Christof M. Kramm

Hotspot Mutations in H3F3A and IDH1 Define Distinct Epigenetic and Biological Subgroups of Glioblastoma

Glioblastoma (GBM) is a brain tumor that carries a dismal prognosis and displays considerable heterogeneity. We have recently identified recurrent H3F3A mutations affecting two critical amino acids (K27 and G34) of histone H3.3 in one-third of pediatric GBM. Here, we show that each H3F3A mutation defines an epigenetic subgroup of GBM with a distinct global methylation pattern, and that they are mutually exclusive with IDH1 mutations, which characterize a third mutation-defined subgroup. Three further epigenetic subgroups were enriched for hallmark genetic events of adult GBM and/or established transcriptomic signatures. We also demonstrate that the two H3F3A mutations give rise to GBMs in separate anatomic compartments, with differential regulation of transcription factors OLIG1, OLIG2, and FOXG1, possibly reflecting different cellular origins.

Intensive chemotherapy improves survival in pediatric high‐grade glioma after gross total resection: results of the HIT‐GBM‐C protocol

The authors hypothesized that intensified chemotherapy in protocol HIT‐GBM‐C would increase survival of pediatric patients with high‐grade glioma (HGG) and diffuse intrinsic pontine glioma (DIPG).

H3F3A K27M mutation in pediatric CNS tumors: a marker for diffuse high-grade astrocytomas.

Brain tumors are one of the most common childhood malignancies. Diffuse high-grade gliomas represent approximately 10% of pediatric brain tumors. Exon sequencing has identified a mutation in K27M of the histone H3.3 gene (H3F3A K27M and G34R/V) in about 20% of pediatric glioblastomas, but it remains to be seen whether these mutations can be considered specific for pediatric diffuse high-grade astrocytomas or also occur in other pediatric brain tumors. We performed a pyrosequencing-based analysis for the identification of H3F3A codon 27 and codon 34 mutations in 338 pediatric brain tumors. The K27M mutation occurred in 35 of 129 glioblastomas (27.1%) and in 5 of 28 (17.9%) anaplastic astrocytomas. None of the other tumor entities showed H3F3A K27M mutation. Because H3F3A K27M mutations occur exclusively in pediatric diffuse high-grade astrocytomas, analysis of codon 27 mutational status could be useful in the differential diagnosis of these neoplasms.

Valproic acid was well tolerated in heavily pretreated pediatric patients with high-grade glioma

Valproic acid (VPA) inhibits histone deacetylase and has been reported to induce apoptosis in glioma. We report 44 heavily pretreated pediatric patients with high-grade glioma or diffuse intrinsic pontine glioma who received VPA as oral continues maintenance treatment with individual dose adaptation. The tumor status when starting the drug was: no measurable disease in 12, measurable but stable disease in 12, and measurable progressive disease in 22 patients. Average trough blood levels of VPA were 99xa0mg/l. The most frequent complaint was somnolence (three patients), but no severe toxicity was reported. One relapse patient responded, early progression of disease was observed in three frontline patients and in six relapsed patients. Median overall survival duration for all patients was 1.33xa0years, with large differences between first-line (5-year overall survival, 44%) and relapse therapy (5-year overall survival, 14%). This shows that valproate is safe in this patient population. The moderate tumor efficacy encourages studying the drug further as an element of multi-agent protocols.

Thalamic high-grade gliomas in children: a distinct clinical subset?

Pediatric high-grade gliomas (HGGs) of the thalamic region account for up to 13% of pediatric HGGs and usually result in only anecdotal long-term survival. Because very little is known about these tumors, we aimed to further characterize them. In our series of 99 pediatric thalamic HGGs, there were no significant differences in survival between patients with tumors affecting the thalamus alone (including bithalamic lesions) and patients with tumors affecting the thalamus plus adjacent structures. Tumor resection (event-free survival/overall survival) and an early treatment response to radiotherapy/chemotherapy (event-free survival) had independent prognostic significance, as shown by Kaplan-Meier and multivariate Cox regression analyses. When we compared clinical characteristics and outcomes of pediatric thalamic HGG with those of pediatric (nonthalamic) supratentorial (n = 177) as well as pediatric pontine HGG (including diffuse intrinsic pontine gliomas; n = 234), we found that thalamic HGG shared more similarities with pontine than with supratentorial HGG, but overall, it appeared to represent a clinically distinct subgroup of pediatric HGG. The varying extent of tumor resection in the different tumor localizations may play some role in the observed clinical differences, as shown by multivariate Cox regression analyses, but the tumor site itself was also identified as an independent prognostic parameter. Thus, an additional location-specific effect on survival and/or tumor biology, despite different neurosurgical accessibility, has to be considered. Therefore, future investigations should try to further characterize the obviously site-specific heterogeneity of pediatric HGG on a molecular genetic basis.

Leukapheresis and Exchange Transfusion in Children with Acute Leukemia and Hyperleukocytosis. A Single Center Experience

BACKGROUNDnThe risk of severe complications or death during the initial period of acute leukemia was markedly decreased due to the progress in pediatric oncology and use of simple measures like hyperhydration, forced diuresis, treatment of hyperuricemia, correction of electrolyte and coagulation disturbances and the careful use of antileukemic drugs. The incidence of leukostasis and tumor lysis syndrome depends on absolute initial white blood cell counts and the underlying type of leukemia. Leukapheresis or exchange transfusion may improve the prognosis of high risk patients.nnnMETHODSnRecords of all pediatric patients who were newly diagnosed with acute leukemia between 1 / 1998 und 12 / 2008 were retrospectively reviewed for presence of hyperleukocytosis(white blood cell count > 100 GPT / l) at diagnosis and subsequent leukapheresis or exchange transfusion in regards to the clinical outcome.nnnRESULTSnAt diagnosis 11 (14 % ) of 77 children with acute leukemia (7 acute lymphoblastic leukemia / ALL; 4 acute myeloblastic leukemia /AML) had hyperleukocytosis. 4 patients (2 ALL, 2 AML) received exchange transfusion and 2 others (1 ALL, 1 AML) underwent leukapheresis. Marked cytoreduction was achieved in all patients within 24 h after therapy initiation. There were no procedure-related adverse events. Symptoms due to hyperleukocytosis markedly improved after cytoreduction.nnnCONCLUSIONnLeukapheresis or exchange transfusion together with conservative management and specific oncological therapy may contribute to rapid leukocyte reduction with acceptable risk. The exact impact of leukapheresis or exchange transfusion on short and long term outcome in pediatric patients with acute leukemia and initial hyperleukocytosis has to be evaluated in future multicentre studies or by the formation of clinical registries.

Anaplastic ganglioglioma in children

Purpose Anaplastic gangliogliomas (AGG) are gangliogliomas with areas of pronounced hypercellularity, vascular proliferation, necrosis, and many mitotic figures. As very few pediatric patients have been studied, we analyzed the cases registered in the HIT-GBM database. Patients and Methods Patient data were obtained from the German HIT-GBM database. Inclusion criteria were diagnosis of AGG proven by a central neuropathological review and patient age 0 to 17xa0years. Eight patients (five male and three female) were identified. Results Patients’ median age was 10xa0years. The median history of disease was 9xa0months (range, 1.0–43.0xa0months). Initial symptoms included signs of raised intracranial pressure, seizures, and, in the case of spinal cord tumor, bladder dysfunction. In five cases, AGGs were localized supratentorially with three patients having multiple lobes involved. The tumors affected the frontal (nxa0=xa03 cases), parietal (nxa0=xa02), temporal (nxa0=xa02), and occipital lobes (nxa0=xa01), as well as the brainstem (nxa0=xa01) and the spinal cord (nxa0=xa02). Gross total tumor resection was achieved in six patients. The estimated 5-year overall survival ratexa0±xa0standard error was 88xa0±xa012%, and the event-free survival rate was 63xa0±xa017%. While gender and tumor location did not affect survival rates, gross total tumor resection provided a better overall survival than non-total resection. Conclusion The prognosis of pediatric patients with AGG is good, especially for those who undergo gross total tumor resection.

Pediatric high grade glioma of the spinal cord: results of the HIT-GBM database

Little is known about pediatric spinal cord high grade gliomas (SCHGG) beyond their dismal prognosis. Here, we analyzed the HIT-GBM® database for the influence of surgical resection on survival. Between 1991 and 2010 the HIT-GBM group collected data from European children diagnosed with high grade glioma. Patients with the following inclusion criteria were analyzed in this study: astrocytic histology, WHO grade III or IV, age at diagnosis <18xa0years, and tumor localized to the spinal cord. 28 patients (mean age 11.28xa0years, 14 male) with primary SCHGG were identified. The tumor sizes were measured by the span across adjacent vertebrae and varied greatly (range: 1–20, median: 4). Histology was classified as WHO grade III in 15 and grade IV in 13 tumors. Of note, the four largest tumors identified were WHO grade III. Surgery was classified as complete resection (nxa0=xa06), subtotal resection (STR) (nxa0=xa07), partial resection (nxa0=xa012) or biopsy only (nxa0=xa03). 27 patients received chemotherapy, 22 of which also received radiation. With the mean follow-up time of 2.88 (SDxa0±xa02.95) years, 14 patients were still alive resulting in a median overall survival of 2.5xa0years (SExa0±xa01.6). The positive prognostic indicators for overall survival were: age younger than 5xa0years (Pxa0=xa00.047), WHO grade III (Pxa0=xa00.046), absence of necrosis (Pxa0=xa00.025) and gross total resection (GTR) (Pxa0=xa00.012). The prognosis of SCHGG might not be as miserable as generally assumed. GTR is of benefit. Larger data sets and meta-analysis are necessary to identify patient sub-groups.

H3-/IDH-wild type pediatric glioblastoma is comprised of molecularly and prognostically distinct subtypes with associated oncogenic drivers

Pediatric glioblastoma (pedGBM) is an extremely aggressive pediatric brain tumor, accounting forxa0~6% of all central nervous system neoplasms in children. Approximately half of pedGBM harbor recurrent somatic mutations in histone 3 variants or, infrequently, IDH1/2. The remaining subset of pedGBM is highly heterogeneous, and displays a variety of genomic and epigenetic features. In the current study, we aimed to further stratify an H3-/IDH-wild type (wt) pedGBM cohort assessed through genome-wide molecular profiling. As a result, we identified three molecular subtypes of these tumors, differing in their genomic and epigenetic signatures as well as in their clinical behavior. We designated these subtypes ‘pedGBM_MYCN’ (enriched for MYCN amplification), ‘pedGBM_RTK1’ (enriched for PDGFRA amplification) and ‘pedGBM_RTK2’ (enriched for EGFR amplification). These molecular subtypes were associated with significantly different outcomes, i.e. pedGBM_RTK2 tumors show a significantly longer survival time (median OS 44xa0months), pedGBM_MYCN display extremely poor outcomes (median OS 14xa0months), and pedGBM_RTK1 tumors harbor an intermediate prognosis. In addition, the various molecular subtypes of H3-/IDH-wt pedGBM were clearly distinguishable from their adult counterparts, underlining their biological distinctiveness. In conclusion, our study demonstrates significant molecular heterogeneity of H3-/IDH-wt pedGBM in terms of DNA methylation and cytogenetic alterations. The recognition of three molecular subtypes of H3-/IDH-wt pedGBM further revealed close correlations with biological parameters and clinical outcomes and may therefore, be predictive of response to standard treatment protocols, but could also be useful for stratification for novel, molecularly based therapies.

Clinical and epidemiological characteristics of pediatric gliosarcomas

Gliosarcoma (GS) is a glioblastoma with a sarcomatous component that is presumed to be a metaplastic differentiation of glioma cells. We studied the clinical relevance of this histological glioblastoma subentity within the pediatric population. We obtained patient data from the German HIT-GBM database, which contains clinical data for more than 600 pediatric patients with centrally reviewed high-grade gliomas. By applying defined inclusion criteria (diagnosis of GS proven by central neuropathological review; patient age 0 to 21xa0years), four patients were identified. In addition, after a review of the English medical scientific literature, 19 additional cases were found. The relative frequency of GS in the German HIT-GBM database was only 1.9%. In the whole series of 23 pediatric GS patients, including previously reported cases, the male-to-female-ratio was 1.2:1. GS was found in all pediatric age groups with a median age of 11xa0years, but there was an unexpectedly high accumulation in infants (6 of 23xa0<3xa0years of age, 26%). GS showed a strong predilection of the cerebral hemispheres (22 out of 23 cases). Increased intracranial pressure was the leading symptom of a short clinical history with a median duration of 0.7xa0month. Interestingly, six patients (26%) were reported with a history of cranial radiotherapy prior to GS diagnosis. In 60% of the GS patients in our series, gross total resection was achieved. Median overall (OS) and event-free survivals (EFS) of the total cohort were 12.1 and 9.8xa0months, respectively. In conclusion, GS is a very rare tumor entity in children. Literature review suggests a relatively higher incidence in infants and in patients with a previous history of radiotherapy.