First-line high-dose therapy and autologous blood stem cell transplantation in patients with primary central nervous system non-Hodgkin lymphomas-a single-centre experience in 61 patients.

Primary central nervous system non-Hodgkin lymphomas (PCNS-NHLs) are extranodal B-cell lymphomas with poor prognosis. The role of high-dose therapy (HDT) followed by autologous blood stem cell transplantation (ASCT) as first-line therapy is still not clear. We retrospectively collected long-term follow up data of 61 consecutive patients with PCNS-NHL at the University Hospital Düsseldorf from January 2004 to December 2016. Thirty-six patients were treated with conventional chemoimmunotherapy (cCIT) only (CT-group). Seventeen patients received an induction cCIT followed by HDT and ASCT. In the CT-group, the overall response rate (ORR) was 61% (CR 47%, PR 14%), and there were 8% treatment-related deaths (TRD). Progression-free survival (PFS) was 31.8 months, and overall survival (OS) was 57.3 months. In the HDT-group, the ORR was 88% (59% CR, 29% PR), and there were 6% TRD. Median PFS and OS were not reached at 5 years. The 5-year PFS and OS were 64.7%. After a median follow up of 71 months, 10 patients (59%) were still alive in CR/PR following HDT and ASCT, one patient was treated for progressive disease (PD), and 7 had died (41%, 6 PD, 1 TRD). All patients achieving CR prior to HDT achieved durable CR. In the CT-group, 8 patients (22%) were alive in CR/PR after a median follow-up of 100 months. Twenty-eight patients died (78%, 24 PD, 2 TRD, 2 deaths in remission). In the univariate analysis, the HDT-group patients had significantly better PFS (not reached vs 31.8 months, p = 0.004) and OS (not reached vs 57.3 months, p = 0.021). The multivariate analysis showed HDT was not predictive for survival. Treatment with HDT + ASCT is feasible and offers the chance for long-term survival with low treatment-related mortality in younger patients. In this analysis, ORR, PFS and OS were better with HDT than with conventional cCIT alone. This result was not confirmed in the multivariate analysis, and further studies need to be done to examine the role of HDT in PCNSL.

Targeted next-generation sequencing of adult gliomas for retrospective prognostic evaluation and up-front diagnostics.

AIMS: We aimed to reclassify a population-based cohort of 529 adult glioma patients to evaluate the prognostic impact of the 2016 World Health Organization (WHO) central nervous system tumour classification. Moreover, we evaluated the feasibility of gene panel next-generation sequencing (NGS) in daily diagnostics of 225 prospective glioma patients. METHODS: The retrospective cohort was reclassified according to WHO 2016 criteria by immunohistochemistry for IDH-R132H, fluorescence in situ hybridization for 1p/19q-codeletion and gene panel NGS. All tumours of the prospective cohort were subjected to NGS analysis up-front. RESULTS: The entire population-based cohort was successfully reclassified according to WHO 2016 criteria. NGS results were obtained for 98% of the prospective patients. Survival analyses in the population-based cohort confirmed three major prognostic subgroups, that is, isocitrate dehydrogenase (IDH)-mutant and 1p/19q-codeleted oligodendrogliomas, IDH-mutant astrocytomas and IDH-wildtype glioblastomas. The distinction between WHO grade II and III was prognostic in patients with IDH-mutant astrocytoma. The survival of patients with IDH-wildtype diffuse astrocytomas carrying TERT promoter mutation and/or EGFR amplification overlapped with the poor survival of IDH-wildtype glioblastoma patients. CONCLUSIONS: Gene panel NGS proved feasible in daily diagnostics. In addition, our study confirms the prognostic role of glioma classification according to WHO 2016 in a large population-based cohort. Molecular features of glioblastoma in IDH-wildtype diffuse glioma were linked to poor survival corresponding to IDH-wildtype glioblastoma patients. The distinction between WHO grade II and III retained prognostic significance in patients with IDH-mutant diffuse astrocytic gliomas.

MiR-16-5p is frequently down-regulated in astrocytic gliomas and modulates glioma cell proliferation, apoptosis and response to cytotoxic therapy.

AIMS: Aberrant expression of microRNAs (miRNAs) is frequent in various cancers including gliomas. We aimed to characterize the role of miR-16-5p as a candidate tumour suppressor miRNA in gliomas. METHODS: Real-time PCR-based approaches were used for miRNA and mRNA expression profiling of glioma and non-neoplastic brain tissues as well as glioma cell lines. Protein levels were determined by Western blotting. In vitro analyses were performed following overexpression of miR-16-5p, trichostatin A (TSA) treatment, and siRNA-mediated knock-down of HDAC3 in glioma cells. Effects of miR-16-5p on glioma cell viability, apoptosis and response to irradiation and temozolomide (TMZ) were assessed. RESULTS: Expression of miR-16-5p was reduced relative to control brain tissue in isocitrate dehydrogenase (IDH)-mutant astrocytomas of World Health Organization (WHO) grades II, III and IV, and a subset of IDH-wildtype glioblastomas WHO grade IV. MiR-16-5p expression was lower in IDH-mutant than in IDH-wildtype gliomas, and down-regulated in IDH-wildtype glioma lines. MiR-16-5p overexpression reduced expression of important cell cycle and apoptosis regulators in glioma cells, including CDK6, CDC25A, CCND3, CCNE1, WEE1, CHEK1, BCL2 and MCL1. In line, CDK6, WEE1, CHEK1, BCL2 and MCL1 transcript levels were increased in WHO grade III or IV gliomas. TSA treatment and HDAC3 knockdown in glioma cells induced miR-16-5p up-regulation and reduced expression of its targets. Moreover, miR-16-5p overexpression inhibited proliferation and induced apoptosis in various glioma cell lines and increased sensitivity of A172 glioma cells to irradiation and TMZ. CONCLUSION: Reduced expression of miR-16-5p contributes to glioma cell proliferation, survival and resistance to cytotoxic therapy.

[Integrated diagnostics of diffuse astrocytic and oligodendroglial tumors. German version]. / Integrierte Diagnostik der diffusen astrozytären und oligodendroglialen Gliome.

BACKGROUND: Diffuse astrocytic and oligodendroglial gliomas are the most common neuroepithelial tumors. Their classification is based on the integration of histological and molecular findings according to the classification of tumors of the central nervous system published by the World Health Organization (WHO) in 2016. OBJECTIVES: This review describes the different entities and variants of diffuse gliomas and summarizes the current diagnostic criteria for these tumors. MATERIALS AND METHODS: Based on the 2016 WHO classification and selected other publications, the histomolecular diagnostics of diffuse gliomas is presented and illustrated. RESULTS: Diffuse gliomas are divided into isocitrate dehydrogenase (IDH)-mutant or IDH-wildtype gliomas by detection of mutations in the IDH1 or IDH2 genes. Among the IDH-mutant gliomas, oligodendroglial tumors are characterized by combined losses of chromosome arms 1p and 19q. Loss of nuclear expression of the ATRX protein is a marker of IDH- mutant astrocytic gliomas. Glioblastoma, IDH-wildtype, is the most common diffuse glioma. Diffuse and anaplastic astrocytic gliomas without IDH mutation should be further evaluated for molecular features of glioblastoma, IDH-wildtype. Diffuse gliomas in the thalamus, brainstem, or spinal cord carrying a histone 3 (H3)-K27M mutation are classified as diffuse midline gliomas, H3-K27M-mutant. By determining the IDH and 1p/19q status, oligoastrocytomas can be stratified into either astrocytic or oligodendroglial gliomas. Gliomatosis cerebri is no longer regarded as a distinct glioma entity. CONCLUSIONS: Diffuse gliomas can today be classified accurately and reproducibly by means of histological, immunohistochemical, and molecular analyses.

Integrated diagnostics of diffuse astrocytic and oligodendroglial tumors.

BACKGROUND: Diffuse astrocytic and oligodendroglial gliomas are the most common neuroepithelial tumors. Their classification is based on the integration of histological and molecular findings according to the classification of tumors of the central nervous system published by the World Health Organization (WHO) in 2016. OBJECTIVES: This review describes the different entities and variants of diffuse gliomas and summarizes the current diagnostic criteria for these tumors. MATERIALS AND METHODS: Based on the 2016 WHO classification and selected other publications, the histomolecular diagnostics of diffuse gliomas is presented and illustrated. RESULTS: Diffuse gliomas are divided into isocitrate dehydrogenase (IDH)-mutant or IDH-wildtype gliomas by detection of mutations in the IDH1 or IDH2 genes. Among the IDH-mutant gliomas, oligodendroglial tumors are characterized by combined losses of chromosome arms 1p and 19q. Loss of nuclear expression of the ATRX protein is a marker of IDH- mutant astrocytic gliomas. Glioblastoma, IDH-wildtype, is the most common diffuse glioma. Diffuse and anaplastic astrocytic gliomas without IDH mutation should be further evaluated for molecular features of glioblastoma, IDH-wildtype. Diffuse gliomas in the thalamus, brainstem, or spinal cord carrying a histone 3 (H3)-K27M mutation are classified as diffuse midline gliomas, H3-K27M-mutant. By determining the IDH and 1p/19q status, oligoastrocytomas can be stratified into either astrocytic or oligodendroglial gliomas. Gliomatosis cerebri is no longer regarded as a distinct glioma entity. CONCLUSIONS: Diffuse gliomas can today be classified accurately and reproducibly by means of histological, immunohistochemical, and molecular analyses.

Bevacizumab plus hypofractionated radiotherapy versus radiotherapy alone in elderly patients with glioblastoma: the randomized, open-label, phase II ARTE trial.

Background: The addition of bevacizumab to temozolomide-based chemoradiotherapy (TMZ/RT â†’ TMZ) did not prolong overall survival (OS) in patients with newly diagnosed glioblastoma in phase III trials. Elderly and frail patients are underrepresented in clinical trials, but early reports suggested preferential benefit in this population. Patients and methods: ARTE was a 2 : 1 randomized, multi-center, open-label, non-comparative phase II trial of hypofractionated RT (40 Gy in 15 fractions) with bevacizumab (10 mg/kg×14 days) (arm A, N = 50) or without bevacizumab (arm B, N = 25) in patients with newly diagnosed glioblastoma aged ≥65 years. The primary objective was to obtain evidence for prolongation of median OS by the addition of bevacizumab to RT. Response was assessed by RANO criteria. Quality of life (QoL) was monitored by the EORTC QLQ-C30/BN20 modules. Exploratory studies included molecular subtyping by 450k whole methylome and gene expression analyses. Results: Median PFS was longer in arm A than in arm B (7.6 and 4.8 months, P = 0.003), but OS was similar (12.1 and 12.2 months, P = 0.77). Clinical deterioration was delayed and more patients came off steroids in arm A. Prolonged PFS in arm A was confined to tumors with the receptor tyrosine kinase (RTK) I methylation subtype (HR 0.25, P = 0.014) and proneural gene expression (HR 0.29, P = 0.025). In a Cox model of OS controlling for established prognostic factors, associations with more favorable outcome were identified for age <70 years (HR 0.52, P = 0.018) and Karnofsky performance score 90%-100% (HR 0.51, P = 0.026). Including molecular subtypes into that model identified an association of the RTK II gene methylation subtype with inferior OS (HR 1.73, P = 0.076). Conclusion: Efficacy outcomes and exploratory analyses of ARTE do not support the hypothesis that the addition of bevacizumab to RT generally prolongs survival in elderly glioblastoma patients. Molecular biomarkers may identify patients with preferential benefit from bevacizumab. Clinical trial registration number: NCT01443676.

[Classification of gliomas. Current progress and perspectives]. / Klassifikation von Gliomen : Aktuelle Fortschritte und Perspektiven.

The diagnostic subdivision of gliomas is traditionally based on histological features as defined by the World Health Organization (WHO) classification of tumors of the central nervous system. In recent years molecular studies have identified a number of genetic and epigenetic markers that could contribute to an improved tumor classification and better prediction of response to therapy and prognosis in the individual patient. The most important molecular tests with differential diagnostic relevance in patients with astrocytic and oligodendroglial tumors include the detection of genetic mutations in the isocitrate dehydrogenase 1 (IDH1), IDH2, alpha thalassemia/mental retardation syndrome X-linked (ATRX), histone H3.3 (H3F3A) and v-raf murine sarcoma viral oncogene homolog B (BRAF) genes as well as the demonstration of codeletions of chromosomal arms 1p and 19q. Important predictive markers that have been linked to the response to alkylating chemotherapy are O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation in glioblastoma patients and 1p/19q codel status in anaplastic glioma patients. Oncogenic c11orf95/RELA fusion gene formation is characteristic for a subgroup of patients with supratentorial ependymoma. In addition to diagnostic testing of individual genes, novel microarray and next generation sequencing (NGS) techniques show promising perspectives in glioma diagnostics. The assessment of DNA methylation profiles using DNA methylation arrays representing 450,000 CpG dinucleotides distributed throughout the human genome (450 k array test) now allows the robust molecular classification of gliomas into clinically relevant entities and variants. Moreover, glioma-associated gene panel NGS promises the timely parallel sequencing of relevant diagnostic and predictive marker genes in a single test. It will now be a major task to integrate these novel results and techniques into the conventional histological procedures in the up-coming revision of the WHO classification.

Gross total but not incomplete resection of glioblastoma prolongs survival in the era of radiochemotherapy.

BACKGROUND: This prospective multicenter study assessed the prognostic influence of the extent of resection when compared with biopsy only in a contemporary patient population with newly diagnosed glioblastoma. PATIENTS AND METHODS: Histology, O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, and clinical data were centrally analyzed. Survival analyses were carried out with the Kaplan-Meier method. Prognostic factors were assessed with proportional hazard models. RESULTS: Of 345 patients, 273 underwent open tumor resection and 72 biopsies; 125 patients had gross total resections (GTRs) and 148, incomplete resections. Surgery-related morbidity was lower after biopsy (1.4% versus 12.1%, P = 0.007). 64.3% of patients received radiotherapy and chemotherapy (RT plus CT), 20.0% RT alone, 4.3% CT alone, and 11.3% best supportive care as an initial treatment. Patients ≤60 years with a Karnofsky performance score (KPS) of ≥90 were more likely to receive RT plus CT (P < 0.01). Median overall survival (OS) (progression free survival; PFS) ranged from 33.2 months (15 months) for patients with MGMT-methylated tumors after GTR and RT plus CT to 3.0 months (2.4 months) for biopsied patients receiving supportive care only. Favorable prognostic factors in multivariate analyses for OS were age ≤60 years [hazard ratio (HR) = 0.52; P < 0.001], preoperative KPS of ≥80 (HR = 0.55; P < 0.001), GTR (HR = 0.60; P = 0.003), MGMT promoter methylation (HR = 0.44; P < 0.001), and RT plus CT (HR = 0.18, P < 0.001); patients undergoing incomplete resection did not better than those receiving biopsy only (HR = 0.85; P = 0.31). CONCLUSIONS: The value of incomplete resection remains questionable. If GTR cannot be safely achieved, biopsy only might be used as an alternative surgical strategy.

Toxicity and survival in primary glioblastoma patients treated with concomitant plus adjuvant temozolomide versus adjuvant temozolomide: results of a single-institution, retrospective, matched-pair analysis.

BACKGROUND: To compare survival and hematological toxicity rates between two postoperative therapy regimens in patients with primary glioblastoma (GBM), namely temozolomide (TMZ) concomitant to radiation, followed by adjuvant TMZ, versus adjuvant TMZ after radiation only. PATIENTS AND METHODS: A total of 191 patients with primary GBM were postoperatively treated with either radiation and concomitant TMZ, followed by adjuvant TMZ (Stupp protocol) (n = 154), or radiation followed by adjuvant TMZ (n = 37). The incidence of hematological adverse effects (AE) was recorded for all patients. From both treatment groups, 26 patients were matched according to age, Karnofsky performance scale (KPS) score, and O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation. RESULTS: Hematological AEs were mild in both unmatched groups, but were significantly more frequent in the concomitant plus adjuvant TMZ group (p < 0.001). Matched-pair analysis confirmed significantly more frequent hematological AEs in the concomitant and adjuvant group compared to the sequential (adjuvant) TMZ group (p = 0,012). Patients treated with concomitant plus adjuvant TMZ showed significantly longer progression-free survival (PFS) (10.6 versus 6.6 months; p = 0.014), but no prolonged overall survival (OS) (16.9 vs. 15.6 months; p = 0.717) compared to patients who received the sequential treatment regimen. CONCLUSION: In this retrospective study, the OS in patients with primary GBM treated with sequential TMZ following radiation appeared to be similar to that in patients treated with concomitant plus adjuvant TMZ. Given the significantly higher risk of hematological AE for concomitant treatment, the role of concomitant plus adjuvant TMZ use compared to sequential administration of TMZ, especially for patients with MGMT-unmethylated tumors, should be further evaluated.

MGMT promoter methylation status and prognosis of patients with primary or recurrent glioblastoma treated with carmustine wafers.

The prognostic role of O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation in glioblastoma patients treated with carmustine (BCNU) wafer implantation is unclear. Here, we report on a retrospective study of 47 patients with either newly diagnosed (30 patients) or recurrent (17 patients) glioblastoma (WHO grade IV) treated with BCNU (bis-chloroethylnitrosourea) wafers. Thirteen of the newly diagnosed patients received local BCNU and irradiation only (first-line BCNU), while 17 patients additionally received concomitant and adjuvant temozolomide (TMZ) radiochemotherapy (first-line BCNU + TMZ). Of the 17 patients treated for recurrent glioblastoma (second-line BCNU), 16 had received radiotherapy with concomitant and adjuvant TMZ as an initial treatment. Median overall survival (OS) did not significantly differ between 19 patients with MGMT promoter methylated tumors when compared to 28 patients with unmethylated tumors (18.9 vs 15.0 months; p = 0.1054). In the first-line BCNU + TMZ group, MGMT promoter methylation was associated with longer OS (21.0 vs 11.1 months, p = 0.0127), while no significant survival differences were detected in the other two subgroups. Progression-free survival did not significantly differ between patients with and without MGMT promoter methylated tumors in the entire patient cohort or any of the three subgroups. The first-line BCNU + TMZ group showed no significant difference in OS when compared to the first-line BCNU group (18.9 vs 14.7 months), but tended to have more therapy-related adverse effects (53% vs 24%, p = 0.105). In summary, MGMT promoter methylation showed a non-significant trend toward longer survival in our patient cohort. The combination of TMZ radiochemotherapy with local delivery of BCNU did not provide a significant survival benefit compared to local BCNU alone, but was associated with a higher rate of adverse effects. Owing to the small number of patients investigated, however, these findings would need to be corroborated in larger patient cohorts.

Identification and functional validation of CDH11, PCSK6 and SH3GL3 as novel glioma invasion-associated candidate genes.

AIMS: The molecular mechanisms underlying the infiltrative growth of glioblastomas, the most common primary tumours of the central nervous system in adults, are still poorly understood. We aimed to identify and functionally validate novel glioma invasion-associated candidate genes. METHODS: Microarray-based expression analysis was applied to identify differentially expressed genes in microdissected infiltrating glioma cells in vivo. Promising candidate genes were selected by the invasion-associated gene ontology terms cell adhesion, endocytosis, extracellular matrix and cell migration and validated in vitro by invasion assays and in situ by immunohistochemistry. RESULTS: We identified 180 up-regulated and 61 down-regulated genes (fold change: ≥ 2; P < 0.01) in the infiltration zone relative to more central cell-rich tumour areas of malignant astrocytic gliomas (n = 11). Twenty-seven of these genes matched to invasion-related gene ontology terms. From these, we confirmed the genes encoding cadherin-11 (CDH11), proprotein convertase subtilisin/kexin type 6 (PCSK6) and SH3-domain GRB2-like 3 (SH3GL3) as novel glioma invasion-associated candidate genes, with knockdown of PCSK6 and SH3GL3 inhibiting glioma cell invasion, while inhibition of CDH11 promoted glioma cell invasion in vitro. Immunohistochemistry on glioblastoma tissue sections revealed expression of CDH11 and PCSK6 protein in glioma cells of more central, cell-rich tumour areas, with only weak or absent CDH11 immunoreactivity but consistent PCSK6 staining in infiltrating glioma cells. CONCLUSION: Using molecular profiling of microdissected primary tumour tissue specimens followed by functional in vitro analysis, we identified and validated CDH11, PCSK6 and SH3GL3 as novel glioma invasion-associated candidate genes that likely contribute to the invasive phenotype of malignant gliomas.

Longitudinal stability of molecular alterations and drug response profiles in tumor spheroid cell lines enables reproducible analyses.

The utility of patient-derived tumor cell lines as experimental models for glioblastoma has been challenged by limited representation of the in vivo tumor biology and low clinical translatability. Here, we report on longitudinal epigenetic and transcriptional profiling of seven glioblastoma spheroid cell line models cultured over an extended period. Molecular profiles were associated with drug response data obtained for 231 clinically used drugs. We show that the glioblastoma spheroid models remained molecularly stable and displayed reproducible drug responses over prolonged culture times of 30 in vitro passages. Integration of gene expression and drug response data identified predictive gene signatures linked to sensitivity to specific drugs, indicating the potential of gene expression-based prediction of glioblastoma therapy response. Our data thus empowers glioblastoma spheroid disease modeling as a useful preclinical assay that may uncover novel therapeutic vulnerabilities and associated molecular alterations.

Molecular neuropathology of low-grade gliomas and its clinical impact.

The term "low-grade glioma" refers to a heterogeneous group of slowly growing glial tumors corresponding histologically to World Health Organization (WHO) grade I or II. This group includes astrocytic, oligodendroglial, oligoastrocytic and ependymal tumor entities, most of which preferentially manifest in children and young adults. Depending on histological type and WHO grade, growth patterns of low-grade gliomas are quite variable, with some tumors diffusely infiltrating the surrounding central nervous system tissue and others showing well demarcated growth. Furthermore, some entities tend to recur and show spontaneous malignant progression while others remain stable for many years. This review provides a condensed overview concerning the molecular genetics of different glioma entities subsumed under the umbrella of low-grade glioma. For a better understanding the cardinal epidemiological, histological and immunohistochemical features of each entity are shortly outlined. Multiple cytogenetic, chromosomal and genetic alterations have been identified in low-grade gliomas to date, with distinct genetic patterns being associated with the individual tumor subtypes. Some of these molecular alterations may serve as a diagnostic adjunct for tumor classification in cases with ambiguous histological features. However, to date only few molecular changes have been associated with clinical outcome, such as the combined losses of chromosome arms 1p and 19q as a favorable prognostic marker in patients with oligodendroglial tumors.

Hypermethylation and transcriptional downregulation of the CITED4 gene at 1p34.2 in oligodendroglial tumours with allelic losses on 1p and 19q.

Deletions of chromosomal arms 1p and 19q are frequent in oligodendroglial tumours and have been associated with sensitivity to radio- and chemotherapy as well as favourable prognosis. By using microarray-based expression profiling, we found that oligodendroglial tumours with 1p and 19q losses showed significantly lower expression of the CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 4 gene (CITED4) at 1p34.2 as compared to tumours without 1p and 19q losses. Mutational analysis showed no CITED4 mutations in gliomas. However, 1p and 19q losses as well as low expression of CITED4 transcripts were significantly associated with hypermethylation of the CITED4-associated CpG island. In line with the latter finding, treatment of CITED4 hypermethylated glioma cell lines with 5-aza-2'-deoxycytidine and trichostatine A resulted in a marked increase of the CITED4 transcript levels. Furthermore, CITED4 hypermethylation was significantly associated with longer recurrence-free and overall survival of patients with oligodendroglial tumours. Taken together, our results indicate that CITED4 is epigenetically silenced in the vast majority of oligodendroglial tumours with 1p and 19q deletions and suggest CITED4 hypermethylation as a novel prognostic marker in oligodendroglioma patients.

Frequent loss of chromosome 9, homozygous CDKN2A/p14(ARF)/CDKN2B deletion and low TSC1 mRNA expression in pleomorphic xanthoastrocytomas.

The molecular pathogenesis of pleomorphic xanthoastrocytoma (PXA), a rare astrocytic brain tumor with a relatively favorable prognosis, is still poorly understood. We characterized 50 PXAs by comparative genomic hybridization (CGH) and found the most common imbalance to be loss on chromosome 9 in 50% of tumors. Other recurrent losses affected chromosomes 17 (10%), 8, 18, 22 (4% each). Recurrent gains were identified on chromosomes X (16%), 7, 9q, 20 (8% each), 4, 5, 19 (4% each). Two tumors demonstrated amplifications mapping to 2p23-p25, 4p15, 12q13, 12q21, 21q21 and 21q22. Analysis of 10 PXAs with available high molecular weight DNA by high-resolution array-based CGH indicated homozygous 9p21.3 deletions involving the CDKN2A/p14(ARF)/CDKN2B loci in six tumors (60%). Interphase fluorescence in situ hybridization to tissue sections confirmed the presence of tumor cells with homozygous 9p21.3 deletions. Mutational analysis of candidate genes on 9q, PTCH and TSC1, revealed no mutations in PXAs with 9q loss and no evidence of TSC1 promoter methylation. However, PXAs consistently showed low TSC1 transcript levels. Taken together, our study identifies loss of chromosome 9 as the most common chromosomal imbalance in PXAs and suggests important roles for homozygous CDKN2A/p14(ARF)/CDKN2B deletion as well as low TSC1 mRNA expression in these tumors.

Primary anaplastic ganglioglioma with a small-cell glioblastoma component.

Gangliogliomas usually present as benign tumors corresponding to World Health Organization (WHO) Grade I. Very rarely, gangliogliomas show histological features of malignancy and are then classified as anaplastic gangliogliomas of WHO Grade III or IV. In most cases, anaplastic gangliogliomas developed after radiation therapy or progression from a pre-existing low-grade ganglioglioma. Here, we report the case of a 77-year-old male patient who was operated on a primary ganglioglioma with a highly anaplastic glial component corresponding to a small-cell glioblastoma. To our knowledge, this is the first reported case of a primary anaplastic ganglioglioma with a small-cell glioblastoma component.

Multicenter validation of cancer gene panel-based next-generation sequencing for translational research and molecular diagnostics.

The simultaneous detection of multiple somatic mutations in the context of molecular diagnostics of cancer is frequently performed by means of amplicon-based targeted next-generation sequencing (NGS). However, only few studies are available comparing multicenter testing of different NGS platforms and gene panels. Therefore, seven partner sites of the German Cancer Consortium (DKTK) performed a multicenter interlaboratory trial for targeted NGS using the same formalin-fixed, paraffin-embedded (FFPE) specimen of molecularly pre-characterized tumors (n = 15; each n = 5 cases of Breast, Lung, and Colon carcinoma) and a colorectal cancer cell line DNA dilution series. Detailed information regarding pre-characterized mutations was not disclosed to the partners. Commercially available and custom-designed cancer gene panels were used for library preparation and subsequent sequencing on several devices of two NGS different platforms. For every case, centrally extracted DNA and FFPE tissue sections for local processing were delivered to each partner site to be sequenced with the commercial gene panel and local bioinformatics. For cancer-specific panel-based sequencing, only centrally extracted DNA was analyzed at seven sequencing sites. Subsequently, local data were compiled and bioinformatics was performed centrally. We were able to demonstrate that all pre-characterized mutations were re-identified correctly, irrespective of NGS platform or gene panel used. However, locally processed FFPE tissue sections disclosed that the DNA extraction method can affect the detection of mutations with a trend in favor of magnetic bead-based DNA extraction methods. In conclusion, targeted NGS is a very robust method for simultaneous detection of various mutations in FFPE tissue specimens if certain pre-analytical conditions are carefully considered.

Amplification at 12q13-14 in human malignant gliomas is frequently accompanied by loss of heterozygosity at loci proximal and distal to the amplification site.

We have recently reported that a subset of human malignant gliomas shows amplification and overexpression of multiple genes from chromosomal segment 12q13-14, including CDK4, SAS, and MDM2. In the present study we have performed an allelotyping for 16 polymorphic loci spanning both arms of chromosome 12 in a series of 136 gliomas. Allelic deletions were found in 50% (7 of 14) of the malignant gliomas with 12q13-14 amplification and involved loci located on 12q proximal and distal to the amplification site. In contrast, the incidence of allelic loss on chromosome 12 was significantly lower in gliomas without 12q13-14 amplification [14% (11 of 79) in the WHO grade III and IV gliomas, 9% (4 of 43) in the WHO grade I and II gliomas]. The frequent association between 12q13-14 amplification and loss of alleles from 12q is in line with a model suggesting chromosome breakage and deletion as important events in the development of gene amplification.

Amplification and overexpression of the MDM2 gene in a subset of human malignant gliomas without p53 mutations.

The MDM2 (murine double minute 2) gene has recently been shown to code for a cellular protein that can complex the p53 tumor suppressor gene product and inhibit its function. We studied a series of 157 primary brain tumors and report here that the MDM2 gene is amplified and overexpressed in 8-10% of glioblastomas and anaplastic astrocytomas. Thus, MDM2 represents the second most frequently amplified gene after the epidermal growth factor receptor gene in these tumor types. Sequencing of the p53 transcripts in the cases with MDM2 amplification revealed no mutations and restriction fragment length polymorphism analysis showed, with one exception, no losses of alleles on chromosome 17. Our results indicate that amplification and overexpression of MDM2 may be an alternative molecular mechanism by which a subset of human malignant gliomas escapes from p53-regulated growth control.