Brainstem Tumors Research Articles

Abstract 4740: Molecular effects of histone deacetylase inhibitor Quisinostat on diffuse midline glioma of the pons

Abstract Diffuse Midline Glioma of the pons (DMG) is a lethal, aggressive heterogeneous brain stem tumor. Median overall survival is less than a year, with radiation as the only standard treatment. Recently, mutations in DMGs have arisen as potential therapeutic targets, specifically a mutation in one of the histone H3 genes, resulting in methionine substituted for lysine at site 27 (H3K27M). H3K27M induces a marked reduction in global acetylation of histone tails, altering chromatin structure and causing aberrant gene expression. Histone deacetylase inhibitors, HDACis, are epigenetic drugs that show anticancer activity. In our studies, Quisinostat (Quis) is used to preserve histone acetylation. Using two H3K27M-DMG treatment-naive preclinical models (PBT22 and PBT29) we detected a 100-fold differential response to the histone deacetylase inhibitor, Quisinostat. PBT-22 harbors mutations in H3F3A, TP53, and ASXL2, while PBT-29 has mutations in H3F3A, TP53, PIK3CA and FGFR1. Following Quis treatment (48 hrs) in both preclinical models, total H3K27ac protein abundance increased 3-fold, suggesting HDACi stabilizes or impedes turnover of K27 acetylated H3 histone. We are pursuing studies to test whether sensitivity to HDACi in DMGs is determined by a shift in relative or total abundance of respective H3wt- and H3K27M- histones. We posit that changes in H3K27ac manifest as shifts in nucleosome integration with genes responsible for cell survival/death. This project will profile differentially expressed genes (DEGs) from Quis-treated PBT22 and PBT29. Additionally, total and relative abundance of H3 proteins (wt and mt, me, me2, me3, and ac) from treated cells will be determined. Gene ontology analysis will focus on pathways accounting for chromatin remodeling, cell death, and growth arrest. RNA (qRT-PCR) and proteins (western blot) from analytes from a larger panel of DMG cell lines and neural stem cells treated with Quis will be used to validate the findings. Overall, the data depicts DMG preclinical models with large differential sensitivity to Quis, which may be partially due to different oncoprints between the models. The markedly different sensitivity of these models enables mechanistic study of the consequences of elevated abundance of histone 3 acetylation. The long term goal is to discover a molecular profile of DMGs indicative of the vulnerability to HDACi. Citation Format: Danyelle Paine, Nanyun Tang, Yue Hao, Matt Biery, Carrie Meyers, Alyssa Noll, Nicholas Vitanza, Michael Berens. Molecular effects of histone deacetylase inhibitor Quisinostat on diffuse midline glioma of the pons. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4740.

MRI-guided focused ultrasound drug delivery to DMG tumors in a mouse model

Diffuse midline glioma (DMG) is the most common and unfortunately the most deadly brainstem tumor in childern. Current clincal treatment methods only involve palliative radiotherapy that does not significantly improve survival beyond its poor mean survival of 9 months. These tumors remain difficult to treat with chemotherapy as they maintain an intact blood brain barrier (BBB). Focused ultrasound (FUS) and microbubbles (MBs) has been shown to disrupt the BBB, allowing chemotherapeutics to enter the perenchyma. Panobinostat is one of the chemotherapeutics that has difficulty crossing the BBB, although it has promising effects in vitro. In this study, we hypothesized that MB + FUS could disrupt the BBB, allowing a higher concentration of Panobinostat to enter the tumor region and provide a therapeutic effect. Our results demonstrate that MB + FUS can successfully deliver Panobinostat to the pons with DMG tumors over 3-fold, while only slightly increasing the concentration of the forebrain. Passive cavitation detection during treatments showed harmonic cavitation throughout the 3-minute treatment, while not having any significant broadband cavitation. The combination of both Panobinostat and MB + FUS showed major decreases in tumor growth by ∼71% by the end of the treatment weeks when compared to Panobinostat alone. A significant survival benefit was also demonstrated.

Evaluating drug distribution in children and young adults with diffuse midline glioma of the pons (DIPG) treated with convection-enhanced drug delivery.

To determine an imaging protocol that can be used to assess the distribution of infusate in children with DIPG treated with CED. 13 children diagnosed with DIPG received between 3.8 and 5.7 ml of infusate, through two pairs of catheters to encompass tumor volume on day 1 of cycle one of treatment. Volumetric T2-weighted (T2W) and diffusion-weighted MRI imaging (DWI) were performed before and after day 1 of CED. Apparent diffusion coefficient (ADC) maps were calculated. The tumor volume pre and post CED was automatically segmented on T2W and ADC on the basis of signal intensity. The ADC maps pre and post infusion were aligned and subtracted to visualize the infusate distribution. There was a significant increase (p < 0.001) in mean ADC and T2W signal intensity (SI) ratio and a significant (p < 0.001) increase in mean tumor volume defined by ADC and T2W SI post infusion (mean ADC volume pre: 19.8 ml, post: 24.4 ml; mean T2W volume pre: 19.4 ml, post: 23.4 ml). A significant correlation (p < 0.001) between infusate volume and difference in ADC/T2W SI defined tumor volume was observed (ADC, r = 0.76; T2W, r = 0.70). Finally, pixel-by-pixel subtraction of the ADC maps pre and post infusion demonstrated a volume of high signal intensity, presumed infusate distribution. ADC and T2W MRI are proposed as a combined parameter method for evaluation of CED infusate distribution in brainstem tumors in future clinical trials.

A Comparison of the Safety, Efficacy, and Accuracy of Frame-Based versus Remebot Robot-Assisted Stereotactic Systems for Biopsy of Brainstem Tumors

Brainstem tumors are rare and extremely heterogeneous and present significant challenges in surgical treatment. Thus, biopsies often set the foundation for the diagnosis of brainstem tumors. Multimodal, image-guided, robot-assisted frameless stereotactic biopsies are increasingly popular in neurosurgery centers. This study aimed to compare the safety, efficacy, and duration of the Remebot robot-assisted (Remebot) frameless brainstem tumor biopsy versus those of frame-based stereotactic biopsy. A retrospective analysis of 33 patients with brainstem tumors who underwent stereotactic brainstem biopsies in the department of neurosurgery from January 2016 to January 2021 was conducted. The patients were divided into two groups: the Remebot group (n = 22) and the frame-based group (n = 11). The clinical characteristics, trajectory strategy, duration of procedure, diagnostic yielding, histopathological diagnosis, and postoperative complications were retrospectively analyzed and compared between the groups. More pediatric patients performed Remebot frameless brainstem tumor biopsy than frame-based biopsy, with a mean age of 17.3 ± 18.7 vs. 32.8 ± 17.1 (p = 0.027). The diagnostic yield had no significant difference in the two groups, with the diagnostic yield of frame-based biopsy and Remebot frameless brain biopsy being 90.9% and 95.5%, respectively. The time of the total process was 124.5 min for the frame-based biopsy and 84.7 min for the Remebot frameless brain biopsy (p < 0.001). There were no significant differences with respect to the occurrence of complication or the duration of the operation between the two groups. Remebot frameless stereotactic brainstem biopsy is as safe and efficacious as frame-based stereotactic biopsy. However, Remebot frameless biopsy can reduce the total duration of the procedure and has better application in young pediatric patients. Remebot frameless stereotactic biopsies can be a better option towards the safe and efficient treatment of brainstem tumors.

Diencephalic syndrome-like presentation of brainstem tumor: a series case-based review.

Russel described a rare clinical entity known as diencephalic syndrome (DS) in 1951, which was traditionally caused by a neoplasm in the hypothalamic-optic chiasmatic region. DS is characterized by severe emaciation despite adequate or slightly reduced caloric intake, locomotor hyperactivity, euphoria and other minor features. Current evidence suggests that a rare population of children with a similar phenotype may have their tumor located in the posterior fossa instead, defining the DS-like presentation, a rare entity with few cases reported in the literature. A thorough search of three databases (PubMed, Ovid Medline, and Ovid Embase) was conducted to identify relevant papers reporting children with DS associated with brainstem tumors. To our knowledge, only seven cases have been documented in the literature. Moreover, we present four of our own cases, focusing on the unusual clinical presentation, the diagnosis process, and the lag time between the initial symptoms and the definitive diagnosis. In this review, the mean lag time between the onset of symptoms and diagnosis was 20.9months (median: 16months; range: 1.5-72months), whereas in our series of cases, the time was 32.5months (median: 33months; range: 7-57months). Despite recent significant advances in neuro-oncology diagnostic tools, this mean lag time did not improve when compared with the previous literature review from 1976. Throughout these data, we aim to raise awareness in the hopes of detecting intracranial neoplasms earlier in cases of children with profound emaciation of unknown cause.

Corticobulbar motor evoked potentials in surgical treatment of tumors of the IV ventricle and brainstem

BACKGROUND: Intraoperative neurophysiological monitoring is an obligatory tool during fossa posterior surgery. Corticobulbar motor evoked potentials is the modality of intraoperative neurophysiological monitoring, which can be used during such neurosurgery interventions. It is used to determine the functional state of the caudal cranial nerves during surgery. However, there are technical features of this modality, therefore, corticobulbar motor evoked potentials are not used routine in neurosurgery now.&#x0D; AIM: To establish the predictive value of corticobulbar motor evoked potentials for development of dysphagia after removal of tumors of brainstem and fourth ventricle.&#x0D; MATERIALS AND METHODS: We analyzed 80 patients aged from 11 months to 67 years. In 49 cases tumor located in forth ventricle (34 adults and 15 children). In 31 cases tumor located in upper brainstem and craniospinal region (16 adults and 15 children). All patients underwent neurosurgery removal of tumor with intraoperative neurophysiological monitoring. We analyzed otoneurological symptoms before and after operation, MR-images, the volume of removed tumor was estimated. We analyzed data of intraoperative neurophysiological monitoring; the main modality of intraoperative neurophysiological monitoring was corticobulbar motor evoked potentials.&#x0D; RESULTS: Progress in neurological symptoms from caudal nerves was observed in 35% cases. Amplitude of corticobulbar motor evoked potentials statistically depends on neurological symptoms from caudal nerves in early postoperative period. When the amplitude of the corticobulbar motor evoked potentials decreases by more than 34% from the initial level, there is a high probability of appearance or increase of symptoms from the caudal group of cranial nerves after surgery. The sensitivity and specificity of the corticobulbar motor evoked potentails are 94.4 and 89.2%, respectively.&#x0D; CONCLUSIONS: It is necessary to use the corticobulbar motor evoked potentials to determine the functional state of the caudal group of cranial nerves during brainstem and forth ventricle surgery and to predict the development of dysphagia and dysarthria after surgery. The modality has a high prognostic value both in children and in adults.

MRI-guided focused ultrasound blood-brain barrier opening increases drug delivery and efficacy in a diffuse midline glioma mouse model.

Diffuse intrinsic pontine glioma (DIPG) is the most common and deadliest pediatric brainstem tumor and is difficult to treat with chemotherapy in part due to the blood-brain barrier (BBB). Focused ultrasound (FUS) and microbubbles (MBs) have been shown to cause BBB opening, allowing larger chemotherapeutics to enter the parenchyma. Panobinostat is an example of a promising in vitro agent in DIPG with poor clinical efficacy due to low BBB penetrance. In this study, we hypothesized that using FUS to disrupt the BBB allows higher concentrations of panobinostat to accumulate in the tumor, providing a therapeutic effect. Mice were orthotopically injected with a patient-derived diffuse midline glioma (DMG) cell line, BT245. MRI was used to guide FUS/MB (1.5 MHz, 0.615 MPa peak negative pressure, 1 Hz pulse repetition frequency, 10-ms pulse length, 3 min treatment time)/(25 µL/kg, i.v.) targeting to the tumor location. In animals receiving panobinostat (10 mg/kg, i.p.) in combination with FUS/MB, a 3-fold increase in tumor panobinostat concentration was observed, without significant increase of the drug in the forebrain. In mice receiving 3 weekly treatments, the combination of panobinostat and FUS/MB led to a 71% reduction of tumor volumes (P = .01). Furthermore, we showed the first survival benefit from FUS/MB improved delivery increasing the mean survival from 21 to 31 days (P < .0001). Our study demonstrates that FUS-mediated BBB disruption can increase the delivery of panobinostat to an orthotopic DMG tumor, providing a strong therapeutic effect and increased survival.

IMT-1 PROS AND CONS OF SURGICAL INTERVENTION FOR DIFFUSE MIDLINE GLIOMA AIMED AT DENDRITIC CELL IMMUNOTHERAPY

Abstract Since a diffuse midline glioma (DMG) has no effective therapy, it is an urgent need to develop new therapeutic strategy. We performed immunotherapy using fusions of autologous dendritic cells (DC) with tumor cells in DMG cases in which tumor tissue was collected by surgery aimed at biopsy, and evaluate the effectiveness and examine the pros and cons of surgical intervention against DMG. Among the patients with basal ganglia or brain stem tumors received surgery at our hospital, 5 adult cases of DMG with H3K27M gene mutation were registered. All patients received radiation therapy and temozolomide chemotherapy. 4 cases received bevacizumab chemotherapy when the patients had recurrence or progression of the disease. The tumor-fused DCs (TFDC) were made by DCs induced from autologous peripheral blood mononuclear cells and tumor cells established from surgical specimens. They were injected subcutaneously into the neck 3 ~ 6 times in a 14 ~ 28 day cycle as the immunotherapy. The adverse events, PFS, and OS were evaluated. A transient complication of facial numbness was observed in one case on right after surgery. Although two patients had CR in those therapies, both of them died of disease (OS at 18 and 32 months, respectively). Since the remaining three cases were registered very recently, adverse event or treatment efficacy judgment have not been determined at the time of submission of the abstract. Serious surgical complications have not been observed in the presented cases. Surgery may be acceptable for DMG as long as the surgery is performed by sufficiently experienced surgeon in an appropriate environment. The TFDC immunotherapy, which can be performed only by collecting a small amount of tumor tissue, expects to be a novel treatment for MDG. In this presentation, the pros and cons of surgical intervention aimed at TFDC immunotherapy for DMG will be examined.

NIMG-57. NON-INVASIVE DIAGNOSIS OF IDH-MUTANT BRAINSTEM GLIOMAS

Abstract INTRODUCTION Treatment of brainstem tumors is often initiated without a tissue diagnosis due to the risk of biopsy. A subset of brainstem gliomas harbor an isocitrate dehydrogenase 1/2 (IDH) mutation, which predicts response to alkylator chemotherapy and IDH inhibitors; non-invasive diagnostic tests are needed to identify these mutations. METHODS We identified a cohort of patients with IDH-mutant brainstem gliomas through chart review of patients who underwent magnetic resonance spectroscopy (MRS) and/or brain biopsy. IDH mutation was established by biopsy, presence of a 2-hydroxyglutarate (2HG) peak on MRS, or identification on cerebrospinal fluid (CSF) sequencing of cell-free DNA (cfDNA). RESULTS We identified 15 patients with IDH-mutant brainstem gliomas, age range 5-48, 47% women. 15/15 were involving/abutting the brachium pontis, and 10/15 were non-enhancing at diagnosis. 13/15 patients were identified by biopsy, 1/15 by MRS and CSF, and 1/15 by MRS only. 10/13 patients with available data had a non-IDH1 R132H mutation in IDH1/2. 7/7 patients with MRS prior to radiation had a 2HG peak (MRS was concordant with tissue in all cases in which biopsy was obtained). 4/6 patients with MRS post-radiation retained a 2HG peak. 4 IDH-mutant tumors had sequencing of cfDNA and an IDH mutation was found in 2/4. Response data was available in 13/15 patients; all received radiation, 10 with concurrent temozolomide: best response was partial response in 8 and stable disease in 5. 4 patients received an IDH inhibitor: 2 patients after progression, and 2 as maintenance after radiation/temozolomide, achieving tumor control in all. For this cohort, median PFS was 71.4 months and median OS has not been reached. CONCLUSION IDH-mutant brainstem gliomas have a characteristic appearance, a high response rate to treatment, and a better overall prognosis than other brainstem tumors. MRS and CSF cfDNA sequencing allow for non-invasive diagnosis of IDH mutations in these patients.

EXTH-29. RADIOSENSITIZATION BY BRD4 INHIBITION IN DIFFUSE INTRINSIC PONTINE GLIOMA

Abstract Diffuse intrinsic pontine glioma (DIPG), the most frequent brainstem tumor in pediatrics, is one of the devastating childhood cancers, and virtually all patients die within two years after diagnosis. Since these tumors occur in the brainstem which is vital area, there are no surgical options for providing relief to patients, and conventional chemotherapy. Radiation therapy (RT) remains the only effective treatment. Radiosensitization is a mean to improve the therapeutic balance between efficacy and toxicity of RT, but not used in clinically. Here, we found BRD4 inhibitor as a radiosensitizer from drug screening. DIPG shows increased H3 K27 acetylation (H3K27ac), which binds to BET bromodomain protein 4 (BRD4) and they are strongly associated with active transcription. We tested two BRD4 inhibiter (BRD4i : AZD5153 and JQ-1) and genetic BRD4 depletion enhances radiation-induced DNA damage, making it a potential radiosensitizer in the treatment of DIPG. We evaluated the effects of BRD4i on genes expression using RNA sequence, inhibited significantly DNA-repair proteins such as BRCA1 and RAD51. CUT-RUN qPCR showed decreased H3K27ac at BRCA1 and RAD51. Combination with BRD4i and RT inhibited cell viability significantly in clonogenic survival assay, apoptosis assay, and showed cell cycle arrest. Radiation-induced DNA double-strand break (DSB) repair was prolonged high level of rH2AHX and 53BP1 with BRD4i because of inhibited DNA-repair. In vivo studies revealed increased survival of animals treated with combination therapy of RT and BRD4i in compared to either monotherapy. Together, these results highlight BRD4i as a potential radiosensitizer and provide a rationale for developing combination therapy with radiation in the treatment of DIPG.

NIMG-38. 2-HYDROXYGLUTARATE MAGNETIC RESONANCE SPECTROSCOPY IN ADULT BRAINSTEM GLIOMA PATIENTS

Abstract INTRODUCTION The onco-metabolite, 2-hydroxyglutarate (2HG), is non-invasive biomarker detected by magnetic resonance spectroscopy (MRS), indicating isocitrate dehydrogenase (IDH) mutant glioma. Especially in patients with brainstem lesions where biopsies are at high risk of causing neurological deficit, 2HG-MRS may be useful. Here, we examined the utility of 2HG-MRS for diagnosing IDH mutant adult diffuse brainstem glioma and the ability of prognosis prediction. METHODS Three tesla -MRS (3T-MRS) was performed on patients with radiographically confirmed brainstem tumor. A single-voxel was set in the lesion with reference to the T2 / FLAIR image, and analyzed according to the 2HG-tailored MRS protocol (Philips, Achieva, PRESS, TE 35 ms). All patients underwent biopsy using an intraoperative navigation system (Brain LABTM) or stereotactic biopsy system (Komai’s CT-stereotactic frame) before initial treatment. IDH and H3K27M mutation status were confirmed by immunohistochemistry and DNA sequence. We examined the relationship between 2HG values and patient survival period. RESULTS Ten patients (7 male and 3 female, median age 33.5) underwent 2HG-MRS and biopsy. Four had H3K27M mutation and 4 had IDH mutation (1 R132H, 2 R132S, and 1 R132G). Two had neither H3K27M nor IDH mutation. H3-K27 and IDH mutations were mutually exclusive. All tumor located at pons mainly. There was no significant radiological difference between H3K27M and IDH mutant in conventional MRI sequence. Pearson's chi-square test demonstrated that 2HG concentrations &amp;gt; 1.5 mM were 100% in sensitivity and 83.3% in specificity for IDH mutant glioma (p = 0.0098). The median overall survival was 130.5 months in IDH mutant glioma (n=4) and 25 months in IDH wild-type glioma (n=6), respectively. CONCLUSIONS 3T-MRS was able to detect 2HG in adult brainstem glioma. A noninvasive 2HG-MRS study may be helpful in the diagnosis and predicting prognosis of adult diffuse brainstem glioma patient.

The neuropsychological profile of children with Diffuse Intrinsic Pontine Glioma (DIPG) before and after radiation therapy: A prospective longitudinal study

ABSTRACT Children with Diffuse Intrinsic Pontine Gliomas (DIPG), a malignant brainstem tumor, experience poor prognosis. Because of the disease’s rarity and highly aggressive course, there is a dearth of research on cognitive and psychosocial outcomes in this underserved, vulnerable population. However, evaluating effects of the disease and treatment on the cognitive and daily functioning of these patients is important to better understand their specific needs and improve their quality of life. The current longitudinal study administered prospective neuropsychological assessments to children diagnosed with CNS malignancies, including the largest sample of children with DIPG to date (n = 21, mean age = 7.86 years, range = 3–16) in neurocognitive, behavioral, social-emotional, and adaptive functioning at baseline, two weeks post-radiation, and six months later. The results describe population-based, cross-sectional characteristics and within-patient longitudinal changes. Prior to radiation, children with DIPG exhibited significant weaknesses compared to normative samples in both parent-report and performance-based measures of attention, and tests of processing speed and verbal learning/memory. Younger children demonstrated poorer inhibitory control on performance tests and worse parent-reported behavioral regulation, depression, and social withdrawal compared to older children. Six-months post-radiation, older children exhibited poorer socialization than younger children. Longitudinally, children with DIPG exhibited short-term improvements immediately post-radiation in performance-based attention tests and parent-reported behavior, including attention, hyperactivity, behavioral regulation, and executive function. However, these improvements did not persist and significant decline was documented on tests of attention by six months. Clinical implications for professionals working with children with DIPG and recommendations for cognitive remediation and quality of life interventions are provided.

Brainstem tumors may increase the impairment of behavioral emotional cognition in children

PurposeIt remains unclear as to whether patients with brainstem tumor experience complex neuropsychiatric problems. In this cohort study, we specifically investigated behavioral, emotional and cognitive symptoms in pediatric patients with brainstem glioma and healthy individuals.MethodsA total of 146 patients with pediatric brainstem tumors (aged 4–18 years old) and 46 age-matched healthy children were recruited to assess their behaviors and emotions examined by the Child Behavior Checklist. A variety of clinical factors were also analyzed.ResultsThere were significant differences in most behavioral and emotional symptoms between pediatric patients and healthy subjects. Moreover, patients with pons tumors exhibited significantly higher scores than patients with medulla oblongata tumors (p = 0.012), particularly in concerning the syndrome categories of Withdrawn (p = 0.043), Anxious/depressed symptoms (p = 0.046), Thought Problems (p = 0.004), Attention deficits (p = 0.008), Externalizing problems (p = 0.013), and Aggressive behavior (p = 0.004). A tumor body located in the pontine (p = 0.01, OR = 4.5, 95% CI = 1.4–14.059) or DIPG in the midbrain (p = 0.002, OR = 3.818, 95% CI = 1.629–8.948) appears to act as a risk factor that is associated with more problems in patients with neuropsychiatric symptoms.ConclusionsPediatric patients with brainstem tumors exhibit severe behavioral and emotional problems. Tumor invades the pontine and midbrain act a risk factor with more problems. It suggests that structural and functional abnormalities in the brainstem will cause prolonged behavioral problems and emotional-cognitive dysfunctions in young children.

Intranasal delivery of nanoliposomal SN-38 for treatment of diffuse midline glioma.

Diffuse midline gliomas, including diffuse intrinsic pontine gliomas (DIPGs), are among the most malignant and devastating childhood brain cancers. Despite aggressive treatment, nearly all children with these tumors succumb to their disease within 2 years of diagnosis. Due to the anatomical location of the tumors within the pons, surgery is not a treatment option, and distribution of most systematically administered drugs is limited by the blood-brain barrier (BBB). New drug delivery systems that bypass the BBB are desperately needed to improve outcomes of DIPG patients. Intranasal delivery (IND) is a practical and noninvasive drug delivery system that bypasses the BBB and delivers the drugs to the brain through the olfactory and trigeminal neural pathways. In this study, the authors evaluated the efficacy of nanoliposomal (LS) irinotecan (CPT-11) and an active metabolite of CPT-11, 7-ethyl-10-hydroxycamptothecin (SN-38), using IND in DIPG patient-derived xenograft models. In vitro responses to LS-CPT-11 and LS-SN-38 in DIPG cells were evaluated with cell viability, colony formation, and apoptosis assays. The cellular uptakes of rhodamine-PE (Rhod)-labeled LS-CPT-11 and LS-SN-38 were analyzed with fluorescence microscopy. Mice bearing DIPG patient-derived xenografts were treated with IND of LS-control (empty liposome), LS-CPT-11, or LS-SN-38 by IND for 4 weeks. In vivo responses were measured for tumor growth by serial bioluminescence imaging and animal subject survival. The concentration of SN-38 in the brainstem tumor administered by IND was determined by liquid chromatography-mass spectrometry (LC-MS). Immunohistochemical analyses of the proliferative and apoptotic responses of in vivo tumor cells were performed with Ki-67 and TUNEL staining. LS-SN-38 inhibited DIPG cell growth and colony formation and increased apoptosis, outperforming LS-CPT-11. Rhod-labeled LS-SN-38 showed intracellular fluorescence signals beginning at 30 minutes and peaking at 24 hours following treatment. LC-MS analysis revealed an SN-38 concentration in the brainstem tumor of 0.66 ± 0.25 ng/ml (5.43% ± 0.31% of serum concentration). IND of LS-SN-38 delayed tumor growth and significantly prolonged animal survival compared with IND of LS-control (p < 0.0001) and LS-CPT-11 (p = 0.003). IND of LS-SN-38 increased the number of TUNEL-positive cells and decreased the Ki-67-positive cells in the brainstem tumor. This study demonstrates that IND of LS-SN-38 bypasses the BBB and enables efficient and noninvasive drug delivery to the brainstem tumor, providing a promising therapeutic approach for treating DIPG.

Reversal of cancer gene expression identifies repurposed drugs for diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) is an aggressive incurable brainstem tumor that targets young children. Complete resection is not possible, and chemotherapy and radiotherapy are currently only palliative. This study aimed to identify potential therapeutic agents using a computational pipeline to perform an in silico screen for novel drugs. We then tested the identified drugs against a panel of patient-derived DIPG cell lines. Using a systematic computational approach with publicly available databases of gene signature in DIPG patients and cancer cell lines treated with a library of clinically available drugs, we identified drug hits with the ability to reverse a DIPG gene signature to one that matches normal tissue background. The biological and molecular effects of drug treatment was analyzed by cell viability assay and RNA sequence. In vivo DIPG mouse model survival studies were also conducted. As a result, two of three identified drugs showed potency against the DIPG cell lines Triptolide and mycophenolate mofetil (MMF) demonstrated significant inhibition of cell viability in DIPG cell lines. Guanosine rescued reduced cell viability induced by MMF. In vivo, MMF treatment significantly inhibited tumor growth in subcutaneous xenograft mice models. In conclusion, we identified clinically available drugs with the ability to reverse DIPG gene signatures and anti-DIPG activity in vitro and in vivo. This novel approach can repurpose drugs and significantly decrease the cost and time normally required in drug discovery.

Clinicopathology &amp; Molecular Analysis of Diffuse Intrinsic Pontine Glioma (DIPG) in Children - Insights from Past, Present, and Future Directions

Diffuse Intrinsic Pontine Glioma, or DIPG, is a rare, highly aggressive, heterogeneous group of brainstem tumors. Around 10-20% of primary brain tumors are considered pediatric brain tumors, of which 10-15% are diffuse brainstem tumors. It is considered untreatable and surgically unremovable due to its intrinsic position within the brain. Over the years, applying radiotherapy and chemotherapy has not shown a better outcome. However, gene-targeted therapy has proven successful, but it is still in the developing phase. This article covers the various aspects of DIPG, from clinical and molecular definitions to a vision for a universally accepted novel approach to beat this severe condition by joining fundamental science and translational research.

Intraventricular B7-H3 CAR T Cells for Diffuse Intrinsic Pontine Glioma: Preliminary First-in-Human Bioactivity and Safety.

This is the first report of repeatedly dosed intracranial B7-H3 CAR T cells for patients with DIPG and includes preliminary tolerability, the detection of CAR T cells in the CSF, CSF cytokine elevations supporting locoregional immune activation, and the feasibility of serial mass spectrometry from both serum and CSF. This article is highlighted in the In This Issue feature, p. 1.

Biopsy of paediatric brainstem intrinsic tumours: Experience from a Singapore Children’s Hospital

BackgroundBiopsy of intrinsic brainstem tumours presumed to be diffuse midline gliomas (previously known as DIPG) is controversial. Surgery has risks of injury to the eloquent brainstem and may not have direct benefit to the patient. Technological improvements in operative adjuncts have allowed the role of biopsy for paediatric brainstem lesions to be revisited with new insights. This study aims to evaluate our institutional experience in brainstem biopsy. MethodsThis is an ethics-approved retrospective study based in KK Women’s and Children’s Hospital. Patients diagnosed with intrinsic brainstem tumours and managed by the Neurosurgical Service were included. Variables of interest included patient demographics, neuroimaging features, type of surgery, histological and molecular diagnosis, treatment, and outcomes. ResultsFrom 2006 to 2021, a total of 27 brainstem intrinsic tumours were referred to the Neurosurgical Service. Eleven (40.7 %) patients underwent stereotactic biopsy and 10 (37 %) had open biopsies. Histologically, 10 (37 %) were confirmed to be high grade gliomas, eight (29.6 %) were low grade gliomas and 3 (11.1 %) were malignant embryonal tumours. No negative diagnostic results or permanent postoperative complications were encountered. Five patients went on to have their tumours interrogated via next-generation sequencing to look for targetable mutations. The remaining 6 (22.2 %) patients did not undergo biopsy, whereby 1 of them is still alive after 6 years. ConclusionBiopsy of paediatric brainstem intrinsic tumours is a safe procedure that concurrs with accurate tissue diagnosis. This option can be offered to affected patients, especially to identify relevant markers for targeted therapy.

Outcomes in Four Children with Persistent, Recurrent, and Progressive Gangliogliomas Treated in Phase II Studies with Antineoplastons A10 and AS2-1

Rationale: Gangliogliomas are generally benign tumors and are classified by the World Health Organization (WHO) as grade I or II tumors. However, in 1-5% of cases, gangliogliomas can behave more aggressively (WHO grade III) and have a worse prognosis. Four children with a ganglioglioma are presented to detail and discuss the efficacy of Antineoplastons A10 (Atengenal) and AS2-1 (Astugenal) in the treatment of gangliogliomas. Objectives: The children were treated with Antineoplastons A10 and AS2-1 (ANP therapy) at the Burzynski Clinic (BC) according to the phase II Protocols, BT-10 and BT-11. ANP therapy was delivered via subclavian catheter and infusion pump. During ANP therapy, tumor response was determined by comparison of sequential magnetic resonance imaging (MRI) of the brain with a baseline brain MRI. Findings: Of the four children treated for gangliogliomas, all had prior surgery but none had radiation therapy (RT) or chemotherapy. Two had recurrent, and progressive tumors with possible high-grade transformation (thalamo-mesencephalic region; temporal lobe with leptomeningeal spread) while two had tumors of the brain stem (persistent multicentric ganglioglioma; persistent and progressive ganglioglioma of the inferior medulla and superior cervical spinal cord), which are more difficult to treat and have a worse prognosis. Physical findings corresponded with the location of each child’s tumor. IV ANP therapy continued for 6.4 to 24.8 months. The two children with possible high-grade transformation achieved a partial response (PR) while the two children with brain stem tumors maintained stable disease (SD). Overall survival for these four children ranged from 10.3 to 22.4 years. Conclusions: The utilization of ANP therapy in children with gangliogliomas is presented. We conclude that ANP therapy is an attractive therapeutic option for children with gangliogliomas who are ineligible for or refuse surgical resection and/or demonstrate persistent, recurrent, or progressive disease with or without high-grade transformation following surgical resection..

Monitoring of corticobulbar motor evoked potentials during surgical remov¬al of brainstem and fourth ventricle tumors in pediatric patients

Introduction. Corticobulbar motor evoked potentials (CB-MEP) are a modality of intraoperative monitoring (IOM) for assessment of the functional state of caudal cranial nerves. CB-MEPs can be used during fossa posterior surgery, when there is a risk of damaging the caudal cranial nerves and their nuclei. The possibility of using this modality in pediatric patients is rarely discussed in the literature. Objective. To assess the CB-MEP validity in the prognosis of neurological symptoms from caudal cranial nerves in the pediatric group of patients after surgery in the brainstem and fourth ventricle. Material and methods. The study included 30 children aged from 11 months to 17 years who underwent brainstem and the fourth ventricle tumor surgery with IOM at the N.N. Burdenko National Medical Research Center for Neurosurgery from January 2020 to November 2021. Results. We obtained statistically significant difference in the dynamics of the CB-MEP amplitude in the groups of patients with and without an increase in neurological symptoms (p&lt;0.05). Conclusion. CB-MEP can be used during brainstem surgery in pediatric patients for assessing the functional state of caudal cranial nerves.