Pediatric brainstem gliomas: new understanding leads to potential new treatments for two very different tumors

Exoscope aided trans-sulcal minimally invasive parafascicular resection of a paediatric brainstem pilocytic astrocytoma using a tubular retractor system

The surgical management of brainstem glioma is challenging and has significant morbidity. Advances in surgical armamentarium has presented the opportunity to tackle these lesions. We present the case of a paediatric patient with a 2.3cm midbrain pilocytic astrocytoma. With the aid of tractography, neuro-navigation, 3-dimensional exoscope and a tubular retractor, near total resection of the tumour was achieved through a trans-sulcal para-fascicular approach without permanent injury to the corticospinal tract. To our knowledge this is the first report of a brainstem tumour resected using this approach and demonstrates what can be achieved with synergistic utility of evolving technologies in neurosurgery.

Brain stem tumors in children less than 3 months: Clinical and radiologic findings of a rare disease

PURPOSE

Brain stem tumors in children < 3 months at diagnosis are extremely rare. Our aim is to study a retrospective cohort to improve the understanding of the disease course and guide patient management.

METHODS

This is a multicenter retrospective analysis across the European Society for Pediatric Oncology SIOP-E HGG/DIPG Working Group linked centers, including patients with a brainstem tumor diagnosed between 2009 and 2020 and aged < 3 months at diagnosis. Clinical data were collected, and imaging characteristics were analyzed blindly and independently by two neuroradiologists.

RESULTS

Five cases were identified. No patient received any therapy. The epicenter of two tumors was in the medulla oblongata alone and in the medulla oblongata and the pons in three. For patients with tumor in equal parts in the medulla oblongata and the pons (n = 3), the extension at diagnosis involved the spinal cord; for the two patients with the tumor epicenter in the medulla oblongata alone (n = 2), the extension at diagnosis included the pons (n = 2) and the spinal cord (n = 1). Biopsy was performed in one patient identifying a pilocytic astrocytoma. Two patients died. In one patient, autopsy revealed a high-grade glioma (case 3). Three survivors showed either spontaneous tumor regression (n = 2) or stable disease (n = 1). Survivors were followed up for 10, 7, and 0.6 years, respectively. One case had the typical imaging characteristics of a dorsal exophytic low-grade glioma.

CONCLUSIONS

No patient fulfilled the radiologic criteria defining a high-grade glioma. Central neuroradiological review and biopsy may provide useful information regarding the patient management.

Clinical, pathological, and radiological features of 80 pediatric diffuse intrinsic pontine gliomas: A single-institute study

Objective

Diffuse intrinsic pontine gliomas (DIPGs) are rare but devastating diseases. This retrospective cross-sectional study aimed to investigate the clinical, radiological, and pathological features of DIPGs.

Materials and methods

The clinical data of 80 pediatric DIPGs under clinical treatment in Beijing Tiantan Hospital from July 2013 to July 2019 were retrospectively collected and studied. A follow-up evaluation was performed.

Results

This study included 48 men and 32 women. The most common symptoms were cranial nerve palsy (50.0%, 40/80 patients) and limb weakness (41.2%, 33/80 patients). Among the 80 patients, 24 cases were clinically diagnosed, 56 cases were pathologically verified, and 45 cases were tested for H3K27 alteration status, with 34 H3K27 alteration cases confirmed. Radiological results indicated that enhancement was common (65.0%, 52/80 patients). Cho/Cr was of predictive value for H3K27 alteration status (P = 0.012, cutoff value = 2.38, AUC = 0.801). Open cranial surgery followed by further chemotherapy and radiotherapy was beneficial for patients' overall survival. Cox regression analysis indicated H3K27 alteration to be the independent prognostic influencing factor for DIPGs in this series (P = 0.002).

Conclusion

DIPGs displayed a wide spectrum of clinical and imaging features. Surgery-suitable patients could benefit from postoperative comprehensive therapy for a better overall survival. H3K27 alteration was the independent prognostic influencing factor for DIPGs.

A novel preclinical model of craniospinal irradiation in pediatric diffuse midline glioma demonstrates decreased metastatic disease

Background

Diffuse midline glioma (DMG) is an aggressive pediatric central nervous system tumor with strong metastatic potential. As localized treatment of the primary tumor improves, metastatic disease is becoming a more important factor in treatment. We hypothesized that we could model craniospinal irradiation (CSI) through a DMG patient-derived xenograft (PDX) model and that CSI would limit metastatic tumor.

Methods

We used a BT245 murine orthotopic DMG PDX model for this work. We developed a protocol and specialized platform to deliver craniospinal irradiation (CSI) (4 Gy x2 days) with a pontine boost (4 Gy x2 days) and compared metastatic disease by pathology, bioluminescence, and MRI to mice treated with focal radiation only (4 Gy x4 days) or no radiation.

Results

Mice receiving CSI plus boost showed minimal spinal and brain leptomeningeal metastatic disease by bioluminescence, MRI, and pathology compared to mice receiving radiation to the pons only or no radiation.

Conclusion

In a DMG PDX model, CSI+boost minimizes tumor dissemination compared to focal radiation. By expanding effective DMG treatment to the entire neuraxis, CSI has potential as a key component to combination, multimodality treatment for DMG designed to achieve long-term survival once novel therapies definitively demonstrate improved local control.

The Current State of Radiotherapy for Pediatric Brain Tumors: An Overview of Post-Radiotherapy Neurocognitive Decline and Outcomes

Tumors of the central nervous system are the most common solid malignancies diagnosed in children. While common, they are also found to have some of the lowest survival rates of all malignancies. Treatment of childhood brain tumors often consists of operative gross total resection with adjuvant chemotherapy or radiotherapy. The current body of literature is largely inconclusive regarding the overall benefit of adjuvant chemo- or radiotherapy. However, it is known that both are associated with conditions that lower the quality of life in children who undergo those treatments. Chemotherapy is often associated with nausea, emesis, significant fatigue, immunosuppression, and alopecia. While radiotherapy can be effective for achieving local control, it is associated with late effects such as endocrine dysfunction, secondary malignancy, and neurocognitive decline. Advancements in radiotherapy grant both an increase in lifetime survival and an increased lifetime for survivors to contend with these late effects. In this review, the authors examined all the published literature, analyzing the results of clinical trials, case series, and technical notes on patients undergoing radiotherapy for the treatment of tumors of the central nervous system with a focus on neurocognitive decline and survival outcomes.

Management and outcome of pediatric brainstem and cerebellar peduncular low-grade gliomas: a retrospective analysis of 62 cases

PURPOSE

This study was designed to present our experience and recommendations regarding the management of pediatric brainstem and peduncular low-grade gliomas (LGGs).

METHODS

Retrospective analysis was performed for pathologically proven brainstem or cerebellar peduncular LGGs in patients admitted between 2014 and 2019. These lesions were classified into the dorsal exophytic, focal brainstem, cervicomedullary, lower peduncular, and upper peduncular groups, and this classification was the basis for the surgical approach for the lesions.

RESULTS

Sixty-two pediatric patients were included, and their distribution among the aforementioned groups were as follows: 12, 12, 3, 16, and 19 cases in the dorsal exophytic, focal brainstem, cervicomedullary, upper peduncular, and lower peduncular groups, respectively. Stereotactic biopsy was performed for all cases in the focal brainstem group, whereas other groups underwent open excision. Gross total resection (GTR) was achieved in 20 cases (40%), near-total resection (NTR) was achieved in 17 cases (34%), and subtotal resection (STR) was achieved in 13 cases (26%). The extent of GTR and NTR for the upper peduncular, lower peduncular, dorsal exophytic, and cervicomedullary groups were 81.2%, 68.4%,75%, and 66.6%, respectively. Then, 32 cases received chemotherapy. The 3- and 5-year progression-free survival rates were 95% (95% confidence interval (CI) 89.5-100%) and 90.3% (95% CI 79.9-100%), respectively. A significant difference in the 3-year progression-free survival rate was observed between the GTR and NTR groups (p = 0.06; 100% vs. 88.2% (95% CI 72.9-100%)).

CONCLUSION

Surgery plays a definitive curative role in grossly resected cases. Additionally, the role of surgical debulking should be considered, even if GTR is impossible. Meanwhile, chemotherapy showed a beneficial role in patients with focal brainstem lesions and progressive lesions, those with STR, and some patients with NTR.

Palliative and end-of-life symptoms management for children with diffuse intrinsic pontine glioma

Background: This study aimed to investigate diffuse intrinsic pontine glioma-specific symptoms in the last 12 weeks before death and to describe current palliative care. Materials & methods: A retrospective study included 80 pediatric diffuse intrinsic pontine glioma patients diagnosed between January 2018 and December 2019. Results: The most frequently encountered symptoms were headache, gait disturbance, vomiting, dysphagia, sensory loss, seizures and constipation. Steroids were used in 96% of patients with a high success rate, as well as analgesics (67.5%), antiemetics (59%), neuropathic medication (42.5%) and anticonvulsants (37.5%). Re-irradiation improved symptoms in 50% of patients. Conclusion: Steroids were efficient in managing many symptoms, with tolerated side effects. The symptomatic treatment succeeded in relieving end-of-life symptoms. Re-irradiation should be considered a good palliative tool in addition to regular symptomatic treatment.

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

PURPOSE

It 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.

METHODS

A 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.

RESULTS

There 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.

CONCLUSIONS

Pediatric 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.

Current state of therapeutic focused ultrasound applications in neuro-oncology

INTRODUCTION

Despite manifold advances in oncology, cancers of the central nervous system remain among the most lethal. Unique features of the brain, including distinct cellular composition, immunological privilege, and physical barriers to therapeutic delivery, likely contribute to the poor prognosis of patients with neuro-oncological disease. Focused ultrasound is an emerging technology that allows transcranial delivery of ultrasound energy to focal brain targets with great precision.

METHODS

A review of the clinical and preclinical focused ultrasound literature was performed to obtain data regarding the current state of the focused ultrasound in context of neuro-oncology. A narrative review was then constructed to provide an overview of current and future applications of this technology.

RESULTS

Focused ultrasound can facilitate direct control of tumors by thermal or mechanical ablation, as well as enhance delivery of diverse therapeutics by disruption of the blood-brain barrier without local tissue damage. Indeed, ultrasound-sensitive drug formulations or sonosensitizers may be combined with ultrasound blood-brain barrier disruption to achieve high local drug concentration while limiting systemic exposure to therapeutics. Furthermore, focused ultrasound can induce radiosensitization, immunomodulation, and neuromodulation. Here we review applications of focused ultrasound with a focus on approaches currently under clinical investigation for the treatment of neuro-oncological disease, such as blood-brain barrier disruption for drug delivery and thermal ablation. We also discuss design of clinical trials, selection of patient cohorts, and emerging approaches to improve the efficacy of transcranial ultrasound, such as histotripsy, as well as combinatorial strategies to exploit synergistic biological effects of existing cancer therapies and ultrasound.

CONCLUSIONS

Focused ultrasound is a promising and actively expanding therapeutic modality for diverse neuro-oncological diseases.

Management strategies for pediatric patients with tectal gliomas: a systematic review

Pediatric tectal gliomas generally have a benign clinical course with the majority of these observed radiologically. However, patients often need treatment for obstructive hydrocephalus and occasionally require cytotoxic therapy. Given the lack of level I data, there is a need to further characterize management strategies for these rare tumors. We have therefore performed the first systematic review comparing various management strategies. The literature was systematically searched from January 1, 2000, to July 30, 2020, to identify studies reporting treatment strategies for pediatric tectal gliomas. The systematic review included 355 patients from 14 studies. Abnormal ocular findings-including gaze palsies, papilledema, diplopia, and visual field changes-were a common presentation with between 13.6 and 88.9% of patients experiencing such findings. CSF diversion was the most performed procedure, occurring in 317 patients (89.3%). In individual studies, use of CSF diversion ranged from 73.1 to 100.0%. For management options, 232 patients were radiologically monitored (65.4%), 69 received resection (19.4%), 30 received radiotherapy (8.4%), and 19 received chemotherapy (5.4%). When examining frequencies within individual studies, chemotherapy ranged from 2.5 to 29.6% and radiotherapy ranged from 2.5 to 28.6%. Resection was the most variable treatment option between individual studies, ranging from 2.3 to 100.0%. Most tectal gliomas in the pediatric population can be observed through radiographic surveillance and CSF diversion. Other forms of management (i.e., chemotherapy and radiotherapy) are warranted for more aggressive tumors demonstrating radiological progression. Surgical resection should be reserved for large tumors and/or those that are refractory to other treatment modalities.

Pediatric brain tumors: the era of molecular diagnostics, targeted and immune-based therapeutics, and a focus on long term neurologic sequelae

Pediatric brain tumors are the second most common malignancy of childhood after acute leukemia and the number one cause of cancer-related mortality¹. Over the past decade, advanced molecular diagnostics have led to the discovery of new molecularly-defined tumor types with prognostic and therapeutic implications. Methylation profiles, whole genome sequencing, and transcriptomics have defined subgroups and revealed heterogeneity within commonly defined tumor entities^2,3. These findings have also revealed important differences between adult and pediatric brain tumors of similar histology. The majority of pediatric low grade gliomas (pLGG) are defined by alterations in the mitogen-activated protein kinase (MAPK) pathway including BRAFV600E point mutation, K1AA1549-BRAF fusion, and FGFR1 alterations as opposed to IDH1/2 mutations and 1p/19q co-deletion seen more frequently in adult low grade gliomas⁴. These findings have led to targeted therapies, namely BRAF and MEK inhibitors, which are currently being evaluated in phase III clinical trials and may soon supplant chemotherapy as standard of care for pLGG's. While targeted therapy trials for pediatric brain tumors have had significant success, immunotherapy remains a challenge in a group of tumors with generally lower mutational burden compared to adult tumors and relatively "cold" immune microenvironment. Despite this, a wide array of immunotherapy trials including vaccine therapies, immune checkpoint blockade, chimeric antigen receptor (CAR) T cells, and viral therapies are on-going. Unique to pediatrics, multiple clinical trials have sought to answer the question of whether the most malignant pediatric brain tumors in the youngest patients can be successfully treated with high dose chemotherapy in lieu of radiation to avoid devastating long-term neurocognitive deficits. Due to the collaborative work of multiple pediatric neuro-oncology consortiums, the recent history of pediatric brain tumor research is one of efficient translation from bench to bedside in a rare group of tumors resulting in significant progress in the field. Here, advances in the areas of molecular characterization, targeted and immune-based therapies, and reduction in long term co-morbidities will be reviewed.

Spatially Fractionated X-Ray Microbeams Elicit a More Sustained Immune and Inflammatory Response in the Brainstem than Homogenous Irradiation

Synchrotron microbeam radiation therapy (MRT) is a preclinical irradiation technique which could be used to treat intracranial malignancies. The goal of this work was to discern differences in gene expression and the predicted regulation of molecular pathways in the brainstem after MRT versus synchrotron broad-beam radiation therapy (SBBR). Healthy C57BL/6 mice received whole-head irradiation with median acute toxic doses of MRT (241 Gy peak dose) or SBBR (13 Gy). Brains were harvested 4 and 48 h postirradiation and RNA was extracted from the brainstem. RNA-sequencing was performed to identify differentially expressed genes (false discovery rate < 0.01) relative to nonirradiated controls and significantly regulated molecular pathways and biological functions were identified (Benjamini-Hochberg corrected P < 0.05). Differentially expressed genes and regulated pathways largely reflected a pro-inflammatory response 4 h after both MRT and SBBR which was sustained at 48 h postirradiation for MRT. Pathways relating to radiation-induced viral mimicry, including HMGB1, NF-κB and interferon signaling cascades, were predicted to be uniquely activated by MRT. Local microglia, as well as circulating leukocytes, including T cells, were predicted to be activated by MRT. Our findings affirm that the transcriptomic signature of MRT is distinct from broad-beam radiotherapy, with a sustained inflammatory and immune response up to 48 h postirradiation.

Ketogenic diet treatment in diffuse intrinsic pontine glioma in children: Retrospective analysis of feasibility, safety, and survival data

Background

Diffuse intrinsic pontine glioma (DIPG) is one of the most devastating diseases among children with cancer, thus novel strategies are urgently needed.

Aims

We retrospectively evaluated DIPG patients exposed to the carbohydrate restricted ketogenic diet (KD) with regard of feasibility, safety, and overall survival (OS).

Methods and results

Searches of MEDLINE and Embase identified five hits meeting the search criteria (diagnosis of DIPG and exposure to KD). One additional case was identified by contact with experts. Individual patient data were extracted from publications or obtained from investigators. The inclusion criteria for analysis of the data were defined as DIPG patients who were exposed to the KD for ≥3 months. Feasibility, as described in the literature, was the number of patients able to follow the KD for 3 months out of all DIPG patients identified. OS was estimated by the Kaplan‐Meier method.

Five DIPG patients (males, n = 3; median age 4.4 years; range, 2.5‐15 years) meeting the inclusion criteria were identified. Analysis of the available data suggested that the KD is generally relatively well tolerated. Only mild gastro‐intestinal complaints, one borderline hypoglycemia (2.4 mmol/L) and one hyperketosis (max 7.2 mmol/L) were observed. Five out of six DIPG patients identified adhered for ≥3 months (median KD duration, 6.5 months; range, 0.25‐2 years) to the diet. The median OS was 18.7 months.

Conclusion

Our study provides evidence that it may be feasible for pediatric DIPG patients to adhere for at least 3 months to KD. In particular cases, diet modifications were done. The clinical outcome and OS appear not to be impacted in a negative way. KD might be proposed as adjuvant therapy when large prospective studies have shown feasibility and safety. Future studies might ideally assess the impact of KD on clinical outcome, quality of life, and efficacy.

Retrospective study of diffuse intrinsic pontine glioma in the Belgian population: a 25 year experience

INTRODUCTION

Diffuse intrinsic pontine glioma is a rare disease with a high mortality. Our primary aim was to determine the incidence of this disease in Belgium. Secondly, we wanted to compare the treatment approach of Belgian pediatric oncology centres, to investigate possibilities for improvement.

METHODS

We retrospectively collected and analysed data on DIPG-patients diagnosed between 1994 and 2018 and recorded in the Belgian Cancer Registry. We included patients ≤ 18 years who were followed in one of the eight Belgian pediatric oncology centres.

RESULTS

We included 100 patients. Files were complete in 87 patients. We observed an increase in diagnoses with an incidence of 3.1 per 1,000,000 persons (aged 0-≤ 18) per year over the last 5 years compared to an overall incidence of 1.8. Biopsy was performed at diagnosis in 51.7% of patients. In one fifth this was study-related. Mutation analysis was known in eight patients, of which six showed the H3 K27M-mutation. 58.8% of patients received chemotherapy, without a significant survival benefit. 12.6% of patients were included in a clinical trial. Biopsy rate and the use of chemotherapy differed widely between centres. Mean OS and PFS were 10.49 and 4.87 months respectively. We observed an improved survival over time.

CONCLUSIONS

Over the past 25 years, we observed an increase of new DIPG-diagnoses. Outcome in our cohort is comparable with literature findings. We demonstrate an important heterogeneity in treatment approach between different centres and limited inclusion in clinical trials. Therefore, collaboration between centres and inclusion of patients in clinical trials is much needed.

MR imaging features of diffuse intrinsic pontine glioma and relationship to overall survival: report from the International DIPG Registry

BACKGROUND

This study describes imaging features of diffuse intrinsic pontine glioma (DIPG) and correlates with overall survival (OS) and histone mutation status in the International DIPG Registry (IDIPGR).

METHODS

Four hundred cases submitted to the IDIPGR with a local diagnosis of DIPG and baseline MRI were evaluated by consensus review of 2 neuroradiologists; 43 cases were excluded (inadequate imaging or alternative diagnoses). Agreement between reviewers, association with histone status, and univariable and multivariable analyses relative to OS were assessed.

RESULTS

On univariable analysis imaging features significantly associated with worse OS included: extrapontine extension, larger size, enhancement, necrosis, diffusion restriction, and distant disease. On central review, 9.5% of patients were considered not to have DIPG. There was moderate mean agreement of MRI features between reviewers. On multivariable analysis, chemotherapy, age, and distant disease were predictors of OS. There was no difference in OS between wild-type and H3 mutated cases. The only imaging feature associated with histone status was the presence of ill-defined signal infiltrating pontine fibers.

CONCLUSIONS

Baseline imaging features are assessed in the IDIPGR. There was a 9.5% discordance in DIPG diagnosis between local and central review, demonstrating need for central imaging confirmation for prospective trials. Although several imaging features were significantly associated with OS (univariable), only age and distant disease were significant on multivariable analyses. There was limited association of imaging features with histone mutation status, although numbers are small and evaluation exploratory.

Diffuse midline glioma presenting with central sleep apnea and pulmonary hypertension in a 4-year-old patient: a case report

NONE

Central sleep apnea is a rare disorder in the pediatric population with various initial presentations and is secondary to many underlying diseases. We report on a 4-year-old boy with episodes of syncope. He also had pulmonary hypertension and cardiomegaly. Polysomnography showed the finding for central sleep apnea with a high apnea-hypopnea index (up to 138.1 events/h). Brain magnetic resonance imaging showed an ill-defined area near the medulla oblongata and lower pons. The lesion from a brainstem biopsy confirmed the diagnosis of low-grade glioma. Conservative medical follow-up was suggested, and brain magnetic resonance imaging 6 months later showed no obvious tumor progression. To our best knowledge, this is the first case report that workup on the cause of syncope and pulmonary hypertension led to the final diagnosis of central sleep apnea and a brain neoplasm.

Surgical treatment and prognosis of focal brainstem gliomas in children: A 7 year single center experience

This study aims to describe the role of open surgical treatment for focal brainstem gliomas (FBSGs) with the assistance of multimodal neuronavigation and intraoperative neurophysiological monitoring (IOM) in children to investigate the efficacy of microsurgical treatment in pediatric FBSGs. Also the prognostic factors related to the overall survival (OS) of FBSGs to describe the patient and tumor characteristics relevant to prognosis/outcome were focused on. Clinical data of 63 pediatric patients below 16 years of age with FBSGs admitted to the Neurosurgical Unit of Beijing Tiantan Hospital from January 2012 to December 2018 were retrospectively analyzed. All patients underwent initial surgical treatment, followed by magnetic resonance diffusion tensor imaging (DTI), neuronavigation and IOM. Gross or near total resection (GTR or NTR) was achieved in 57/63 (90.5%) cases, and subtotal resection (STR) was achieved in 6/63 (9.5%) cases. Postoperative adjuvant therapy was received by 27/63 (42.9%) cases. Postoperative pathological examination revealed that 36/63 (57.1%) cases had grade I gliomas, 22/63 (34.9%) had grade II, and 5/63 (8.0%) had grade III-IV gliomas according to the WHO classification. The mean Karnofsky score preoperatively was 60, and at the time of follow-up was 90. Consecutively, 6 cases demonstrated disease progression, and 5 of these were deceased. The OS in all patients was 81.2% at 5 years. Histological grade (P < .001) and age at diagnosis (P = .023) showed significant association with prolonged OS. Multimodal neuronavigation and IOM allow very precise intracranial surgery, contributing to a maximally safe resection that might decrease the postoperative disability and mortality rate. This study also showed that pediatric FBSGs were mostly low-grade tumors with excellent surgical outcomes. Consequently, it is suggested that microsurgery can be used to treat FBSGs in children in order to provide better prognosis and survival outcomes.

Pediatric low grade focal brainstem glioma: outcomes of different treatment strategies and prognostic factors

Background: This study explores the prognostic factors and outcomes of different treatment modalities in focal brain stem glioma (FBSG). Materials & methods: Pediatric FBSG patients diagnosed during 2010-2017 were retrospectively reviewed for clinical and therapeutic data. Results: A total of 71 cases were identified and the median age was 6.4 years. The 5-year overall- and progression-free survival were 74.5 and 70.6%, respectively. Radiotherapy was the main line of treatment (66.2%) and there were no survival differences between radiotherapy, chemotherapy and surveillance groups. Two independent poor prognostic factors were identified on multivariate analysis: age <8 years and cervicomedullary tumor site (p = 0.02 for both). Conclusion: Surveillance, radiotherapy and chemotherapy have comparable clinical outcomes in pediatric FBSG.

Preclinical and clinical investigation of intratumoral chemotherapy pharmacokinetics in DIPG using gemcitabine

Background

Hundreds of systemic chemotherapy trials in diffuse intrinsic pontine glioma (DIPG) have not improved survival, potentially due to lack of intratumoral penetration, which has not previously been assessed in humans.

Methods

We used gemcitabine as a model agent to assess DIPG intratumoral pharmacokinetics (PK) using mass spectrometry.

Results

In a phase 0 clinical trial of i.v. gemcitabine prior to biopsy in children newly diagnosed with DIPG by MRI, mean concentration in 4 biopsy cores in patient 1 (H3K27M diffuse midline glioma) was 7.65 µM. These compare favorably to levels for patient 2 (mean 3.85 µM, found to have an H3K27-wildtype low-grade glioma on histology), and from a similar study in adult glioblastoma (adjusted mean 3.48 µM). In orthotopic patient-derived xenograft (PDX) models of DIPG and H3K27M-wildtype pediatric glioblastoma, gemcitabine levels and clearance were similar in tumor, pons, and cortex and did not depend on H3K27 mutation status or tumor location. Normalized gemcitabine levels were similar in patient 1 and the DIPG PDX.

Conclusions

These findings, while limited to one agent, provide preliminary evidence for the hypotheses that lack of intratumoral penetration is not why systemic chemotherapy has failed in DIPG, and orthotopic PDX models can adequately model intratumoral PK in human DIPG.

Pediatric Brainstem Gliomas: An Institutional Experience

Objective:

The aim of this study was to analyze the clinical profiles and outcomes of pediatric brainstem gliomas treated at our institute.

Methodology:

We reviewed the files of 18 pediatric age group patients diagnosed with brainstem glioma at our institution. The following variables were recorded: age, sex, duration of symptoms, date of diagnosis, main clinical symptoms, Karnofsky performance status score, magnetic resonance imaging findings, histopathology findings, details of the treatment given, disease progression, and date of mortality/last follow-up. This data were then transferred to SPSS version 23 which was used for further analysis.

Results:

The mean age of our cohort was 8.6 years (range 3–15). There were 11 (61.1%) males and 7 (38.9%) females. There were 16 (88.9%) patients with diffuse intrinsic pontine gliomas (DIPGs), 1 (5.6%) patients with exophytic medullary gliomas, and 1 (5.6%) patient with midbrain/tectal glioma. Mean overall survival (OS) was 9.7 months. Mean progression-free survival (PFS) was 6.3 months. All patients with DIPG eventually passed away from their disease. Patients with DIPG who received radiotherapy had a longer OS and PFS than those who did not (9.8 and 6 months vs. 3.4 and 2.4 months). Diagnostic latency >1 month was found to have a statistically significant longer progression-free interval.

Conclusion:

DIPGs in the pediatric population have a poor prognosis. Radiotherapy serves to increase survival time but is not curative.

Diverse immunotherapies can effectively treat syngeneic brainstem tumors in the absence of overt toxicity

BACKGROUND

Immunotherapy has shown remarkable clinical promise in the treatment of various types of cancers. However, clinical benefits derive from a highly inflammatory mechanism of action. This presents unique challenges for use in pediatric brainstem tumors including diffuse intrinsic pontine glioma (DIPG), since treatment-related inflammation could cause catastrophic toxicity. Therefore, the goal of this study was to investigate whether inflammatory, immune-based therapies are likely to be too dangerous to pursue for the treatment of pediatric brainstem tumors.

METHODS

To complement previous immunotherapy studies using patient-derived xenografts in immunodeficient mice, we developed fully immunocompetent models of immunotherapy using transplantable, syngeneic tumors. These four models - HSVtk/GCV suicide gene immunotherapy, oncolytic viroimmunotherapy, adoptive T cell transfer, and CAR T cell therapy - have been optimized to treat tumors outside of the CNS and induce a broad spectrum of inflammatory profiles, maximizing the chances of observing brainstem toxicity.

RESULTS

All four models achieved anti-tumor efficacy in the absence of toxicity, with the exception of recombinant vaccinia virus expressing GMCSF, which demonstrated inflammatory toxicity. Histology, imaging, and flow cytometry confirmed the presence of brainstem inflammation in all models. Where used, the addition of immune checkpoint blockade did not introduce toxicity.

CONCLUSIONS

It remains imperative to regard the brainstem with caution for immunotherapeutic intervention. Nonetheless, we show that further careful development of immunotherapies for pediatric brainstem tumors is warranted to harness the potential potency of anti-tumor immune responses, despite their possible toxicity within this anatomically sensitive location.

Ketogenic diet treatment in recurrent diffuse intrinsic pontine glioma in children: A safety and feasibility study

BACKGROUND

The mean overall survival rate of children with diffuse intrinsic pontine glioma (DIPG) is 9-11 months, with current standard treatment with fractionated radiotherapy and adjuvant chemotherapy. So far, novel therapeutic strategies have not yet resulted in significantly better survival. The main source of energy for glioblastoma cells is glucose. Therefore, metabolic alterations induced by the use of the extremely carbohydrate-restricted ketogenic diet (KD) as adjuvant therapy are subject of interest in cancer research.

PROCEDURE

This study explores the safety and feasibility of the KD in children with recurrent DIPG and no remaining treatment options. Safety was defined as the number of adverse effects. Feasibility was defined as the number of patients who were able to use the KD for three months. Coping of patients and parents was measured with questionnaires.

RESULTS

Three of 14 children referred to our hospital between 2010 and 2015 were included. Two patients completed the study, and one died before the end of the study. Hospitalizations were needed for placing a nasogastric tube (n = 1) and epileptic seizures (n = 1). Adverse effects related to the diet were mild and transient. Parents were highly motivated during the study.

CONCLUSION

Use of KD is safe and feasible, but the effect on survival has to be proven in a larger cohort of children who start the KD earlier after diagnosis, preferably as adjuvant therapy to fractionated radiotherapy.

Passive Immunotherapies for Central Nervous System Disorders: Current Delivery Challenges and New Approaches

Passive immunotherapy, i.e., the administration of exogenous antibodies that recognize a specific target antigen, has gained significant momentum as a potential treatment strategy for several central nervous system (CNS) disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and brain cancer, among others. Advances in antibody engineering to create therapeutic antibody fragments or antibody conjugates have introduced new strategies that may also be applied to treat CNS disorders. However, drug delivery to the CNS for antibodies and other macromolecules has thus far proven challenging, due in large part to the blood-brain barrier and blood-cerebrospinal fluid barriers that greatly restrict transport of peripherally administered molecules from the systemic circulation into the CNS. Here, we summarize the various passive immunotherapy approaches under study for the treatment of CNS disorders, with a primary focus on disease-specific and target site-specific challenges to drug delivery and new, cutting edge methods.

Population-based Study Determining Predictors of Cancer-Specific Mortality and Survival in Pediatric High-grade Brainstem Glioma

BACKGROUND

Pediatric high-grade brainstem gliomas are aggressive tumors with dismal prognoses. Large-scale studies are needed to further characterize these tumors and determine factors influencing cancer-specific mortality and survival at varying time points.

METHODS

We used the SEER (Surveillance Epidemiology and End Results) database to conduct a population-based study of pediatric patients with histologically confirmed anaplastic astrocytoma or glioblastoma tumors located within the brainstem. Multivariate analyses incorporating patient demographics, tumor characteristics, and treatments were used to determine predictors of cancer-specific mortality and survival at 6 months, 9 months, 1 year, and 2 years.

RESULTS

We included 154 patients from the SEER database: 72 patients with anaplastic astrocytoma (47%) and 82 (53%) with glioblastoma. Median survival for the entire cohort was 10.0 months. Glioblastoma histology, developmental stage, and large tumor size were significantly associated with cancer-specific mortality. Six-month, 9-month, 1-year, and 2-year survival was 75%, 57%, 42%, and 20%, respectively. Glioblastoma histology was associated with worsened survival at 6 months (odds ratio [OR], 0.19; P = 0.0081), 9 months (OR, 0.18; P < 0.001), 1 year (OR, 0.19; P < 0.001), and 2 years (OR, 0.14; P = 0.0055). Radiation therapy was associated with improved survival at 6 (OR, 8.53; P = 0.0012) and 9 months (OR, 3.58; P = 0.035) but not at 1 or 2 years. Radiation therapy was associated with improved survival in glioblastoma (9.0 vs. 3.0 months; P < 0.001).

CONCLUSIONS

This population-based study showed that glioblastoma histology is associated with a poor prognosis in pediatric patients with high-grade brainstem gliomas. Regardless of histology, radiation therapy improved survival at 6 and 9 months but not long-term.

Characterization of Diffuse Intrinsic Pontine Glioma Radiosensitivity using Synchrotron Microbeam Radiotherapy and Conventional Radiation Therapy In Vitro

Synchrotron microbeam radiation therapy is a promising preclinical radiotherapy modality that has been proposed as an alternative to conventional radiation therapy for diseases such as diffuse intrinsic pontine glioma (DIPG), a devastating pediatric tumor of the brainstem. The primary goal of this study was to characterize and compare the radiosensitivity of two DIPG cell lines (SF7761 and JHH-DIPG-1) to microbeam and conventional radiation. We hypothesized that these DIPG cell lines would exhibit differential responses to each radiation modality. Single cell suspensions were exposed to microbeam (112, 250, 560, 1,180 Gy peak dose) or conventional (2, 4, 6 and 8 Gy) radiation to produce clonogenic cell-survival curves. Apoptosis induction and the cell cycle were also analyzed five days postirradiation using flow cytometry. JHH-DIPG-1 cells displayed greater radioresistance than SF7761 to both microbeam and conventional radiation, with higher colony formation and increased accumulation of G₂/M-phase cells. Apoptosis was significantly increased in SF7761 cells compared to JHH-DIPG-1 after microbeam irradiation, demonstrating cell-line specific differential radiosensitivity to microbeam radiation. Additionally, biologically equivalent doses to microbeam and conventional radiation were calculated based on clonogenic survival, furthering our understanding of the response of cancer cells to these two radiotherapy modalities.

Diffuse intrinsic pontine gliomas (DIPG) at recurrence: is there a window to test new therapies in some patients?

Children with diffuse intrinsic pontine glioma (DIPG) need new and more efficient treatments. They can be developed at relapse or at diagnosis, but therefore they must be combined with radiotherapy. Survival of children after recurrence and its predictors were studied to inform the possibility to design early phase clinical trials for DIPG at this stage. Among 142 DIPG patients treated between 1998 and 2014, 114 had biopsy-proven DIPG with histone H3 status available for 83. We defined as long survivors' patients who survived more than 3 months after relapse which corresponds to the minimal life expectancy requested for phase I/II trials. Factors influencing post-relapse survival were accordingly compared between short and long-term survivors after relapse. Fifty-seven percent of patients were considered long survivors and 70% of them had a Lansky Play Scale (LPS) above 50% at relapse. Patients who became steroids-independent after initial treatment for at least 2 months had better survival after relapse (3.7 versus 2.6 months, p = 0.001). LPS above 50% at relapse was correlated with better survival after relapse (3.8 versus 1.8 months, p < 0.001). Patients with H3.1 mutation survived longer after relapse (4.9 versus 2.7 months, p = 0.007). Patients who received a second radiotherapy at the time of relapse had an improved survival (7.5 versus 4 months, p = 0.001). In the two-way ANOVA analysis, steroid-independence and LPS predicted survival best and the type of histone H3 (H3.1 or H3.3) mutated did not improve prediction. Survival of many DIPG patients after relapse over 3 months would make possible to propose specific trials for this condition. Steroid-independence, H3 mutation status and LPS should be considered to predict eligibility.

Preclinical analysis of MTOR complex 1/2 inhibition in diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) is an incurable childhood brain tumor. The mechanistic target of rapamycin (MTOR), a key oncogene, functions as two distinct signaling complexes, MTORC1 and MTORC2. We set out to determine the preclinical efficacy and mechanism of action of MTOR inhibitors in DIPG. We evaluated the MTORC1 inhibitor everolimus and the MTORC1/2 inhibitor AZD2014 in three patient-derived DIPG cell lines using cell culture models. We created dose-response curves for both compounds. We measured phenotypic effects on cell self-renewal, apoptosis, cell cycle, differentiation, senescence, and autophagy. We assessed the effects of each compound on the AKT pathway. Finally, we measured the efficacy of AZD2014 in combination with radiation therapy (RT) and a panel of FDA-approved chemotherapy drugs. While everolimus showed minimal antitumor efficacy, AZD2014 revealed IC₅₀ levels of 410–552 nM and IC₉₀ levels of 1.30–8.86 µM in the three cell lines. AZD2014 demonstrated increased inhibition of cell self-renewal compared to everolimus. AZD2014 decreased expression of phospho-AKT, while no such effect was noted with everolimus. Direct AKT inhibition showed similar efficacy to AZD2014, and induction of constitutive AKT activity rescued DIPG cells from the effects of AZD2014. AZD2014 exhibited synergistic relationships with both RT and various chemotherapy agents across classes, including the multikinase inhibitor ponatinib. MTORC1/2 inhibition shows antitumor activity in cell culture models of DIPG due to the effect of MTORC2 inhibition on AKT. This strategy should be further assessed for potential incorporation into combinatorial approaches to the treatment of DIPG.

Influence of an intratumoral cyst on drug distribution by convection-enhanced delivery: case report

Convection-enhanced delivery (CED) uses positive pressure to induce convective flow of molecules and maximize drug distribution. Concerns have been raised about the effect of cystic structures on uniform drug distribution with CED. The authors describe the case of a patient with a diffuse intrinsic pontine glioma (DIPG) with a large cyst and examine its effect on drug distribution after CED with a radiolabeled antibody. The patient was treated according to protocol with CED of ¹²⁴I-8H9 to the pons for nonprogressive DIPG after radiation therapy as part of a Phase I trial (clinical trial registration no. NCT01502917, clinicaltrials.gov). Care was taken to avoid the cystic cavity in the planned catheter track and target point. Co-infusion with Gd-DTPA was performed to assess drug distribution. Infusate distribution was examined by MRI immediately following infusion and analyzed using iPlan Flow software. Analysis of postinfusion MR images demonstrated convective distribution around the catheter tip and an elongated configuration of drug distribution, consistent with the superoinferior corticospinal fiber orientation in the brainstem. This indicates that the catheter was functioning and a pressure gradient was established. No infusate entry into the cystic region could be identified on T2-weighted FLAIR or T1-weighted images. The effects of ependymal and pial surfaces on drug delivery using CED in brainstem tumors remain controversial. Drug distribution is a critical component of effective application of CED to neurosurgical lesions. This case suggests that cyst cavities may not always behave as fluid "sinks" for drug distribution. The authors observed that infusate was not lost into the cyst cavity, suggesting that lesions with cystic components can be treated by CED without significant alterations to target and infusion planning.

Concomitant Use of Panobinostat and Reirradiation in Progressive DIPG: Report of 2 Cases

Diffuse intrinsic pontine glioma (DIPG) remains a devastating disease. Panobinostat has been shown to have therapeutic efficacy both in vitro and in DIPG orthotopic xenograft models; however, clinical data in patients with DIPG are lacking. We present 2 cases of DIPG, who were treated with panobinostat at 22 to 25 mg/m/dose, 3 times weekly for 2 weeks in 3-week cycles and concomitant reirradiation after disease progression. Two episodes of asymptomatic thrombocytopenia were observed in 1 patient. Hyperacetylation of histone H4 of peripheral blood mononuclear cells was evident following treatment. In our experience, panobinostat administered with reirradiation was well tolerated at a relatively higher dose than that used in adult studies.

Diffuse Intrinsic Pontine Glioma: Time for Cautious Optimism

Diffuse intrinsic pontine glioma is a lethal brain cancer that arises in the pons of children. The median survival for children with diffuse intrinsic pontine glioma is less than 1 year from diagnosis, and no improvement in survival has been realized in more than 30 years. Currently, the standard of care for diffuse intrinsic pontine glioma is focal radiation therapy, which provides only temporary relief. Recent genomic analysis of tumors from biopsies and autopsies, have resulted in the discovery of K27M H3.3/H3.1 mutations in 80% and ACVR1 mutations in 25% of diffuse intrinsic pontine gliomas, providing renewed hope for future success in identifying effective therapies. In addition, as stereotactic tumor biopsies at diagnosis at specialized centers have been demonstrated to be safe, biopsies have now been incorporated into several prospective clinical trials. This article summarizes the epidemiology, clinical presentation, diagnosis, prognosis, molecular genetics, current treatment, and future therapeutic directions for diffuse intrinsic pontine glioma.

Imaging the DNA Alkylator Melphalan by CEST MRI: An Advanced Approach to Theranostics

Brain tumors are among the most lethal types of tumors. Therapeutic response variability and failure in patients have been attributed to several factors, including inadequate drug delivery to tumors due to the blood-brain barrier (BBB). Consequently, drug delivery strategies are being developed for the local and targeted delivery of drugs to brain tumors. These drug delivery strategies could benefit from new approaches to monitor the delivery of drugs to tumors. Here, we evaluated the feasibility of imaging 4-[bis(2-chloroethyl)amino]-l-phenylalanine (melphalan), a clinically used DNA alkylating agent, using chemical exchange saturation transfer magnetic resonance imaging (CEST MRI), for theranostic applications. We evaluated the physicochemical parameters that affect melphalan's CEST contrast and demonstrated the feasibility of imaging the unmodified drug by saturating its exchangeable amine protons. Melphalan generated a CEST signal despite its reactivity in an aqueous milieu. The maximum CEST signal was observed at pH 6.2. This CEST contrast trend was then used to monitor therapeutic responses to melphalan in vitro. Upon cell death, the decrease in cellular pH from ∼7.4 to ∼6.4 caused an amplification of the melphalan CEST signal. This is contrary to what has been reported for other CEST contrast agents used for imaging cell death, where a decrease in the cellular pH following cell death results in a decrease in the CEST signal. Ultimately, this method could be used to noninvasively monitor melphalan delivery to brain tumors and also to validate therapeutic responses to melphalan clinically.

Long-term survival of an infant with diffuse brainstem lesion diagnosed by prenatal MRI: a case report and review of the literature

BACKGROUND

We describe a unique case of expansive diffuse brainstem lesion diagnosed prenatally by magnetic resonance imaging (MRI) with long-term survival. Findings of fetal and postpartum MRI were highly consistent with the characteristics of diffuse brainstem glioma.

METHODS

Diagnosis was based on the features of MRI, and histopathology was not confirmed by biopsy. Although the prognosis of diffuse brainstem tumor is usually poor, this child was asymptomatic at birth and the neurological condition is still normal at 4 years of age without any treatment.

RESULTS

During routine imaging follow-up, diameters of the expansion have remained stable, while the size of the lesion compared to the posterior fossa size has diminished. In addition to brainstem tumor, a skin lesion of the back was observed and MRI of the thoracic spine showed a large asymptomatic extradural cystic lesion suggesting an arachnoid cyst. The pontine tumor of this infant, in agreement with a few previously reported cases, suggests a subgroup of beneficial outcome of expansive diffuse brainstem lesions, particularly in the neonatal period.

DISCUSSION

In this article, we discuss the prognosis and characteristics of pediatric brainstem tumors and differential diagnosis of neonatal brainstem lesions.