Michael C. Frühwald

Driver mutations in histone H3.3 and chromatin remodelling genes in paediatric glioblastoma

Glioblastoma multiforme (GBM) is a lethal brain tumour in adults and children. However, DNA copy number and gene expression signatures indicate differences between adult and paediatric cases. To explore the genetic events underlying this distinction, we sequenced the exomes of 48 paediatric GBM samples. Somatic mutations in the H3.3-ATRX-DAXX chromatin remodelling pathway were identified in 44% of tumours (21/48). Recurrent mutations in H3F3A, which encodes the replication-independent histone 3 variant H3.3, were observed in 31% of tumours, and led to amino acid substitutions at two critical positions within the histone tail (K27M, G34R/G34V) involved in key regulatory post-translational modifications. Mutations in ATRX (α-thalassaemia/mental retardation syndrome X-linked) and DAXX (death-domain associated protein), encoding two subunits of a chromatin remodelling complex required for H3.3 incorporation at pericentric heterochromatin and telomeres, were identified in 31% of samples overall, and in 100% of tumours harbouring a G34R or G34V H3.3 mutation. Somatic TP53 mutations were identified in 54% of all cases, and in 86% of samples with H3F3A and/or ATRX mutations. Screening of a large cohort of gliomas of various grades and histologies (n = 784) showed H3F3A mutations to be specific to GBM and highly prevalent in children and young adults. Furthermore, the presence of H3F3A/ATRX-DAXX/TP53 mutations was strongly associated with alternative lengthening of telomeres and specific gene expression profiles. This is, to our knowledge, the first report to highlight recurrent mutations in a regulatory histone in humans, and our data suggest that defects of the chromatin architecture underlie paediatric and young adult GBM pathogenesis.

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.

Atypical Teratoid/Rhabdoid Tumors Are Comprised of Three Epigenetic Subgroups with Distinct Enhancer Landscapes

Atypical teratoid/rhabdoid tumor (ATRT) is one of the most common brain tumors in infants. Although the prognosis of ATRT patients is poor, some patients respond favorably to current treatments, suggesting molecular inter-tumor heterogeneity. To investigate this further, we genetically and epigenetically analyzed 192 ATRTs. Three distinct molecular subgroups of ATRTs, associated with differences in demographics, tumor location, and type of SMARCB1 alterations, were identified. Whole-genome DNA and RNA sequencing found no recurrent mutations in addition to SMARCB1 that would explain the differences between subgroups. Whole-genome bisulfite sequencing and H3K27Ac chromatin-immunoprecipitation sequencing of primary tumors, however, revealed clear differences, leading to the identification of subgroup-specific regulatory networks and potential therapeutic targets.

Important Aspects of Nutrition in Children with Cancer

Adequate nutrition during cancer plays a decisive role in several clinical outcome measures, such as treatment response, quality of life, and cost of care. However, the importance of nutrition in children and young adults with malignancies is still an underestimated topic within pediatric oncology. The importance of our work is to reinforce and indicate that malnutrition in children with cancer should not be accepted at any stage of the disease or tolerated as an inevitable process. Unique to our manuscript is the close collaboration, the exchange of knowledge and expertise between pediatric oncologists and a nutritional specialist, as well as the comprehension of the mechanisms during cancer cachexia and malnutrition. We provide a critical review of the current state of research and new knowledge related to nutritional management in childhood cancer.

High-resolution genomic analysis suggests the absence of recurrent genomic alterations other than SMARCB1 aberrations in atypical teratoid/rhabdoid tumors.

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignant pediatric brain tumor characterized by genetic alterations affecting the SMARCB1 (hSNF5/INI1) locus in chromosome band 22q11.2. To identify potential additional genetic alterations, high‐resolution genome‐wide analysis was performed using a molecular inversion probe single‐nucleotide polymorphism (MIP SNP) assay (Affymetrix OncoScan formalin‐fixed paraffin‐embedded express) on DNA isolated from 18 formalin‐fixed paraffin‐embedded archival samples. Alterations affecting the SMARCB1 locus could be demonstrated by MIP SNP in 15 out of 16 evaluable cases (94%). These comprised five tumors with homozygous deletions, six tumors with heterozygous deletions, and four tumors with copy number neutral loss of heterozygosity (LOH) involving chromosome band 22q11.2. Remarkably, MIB SNP analysis did not yield any further recurrent chromosomal gains, losses, or copy neutral LOH. On MIP SNP screening for somatic mutations, the presence of a SMARCB1 mutation (c.472C>T p.R158X) was confirmed, but no recurrent mutations of other cancer relevant genes could be identified. Results of fluorescence in situ hybridization, multiplex ligation‐dependent probe amplification, and SMARCB1 sequencing were highly congruent with that of the MIP SNP assay. In conclusion, these data further suggest the absence of recurrent genomic alterations other than SMARCB1 in AT/RT.

SMARCA4-mutated atypical teratoid/rhabdoid tumors are associated with inherited germline alterations and poor prognosis.

Martin Hasselblatt · Inga Nagel · Florian Oyen · Kerstin Bartelheim · Robert B. Russell · Ulrich Schuller · Reimar Junckerstorff · Marc Rosenblum · Ali H. Alassiri · Sabrina Rossi · Irene Schmid · Nicholas G. Gottardo · Helen Toledano · Elisabetta Viscardi · Milagros Balbin · Leora Witkowski · Qianhao Lu · Matthew J. Betts · William D. Foulkes · Reiner Siebert · Michael C. Fruhwald · Reinhard Schneppenheim

Health-related quality of life in children and adolescents with stroke, self-reports, and parent/proxies reports: cross-sectional investigation.

Limited data are available on health‐related quality of life (HR‐QoL) in pediatric stroke survivors. The aim of the present study was to assess HR‐QoL by self‐assessment and parent/proxy‐assessment in children and adolescents who survived a first stroke episode.

Poorly differentiated chordoma with SMARCB1/INI1 loss: a distinct molecular entity with dismal prognosis

Martin Hasselblatt1 · Christian Thomas1 · Volker Hovestadt2,3 · Daniel Schrimpf3,4,5 · Pascal Johann3,6,7 · Susanne Bens8 · Florian Oyen9 · Susanne Peetz‐Dienhart1 · Yvonne Crede1 · Annika Wefers3,4,5 · Hannes Vogel10 · Markus J. Riemenschneider11 · Manila Antonelli12,13 · Felice Giangaspero12,13 · Marie Christine Bernardo14 · Caterina Giannini15 · Nasir Ud Din16 · Arie Perry17 · Kathy Keyvani18 · Frank van Landeghem19 · David Sumerauer20 · Peter Hauser21 · David Capper3,4,5 · Andrey Korshunov3,4,5 · David T. W. Jones3,6 · Stefan M. Pfister3,6,7 · Reinhard Schneppenheim9 · Reiner Siebert8 · Michael C. Frühwald22 · Marcel Kool3,6

Favorable outcome of patients affected by rhabdoid tumors due to rhabdoid tumor predisposition syndrome (RTPS).

Rhabdoid tumor predisposition syndrome is usually associated with shorter survival in patients with malignant rhabdoid tumors regardless of anatomical origin. Here we present four children harboring truncating heterozygous SMARCB1/INI1 germline mutations with favorable outcome. All four patients received multi‐modality treatment, three according to therapeutic recommendations by the EU‐RHAB registry, two without radiotherapy, and mean event‐free survival accounts for 7 years. In conclusion, intensive treatment with curative intent is justified for children with rhabdoid tumors even if an underlying rhabdoid predisposition syndrome is demonstrated. Pediatr Blood Cancer 2014;61:919–921.

The histone deacetylase inhibitor SAHA acts in synergism with fenretinide and doxorubicin to control growth of rhabdoid tumor cells.

BackgroundRhabdoid tumors are highly aggressive malignancies affecting infants and very young children. In many instances these tumors are resistant to conventional type chemotherapy necessitating alternative approaches.MethodsProliferation assays (MTT), apoptosis (propidium iodide/annexin V) and cell cycle analysis (DAPI), RNA expression microarrays and western blots were used to identify synergism of the HDAC (histone deacetylase) inhibitor SAHA with fenretinide, tamoxifen and doxorubicin in rhabdoidtumor cell lines.ResultsHDAC1 and HDAC2 are overexpressed in primary rhabdoid tumors and rhabdoid tumor cell lines. Targeting HDACs in rhabdoid tumors induces cell cycle arrest and apoptosis. On the other hand HDAC inhibition induces deregulated gene programs (MYCC-, RB program and the stem cell program) in rhabdoid tumors. These programs are in general associated with cell cycle progression. Targeting these activated pro-proliferative genes by combined approaches of HDAC-inhibitors plus fenretinide, which inhibits cyclinD1, exhibit strong synergistic effects on induction of apoptosis. Furthermore, HDAC inhibition sensitizes rhabdoid tumor cell lines to cell death induced by chemotherapy.ConclusionOur data demonstrate that HDAC inhibitor treatment in combination with fenretinide or conventional chemotherapy is a promising tool for the treatment of chemoresistant rhabdoid tumors.