CNS tumors with PLAGL1-fusion: beyond ZFTA and YAP1 in the genetic spectrum of supratentorial ependymomas.

A novel methylation class, "neuroepithelial tumor, with PLAGL1 fusion" (NET-PLAGL1), has recently been described, based on epigenetic features, as a supratentorial pediatric brain tumor with recurrent histopathological features suggesting an ependymal differentiation. Because of the recent identification of this neoplastic entity, few histopathological, radiological and clinical data are available. Herein, we present a detailed series of nine cases of PLAGL1-fused supratentorial tumors, reclassified from a series of supratentorial ependymomas, non-ZFTA/non-YAP1 fusion-positive and subependymomas of the young. This study included extensive clinical, radiological, histopathological, ultrastructural, immunohistochemical, genetic and epigenetic (DNA methylation profiling) data for characterization. An important aim of this work was to evaluate the sensitivity and specificity of a novel fluorescent in situ hybridization (FISH) targeting the PLAGL1 gene. Using histopathology, immunohistochemistry and electron microscopy, we confirmed the ependymal differentiation of this new neoplastic entity. Indeed, the cases histopathologically presented as "mixed subependymomas-ependymomas" with well-circumscribed tumors exhibiting a diffuse immunoreactivity for GFAP, without expression of Olig2 or SOX10. Ultrastructurally, they also harbored features reminiscent of ependymal differentiation, such as cilia. Different gene partners were fused with PLAGL1: FOXO1, EWSR1 and for the first time MAML2. The PLAGL1 FISH presented a 100% sensitivity and specificity according to RNA sequencing and DNA methylation profiling results. This cohort of supratentorial PLAGL1-fused tumors highlights: 1/ the ependymal cell origin of this new neoplastic entity; 2/ benefit of looking for a PLAGL1 fusion in supratentorial cases of non-ZFTA/non-YAP1 ependymomas; and 3/ the usefulness of PLAGL1 FISH.

"Hemispheric pilocytic astrocytoma" revisited: A comprehensive clinicopathological and molecular series emphasizing their overlap with other glioneuronal tumors.

Pilocytic astrocytomas (PA) typically exhibit distinct clinical, radiological, histopathological, and genetic features. DNA-methylation profiling distinguishes PA according to their location (infratentorial, midline, hemispheric, or spinal). In the hemispheric location, distinguishing PA from glioneuronal tumors remains a common diagnostic challenge for neuropathologists. Furthermore, the current version of the DKFZ classifier seems to have difficulty separating them from gangliogliomas. In this study, after central radiological review, we identified a histopathologically defined set of PA (histPA, n = 11) and a cohort of DNA-methylation defined PA (mcPA, n = 11). Nine out of the 11 histPA matched the methylation class of hemispheric PA, whereas 2 cases were classified at the end of the study as dysembryoplastic neuroepithelial tumors. Similarly, the mcPA cohort contained tumors mainly classified as PA (7/11), but 4 cases were classified as glioneuronal. The analysis of the 16 tumors with an integrated diagnosis of PA revealed that they affect mainly children with a wide spectrum of radiological, histopathological (i.e. a predominantly diffuse growth pattern), and genetic characteristics (large range of mitogen-activated protein kinase alterations). Based on these results, we consider hemispheric PA to be different from their counterparts in other locations and to overlap with other glioneuronal tumors, reinforcing the necessity of interpreting all data to obtain an accurate diagnosis.

Intraputaminal Gene Delivery in Two Patients with Aromatic L-Amino Acid Decarboxylase Deficiency.

Background: Aromatic l-amino acid decarboxylase deficiency (AADCD) is a rare, early-onset, dyskinetic encephalopathy mostly reflecting a defective synthesis of brain dopamine and serotonin. Intracerebral gene delivery (GD) provided a significant improvement among AADCD patients (mean age, ≤6 years). Objective: We describe the clinical, biological, and imaging evolution of two AADCD patients ages >10 years after GD. Methods: Eladocagene exuparvovec, a recombinant adeno-associated virus containing the human complimentary DNA encoding the AADC enzyme, was administered into bilateral putamen by stereotactic surgery. Results: Eighteen months after GD, patients showed improvement in motor, cognitive and behavioral function, and in quality of life. Cerebral l-6-[18F] fluoro-3, 4-dihydroxyphenylalanine uptake was increased at 1 month, persisting at 1 year compared to baseline. Conclusion: Two patients with a severe form of AADCD had an objective motor and non-motor benefit from eladocagene exuparvovec injection even when treated after the age of 10 years, as in the seminal study.

Assessment of Puberty and Hypothalamic-Pituitary-Gonadal Axis Function After Childhood Brain Tumor Treatment.

CONTEXT: Endocrine complications are common in pediatric brain tumor patients. OBJECTIVE: To describe hypothalamic-pituitary-gonadal axis (HPGA) function in patients treated in childhood for a primary brain tumor more than 5 years earlier, in order to identify risk factors for HPGA impairment. METHODS: We retrospectively included 204 patients diagnosed with a primary brain tumor before 18 years of age and monitored at the pediatric endocrinology unit of the Necker Enfants-Malades University Hospital (Paris, France) between January 2010 and December 2015. Patients with pituitary adenoma or untreated glioma were excluded. RESULTS: Among patients with suprasellar glioma not treated by radiotherapy, the prevalence of advanced puberty was 65% overall and 70% when the diagnosis occurred before 5 years of age. Medulloblastoma chemotherapy caused gonadal toxicity in 70% of all patients and in 87.5% of those younger than 5 years at diagnosis. In the group with craniopharyngioma, 70% of patients had hypogonadotropic hypogonadism, which was consistently accompanied by growth hormone deficiency. CONCLUSION: Tumor type, location, and treatment were the risk main factors for HPGA impairment. Awareness that onset can be delayed is essential to guide information of parents and patients, patient monitoring, and timely hormone replacement therapy.

Chiari malformation type I surgery in children: French multicenter 10-year cohort.

OBJECTIVE: Chiari malformation type I (CM-I) is frequent in children and remains a surgical challenge. Several techniques have been described for posterior fossa decompression. No decision algorithm has been validated, and strategies are highly variable between institutions. The goal of this study was to define therapeutic guidelines that take into consideration patient specificities. METHODS: The authors retrospectively collected data from patients who were < 18 years of age, were diagnosed with CM-I, and were treated surgically between 2008 and 2018 in 8 French pediatric neurosurgical centers. Data on clinical features, morphological parameters, and surgical techniques were collected. Clinical outcomes at 3 and 12 months after surgery were assessed by the Chicago Chiari Outcome Scale. The authors used a hierarchical clustering method to define clusters of patients by considering their anatomical similarities, and then compared outcomes between surgical strategies in each of these clusters. RESULTS: Data from 255 patients were collected. The mean age at surgery was 9.6 ± 5.0 years, syringomyelia was reported in 60.2% of patients, the dura mater was opened in 65.0% of patients, and 17.3% of patients underwent a redo surgery for additional treatment. The mean Chicago Chiari Outcome Scale score was 14.4 ± 1.5 at 3 months (n = 211) and 14.6 ± 1.9 at 12 months (n = 157). The hierarchical clustering method identified three subgroups with potentially distinct mechanisms underlying tonsillar herniation: bony compression, basilar invagination, and foramen magnum obstruction. Each cluster matched with specific outcomes. CONCLUSIONS: This French multicenter retrospective cohort study enabled the identification of three subgroups among pediatric patients who underwent surgery for CM-I, each of which was associated with specific outcomes. This morphological classification of patients might help in understanding the underlying mechanisms and providing personalized treatment.

High Prevalence of Early Endocrine Disorders After Childhood Brain Tumors in a Large Cohort.

CONTEXT: Endocrine complications are common in pediatric brain tumor patients. OBJECTIVE: We aimed to describe the endocrine follow-up of patients with primary brain tumors. METHODS: This is a noninterventional observational study based on data collection from medical records of 221 patients followed at a Pediatric Endocrinology Department. RESULTS: Median age at diagnosis was 6.7 years (range, 0-15.9), median follow-up 6.7 years (0.3-26.6), 48.9% female. Main tumor types were medulloblastoma (37.6%), craniopharyngioma (29.0%), and glioma (20.4%). By anatomic location, 48% were suprasellar (SS) and 52% non-suprasellar (NSS). Growth hormone deficiency (GHD) prevalence was similar in both groups (SS: 83.0%, NSS: 76.5%; P = 0.338), appearing at median 1.8 years (-0.8 to 12.4) after diagnosis; postradiotherapy GHD appeared median 1.6 years after radiotherapy (0.2-10.7). Hypothyroidism was more prevalent in SS (76.4%), than NSS (33.9%) (P < 0.001), as well as ACTH deficiency (SS: 69.8%, NSS: 6.1%; P < 0.001). Early puberty was similar in SS (16%) and NSS (12.2%). Hypogonadotropic hypogonadism was predominant in SS (63.1%) vs NSS (1.3%), P < 0.001, and postchemotherapy gonadal toxicity in NSS (29.6%) vs SS (2.8%), P < 0.001. Adult height was lower for NSS compared to target height (-1.0 SD, P < 0.0001) and to SS patients (P < 0.0001). Thyroid nodules were found in 13/45 patients (28.8%), including 4 cancers (4.8-11.5 years after radiotherapy). Last follow-up visit BMI was higher in both groups (P = 0.0001), and obesity incidence was higher for SS (46.2%) than NSS (17.4%). CONCLUSION: We found a high incidence of early-onset endocrine disorders. An endocrine consultation and nutritional evaluation should be mandatory for all patients with a brain tumor, especially when the tumor is suprasellar or after hypothalamus/pituitary irradiation.

Gene therapy in the putamen for curing AADC deficiency and Parkinson's disease.

This commentary provides an overview of the putamen as an established target site for gene therapy in treating aromatic l-amino acid decarboxylase (AADC) deficiency and Parkinson's disease, two debilitating neurological disorders that involve motor dysfunction caused by dopamine deficiencies. The neuroanatomy and the function of the putamen in motor control provide good rationales for targeting this brain structure. Additionally, the efficacy and safety of intraputaminal gene therapy demonstrate that restoration of dopamine synthesis in the putamen by using low doses of adeno-associated viral vector serotype 2 to deliver the hAADC gene is well tolerated. This restoration leads to sustained improvements in motor and nonmotor symptoms of AADC deficiency and improved uptake and conversion of exogenous l-DOPA into dopamine in Parkinson's patients.

Role of neoadjuvant chemotherapy in metastatic medulloblastoma: a comparative study in 92 children.

BACKGROUND: Previous pilot studies have shown the feasibility of preoperative chemotherapy in patients with medulloblastoma, but benefits and risks compared with initial surgery have not been assessed. METHODS: Two therapeutic strategies were retrospectively compared in 92 patients with metastatic medulloblastoma treated at Gustave Roussy between 2002 and 2015: surgery at diagnosis (n = 54, group A) and surgery delayed after carboplatin and etoposide-based neoadjuvant therapy (n = 38, group B). Treatment strategies were similar in both groups. RESULTS: The rate of complete tumor excision was significantly higher in group B than in group A (93.3% vs 57.4%, P = 0.0013). Postoperative complications, chemotherapy-associated side effects, and local progressions were not increased in group B. Neoadjuvant chemotherapy led to a decrease in the primary tumor size in all patients; meanwhile 4/38 patients experienced a distant progression. The histological review of 19 matched tumor pairs (before and after chemotherapy) showed that proliferation was reduced and histological diagnosis feasible and accurate even after neoadjuvant chemotherapy. The 5-year progression-free and overall survival rates were comparable between groups. Comparison of the longitudinal neuropsychological data showed that intellectual outcome tended to be better in group B (the mean predicted intellectual quotient value was 6 points higher throughout the follow-up). CONCLUSION: Preoperative chemotherapy is a safe and efficient strategy for metastatic medulloblastoma. It increases the rate of complete tumor excision and may improve the neuropsychological outcome without jeopardizing survival. KEY POINTS: 1. Preoperative chemotherapy increases the rate of complete tumor removal.2. No additional risk (toxic or disease progression) is linked to the delayed surgery.3. Preoperative chemotherapy could have a positive impact on the neuropsychological outcome of patients.

An epidemiology report for primary central nervous system tumors in adolescents and young adults: a nationwide population-based study in France, 2008-2013.

BACKGROUND: Primary central nervous system tumors (PCNST) among adolescents and young adults (AYA, 15-39 y) have rarely been reported. We present a nationwide report of PCNST histologically confirmed in the French AYA population between 2008 and 2013. METHODS: Patients were identified through the French Brain Tumor Database (FBTDB), a national dataset that includes prospectively all histologically confirmed cases of PCNST in France. Patients aged 15 to 39 years with histologically confirmed PCNST diagnosed between 2008 and 2013 were included. For each of the 143 histological subtypes of PCNST, crude rates, sex, surgery, and age distribution were provided. To enable international comparisons, age-standardized incidence rates were adjusted to the world-standard, European, and USA populations. RESULTS: For 6 years, 9661 PCNST (males/females: 4701/4960) were histologically confirmed in the French AYA population. The overall crude rate was 8.15 per 100 000 person-years. Overall, age-standardized incidence rates were (per 100 000 person-years, population of reference: world/Europe/USA): 7.64/8.07/8.21, respectively. Among patients aged 15-24 years, the crude rate was 5.13 per 100 000. Among patients aged 25-39 years, the crude rate was 10.10 per 100 000. Age-standardized incidence rates were reported for each of the 143 histological subtypes. Moreover, for each histological subtype, data were detailed by sex, age, type of surgery (surgical resection or biopsy), and cryopreserved samples. CONCLUSION: These data represent an exhaustive report of all histologically confirmed cases of PCNST with their frequency and distribution in the French AYA population in 2008-2013. For the first time in this age group, complete histological subtypes and rare tumor identification are detailed.

Decompressive Craniectomy in Children with Severe Traumatic Brain Injury: A Multicenter Retrospective Study and Literature Review.

BACKGROUND: Severe traumatic brain injury (TBI) is the most common cause of disability in children. Refractory increased intracranial pressure can be a therapeutic challenge. Decompressive craniectomy can be proposed when medical management is insufficient, but its place is not clearly defined in guidelines. The aim of this study was to identify prognostic factors in children with TBI. METHODS: We performed a retrospective, multicenter study to analyze long-term outcomes of 150 children with severe TBI treated by decompressive craniectomy and to identify prognostic factors. RESULTS: A satisfactory neurologic evolution (represented by a King's Outcome Scale for Childhood Head Injury score >3) was observed in 62% of children with a mean follow-up of 3.5 years. Mortality rate was 17%. Prognostic factors associated with outcome were age, initial Glasgow Coma Scale score, presence of mydriasis, neuromonitoring values (maximal intracranial pressure >30 mm Hg), and radiologic findings (Rotterdam score ≥4). CONCLUSIONS: This study in a large population confirms that children with severe TBI treated by decompressive craniectomy can achieve a good neurologic outcome. Further studies are needed to clarify the use of this surgery in the management of children with severe TBI.

Cerebrospinal fluid volume does not have etiological role in the incidence of positional skull deformities.

BACKGROUND: Positional skull deformities (PSD) are becoming a daily health concern for craniofacial surgeons. Several reports have indicated that cerebrospinal fluid (CSF) space increases on computed tomography (CT) scans of infants suffering from PSD, suggesting a potential causal link. Here, we describe a semi-automatic method to estimate total brain and CSF volumes quantitatively. We tested the potential correlation between total CSF volume and the occurrence of PSD. METHODS: A single-center retrospective study was carried out using 79 CT scans of PSD and 60 CT scans of control subjects. The endocranium was segmented automatically using a three-dimensional deformable surface model, and the brain was segmented using a semi-automatic threshold-based method. Total CSF volume was estimated based on the difference between endocranial and brain volumes. RESULTS: Automatic segmentation of the endocranium was possible in 75 CT scans. Semi-automatic brain and CSF volume evaluations were performed in 40 CT scans of infants with PSD (18 = occipital plagiocephaly, 11 = fronto-occipital plagiocephaly, and 11 = posterior brachycephaly) and in six control CT scans. Endocranial and total CSF volumes were not significantly different between patients with PSD and controls. The occipital plagiocephaly group had an enlarged brain volume compared with that in patients in the other groups. CONCLUSIONS: Total CSF volume did not change in infants with PSD, and the results do not support a role for volume changes in CSF in the etiology of PSD. Macrocephaly in patients with occipital plagiocephaly may be a specific etiological factor compared with that in other PSDs.

Brain and skull base MRI findings in patients with Ollier-Maffucci disease: A series of 12 patient-cases.

OBJECTIVES: To estimate the prevalence rate of silent cranial and intracranial lesions in a series of Ollier-Maffucci patients. PATIENTS AND METHODS: Cerebral MRI was routinely performed in Ollier-Maffucci patients followed-up in our tertiary centers. Patients with previous history of skull base or intracranial tumors were excluded from the study. Clinical and radiological datas were retrospectively collected. The occurrence rate and nature of abnormal cerebral MRIs were determined. RESULTS: Twelve patients were included. A glioma-looking lesion was found in one patient (8%), while skull base lesions were evidenced in 3 others (25%). A regular MRI follow-up was recommended for each patient, with a time interval varying between 1year and 3years depending on the likelihood of tumoral evolutivity, as infered from the MRI findings. CONCLUSION: All in all, the high rate of intracranial and skull base lesions with a malignant potential warrants to include cerebral MRI in the routine follow-up of Ollier-Maffucci patients.

Intracerebral gene therapy in children with mucopolysaccharidosis type IIIB syndrome: an uncontrolled phase 1/2 clinical trial.

BACKGROUND: Mucopolysaccharidosis type IIIB syndrome (also known as Sanfilippo type B syndrome) is a lysosomal storage disease resulting in progressive deterioration of cognitive acquisition after age 2-4 years. No treatment is available for the neurological manifestations of the disease. We sought to assess the safety and efficacy of a novel intracerebral gene therapy. METHODS: Local regulatory authorities in France allowed inclusion of up to four children in this phase 1/2 study. Treatment was 16 intraparenchymal deposits (four in the cerebellum) of a recombinant adenoassociated viral vector serotype 2/5 (rAAV2/5) encoding human α-N-acetylglucosaminidase (NAGLU) plus immunosuppressive therapy. We assessed tolerance, neurocognitive progression, brain growth, NAGLU enzymatic activity in CSF, and specific anti-NAGLU immune response for 30 months after surgery. This trial is registered with EudraCT, number 2012-000856-33, and the International Standard Clinical Trial Registry, number ISRCTN19853672. FINDINGS: Of seven eligible children, the four youngest, from France (n=2), Italy (n=1), and Greece (n=1), aged 20, 26, 30, and 53 months, were included between February, 2012, and February, 2014. 125 adverse events were recorded, of which 117 were treatment emergent and included six classified as severe, but no suspected unexpected serious adverse drug reactions were seen. Vector genomes were detected in blood for 2 days after surgery. Compared with the natural history of mucopolysaccharidosis type III syndromes, neurocognitive progression was improved in all patients, with the youngest patient having function close to that in healthy children. Decrease in developmental quotient was -11·0 points in patient one, -23·0 in patient two, -29·0 in patient three, and -17·0 in patient four, compared with -37·7 in the natural history of the disease. NAGLU activity was detected in lumbar CSF and was 15-20% of that in unaffected children. Circulating T lymphocytes that proliferated and produced tumour necrosis factor α upon ex-vivo exposure to NAGLU antigens were detectable at 1-12 months and 3-12 months, respectively, but not at 30 months in three of four patients. INTERPRETATION: Intracerebral rAVV2/5 was well tolerated and induced sustained enzyme production in the brain. The initial specific anti-NAGLU immune response that later subsided suggested acquired immunological tolerance. The best results being obtained in the youngest patient implies a potential window of opportunity. Longer follow-up is needed to further assess safety outcomes and persistence of improved cognitive development. FUNDING: Association Française Contre les Myopathies, Vaincre les Maladies Lysosomales, Institut Pasteur, and UniQure.

Awake surgery for hemispheric low-grade gliomas: oncological, functional and methodological differences between pediatric and adult populations.

INTRODUCTION: Brain mapping through a direct cortical and subcortical electrical stimulation during an awake craniotomy has gained an increasing popularity as a powerful tool to prevent neurological deficit while increasing extent of resection of hemispheric diffuse low-grade gliomas in adults. However, few case reports or very limited series of awake surgery in children are currently available in the literature. METHODS: In this paper, we review the oncological and functional differences between pediatric and adult populations, and the methodological specificities that may limit the use of awake mapping in pediatric low-grade glioma surgery. RESULTS: This could be explained by the fact that pediatric low-grade gliomas have a different epidemiology and biologic behavior in comparison to adults, with pilocytic astrocytomas (WHO grade I glioma) as the most frequent histotype, and with WHO grade II gliomas less prone to anaplastic transformation than their adult counterparts. In addition, aside from the issue of poor collaboration of younger children under 10 years of age, some anatomical and functional peculiarities of children developing brain (cortical and subcortical myelination, maturation of neural networks and of specialized cortical areas) can influence direct electrical stimulation methodology and sensitivity, limiting its use in children. CONCLUSIONS: Therefore, even though awake procedure with cortical and axonal stimulation mapping can be adapted in a specific subgroup of children with a diffuse glioma from the age of 10 years, only few pediatric patients are nonetheless candidates for awake brain surgery.

Spinal lipoma of the filum terminale: review of 174 consecutive patients.

PURPOSE: Spinal lipoma of the filum terminale (LFT) is a congenital lumbosacral anomaly that can cause tethered cord syndrome. Purposes of this study are to clarify preoperative characteristics of LFT, to elucidate surgical effects, and to discuss the rationale of prophylactic surgery for LFT. METHODS: Medical data of 174 children (2008-2014) who underwent section of LFT were prospectively recorded for prevalence of symptoms, skin stigmas, and associated malformations, motivator of diagnosis, conus level, and surgical outcome. Mean age at surgery was 4.1 ± 4.2 years (37 days to 17.7 years). RESULTS: Ninety-four children (54.0 %) had skin stigmas and 60 (34.5 %) had certain perineal malformations. Seventy-nine children (45.4 %) were symptomatic. The most common motivator for diagnosis was skin stigmas (44.3 %), followed by associated malformations (33.3 %), and symptoms (20.1 %). The age at surgery was significantly older in symptomatic patients than in asymptomatic patients (p < 0.001). Surgery improved symptoms in 50 % of patients at 2.1-year follow-up period. Of 85 asymptomatic patients, all except one remained asymptomatic postoperatively and none of the symptomatic patients deteriorated. The presence of associated malformations and the conus level did not affect surgical outcome. Postoperative complications developed in nine patients (5.2 %): seven transient local problems, one definitive urological deterioration, and one transient respiratory problem. CONCLUSIONS: Surgery for LFT was a simple and safe procedure. It improved half of symptomatic patients and stopped the deterioration of the others. Even if only one of the asymptomatic patients deteriorated at maximum follow-up, the role of prophylactic surgery remains a point of discussion.

Suprasellar Arachnoid Cysts: Toward a New Simple Classification Based on Prognosis and Treatment Modality.

BACKGROUND: Suprasellar arachnoid cysts (SAC) represent between 9% and 21% of pediatric arachnoid cysts. Recent improvements in magnetic resonance imaging, as well as increasing prenatal diagnosis, have allowed more precise knowledge and follow-up. OBJECTIVE: To describe a novel classification of SAC. METHODS: We present 35 cases of SAC treated between 1996 and 2014. Patient records and imaging studies were reviewed retrospectively to assess symptomatology, radiological findings, treatment, and long-term follow-up. RESULTS: Fourteen SAC were diagnosed prenatally (39%). We observed 15 (43%) cases presenting hydrocephalus (SAC-1) removing Liliequist membrane downward. Lower forms (SAC-2) with free third ventricle were observed in 11 (31%) cases. Asymmetrical forms (SAC-3) with Sylvian or temporal extension were seen in the 9 (26%) remaining patients. Twenty-three (66%) patients were treated by ventriculocisternostomy, 3 (8.5%) by shunt surgery, and 3 (8.5%) by craniotomy. Six (17%) patients had no surgery, including 5 cases (14%) that had prenatal diagnosis. Outcomes were initially favorable in 26 cases (87%). Eight (22%) patients had endocrine abnormalities at the end of the follow-up, 3 (8.5%) had developmental delay, and 6 (17%) had minor neuropsychological disturbances. CONCLUSION: SAC are heterogeneous entities. SAC-1 may come from an expansion of the diencephalic leaf of the Liliequist membrane. SAC-2 show a dilatation of the interpeduncular cistern and correspond to a defect of the mesencephalic leaf of the Liliequist membrane. SAC-3 correspond to the asymmetrical forms expanding to other subarachnoid spaces. Surgical treatment is not always necessary. The recognition of the different subtypes will allow choosing the best treatment option.

Biopsy in a series of 130 pediatric diffuse intrinsic Pontine gliomas.

PURPOSE: Diffuse intrinsic pontine glioma (DIPG) is the most severe pediatric solid tumor, with no significant improvement in the past 50 years. Possible reasons for failure to make therapeutic progress include poor understanding of the underlying molecular biology due to lack of tumor material. METHODS: We performed a prospective analysis of children with typical appearance of DIPG who had a stereotactic biopsy in our unit since 2002. Technical approach, complications, histopathological results, and samples processing are exposed. The literature on this subject is discussed. RESULTS: Reviewing our own 130 cases of DIPG biopsies and previous published data, these procedures appear to have a diagnostic yield and morbidity rates similar to those reported for other brain locations (3.9 % of transient morbidity in our series). In addition, the quality and the quantity of the material obtained allow to (1) confirm the diagnosis, (2) reveal that WHO grading was useless to predict outcome, and (3) perform an extended molecular screen, including biomarkers study and the development of preclinical models. Recent studies reveal that DIPG may comprise more than one biological entity and a unique oncogenesis involving mutations never described in other types of cancers, i.e., histones H3 K27M and activin receptor ACVR1. CONCLUSION: Stereotactic biopsies of DIPG can be considered as a safe procedure in well-trained neurosurgical teams and could be incorporated in protocols. It is a unique opportunity to integrate DIPG biopsies in clinical practice and use the biology at diagnosis to drive the introduction of innovative targeted therapies, in combination with radiotherapy.

Intracerebral Gene Therapy Using AAVrh.10-hARSA Recombinant Vector to Treat Patients with Early-Onset Forms of Metachromatic Leukodystrophy: Preclinical Feasibility and Safety Assessments in Nonhuman Primates.

No treatment is available for early-onset forms of metachromatic leukodystrophy (MLD), a lysosomal storage disease caused by autosomal recessive defect in arylsulfatase A (ARSA) gene causing severe demyelination in central and peripheral nervous systems. We have developed a gene therapy approach, based on intracerebral administration of AAVrh.10-hARSA vector, coding for human ARSA enzyme. We have previously demonstrated potency of this approach in MLD mice lacking ARSA expression. We describe herein the preclinical efficacy, safety, and biodistribution profile of intracerebral administration of AAVrh.10-hARSA to nonhuman primates (NHPs). NHPs received either the dose planned for patients adjusted to the brain volume ratio between child and NHP (1×dose, 1.1×10(11) vg/hemisphere, unilateral or bilateral injection) or 5-fold this dose (5×dose, 5.5×10(11) vg/hemisphere, bilateral injection). NHPs were subjected to clinical, biological, and brain imaging observations and were euthanized 7 or 90 days after injection. There was no toxicity based on clinical and biological parameters, nor treatment-related histological findings in peripheral organs. A neuroinflammatory process correlating with brain MRI T2 hypersignals was observed in the brain 90 days after administration of the 5×dose, but was absent or minimal after administration of the 1×dose. Antibody response to AAVrh.10 and hARSA was detected, without correlation with brain lesions. After injection of the 1×dose, AAVrh.10-hARSA vector was detected in a large part of the injected hemisphere, while ARSA activity exceeded the normal endogenous activity level by 14-31%. Consistently with other reports, vector genome was detected in off-target organs such as liver, spleen, lymph nodes, or blood, but not in gonads. Importantly, AAVrh.10-hARSA vector was no longer detectable in urine at day 7. Our data demonstrate requisite safe and effective profile for intracerebral AAVrh.10-hARSA delivery in NHPs, supporting its clinical use in children affected with MLD.