Lack of SMARCB1 expression characterizes a subset of human and murine peripheral T-cell lymphomas.

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a heterogeneous group of malignancies with poor outcome. Here, we identify a subgroup, PTCL-NOSSMARCB1-, which is characterized by the lack of the SMARCB1 protein and occurs more frequently in young patients. Human and murine PTCL-NOSSMARCB1- show similar DNA methylation profiles, with hypermethylation of T-cell-related genes and hypomethylation of genes involved in myeloid development. Single-cell analyses of human and murine tumors revealed a rich and complex network of interactions between tumor cells and an immunosuppressive and exhausted tumor microenvironment (TME). In a drug screen, we identified histone deacetylase inhibitors (HDACi) as a class of drugs effective against PTCL-NOSSmarcb1-. In vivo treatment of mouse tumors with SAHA, a pan-HDACi, triggered remodeling of the TME, promoting replenishment of lymphoid compartments and reversal of the exhaustion phenotype. These results provide a rationale for further exploration of HDACi combination therapies targeting PTCL-NOSSMARCB1- within the TME.

Constitutional mosaicism of pathogenic variants in SMARCB1 in a subset of patients with sporadic rhabdoid tumors.

BACKGROUND: Malignant rhabdoid tumors are aggressive malignancies predominantly affecting very young children. The characteristic genetic alteration is biallelic inactivation of SMARCB1. In approximately 30% of patients one SMARCB1 allele is constitutionally altered conferring a particularly unfavourable prognosis. Constitutional mosaicism for pathogenic SMARCB1 mutations has recently been reported in distinct cases of allegedly sporadic rhabdoid tumors. We aimed to systematically investigate the frequency and clinical impact of constitutional mosaicism in patients with sporadic rhabdoid tumors included in the EU-RHAB registry. METHODS: We selected 29 patients with rhabdoid tumors displaying at least one pathogenic small variant in SMARCB1 in the tumor DNA and absence of a germline mutation. We re-screened blood-derived patient and control DNA for the respective small variant by PCR with unique molecular identifiers and ultra-deep next generation sequencing. Clinical data in patients with and without mosaicism and 174 EU-RHAB controls were compared. RESULTS: Employing an ultra-deep sequencing approach, we detected tumor-associated SMARCB1 variants in blood-derived DNA in 9/29 patients. In 6/29 patients (21%), whose variant allele frequency (VAF) exceeded 2%, constitutional mosaicism was assumed whereas tumor DNA contamination was documented in 1/3 patients with VAF below 1%. No significant differences were observed between 6 mosaic-positive and 20 -negative patients regarding age at diagnosis, presence of metastases, event-free or overall survival. CONCLUSION: Constitutional mosaicism for pathogenic small SMARCB1 variants is recurrent in patients with allegedly sporadic rhabdoid tumors. The clinical implications of such variants need to be determined in larger, prospective cohorts also including detection of structural variants of SMARCB1.

Natural and cryptic peptides dominate the immunopeptidome of atypical teratoid rhabdoid tumors.

BACKGROUND: Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive CNS tumors of infancy and early childhood. Hallmark is the surprisingly simple genome with inactivating mutations or deletions in the SMARCB1 gene as the oncogenic driver. Nevertheless, AT/RTs are infiltrated by immune cells and even clonally expanded T cells. However, it is unclear which epitopes T cells might recognize on AT/RT cells. METHODS: Here, we report a comprehensive mass spectrometry (MS)-based analysis of naturally presented human leukocyte antigen (HLA) class I and class II ligands on 23 AT/RTs. MS data were validated by matching with a human proteome dataset and exclusion of peptides that are part of the human benignome. Cryptic peptide ligands were identified using Peptide-PRISM. RESULTS: Comparative HLA ligandome analysis of the HLA ligandome revealed 55 class I and 139 class II tumor-exclusive peptides. No peptide originated from the SMARCB1 region. In addition, 61 HLA class I tumor-exclusive peptide sequences derived from non-canonically translated proteins. Combination of peptides from natural and cryptic class I and class II origin gave optimal representation of tumor cell compartments. Substantial overlap existed with the cryptic immunopeptidome of glioblastomas, but no concordance was found with extracranial tumors. More than 80% of AT/RT exclusive peptides were able to successfully prime CD8+ T cells, whereas naturally occurring memory responses in AT/RT patients could only be detected for class II epitopes. Interestingly, >50% of AT/RT exclusive class II ligands were also recognized by T cells from glioblastoma patients but not from healthy donors. CONCLUSIONS: These findings highlight that AT/RTs, potentially paradigmatic for other pediatric tumors with a low mutational load, present a variety of highly immunogenic HLA class I and class II peptides from canonical as well as non-canonical protein sources. Inclusion of such cryptic peptides into therapeutic vaccines would enable an optimized mapping of the tumor cell surface, thereby reducing the likelihood of immune evasion.

Genotypes of European and Iranian patients with type 3 von Willebrand disease enrolled in 3WINTERS-IPS.

Type 3 von Willebrand disease (VWD3) is a rare and severe bleeding disorder characterized by often undetectable von Willebrand factor (VWF) plasma levels, a recessive inheritance pattern, and heterogeneous genotype. The objective of this study was to identify the VWF defects in 265 European and Iranian patients with VWD3 enrolled in 3WINTERS-IPS (Type 3 Von Willebrand International Registries Inhibitor Prospective Study). All analyses were performed in centralized laboratories. The VWF genotype was studied in 231 patients with available DNA (121 [115 families] from Europe [EU], and 110 [91 families] from Iran [IR]). Among 206 unrelated patients, 134 were homozygous (EU/IR = 57/77) and 50 were compound heterozygous (EU/IR = 43/7) for VWF variants. In 22 patients, no or only one variant was found. A total of 154 different VWF variants (EU/IR = 101/58 [5 shared]) were identified among the 379 affected alleles (EU/IR = 210/169), of which 48 (EU/IR = 18/30) were novel. The variants p.Arg1659*, p.Arg1853*, p.Arg2535*, p.Cys275Ser, and delEx1_Ex5 were found in both European and Iranian VWD3 patients. Sixty variants were identified only in a single allele (EU/IR = 50/10), whereas 18 were recurrent (≥3 patients) within 144 affected alleles. Nine large deletions and one large insertion were found. Although most variants predicted null alleles, 21% of patients carried at least 1 missense variant. VWD3 genotype was more heterogeneous in the European population than in the Iranian population, with nearly twice as many different variants. A higher number of novel variants were found in the Iranian VWD3 patients.

Genetic and Clinical Predictors of Left Atrial Thrombus: A Single Center Case-Control Study.

Left atrial (LA) thrombus formation is the presumed origin of thromboembolic complications in patients with atrial fibrillation (AF). Beyond clinical risk factors, the factors causing formation of LA thrombi are not well known. In this case-control study, we analyzed clinical characteristics and genetic thrombophilia markers (factor V Leiden (FVL), prothrombin G20210A (FIIV), Tyr2561 variant of von Willebrand factor (VWF-V)) in 42 patients with AF and LA thrombus (LAT) and in 68 control patients with AF without LAT (CTR). Patients with LAT had more clinical conditions predisposing to stroke (mean CHA2DS2-VASc-score 3.4 ± 1.5 vs. 1.9 ± 1.4; P < 0.001), a higher LA volume (96 ± 32 vs. 76 ± 21 ml, P = 0.002) and lower LA appendage emptying velocity (0.21 ± 0.11vs. 0.43 ± 0.19 m/s, P < 0.001). Prevalence of FVL, FIIV and VWF-V mutations was not different, but in the subgroup of patients <65 years (y) there was a tendency for a higher incidence of VWF-V with a prevalence of 27% (LAT <65 y) vs. 7% (CTR <65 y, P = 0.066). These findings warrant further investigation of the VWF-V as a risk factor for LA thrombogenesis in younger patients.

Inhibition of nuclear export restores nuclear localization and residual tumor suppressor function of truncated SMARCB1/INI1 protein in a molecular subset of atypical teratoid/rhabdoid tumors.

Loss of nuclear SMARCB1 (INI1/hSNF5/BAF47) protein expression due to biallelic mutations of the SMARCB1 tumor suppressor gene is a hallmark of atypical teratoid/rhabdoid tumors (ATRT), but the presence of cytoplasmic SMARCB1 protein in these tumors has not yet been described. In a series of 102 primary ATRT, distinct cytoplasmic SMARCB1 staining on immunohistochemistry was encountered in 19 cases (19%) and was highly over-represented in cases showing pathogenic sequence variants leading to truncation or mutation of the C-terminal part of SMARCB1 (15/19 vs. 4/83; Chi-square: 56.04, p = 1.0E-10) and, related to this, in tumors of the molecular subgroup ATRT-TYR (16/36 vs. 3/66; Chi-square: 24.47, p = 7.6E-7). Previous reports have indicated that while SMARCB1 lacks a bona fide nuclear localization signal, it harbors a masked nuclear export signal (NES) and that truncation of the C-terminal region results in unmasking of this NES leading to cytoplasmic localization. To determine if cytoplasmic localization found in ATRT is due to unmasking of NES, we generated GFP fusions of one of the SMARCB1 truncating mutations (p.Q318X) found in the tumors along with a p.L266A mutation, which was shown to disrupt the interaction of SMARCB1-NES with exportin-1. We found that while the GFP-SMARCB1(Q318X) mutant localized to the cytoplasm, the double mutant GFP-SMARCB1(Q318X;L266A) localized to the nucleus, confirming NES requirement for cytoplasmic localization. Furthermore, cytoplasmic SMARCB1(Q318X) was unable to cause senescence as determined by morphological observations and by senescence-associated ß-galactosidase assay, while nuclear SMARCB1(Q318X;L266A) mutant regained this function. Selinexor, a selective exportin-1 inhibitor, was effective in inhibiting the nuclear export of SMARCB1(Q318X) and caused rapid cell death in rhabdoid tumor cells. In conclusion, inhibition of nuclear export restores nuclear localization and residual tumor suppressor function of truncated SMARCB1. Therapies aimed at preventing nuclear export of mutant SMARCB1 protein may represent a promising targeted therapy in ATRT harboring truncating C-terminal SMARCB1 mutations.

Transposable element insertion as a mechanism of SMARCB1 inactivation in atypical teratoid/rhabdoid tumor.

Atypical teratoid/rhabdoid tumor (AT/RT) is a malignant brain tumor predominantly occurring in infants. Biallelic SMARCB1 mutations causing loss of nuclear SMARCB1/INI1 protein expression represent the characteristic genetic lesion. Pathogenic SMARCB1 mutations comprise single nucleotide variants, small insertions/deletions, large deletions, which may be also present in the germline (rhabdoid tumor predisposition syndrome 1), as well as somatic copy-number neutral loss of heterozygosity (LOH). In some SMARCB1-deficient AT/RT underlying biallelic mutations cannot be identified. Here we report the case of a 24-months-old girl diagnosed with a large brain tumor. The malignant rhabdoid tumor showed loss of nuclear SMARCB1/INI1 protein expression and the diagnosis of AT/RT was confirmed by DNA methylation profiling. While FISH, MLPA, Sanger sequencing and DNA methylation data-based imbalance analysis did not disclose alterations affecting SMARCB1, OncoScan array analysis revealed a 28.29 Mb sized region of copy-number neutral LOH on chromosome 22q involving the SMARCB1 locus. Targeted next-generation sequencing did also not detect a single nucleotide variant but instead revealed insertion of an AluY element into exon 2 of SMARCB1. Specific PCR-based Sanger sequencing verified the Alu insertion (SMARCB1 c.199_200 Alu ins) resulting in a frame-shift truncation not present in the patient's germline. In conclusion, transposable element insertion represents a hitherto not widely recognized mechanism of SMARCB1 disruption in AT/RT, which might not be detected by several widely applied conventional diagnostics assays. This finding has particular clinical implications, if rhabdoid predisposition syndrome 1 is suspected, but germline SMARCB1 alterations cannot be identified.

Atypical Teratoid/Rhabdoid Tumor (AT/RT) With Molecular Features of Pleomorphic Xanthoastrocytoma.

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant central nervous system tumor predominantly occurring in infants that may also arise in older children and adults. Rare secondary AT/RT developing from other tumors such as pleomorphic xanthoastrocytoma (PXA) are on record, but AT/RT presenting with molecular features of PXA have not been described. Here, we report 3 malignant central nervous system tumors in children (10, 13, and 18 y old). All tumors were located in the temporal lobe. In 2 cases, there was no history of a low-grade precursor lesion; in 1 case anaplastic PXA had been diagnosed 3 months earlier. Histopathologically, all tumors were composed of RT cells and showed frank signs of malignancy as well as loss of nuclear SMARCB1/INI1 protein expression. Two cases displayed homozygous deletions of the SMARCB1 region while the third case showed an exon 7 mutation (c.849_850delGT; p.Met283Ilefs*77). Of note, DNA methylation profiles did not group with AT/RT or other tumor entities using the Heidelberg Brain Tumor Classifier (version v11b4). By unsupervised t-distributed stochastic neighbor embedding analysis and hierarchical clustering analysis, however, all tumors clearly grouped with PXA. Genome-wide copy number analysis revealed homozygous CDNK2A/B deletions and gains of whole chromosome 7. BRAF V600E mutations could be demonstrated in all cases. In conclusion, the possibility of AT/RT with molecular features of PXA needs to be taken into account and warrants molecular characterization of AT/RT especially in older children. Since treatments targeting mutated BRAF are available, identification of such cases may also have therapeutic consequences.

Desmoplastic myxoid tumor, SMARCB1-mutant: clinical, histopathological and molecular characterization of a pineal region tumor encountered in adolescents and adults.

Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant brain tumor predominantly occurring in infants. Mutations of the SMARCB1 gene are the characteristic genetic lesion. SMARCB1-mutant tumors in adolescents and adults are rare and may show uncommon histopathological and clinical features. Here we report seven SMARCB1-deficient intracranial tumors sharing distinct clinical, histopathological and molecular features. Median age of the four females and three males was 40 years (range 15-61 years). All tumors were located in the pineal region. Histopathologically, these tumors displayed spindled and epithelioid cells embedded in a desmoplastic stroma alternating with a variable extent of a loose myxoid matrix. All cases showed loss of nuclear SMARCB1/INI1 protein expression, expression of EMA and CD34 was frequent and the Ki67/MIB1 proliferation index was low in the majority of cases (median 3%). Three cases displayed heterozygous SMARCB1 deletions and two cases a homozygous SMARCB1 deletion. On sequencing, one tumor showed a 2 bp deletion in exon 4 (c.369_370del) and one a short duplication in exon 3 (c.237_276dup) both resulting in frameshift mutations. Most DNA methylation profiles were not classifiable using the Heidelberg Brain Tumor Classifier (version v11b4). By unsupervised t-SNE analysis and hierarchical clustering analysis, however, all tumors grouped closely together and showed similarities with ATRT-MYC. After a median observation period of 48 months, three patients were alive with stable disease, whereas one patient experienced tumor progression and three patients had succumbed to disease. In conclusion, our series represents an entity with distinct clinical, histopathological and molecular features showing epigenetic similarities with ATRT-MYC. We propose the designation desmoplastic myxoid tumor (DMT), SMARCB1-mutant, for these tumors.

Germline variants in SMARCB1 and other members of the BAF chromatin-remodeling complex across human disease entities: a meta-analysis.

Germline variants that affect function are found in seven genes of the BAF chromatin-remodeling complex. They are linked to a broad range of diseases that, according to the gene affected, range from non-syndromic or syndromic neurodevelopmental disorders to low-grade tumors and malignancies. In the current meta-analysis, we evaluate genetic and clinical data from more than 400 families and 577 patients affected by BAF germline alterations. We focus on SMARCB1, including 43 unpublished patients from the EU-RHAB registry and our institution. For this gene, we further demonstrate whole gene as well as exon deletions and truncating variants to be associated with malignancy and early-onset disease. In contrast, non-truncating variants are associated with non-malignant disorders, such as Coffin-Siris syndrome or late-onset tumors like schwannoma or meningioma (p < 0.0001). SMARCB1 germline variants are distributed across the gene with variants in exons 1, 2, 8, and 9 being associated with low-grade entities, and single-nucleotide variants or indels outside of exon 9 that appear in patients with malignancies (p < 0.001). We attribute variants in specific BAF genes to certain disease entities. Finally, single-nucleotide variants and indels are sometimes detected in the healthy relatives of tumor patients, while Coffin-Siris syndrome and Nicolaides-Baraitser syndrome generally seem to appear de novo. Our findings add further information on the genotype-phenotype association of germline variants detected in genes of the BAF complex. Functional studies are urgently needed for a deeper understanding of BAF-related disorders and may take advantage from the comprehensive information gathered in this article.

Genetic and Functional Characterization of ADAMTS13 Variants in a Patient Cohort with Upshaw-Schulman Syndrome Investigated in Germany.

Upshaw-Schulman syndrome (USS) is caused by severe ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency due to homozygous or compound heterozygous mutations in the ADAMTS13 gene. Previous studies suggest three possible disease mechanisms: (1) reduced secretion of ADAMTS13 variants, (2) impaired proteolytic activity, (3) defective biosynthesis due to nonsense-mediated decay. Expression studies have failed to establish a clear genotype/phenotype correlation that could explain the significant variability in the age of onset and patients' clinical courses. In this study, we investigated ADAMTS13 sequence variations in 30 USS patients and identified 31 disease-causing mutations; among them 10 novel variants. While none of the recombinant proteins exhibited significant retention in the endoplasmic reticulum, secretion and activity analysis revealed defective release for all but one missense mutant. The latter exhibited normal secretion but impaired activity due to inactivation of the catalytic domain. Truncated mutants showed secretion and residual activity even though the patients suffered from a severe phenotype. The expression systems which we used may not be appropriate here, as they do not assess nonsense-mediated decay causing degradation of mRNA. In some patients, phenotypic severity could be explained by the combined effects of two mutations. Genetic screening in combination with in vitro characterization of ADAMTS13 variants from both alleles is a valuable tool to predict the phenotypic severity of USS. When necessary, supplementary methods, such as kinetics under flow conditions and mRNA processing assays, can be included. Such data are helpful to identify patients who are at high risk for severe attacks and therefore might benefit from prophylactic treatment.

Sellar Region Atypical Teratoid/Rhabdoid Tumors (ATRT) in Adults Display DNA Methylation Profiles of the ATRT-MYC Subgroup.

Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant brain tumor predominantly encountered in infants. Mutations of the SMARCB1 gene are the characteristic genetic lesion. A small group of ATRT stands out clinically, because these tumors are located in the sellar region of adults. To investigate if sellar region ATRT in adults represents a molecular distinct entity, we characterized molecular alterations in 7 sellar region ATRTs in adults as compared with 150 pediatric ATRTs and 47 pituitary adenomas using SMARCB1 sequencing, multiplex ligation-dependent probe amplification and fluorescence in situ hybridization as well as DNA methylation profiling. The median age of the 6 female and 1 male patients was 56 years. On histopathologic examination, all tumors were malignant rhabdoid tumors showing loss of SMARCB1/INI1 protein expression. Two cases displayed compound heterozygous SMARCB1 point mutations, 3 cases showed heterozygous SMARCB1 deletions with point mutations of the other allele and 1 case a homozygous SMARCB1 deletion; in 1 case, underlying SMARCB1 alterations could not be identified. On unsupervised hierarchical cluster analysis of DNA methylation profiles, sellar region ATRTs did not form a distinct group, but clustered with ATRT-MYC, 1 of 3 recently described molecular subgroups of ATRT. On analysis of DNA methylation array intensity data, only 1 sellar region ATRT showed characteristic features of pediatric ATRT-MYC, that is, major copy number losses affecting the SMARCB1 region. In conclusion, these results suggest that sellar region ATRTs in adults form a clinically distinct entity with a different mutational spectrum, but epigenetic similarities with pediatric ATRTs of the ATRT-MYC subgroup.

Cribriform neuroepithelial tumor: molecular characterization of a SMARCB1-deficient non-rhabdoid tumor with favorable long-term outcome.

Rhabdoid phenotype and loss of SMARCB1 expression in a brain tumor are characteristic features of atypical teratoid/rhabdoid tumors (ATRT). Rare non-rhabdoid brain tumors showing cribriform growth pattern and SMARCB1 loss have been designated cribriform neuroepithelial tumor (CRINET). Small case series suggest that CRINETs may have a relatively favorable prognosis. However, the long-term outcome is unclear and it remains uncertain whether CRINET represents a distinct entity or a variant of ATRT. Therefore, 10 CRINETs were clinically and molecularly characterized and compared with 10 ATRTs of each of three recently described molecular subgroups (i.e. ATRT-TYR, ATRT-SHH and ATRT-MYC) using Illumina Infinium HumanMethylation450 arrays, FISH, MLPA, and sequencing. Furthermore, outcome was compared to a larger cohort of 27 children with ATRT-TYR. Median age of the 6 boys and 4 girls harboring a CRINET was 20 months. On histopathological examination, all CRINETs demonstrated a cribriform growth pattern and distinct tyrosinase staining. On unsupervised cluster analysis of methylation data, all CRINETs examined exclusively clustered within the ATRT-TYR molecular subgroup. As ATRT-TYR, CRINETs mainly showed large heterozygous 22q deletions (9/10) and SMARCB1 mutations of the other allele. In two patients, SMARCB1 mutations were also present in the germline. Estimated mean overall survival in patients with CRINETs was 125 months (95% confidence interval 100-151 months) as compared to only 53 (33-74) months in patients with ATRTs of the ATRT-TYR subgroup (Log-Rank P < 0.05). In conclusion, CRINET represents a SMARCB1-deficient non-rhabdoid tumor, which shares molecular similarities with the ATRT-TYR subgroup but has distinct histopathological features and favorable long-term outcome.

Inherited Thrombotic Thrombocytopenic Purpura (Upshaw Schulman Syndrome) as Differential Diagnosis to Neonatal Septicaemia with Disseminated Intravascular Coagulation - a Case Series.

We report on 3 male neonates with hereditary ADAMTS13 deficiency (Upshaw Schulman syndrome, USS), the inherited form of thrombotic thrombocytopenic purpura (TTP). 2 presented shortly after birth with thrombocytopenia followed by microangiopathic Coombs-negative haemolytic anaemia. Both initially received antibiotic treatment for suspected infection-associated thrombocytopenia. In one patient's brother, the first bout of incipient TTP did not occur before 6 months of age, despite the same genetic defect. ADAMTS13 activity was<5%, compound heterozygous mutations were found in all patients. USS constitutes a differential diagnosis to thrombocytopenia caused by disseminated intravascular coagulation in neonatal septicaemia. Administration of fresh frozen plasma usually resolves acute bouts of the disease. In some cases of thrombocytopenia of unknown origin in infancy, the resolution of signs and symptoms after infusion of plasma may point towards the diagnosis.

Molecular Analysis of Hybrid Neurofibroma/Schwannoma Identifies Common Monosomy 22 and α-T-Catenin/CTNNA3 as a Novel Candidate Tumor Suppressor.

Neurofibromas and schwannomas are benign Schwann cell-derived peripheral nerve sheath tumors arising sporadically and within neurofibromatoses. Multiple tumors are a hallmark of neurofibromatosis type 1 (NF1) and type 2 (NF2) and schwannomatosis. Neurofibromas in NF1 and schwannomas in NF2 or schwannomatosis are defined by distinctive molecular hits. Among these, multiple hybrid neurofibromas/schwannomas may also appear, not yet being defined by a molecular background. We therefore performed molecular analysis of 22 hybrid neurofibromas/schwannomas using array comparative genomic hybridization, immunohistochemistry, quantitative RT-PCR, and functional analyses of cultured Schwann cells. Furthermore, we analyzed SMARCB1 by fluorescence in situ hybridization and multiplex ligation-dependent probe. Monosomy 22 was identified in 44% of tumors of tested patients with hybrid neurofibromas/schwannomas. In addition, in a single case, we detected focal deletion of the α-T-catenin/CTNNA3 gene (10q21.3). To further characterize this candidate, transient knockdown of α-T-catenin in Schwann cells was performed. CTNNA3 depleted cells showed cytoskeletal abnormalities and reduced E-cadherin expression, indicating epithelial-mesenchymal transition-like abnormalities. To conclude, we uncovered loss of chromosome 22 in almost half of all cases with hybrid neurofibromas/schwannomas of patients with multiple peripheral nerve sheath tumors. We tagged α-T-catenin/CTNNA3 as a novel candidate gene. Our functional investigations might indicate involvement of α-T-catenin/CTNNA3 in the biology of peripheral nerve sheath tumors.

Small cell undifferentiated (SCUD) hepatoblastomas: All malignant rhabdoid tumors?

Small cell undifferentiated (SCUD) hepatoblastoma is a rare variant of hepatoblastoma with poor outcome and loss of INI1 expression, sharing this with malignant rhabdoid tumors (MRT). We studied all tumors from the files of the Kiel Pediatric Tumor Registry (KTR) with the initial diagnosis of SCUD and MRT. After re-review, we performed immunistochemistry, fluorescence in situ hybridization, and multiplex ligation dependent probe amplification for loss of expression and deletion of INI1/SMARCB1 in 23 tumors. Morphologically, 12 of the tumors had a small cell morphology, 9 showed the typical picture of MRT, and 2 were composed of both small cells and rhabdoid cells. All but 1 of the 23 tumors showed loss of INI1 protein expression by immunohistochemistry. Nineteen of the INI1 negative tumors were analyzed by FISH technique and all showed a deletion of the INI1/SMARCB1 gene (17 homozygous deletions, 2 heterozygous deletions). We investigated 14 of these cases by multiplex ligation dependent probe amplification and verified the deletions in all cases. In conclusion, we postulate that SCUD hepatoblastoma is not a hepatoblastoma but represents a malignant rhabdoid tumor of the liver. © 2016 Wiley Periodicals, Inc.

Improved 6-year overall survival in AT/RT - results of the registry study Rhabdoid 2007.

Atypical teratoid rhabdoid tumors (AT/RT) are characterized by mutations and subsequent inactivation of SMARCB1 (INI1, hSNF5), a predilection for very young children and an unfavorable outcome. The European Registry for rhabdoid tumors (EU-RHAB) was established to generate a common European database and to establish a standardized treatment regimen as the basis for phase I/II trials. Thus, genetic analyses, neuropathologic and radiologic diagnoses, and a consensus treatment regimen were prospectively evaluated. From 2005 to 2009, 31 patients with AT/RT from four countries were recruited into the registry study Rhabdoid 2007 and treated with systemic and intraventricular chemotherapy. Eight patients received high-dose chemotherapy, 23 radiotherapy, and 17 maintenance therapy. Reference evaluations were performed in 64% (genetic analyses, FISH, MLPA, sequencing) up to 97% (neuropathology, INI1 stain). Germ-line mutations (GLM) were detected in 6/21 patients. Prolonged overall survival was associated with age above 3 years, radiotherapy and achievement of a complete remission. 6-year overall and event-free survival rates were 46% (±0.10) and 45% (±0.09), respectively. Serious adverse events and one treatment-related death due to insufficiency of a ventriculo peritoneal shunt (VP-shunt) and consecutive herniation were noted. Acquisition of standardized data including reference diagnosis and a standard treatment schedule improved data quality along with a survival benefit. Treatment was feasible with significant but manageable toxicity. Although our analysis is biased due to heterogeneous adherence to therapy, EU-RHAB provides the best available basis for phase I/II clinical trials.