Pure Germinoma Research Articles

GC-01 * ELUCIDATION OF PATHOGENESIS IN INTRACRANIAL GERM CELL TUMORS BASED ON A GENOME-WIDE METHYLATION STUDY

OBJECTIVE: Although “germ cell theory” that primordial germ cells (PGCs) might be a cell of origin of intracranial germ cell tumors (iGCTs) is now widely accepted, the nature of this heterogeneous tumor remains largely unknown. To elucidate the pathogenesis of iGCT, we are currently conducting a comprehensive methylation analysis. METHODS: Bisulfite-modified DNA of 58 iGCTs from frozen tissues (20 germinomas, and 38 NGGCTs), and 4 mixed-GCTs from FFPE tissues after microdissection (germinoma and the other histological component) were subjected to a genome-wide methylation analysis using HumanMethylation450 BeadChip, which were subclassified by an unsupervised hierarchical clustering. The DNA methylation levels of iGCTs were compared to those of mice PGCs in the published data. In mixed-GCTs after microdissection, mutation status of each component was analyzed by Sanger sequencing. RESULTS: According to the methylation profiles, iGCTs were subclassified into the following 3 groups; global lower methylation (GLM), partial lower methylation (PLM) and higher methylation (HM). Pure germinomas showed a prominent hypomethylation pattern clustered to GLM, which is a unique epigenomic feature distinguishable from NGGCTs. DNA methylation profiles in pure germinoma are similar to those in mice PGCs at E10.5. Mixed-GCTs show different methylation, but common mutation profiles between germinoma and the other histological component. CONCLUSION: We conclude that intracranial germinoma might originate from the migration phase of PGC, but the other subtypes of GCTs might not. We further propose that mutation is earlier event than methylation in the pathogenesis of iGCTs.

Predictors of long-term survival following postoperative radiochemotherapy for pathologically confirmed suprasellar germ cell tumors.

The aim of this study was to evaluate the predictors of long-term survival following postoperative therapy for suprasellar germ cell tumors (GCTs). A total of 23 patients with pathologically confirmed suprasellar GCTs were reviewed between April, 1987 and October, 2008. The predictors were identified with a univariate Cox proportional hazards model and the results were used to group patients according to outcome. The overall survival (OS) and progression-free survival (PFS) rates for the good- and poor-prognosis two groups were estimated with Kaplan-Meier analysis, with log-rank tests used to assess differences between the groups. The OS rate for all patients was 82.6% at 5 and 72.9% at 10 years. Lesion size (2-4 vs. >4 cm) and pathological type (pure germinoma vs. mixed GCT) were the only significant predictors of OS (P<0.05). The OS rate for the good-prognosis group was 92.9% at both 5 and 10 years, whereas the corresponding rates for the poor-prognosis group were 66.7 and 40.0%, respectively (P=0.020). The PFS rate for the good-prognosis group was 92.9% at 5 and 85.7% at 10 years, whereas the corresponding PFS rates for the poor-prognosis group were 44.4 and 33.3%, respectively (P=0.007). Lesion size and histology predicted outcome following postoperative therapy for suprasellar GCT. Therefore, pathological diagnosis is recommended whenever possible, as histology may dictate the choice of treatment.

GE-13 * A NOVEL ASSOCIATION OF PRIMARY CNS GERMINOMA IN A PATIENT WITH NAIL PATELLA SYNDROME

Nail patella syndrome (NPS) is an autosomal dominant disorder with a prevalence of 1/50,000 characterized by developmental abnormalities of the nails, knees and elbows, as well as renal dysplasia and open angle glaucoma. NPS is caused by a mutation in the LMX1B gene, a transcription factor involved in ventral/dorsal patterning of the vertebrate limb. While malignancy is rare in patients with NPS, Ewing's sarcoma and colon cancer have been reported. Additionally, NPS has been described in a 5 generation family with neurofibromatosis type 1. We report a novel association of NPS with primary CNS germinoma. A 22-year-old male presented with a two-month history of diabetes insipidus (DI) and headaches. Physical examination revealed partial Parinaud's syndrome, dystrophic nails and surgical repair of left hypoplastic patella. Because the family history revealed numerous maternal family members with dystrophic nails and hypoplastic patellae, we subsequently made a formal clinical diagnosis of NPS. Contrast enhanced MRI of the brain revealed an enhancing cystic pineal mass and a Chiari I malformation; serum and CSF alpha-fetoprotein and beta-human chorionic gonadotropin were negative. Biopsy of the pineal mass was consistent with pure germinoma for which the patient received external beam radiation therapy via intensity modulated radiation therapy (IMRT) as follows: 1) 2520 cGy to the craniospinal axis; 2) 5040 cGy to the pineal region; 3) and 4620 cGy to the suprasellar region (for presumed tumor in the posterior pituitary given the history of DI). He remains in remission 9 years post-treatment. For the NPS, the patient declined referral to genetics due to insurance concerns but he and his family have been referred to appropriate services for screening of other abnormalities associated with the syndrome. This case report suggests that LMX1B may play a role in the development of CNS germinoma.

Abstract PR04: Novel somatic and germline mutations in intracranial germ cell tumors

Abstract Intracranial germ cell tumors (IGCTs) are rare and biologically diversified tumors affecting mainly male adolescents with the highest incidence in Japan and other Asian countries2. They are divided into two main groups, pure germinoma and nongerminomatous GCTs (NGGCTs). About 10% of germinomas and most NGGCTs remain refractory to multimodality therapy. Little is currently known about IGCTs except for KIT mutation/overexpression, which is observed in ∼25% of pure germinomas and is rarely seen in NGGCTs. As yet, there are no clues for the puzzle of onset during puberty, geographic and gender discrepancy in incidence of IGCTs. Here we report the analysis of 62 cases by whole-exome sequencing, deep-targeted sequencing and SNP array. The KIT/RAS pathway was frequently mutated in pure germinomas and mixed GCTs with germinoma components. In contrast, NGGCTs appear to have a paucity of clinically actionable mutations. We identified novel recurrent somatic mutations in KIT and 8 additional genes in KIT/RAS pathway that have not been previously associated with IGCTs: downstream mediators of KIT including KRAS, NRAS, MTOR, AKT1 and its negative regulator CBL (11%). We showed frequent focal amplification at AKT1 locus (19%), leading to AKT1 overexpression. Moreover, we identified loss-of-function mutations in BCORL1 (10%), a transcriptional corepressor and tumor suppressor. Furthermore, we report for the first time, significant enrichment of novel and rare germline variants in JMJD1C, a histone demethylase and coactivator of the androgen receptor, among Japanese IGCT patients. Our data suggested a strong association of JMJD1C variants and the risk of developing of IGCTs (odds ratio=3.57). This study establishes a molecular foundation for understanding the biology of IGCTs and suggests potential promising targets for development of novel therapeutics. This abstract is also presented as Poster A14. Citation Format: Linghua Wang, Shigeru Yamaguchi, Keita Terashima, Mathew D. Burstein, Hideo Nakamura, Tomonari Susuki, Ryo Nishikawa, Atsushi Natsume, Shunsuke Terasaka, Ho Keung Ng, Adekunle Adesina, Richard Gibbs, David Wheeler, Ching Lau. Novel somatic and germline mutations in intracranial germ cell tumors. [abstract]. In: Proceedings of the AACR Special Conference on Pediatric Cancer at the Crossroads: Translating Discovery into Improved Outcomes; Nov 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;74(20 Suppl):Abstract nr PR04.

Abstract 4264: Whole exome and targeted sequencing identified the MAPK and PI3K pathways as the main targets in intracranial and testicular germ cell tumors

Abstract Intracranial germ cell tumors (iGCTs) are the second most common central nervous system tumors in patients under 14 in Japan. The majority of germinomas respond well to combined chemo- and radiotherapy, however non-germinoma germ cell tumors (NGGCTs) may show resistance to therapy and have a poor clinical outcome. Despite their clinical significance, the biology of iGCTs is mostly unknown. The aim of this study is to elucidate the molecular pathogenesis of iGCTs through a comprehensive genomic analysis. A total of 198 germ cell tumors (GCTs) including 133 iGCTs (69 pure germinomas, 56 NGGCTs and 8 metastatic tumors) as well as 65 testicular germ cell tumors (tGCTs) (39 seminomas and 26 non-seminoma GCTs) were collected from 13 centers participating in the Intracranial Germ Cell Tumor Consortium in Japan. Matched normal DNA was available for 70 iGCTs and 4 tGCTs. Somatic mutations in all coding exons were investigated by whole exome sequencing (WES) using SureSelectXT Human All Exon v4 and a GAIIx or HiSeq 2000 system in 41 tumors and the matched normal DNAs. Targeted sequencing with a set of custom made PCR primers was performed using either an IonTorrent PGM or Proton System. The results were integrated with the patients' clinical information that was available for 124 iGCT patients. Mutations in selected candidate genes were further evaluated in an independent tumor cohort using the IonTorrent PGM system. On average, 15.4 non-synonymous somatic mutations were observed in each tumor, ranging from 1 to 140 by WES in 41 iGCTs. Based on the WES data, 41 candidate genes were selected according to the frequency and/or significance of the mutations found. All coding exons of these 41 genes spanning over 160kb were PCR-amplified in a further 157 GCTs using the IonTorrent system. The combined WES and IonTorrent screenings showed that KIT was the most frequently mutated gene in both iGCTs (27%) and tGCTs (18%). MTOR was the second most frequently mutated also in both iGCTs (7%) and tGCTs (6%). RAS mutations (KRAS, HRAS, NRAS) were altogether found in 13% of iGCTs and 12% of tGCTs. These mutations were mutually exclusive to each other and also to KIT mutations. Collectively, the genes involved in the MAPK pathway (e.g., KIT, RAS, NF1) and the PI3K/MTOR pathway (e.g., MTOR, PTEN) were mutated in 44% and 13% of all GCTs. These alterations were significantly more common among pure germinomas than NGGCTs. The mutated MTOR protein was shown to have increased kinase activity, which was suppressed by a specific MTOR inhibitor. Our comprehensive mutational genomic analysis of GCTs revealed that alterations of the MAPK and/or PI3K/MTOR pathways play a critical role in the pathogenesis of both iGCTs and tGCTs, although the extent of their involvement depends on the histopathological subtypes. Our findings will hopefully lead to the development of a targeted therapy for treatment-resistant iGCTs. Citation Format: Koichi Ichimura, Shintaro Fukushima, Yasushi Totoki, Yuko Matsushita, Ayaka Otsuka, Arata Tomiyama, Tohru Niwa, Ryuichi Sakai, Toshikazu Ushijima, Taishi Nakamura, Tomonari Suzuki, Kouhei Fukuoka, Takaaki Yanagisawa, Kazuhiko Mishima, Yoichi Nakazato, Fumie Hosoda, Yoshitaka Narita, Soichiro Shibui, Akihiko Yoshida, Hirokazu Takami, Akitake Mukasa, Koki Aihara, Nobuhito Saito, Toshihiro Kumabe, Masayuki Kanamori, Teiji Tominaga, Keiichi Kobayashi, Saki Shimizu, Motoo Nagane, Toshihiko Iuchi, Masahiro Mizoguchi, Koji Yoshimoto, Kaoru Tamura, Taketoshi Maehara, Kazuhiko Sugiyama, Mitsutoshi Nakada, Keiichi Sakai, Yonehiro Kanemura, Masahiro Nonaka, Kiyotaka Yokogami, Hideo Takeshima, Nobutaka Kawahara, Tatsuya Takayama, Masahiro Yao, Hiromi Nakamura, Natsuko Hama, Masao Matsutani, Tatsuhiro Shibata, Ryo Nishikawa. Whole exome and targeted sequencing identified the MAPK and PI3K pathways as the main targets in intracranial and testicular germ cell tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4264. doi:10.1158/1538-7445.AM2014-4264

Pure germinomas of the central nervous system: treatment strategies and outcomes.

To evaluate the role of chemotherapy and radiation therapy in the treatment of pure germinomas of the central nervous system (CNS). We reviewed a historical cohort of 79 patients between the ages of 3-35years who received definitive treatment for newly diagnosed, pure CNS germinoma between 1985 and 2010 at the University of California, San Francisco (UCSF). Median age at diagnosis was 15years (interquartile range, IQR 12-20years) and 61 (77.2%) patients were male. Median follow-up for the cohort was 111.1months (IQR 45.7-185.1months). Five-year PFS rate was 86.4% (95% CI 76.1-92.4) and 5year OS rate was 93.0% (95% CI 84.1-97.1). Median PFS was 104.6months (IQR 41.4-170.1months). Fourteen patients progressed and 8 died of their disease. Patients who received focal irradiation (XRT) and chemotherapy had a significantly higher rate of progression compared to those who received whole brain irradiation (WBI) or whole ventricle irradiation (WVI). Three of 8 patients had a PR to chemotherapy and received focal XRT progressed whereas only 1 of 9 patients who had a CR to chemotherapy who went on to receive focal XRT progressed. Elevation of hCGβ>50mIU/ml was not significantly associated with disease progression (HR 5.64, 95% CI 0.97-32.7, p=0.054). Patients treated with WBI or WVI with or without chemotherapy achieve better disease control compared to patients treated with focal XRT+chemotherapy.

Incidence of Optic Nerve Involvement in Pediatric Intracranial Germ Cell Tumors

Optic nerve (ON) involvement for intracranial germ cell tumors (GCT) is rare and only reported in the literature in case reports. ON involvement has important implications for radiation (RT) planning as this region may not be included in craniospinal (CSI) and whole ventricle (WV) volumes. In addition, brain MRIs may not optimally image the ON and orbital MRIs, if obtained at diagnosis, may better characterize ON involvement. We investigated the incidence of ON involvement in patients with intracranial GCTs in a large cohort of patients. All patients with intracranial pure germinoma and nongerminomatous GCTs treated at our institution with proton radiation therapy between 1998 and 2013 were included. We identified 78 patients with intracranial GCTs treated with proton radiation therapy at our institution: 45 pure germinoma and 33 nongerminomatous GCT. Of these patients, 4 (5.1%) had ON involvement based on pre-treatment MRI. Of the 4 patients with ON involvement at diagnosis, 3 had localized suprasellar tumors and 1 had disseminated disease. Median age at diagnosis was 16 years, and 3/4 patients were male. The histology was pure germinoma in 3/4 patients, and NGGCT in one patient. All were treated with induction chemotherapy for 3-6 cycles with near complete (n = 2/4) to complete (n = 2/4) response, followed by proton radiation therapy with craniospinal irradiation (n = 3/4) or whole-ventricular irradiation (n = 1/4) and involved-field radiation therapy. Optic nerve involvement meaningfully impacts radiation field planning in the treatment of intracranial GCTs. While relatively rare overall, it may be more common than previously recognized. It is important to look for ON involvement and adjust fields appropriately to ensure full radiation dose to this area of disease involvement.

POTENCY OF SECRETING HCG- IN GERMINOMAS. CLINICAL AND BIOLOGICAL ANALYSIS

BACKGROUND: It has long been discussed whether HCG secreting germinomas are more malignant than pure germinomas. The Japanese study group insists of no difference in survival between two kinds of germinomas, whereas the European and American study groups put HCG germinomas into the high risk group. In order to solve the question, we analyzed the treatment results, the titer of a small amount of HCG-β in the cerebrospinal fluid (CSF), and the expression of HCGβ mRNA in germinoma cells. METHODS: (1) We selected 80 germinoma patients with or without HCG secretion for PFS analysis who were treated by proper radiation volume for their tumors developing in/around the third ventricle in the Japanese prospective study. (2) The initial serum and CSF samples were measured for HCG-β with the ultrasensitive technique to detect picogram levels of HCG-β in 36 histologically confirmed germinomas. (3) The expression of HCGβ mRNA was analyzed by qPCR in 76 germ cell tumors. RESULTS: (1) There was no significant difference in 15 year PFS between pure germinomas (93.1%, n = 61) and HCG-germinomas (80.7%, n = 19) in the Japanese prospective study. (2) In 36 germinomas examined, the HCG-β was detectable in both serum and CSF. The serum levels were 3.1–5851 pg/mL (median 44.8), and the CSF levels were 13–13116.3 pg/mL (median 119.5). (3) Most of the germ cell tumors expressed HCG-β mRNA in higher degrees compared with the normal brain tissue (comparative ratio to brain: 0.46 - 7.6 × 107). The expression of HCG-β mRNA in germinomas was highly variable, ranging from 72.6 - 2.1 × 105 to below the brain (0.46 - 1.4 × 103), and the differences of the expression among cases were linear, and not bimodal, suggesting no clear cut-off titer. CONCLUSIONS: These results suggest that all germinomas can produce HCG-β and fall into the same category in terms of HCG-β productivity. Based on this theory, all germinoma patients should be treated with the same protocol. SECONDARY CATEGORY: Pediatrics.

WHOLE EXOME SEQUENCING IDENTIFIED THAT THE MAPK AND PI3K PATHWAYS ARE THE MAIN TARGETS FOR MUTATIONS IN INTRACRANIAL GERM CELL TUMORS

BACKGROUND: Intracranial germ cell tumors (iGCTs) are rare in the Western countries, however they are the second most common brain tumors in patients under 14 in Japan. Unlike other common pediatric brain tumors, the biology of iGCTs is largely unknown. METHODS: We performed a whole exome sequencing in a large series of iGCTs to elucidate their molecular pathogenesis. A total of 198 germ cell tumors (GCTs) including 133 iGCTs (69 pure germinomas, 56 NGGCTs and 8 metastatic tumors) as well as 65 testicular germ cell tumors (tGCTs) (39 seminomas and 26 non-seminoma GCTs) were collected from 13 centers participating in the Intracranial Germ Cell Tumor Consortium in Japan. Somatic mutations in all coding exons were investigated by whole exome sequencing (WES) in 41 tumors and the matched normal DNAs. Based on the WES data, 41 candidate genes were selected according to the frequency and/or significance of the mutations found. All coding exons of these 41 genes spanning over 160kb were PCR-amplified in a further 157 GCTs and sequenced using the IonTorrent system. The results were integrated with the patients' clinical information that was available for 124 iGCT patients. RESULTS: On average, 15.4 non-synonymous somatic mutations were observed in each tumor, ranging from 1 to 140 by WES in 41 iGCTs. The combined WES and IonTorrent screenings showed that KIT was the most frequently mutated gene in both iGCTs (27%) and tGCTs (18%). MTOR was the second most frequently mutated also in both iGCTs (7%) and tGCTs (6%). RAS mutations (KRAS, HRAS, NRAS) were altogether found in 13% of iGCTs and 12% of tGCTs. These mutations were mutually exclusive to each other and also to KIT mutations. Collectively, the genes involved in the MAPK pathway (e.g., KIT, RAS, NF1) and the PI3K/MTOR pathway (e.g., MTOR, PTEN) were mutated in 44% and 13% of all GCTs. Among the iGCTs, these alterations were significantly more common among pure germinomas than NGGCTs. The mutated MTOR protein was shown to have increased kinase activity, which was suppressed by specific MTOR inhibitors. CONCLUSIONS: Our comprehensive mutational genomic analysis of GCTs revealed that alterations of the MAPK and/or PI3K/MTOR pathways play a critical role in the pathogenesis of both iGCTs and tGCTs, although the extent of their involvement depends on the histopathological subtypes. Our findings will hopefully lead to the development of a targeted therapy for treatment-resistant iGCTs. SECONDARY CATEGORY: Tumor Biology.

INTRACRANIAL GERM CELL TUMORS WITH MTOR MUTATION ARE COMMON IN BASAL GANGLIA

BACKGROUND: Intracranial germ cell tumors (iGCTs) are the second most common CNS tumors in patients under 14 years old in Japan. But, their molecular genetic profile is largely unknown. METHODS: We have analyzed a total of 198 germ cell tumors (GCTs) including 133 iGCTs (69 pure germinomas, 56 non-germinomatous GCTs and 8 metastatic tumors) as well as 65 testicular germ cell tumors (tGCTs) (39 seminomas and 26 non-seminoma GCTs) were collected from 13 centers participating in the Intracranial Germ Cell Tumor Consortium in Japan. Somatic mutations in all coding exons were investigated by whole exome sequencing (WES) using SureSelectXT Human All Exon v4 and a GAIIx or HiSeq 2000 system in 41 tumors and the matched normal DNAs. Targeted sequencing with a set of custom made PCR primers was performed using either an IonTorrent PGM or Proton System. The results were integrated with the patients' clinical information that was available for 124 iGCT patients. RESULTS: On average, 15.4 non-synonymous somatic mutations were observed in each tumor, ranging from 1 to 140 by WES in 41 iGCTs. MTOR was the second most frequently mutated in both iGCTs (9 cases, 7%) and tGCTs (6%). Collectively, the genes involved in the PI3K/MTOR pathway (e.g., MTOR, PTEN) were mutated in 13% of all GCTs. Clinical parameters of the 9 iGCTs with MTOR mutation were: median age of onset = 15 years old; 7 males and 2 females; 5 germinomas, 3 teratomas and one yolk sac tumor; 5 basal ganglia tumors, 2 pineal tumors, one neurohypophyseal tumor and a medulla oblongata tumor. Age, sex, histology and clinical behavior are within the scope of iGCT except for extraordinary high frequency of basal ganglia GCTs. CONCLUSIONS: iGCTs with MTOR mutation are frequent in iGCTs in basal ganglia. SECONDARY CATEGORY: Pediatrics.

Primary intracranial germ cell tumours: Experience of a single South-East Asian institution

Primary intracranial germ cell tumours (ICGCT) are a rare group of brain tumours arising predominantly in the paediatric and pre-adult population, accounting for up to 9.5% of paediatric brain tumours in East Asia. The National Cancer Centre Singapore (NCCS) is a tertiary referral centre for patients from all over South-East Asia. Our study aims to describe the characteristics of ICGCT patients in South-East Asia. Data on all patients with ICGCT who were seen at the Therapeutic Radiology Department of NCCS from 2000 to 2013 were collected retrospectively. Patient demographics, disease characteristics and treatment outcomes were analysed. Characteristics and survival of our patients were similar to other centres. Pure germinomas demonstrated 5year overall survival (OS) and disease-free survival (DFS) rates of 89.2% (95% confidence interval [CI] 60.2–97.5) and 85.2% (95%CI 60.8–95.0) respectively. Secreting germinomas, non-germinomatous germ cell tumours and mixed germ cell tumours were evaluated together and demonstrated 5year OS of 70.6% (95%CI 41.0–87.3) and DFS of 61.4% (95%CI 31.9–81.3). Patients ⩽12years had marginally better 5year OS than their older counterparts (81.0% [95%CI 49.5–93.9] versus 77.9% [95%CI 47.3–92.0], respectively). Patients who underwent extended field radiotherapy had longer OS and DFS than those who received local field irradiation. Treatment outcomes of our ICGCT patients are comparable with those in other Asian and Western centres. Extended field radiotherapy is a pivotal component of ICGCT treatment. Adding chemotherapy confers no extra survival benefit in treating germinomas. Treatment of mixed germ cell tumours and non-germinomatous germ cell tumours involves a multidisciplinary approach that varies for each histological subtype.

The pathogenesis of intracranial growing teratoma syndrome: proliferation of tumor cells or formation of multiple expanding cysts? Two case reports and review of the literature

Growing teratoma syndrome (GTS) is a rare clinical phenomenon defined as the paradoxical growth of mature teratoma components during or after chemotherapy. The mechanism of this phenomenon is not well understood. We present two cases of pineal mixed germ cell tumors that exhibited the similar course to GTS and speculate its pathogenesis. The first case was accompanied by slightly elevated alpha-fetoprotein (8.8 ng/ml; normal <6.6 ng/ml). The tumor rapidly grew from 1.5 to 2.7 cm in diameter within 4 weeks. Despite this rapid preoperative growth, thorough pathological investigation found only mature teratoma components along with multiple micro- and macro-cysts. The other case was diagnosed as a pure germinoma based on biopsy and serological examinations. During three courses of chemotherapy, this tumor presented a honeycomb-like appearance on magnetic resonance (MR) images and an exceptionally rapid enlargement. Second-look surgery confirmed the histological diagnosis of a mature teratoma. In both cases, meticulous pathological examination of all whole tumor sections revealed no malignant histological features, and the MIB-1 labeling indices were too low to account for the extremely rapid tumor growth. Instead, both MR images and histological findings demonstrated a predominant formation of multiple cysts. We speculate that this paradoxical growth might not be tumorous proliferation but instead the formation and expansion of multiple cysts inside mature teratoma components and that the presence or absence of growth might be a subsidiary phenomenon. Our hypothesis appears consistent with the characteristic radiological findings of GTS reported in the literature.

Intensive chemotherapy followed by reduced-dose radiotherapy for biopsy-proven CNS germinoma with elevated beta-human chorionic gonadotropin

In this study, 10 patients with biopsy-proven germinoma with a beta-human chorionic gonadotropin (β-HCG) level >50 mIU/ml received intensive chemotherapy followed by reduced-dose radiotherapy (RT) to reduce late effects from RT. CSF β-HCG levels were >200 mIU/ml in five patients. After endoscopic or stereotactic biopsy, four cycles of induction chemotherapy were administered prior to RT. A CEB regimen (carboplatin+etoposide+bleomycin) and a CyEB regimen (cyclophosphamide+etoposide+bleomycin) were alternated. No residual tumor remained after induction chemotherapy in six patients, only cystic lesions were present at the primary tumor site in three, and a small solid residual tumor was observed in the remaining patient; however, all these patients had normal β-HCG levels. If complete response was achieved before initiation of RT, 19.5Gy craniospinal RT (CSRT)+10.8Gy local RT was administered to the tumor bed. If residual lesion was suspected, the dose of RT was selected according to the presence/absence of tumor dissemination at diagnosis (19.5Gy CSRT+19.8Gy local RT for localized tumors and 24.0Gy CSRT+16.2Gy local RT for disseminated tumors). Eight patients, including four patients with a β-HCG level >200mIU/ml, received 19.5Gy CSRT. All patients remain disease free at a median follow-up of 58 (range 35-94) months from diagnosis. Our data suggest that pathologically pure germinoma with a significantly elevated β-HCG level might be cured with reduced-dose RT if intensive chemotherapy is provided.

Mutually exclusive mutations of KIT and RAS are associated with KIT mRNA expression and chromosomal instability in primary intracranial pure germinomas

Intracranial germ cell tumors (iGCTs) are the second most common brain tumors among children under 15 in Japan. The pathogenesis of iGCTs is largely unexplored. Although a subset of iGCTs is known to have KIT mutation, its impact on the biology and patients' survival has not been established. In this study, we investigated genes involved in the KIT signaling pathway. 65 iGCTs (30 pure germinomas, 14 teratomas, 18 mixed GCTs, 2 yolk sac tumors, 1 choriocarcinoma) were screened for mutation of KIT, KRAS, NRAS, HRAS, BRAF, PDGFRA, and IDH1 by direct sequencing. KIT expression was examined by immunohistochemistry and quantitative PCR. Chromosomal status was analyzed by array-comparative genomic hybridization (aCGH). Somatic mutations were detected only in KIT and RAS, which were frequently observed in pure germinomas (60.0%), but rare in non-germinomatous GCTs (NGGCTs) (8.6%). All KIT/RAS mutations were mutually exclusive. Regardless of the mutation status or mRNA expression, the KIT protein was expressed in all germinomas, while only in 54.3% of NGGCTs. Amplification of KIT was found in one pure germinoma by aCGH. In pure germinomas, high expression of KIT mRNA was associated with the presence of KIT/RAS alterations and severe chromosomal instability. Our results indicate that alterations of the KIT signaling pathway play an important role in the development of germinomas. Pure germinomas may develop through two distinct pathogeneses: one with KIT/RAS alterations, elevated KIT mRNA expression and severe chromosomal instability, and the other through yet an unidentified mechanism without any of the above abnormalities.

Manifestations of CNS germ cell tumors

Sethi et al collected data retrospectively on symptoms, as well as time to and method of diagnosis, in 70 pediatric patients with an intracranial germ cell tumor (GCT) cared for at the Massachusetts General Hospital from 1998 to 2012. Forty patients had a pure germinoma (PG) and 30 had a nongerminomatous GCT. More than one-half of patients were evaluated by one or more pediatric subspecialists prior to diagnosis and more than one-half of patients had a delay of ≥6 months from onset of symptoms to the diagnostic magnetic resonance imaging study.

Delayed Diagnosis in Children with Intracranial Germ Cell Tumors

To review symptoms and provider history in a large cohort of patients with germ cell tumors (GCTs) to highlight the variety of manifestations and assess the effect of delayed diagnosis on outcomes. Patients treated for intracranial pure germinoma and nongerminomatous GCTs at Massachusetts General Hospital between 1998 and 2012 were included (n = 70). The primary outcome was time from onset of symptoms to diagnostic imaging. Delay was defined as an interval of ≥ 6 months. The median duration of symptoms before diagnostic magnetic resonance imaging was 6 months (range, 2 days to 72 months). Thirty-eight of the 70 patients (54%) had a delayed diagnosis. Patients with suprasellar tumors presented with symptoms related to endocrinopathies, and patients with pineal region tumors presented with symptoms related to hydrocephalus. Most of the patients were evaluated by a general pediatrician (49%) and/or pediatric subspecialists (66%) before diagnosis. Patients with delayed diagnosis saw a greater number of physicians before diagnosis (P = .006). The majority of patients (63%) with delayed diagnosis were seen by 2 or more physicians, and many (40%) were seen by 2 or more subspecialists. Progression-free survival was similar in the patients with delayed diagnosis and those without delayed diagnosis (P = .90), but the former were more likely to present with disseminated disease at diagnosis (34% vs 6%; P = .007). A significant proportion of patients with GCT experience a delay in time to diagnosis, in some cases despite evaluation by general pediatricians and specialists. This delay increases the risk of disseminated disease.

Multimodality treatment for intracranial germ cell tumors: Experience from an Asian tertiary hospital.

e13027 Background: Intracranial germ cell tumors (GCTs) represent up to 11 percent of pediatric central nervous system (CNS) tumors in Asia. We compared the efficacy of radiotherapy alone (RT) with platinum-based chemotherapy (CT) in combination with dose-attenuated RT. Methods: We identified 61 patients treated at National Cancer Centre Singapore from 1995 to 2011. Patient’s demographics, histopathologic characteristics and survival data were collected. Median follow up was 39 months. Results: Forty-eight (79%) patients were male; mean age at diagnosis was 17 years. Most (87%) patients had pineal or suprasellar tumors. The distribution of pure germinomas, non-germinomatous tumors and mixed tumors was 54 (89%), 5 (8%) and 2 (3%) patients, respectively. Twenty patients had RT alone, 2 had CT alone, and 31 received a combination of CT and attenuated RT. There was no difference in overall survival (OS) between unifocal or multifocal disease (p = 0.81). Amongst the germinomas, there was no difference in OS between patients given RT alone and CT combined with attenuated RT (median OS not reached vs 145 months, respectively, p = 0.668). Conclusions: Treatment with CT followed by dose attenuated RT is an alternative to conventional craniospinal RT and did not compromise survival in patients with germinomas. This may represent a therapeutic modality with a more favorable long term toxicity profile in these patients who have excellent long term outcomes.

Bifocal intracranial tumors of nongerminomatous germ cell etiology: diagnostic and therapeutic implications

Patients presenting with synchronous bifocal intracranial tumors (masses in the pineal and neurohypophyseal region), detectable human chorionic gonadotropin (hCG) levels (5-100 mIU/mL), and normal alpha feto-protein (AFP) levels (≤10 ng/mL) are often diagnosed empirically with pure germinoma. In such scenarios, pathologic confirmation is often deferred, given that bifocal nongerminomatous germ cell tumors (NGGCTs) are considered rare and because available literature and research protocols support such an approach. We sought to characterize the association between bifocal intracranial tumors and NGGCT histology. Seventy-one patients treated for intracranial germ cell tumors at Massachusetts General Hospital in 1998-2012 were identified. Patients presenting with synchronous bifocal disease were selected for further review. Of the 71 patients presenting with intracranial germ cell tumors, 14 (19.7%) had synchronous bifocal disease. Of these 14 patients, 7 (50.0%) had germinoma, 3 (21.4%) had NGGCT, and 4 (28.6%) had hCG levels <200 mIU/mL and normal AFP levels and were treated without pathologic confirmation. Of the 3 patients with confirmed bifocal NGGCT, 2 had detectable hCG levels with AFP <10 ng/mL and 1 patient had a detectable hCG level with a modest elevation in AFP. NGGCTs should be considered in the differential diagnosis for patients presenting with bifocal intracranial tumors. Given differences in the management of germinomas and NGGCTs, clinicians should strongly consider a biopsy in patients presenting with bifocal masses and normal or modestly elevated biomarkers. Misclassification of such cases as germinomas could result in undertreatment and a possible increased risk for recurrence.

Abstract LB-355: Whole-exome sequencing of intracranial germ cell tumors reveals frequent mutations in KIT and RAS pathways and histone demethylases.

Abstract Intracranial germ cell tumors (IGCTs) are a group of rare pediatric brain tumors affecting mainly male adolescents and young adults. The incidence of IGCTs varies significantly according to geographic locations with the highest incidence in Japan and other East Asian countries. Taken together, these characteristics suggest predisposing germline factors. IGCTs can be divided into two main groups, pure germinoma and nongerminomatous germ cell tumor (NGGCT). The former in general responds well to chemoradiotherapy whereas the latter has a rather poor prognosis. Currently the only known gene associated with this disease is KIT, which is mutated in ~25% of IGCTs. Due to the scarcity of tissues available for research, the molecular biology of IGCTs remains largely unknown. Thus, deeper understanding of the pathogenesis of these unusual tumors should lead to new insights into the underlying cancer biology and the development of novel therapeutics for this rare and deadly disease. Using whole-exome sequencing and SNP array, we have analyzed 28 IGCT tumors (12 pure germinomas, 12 NGGCTs and 4 mixed GCTs) collected from Japan (21), Hong Kong (4) and United States (3). Somatic mutations of KIT were detected in 29% of cases, primarily in germinomas. In an additional 38% of the cases, deleterious somatic mutations were identified in important downstream mediators of KIT signal transduction including KRAS, NRAS, MTOR and their respective regulators, NF1 and PTEN. Mutations in KIT were mutually exclusive with mutations in RAS. Furthermore, 21% of patients showed inactivation of tumor suppressor genes (TSGs) including BCORL1, PTEN, NF1 and SMAD3. Inactivation of TSGs coexisted in tumors with activation of KIT/RAS oncogenes, suggesting these mutations act cooperatively in tumorigenesis. Copy-number analysis revealed almost exclusively arm-level gains and losses. Over 90% of the germinomas exhibited chromosomal imbalance and uniparental disomy of multiple chromosomes, suggesting aberrant meiotic division may possibly play a role in the pathogenesis of this disease. Patterns of chromosome imbalance within a given tumor revealed subclonal structure in 58% of the analyzed cases. Finally, we found in this cohort a significant enrichment (39%) of novel or rare germline variants in histone demethylases, compared with the control cohorts, suggesting epigenetic deregulation may be an important early event in tumorigenesis. One histone demethylase harbored a risk allele present at significantly higher frequency in our male cases compared to a Japanese control population, a finding that could explain both the population prevalence and sex differences in this disease. This study has important implications for our understanding of the pathogenesis of IGCTs, and suggests potential targets for the development of therapeutics focused on inhibitors of KIT/RAS activation. Citation Format: Linghua Wang, Shigeru Yamaguchi, Keita Terashima, Matthew D. Burstein, Jiayi M. Sun, Tomonari Suzuki, Ryo Nishikawa, Hideo Nakamura, Atsushi Natsume, Shunsuke Terasaka, Ho-Keung Ng, Robert C. Dauser, William E. Whitehead, Adesina M. Adekunle, Donna M. Muzny, Richard A. Gibbs, Ching C. Lau, David A. Wheeler. Whole-exome sequencing of intracranial germ cell tumors reveals frequent mutations in KIT and RAS pathways and histone demethylases. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-355. doi:10.1158/1538-7445.AM2013-LB-355

Paediatric germ cell tumours of the central nervous system: Results and experience from a tertiary-referral paediatric institution in Australia

A retrospective analysis was conducted on consecutive patients with intracranial germ cell tumours diagnosed and treated from 1 January 1997 to 31 December 2007 to assess and determine demographic factors and treatment outcomes of children with these tumours treated in a major paediatric referral hospital in Australia. In this study, intracranial germ cell tumours represented 4.8% of paediatric brain tumours seen. Of the 21 patients identified, 15 (71.4%) were diagnosed with pure germinoma and six (28.6%) with non-germinomatous germ cell tumours (NGGCT) or mixed tumours. One patient received chemotherapy alone, two patients were treated with radiation alone and the remaining 18 received a combination of chemotherapy and radiotherapy. A total of 33 neurosurgical operations were performed with 15 biopsies via open, endoscopic or transphenoidal means; nine open resections; and nine procedures for hydrocephalus comprising seven third ventriculostomies and two ventriculoperitoneal shunts. For patients with pure germinomas, the 5-year disease-free rate (DFS) was 93.3%, and overall survival (OS) rate was 100% compared to NGGCT or mixed tumours (DFS 50%; OS 50%) (DFS p=0.019, OS p=0.004). The data presented show that pure germinomas carry a favourable prognosis. The data also support that treatment with induction chemotherapy followed by dose-attenuated radiotherapy is an effective alternative with results comparable to historical controls treated with craniospinal irradiation. Although chemoradiotherapy has become the mainstay of treatment in intracranial germ cell tumours, surgery remains integral to the management of this condition. Surgery remains important in establishing the histological diagnosis, as well as in the treatment of hydrocephalus. Furthermore, debulking procedures may be advocated in NGGCT as they are often resistant to chemotherapy.