximum tolerated dose (MTD) for phase II studies. This is the first ongoing phase I multi-targeted therapeutic study, in pediatric DIPG, using SAHA and temsirolimus in a combinatorial approach, targeting the key oncogenic pathway and molecules (NCT02420613 currently recruiting). Patients with a performance score of 50 or greater, with newly diagnosed (Stratum I), or progressive (stratum II) DIPG will be eligible. Biopsy is not mandatory. A standard 3 + 3 design is being used for this study. 1 dose escalation and 2 dose de-escalations are permitted beyond the starting dose level. In stratum I patients receive radiation therapy concurrently with vorinostat on the days of radiation, followed by adjuvant therapy with vorinostat and temsirolimus for 10 cycles if they do not have progressive disease. In stratum II patients receive vorinostat and temsirolimus for 12 cycles (28 day cycle), if they do not have progressive disease. Correlative studies evaluating histone acetylation, phosphorylated 70S6K and Akt are being performed. Currently 5 patients have been enrolled, and the study is at the dose escalation level with no dose limiting toxicity (DLT) seen so far. Safety, adverse effects, biological correlatives, and clinical outcomes will be reported once study is completed.

Diffuse Intrinsic Pontine Glioma (DIPG) is an incurable pediatric brain tumor that occur in the pons and brainstem and have a peak onset of age between 6–9 years of age. Radiation is currently used as standard of care. Chemotherapy has shown no improvements in survival. Here, we report our study of ONC201, a first-in-class anticancer small molecule developed by Oncoceutics, Inc., against DIPG cells in vitro and in mouse orthotopic models. ONC201 was discovered in a screen as a p53-independent inducer of the pro-apoptotic cytokine TRAIL. It is known to directly and selectively inhibit dopamine receptor D2 (DRD2), a member of the G protein-coupled receptor (GPCR) family. MTT assays to determine the sensitivity of DIPG cells to ONC201 revealed a slight but not significantly different response to the drug based on their expression of wild type (WT) histone H3 or histone H3K27M mutant protein, with IC50 values in the range of 3-8mM. Decrease in cell growth was associated with a decrease in AKT and ERK phosphorylation and an increase in TRAIL expression. In vivo, intraperitoneal administration of ONC201 to mice bearing pontine DIPG tumors, once every week for 6 weeks, caused a significant reduction in tumor burden relative to untreated controls as measured by bioluminescence assays. However, stoppage of treatment resulted in tumor regrowth within 6 weeks, suggesting the existence of a population that were not eliminated by the current schedule of ONC210. Single cell proteomic analyses-based comparison of untreated and ONC201-treated DIPG cells showed an expected global reduction in pro-survival signals such as phosphorylated AKT and ERK. Molecules with potential to predict susceptibility of cells to ONC201 were also revealed, and are being confirmed by transcriptome analyses. Results of a chemical screen to target ONC201-refractory tumor cells will be discussed.

INTRODUCTION The new understanding of molecular pathways in cancer is paving the way towards personalized cancer medicine, especially in refractory disease. High-grade gliomas (HGG) are common pediatric brain tumors that tend to recur, with no available standard therapy upon recurrence. HGG are challenging tumors with illusive biology and poor outcome. We report here the molecular testing of 27 pediatric HGG patients. MATERIALS AND METHODS An analysis of pediatric patients with HGG treated at UT MD Anderson Cancer Center (MDACC) who underwent molecular genetic profiling using next generation sequencing with different genomic panels (AmpliSeq™Cancer Hotspot and Oncomine Panels – by Thermo Fisher Scientific). RESULTS 27 patients with HGG (median age 14 years, range 3–18 years old) underwent genomic profiling. Primary diagnoses were glioblastoma multiforme (n=22), anaplastic astrocytoma (n = 2), gliosarcoma (n= 1), anaplastic pleomorphic xanthoastrocytoma (n= 1) and anaplastic oligoastrocytoma (n= 1). There are 46 genes common to the panels used. The most common mutation was in TP53 (73%). Other mutations included PIK3CA (19%), IDH1 (11.5%), 7.7% for ATM, EGFR and PTEN, and 3.8% for BRAF, FGFR1 and FGFR2. 24 out of 27 patients were tested at initial diagnosis and 3 upon relapse/progression. Patients at initial diagnosis received standard of care therapy of radiation and temozolomide. Only 5 patients received targeted therapy upon progression/recurrence. Some challenges of genomically-matched therapy included lack of clinical trials accepting pediatric patients, unavailability of a liquid form of a drug, and insurance disapproval for off-label use. CONCLUSION The next generation of therapy for childhood cancers will be based upon in-depth molecular phenotyping that may facilitate the development of rational risk-adapted and target-based therapies. This cohort, though limited by sample size, highlights the opportunity to perform molecular testing and identification of alterations in actionable genes.

Pediatric midline gliomas, mainly DIPGs, are a rare and deadly cancer of early childhood, with a 9-month median survival post-diagnosis and a 2-year survival rate of

Midline K27M gliomas are the most challenging type of gliomas in pediatric patients with very poor outcome (median survival, 9–12 months). Because their anatomic location, brainstem and thalamic gliomas are inoperable and hence no tissue is available to perform molecular analysis. Analysis of circulating biomarkers (liquid biopsies, including cfDNA) is a novel and promising, non-invasive alternative method for monitoring disease status that can tremendously facilitate biomarker screening for these pediatric patients. We have developed a robust cfDNA assay to detect genomic aberrations in plasma samples, despite genomic DNA contamination, which is a common issue in archival plasma samples. Our approach consisted of a modified droplet digital PCR (ddPCR) protocol that pre-selected the cfDNA molecules through the ligation of specific primers followed by PCR amplification. After pre-selection, cfDNA samples from 27 pediatric patients diagnosed with gliomas (17 diffuse intrinsic pontine glioma, 3 midline glioma, 7 high grade glioma) were screened using specific probes on a ddPCR platform to identify specific mutations in the H3F3A, PIK3CA and BRAF genes. Using this approach, we were able to identify low allele frequency mutations for H3F3A_K27M in 15 patients (62%; 11 with DIPG), PIK3CA_H1047R in 10 patients (37%), and BRAF_V600E with mutation allele frequencies ranging from 2% through 0.03% in 7 patients (26%). This very high sensitivity was achieved not only due to the nature of the ddPCR assay (1:20.000), but also due to the pre-selection of cfDNA molecules in our customized protocol. Since surgical resection is rarely an option for these patients, our non-invasive assay shows the feasibility of identifying these aberrations with a single blood sample. Additionally, because these mutations are associated with distinct prognosis and therapeutic implications, this cfDNA test can significantly impact clinical outcomes once implemented in a clinical lab to complement imaging for diagnosis and disease monitoring.

BACKGROUND: Adult medulloblastoma (MB) is rare, accounting for 150–300 new cases in the US annually. Given the low incidence, prospective studies are challenging, and treatment guidelines and recurrence characteristic are derived from pediatrics. However, adult MB is a distinct entity, and further studies are warranted. Surgery followed by radiation and chemotherapy are accepted treatment modalities, but there is limited information on characteristics and outcomes of adult MB at recurrence. METHODS: 136 adult MB patients (≥18 years at diagnosis) were identified at MD Anderson from January 1978 to April 2017. Median progression-free survival (PFS) and overall survival (mOS) were estimated using the Kaplan-Meier method. RESULTS: Median age 28 (18–63); 53.7% standard risk (SR) (minimal residual disease and no metastasis) and 32.4% high risk (HR) (indeterminate in 19). Median PFS and mOS for the entire cohort were 98 and 133 months, respectively. No residual tumor after initial surgery and use of adjuvant chemotherapy were associated with improved survival, but M status was not. 44.9% had developed recurrence at median follow-up of 59.5 months (34.4% were SR and 42.6% were HR); median time to 1(st) recurrence was 34 months; mOS after first recurrence was 23 months. Local recurrence was associated with improved survival compared to distant recurrence. CONCLUSION: To our knowledge, this is the largest series of adult MB from a single institution. Extent of surgery was associated with improved survival, which is an established positive prognostic indicator in pediatric MB but has been controversial in adults. Adjuvant chemotherapy was associated with improved survival in patients without residual tumor after first surgery. Late recurrences were more common than in the pediatric population, highlighting the need for long term follow-up. Adult MB patients have a poor mOS of 23 months after recurrence, and optimizing treatments at recurrence is an unmet need.

BACKGROUND: H3 K27M-mutant gliomas have a dismal clinical prognosis and no proven curative therapy. We report the updated clinical experience with ONC201, the first cancer-specific DRD2 antagonist, in adult and pediatric H3 K27M-mutant gliomas. METHODS: As of May 28, 2018, 26 patients with H3 K27M-mutant glioma have been treated with ONC201: 9 pediatric (18 years old). Twelve patients had recurrent disease and 14 had previously-treated stable disease prior to initiating ONC201. Patients had 1–4 prior lines of therapy and all received prior radiation. Ten adult patients were enrolled on clinical trials and the other 16 were on compassionate use. ONC201 was orally administered at 625 mg to adults and scaled by body weight for pediatric patients. All patients, except one, were dosed weekly. RESULTS: Fourteen of 26 patients (54%) remain progression-free on ONC201 with a median follow up of 3.6 (range 1.6–24.5) months. No dose modifications or discontinuation due to toxicity have occurred. Among the 12 adult patients with recurrent disease who received single agent ONC201, the estimated PFS6 is 36.5%. Seven patients have experienced radiographic and/or clinical benefit (neurological stabilization or improvement). Among the 5 adults with recurrent thalamic glioma, three have experienced durable complete regression of their thalamic tumors, including the first H3 K27M-mutant glioma patient treated with ONC201 who has experienced 96% regression of her recurrent disease and continues single agent ONC201 for >2 years. Two DIPG pediatric patients who initiated single agent ONC201 6–8 weeks after radiation have experienced radiographic and neurological improvements and exhibited PFS of >13 months from diagnosis. CONCLUSIONS: Emerging clinical data suggest that ONC201 exhibits clinical activity for some patients with H3 K27M-mutant glioma.

INTRODUCTION: Primary intracranial sarcoma (ISTS) is rare with unknown origin and ill-defined incidence in pediatric population. There is paucity of literature reporting outcomes of ISTS for children and young adults. Multimodality approach is used in most of the studies to treat this tumor with no well-defined treatment consensus. PATIENTS AND METHODS: A retrospective analysis of pediatric patients with primary diagnosis of ISTS treated at MD Anderson Cancer Center was conducted using descriptive measures, to describe clinical findings, treatment and long-term outcomes of children and adolescents with ISTS. RESULTS: Eleven patients (median age 6 years, range 1-20 year) with primary diagnosis of ISTS treated at our center between 2000 and 2014. Six patients were male, primary diagnosis as follows: Undifferentiated sarcoma (n = 5), Primitive neuroectodermal tumor (n = 2), Hemangiopericytoma (n = 1), Chondrosarcoma (n = 1), Aggressive mesenchymal tumor (n = 1), Neurofibrosarcoma (n = 1). Two patients had extraneural spread to the bone and the spine. Nine patients underwent gross total resection at time of diagnosis. Six cycles of the 3 drug regimens (Etoposide/ifosfamide/ Carboplatin) was the most common chemotherapy given at primary diagnosis or recurrence. Local radiation therapy with/without temozolomide were given to nine patients either after primary surgery or following surgery and adjuvant chemotherapy. Second look surgery was pursued in two patients before starting radiation and microscopic disease was found at site of the primary tumor despite of no radiologic evidence of residual disease. Five patients had disease progression, of whom four died of their disease. CONCLUSION: ISTS is rare neoplasm with dismal outcome. Despite Multimodality therapy, ISTS remains a challenge to treat with high rate of recurrence or treatment failure. Primary surgery followed by systemic chemotherapy and second look surgery at time of local control along with radiation therapy are associated with best chance for complete cure.

Emerging evidence confirms dysregulation of BRAF gene inducing oncogenesis of pediatric brain tumors. To-date few reports show short-lived efficacy using BRAF inhibitors in these tumors. This indicates the need to target diverse pathways to have sustained clinical efficacy. We present two cases where a combination of vemurafenib (BRAF inhibitor) with everolimus (mTOR inhibitor) as a part of an IRB approved protocol was used. A 10-year-boy diagnosed with a left parietal pleomorphic xanthoastrocytoma (PXA) demonstrated tumor progression despite radiotherapy and three surgical interventions over two years. The tumor showed BRAF mutation for which he received a combinatorial therapeutic approach using the above two drugs given orally every day on a 28 day cycle. He experienced a partial response after two cycles and continued response after 13 cycles. This therapy has been well-tolerated with only minor (Grade I) skin rash. The child remains clinically stable with a Lansky score of 100. The second case is a 13-year-old female diagnosed at 1 year of age with a right-sided optic pathway glioma. The biopsy was consistent with pilocytic astrocytoma. The tumor progressed through multiple chemotherapeutic regimens, including carboplatin, vincristine, vinblastine, celexocib. Molecular analysis performed at our institution demonstrated the tumor to harbor a BRAF mutation for which she is currently receiving the above therapeutic regimen. She is tolerating the therapy well, with mild mouth sores. Her tumor after four cycles shows ongoing response and stable vision. It is now known that these tumors can induce escape mechanisms conferring therapeutic resistance and short-lived efficacy, undermining single drug BRAF targeted approach. This is the first ongoing study targeting these pathways (RAF/MAPK/ERK) and PI3K/mTOR pathway in pediatric brain tumors with BRAF mutation. Larger prospective larger studies are warranted to overcome therapeutic limitations through optimal combination therapy targeting multiple signaling pathways.

BACKGROUND: We hypothesize that chemotherapy can be safely and repeatedly administered directly into the fourth ventricle to treat recurrent malignant brain tumors in children. METHODS: For the first time in humans, methotrexate was infused into the fourth ventricle in children with recurrent, malignant brain tumors. A catheter was surgically placed into the fourth ventricle under direct visualization and attached to a ventricular access device. Cerebrospinal fluid (CSF) flow was confirmed by CINE MRI postoperatively. Each cycle consisted of 4 consecutive daily methotrexate infusions (2 milligrams). Disease response was monitored with serial MRI scans and CSF cytologic analysis. Trough CSF methotrexate levels were sampled. RESULTS: Five patients (3 with medulloblastoma and 2 with ependymoma) received 18, 18, 12, 9, and 3 cycles, respectively. There were no serious adverse events or new neurological deficits attributed to methotrexate. Two additional enrolled patients were withdrawn prior to planned infusions due to rapid disease progression. Median serum methotrexate level four hours after infusion was 0.04 micromoles per liter (µmol/L). Range was 0.02–0.13 µmol/L. Median trough CSF methotrexate level 24 hours after infusion was 3.18 µmol/L (range 0.53 - 212.36 µmol/L). All three patients with medulloblastoma had partial response or stable disease until one patient had progressive disease after cycle 18. Both patients with ependymoma had progressive disease after 9 and 3 cycles, respectively. CONCLUSIONS: These data establish the safety of neurosurgical implantation of a catheter into the fourth ventricle and direct infusion of low-dose methotrexate into the fourth ventricle. Some patients with recurrent medulloblastoma experience a beneficial anti-tumor effect both within the fourth ventricle and at distant sites. These results support future clinical trials of direct infusion of chemotherapy and novel agents into the fourth ventricle for children with malignant posterior fossa tumors.