In vitro co-culture model of medulloblastoma and human neural stem cells for drug delivery assessment

Physiologically relevant in vitro models can serve as biological analytical platforms for testing novel treatments and drug delivery systems. We describe the first steps in the development of a 3D human brain tumour co-culture model that includes the interplay between normal and tumour tissue along with nutrient gradients, cell-cell and cell-matrix interactions. The human medulloblastoma cell line UW228-3 and human foetal brain tissue were marked with two supravital fluorescent dyes (CDCFDASE, Celltrace Violet) and cultured together in ultra-low attachment 96-well plates to form reproducible single co-culture spheroids (d = 600 μm, CV% = 10%). Spheroids were treated with model cytotoxic drug etoposide (0.3-100 μM) and the viability of normal and tumour tissue quantified separately using flow cytometry and multiphoton microscopy. Etoposide levels of 10 μM were found to maximise toxicity to tumours (6.5% viability) while stem cells maintained a surviving fraction of 40%. The flexible cell marking procedure and high-throughput compatible protocol make this platform highly transferable to other cell types, primary tissues and personalised screening programs. The model's key anticipated use is for screening and assessment of drug delivery strategies to target brain tumours, and is ready for further developments, e.g. differentiation of stem cells to a range of cell types and more extensive biological validation.

Energy metabolism in neurodevelopment and medulloblastoma

New, less toxic therapies are needed for medulloblastoma, the most common malignant brain tumor in children. Like many cancers, medulloblastomas demonstrate metabolic patterns that are markedly different from the surrounding non-neoplastic tissue and are highly organized to support tumor growth. Key aspects of medulloblastoma metabolism, including increased lipogenesis and aerobic glycolysis are derived from the metabolic programs of neural progenitors. During neural development, Sonic Hedgehog (Shh) signaling induces lipogenesis and aerobic glycolysis in proliferating progenitors to support rapid growth. Shh-regulated transcription induces specific genes, including hexokinase 2 (Hk2) and fatty acid synthase (FASN) that mediate these metabolic patterns. Medulloblastomas co-opt these developmentally-regulated patterns of metabolic gene expression for sustained tumor growth. Additionally, medulloblastomas limit protein translation through activation of eukaryotic elongation factor 2 kinase (eEF2K), to restrict energy expenditure. The activation of eEF2K reduces the need to generate ATP, enabling reduced dependence on oxidative phosphorylation and increased metabolism of glucose through aerobic glycolysis. Lipogenesis, aerobic glycolysis and restriction of protein translation operate in a network of metabolic processes that is integrated by adenosine monophosphate-activated protein kinase (AMPK) to maintain homeostasis. The homeostatic effect of AMPK has the potential to limit the impact of metabolically targeted interventions. Through combinatorial targeting of lipogenesis, glycolysis and eEF2K, however, this homeostatic effect may be overcome. We propose that combinatorial targeting of medulloblastoma metabolism may produce the synergies needed for effective anti-cancer therapy.

Basal cell nevus syndrome or Gorlin syndrome

Basal cell nevus syndrome (BCNS) or Gorlin syndrome is a rare neurocutaneous syndrome sometimes known as the fifth phacomatosis, inherited in autosomal dominant fashion with complete penetrance and variable expressivity. Gorlin syndrome is characterized by development of multiple basal cell carcinomas (BCCs), jaw cysts, palmar or plantar pits, calcification of falx cerebri, various developmental skeletal abnormalities such as bifid rib, hemi- or bifid vertebra and predisposition to the development of various tumors. BCNS is caused by a mutation in the PTCH1 gene localized to 9q22.3. Its estimated prevalence varies between 1/55600 and 1/256000 with an equal male to female ratio. The medulloblastoma variant seen in Gorlin syndrome patients is of the desmoplastic type, characteristically presenting during the first 3 years of life. Therefore, children with desmoplastic medulloblastoma should be carefully screened for other features of BCNS. Radiation therapy for desmoplastic medulloblastoma should be avoided in BCNS patients as it may induce development of invasive BCCs and other tumors in the skin area exposed to radiation. This syndrome is a multisystem disorder so involvement of multiple specialists with a multimodal approach to detect and treat various manifestations at early stages will reduce the long-term sequelae and severity of the condition. Life expectancy is not significantly altered but morbidity from complications and cosmetic scarring can be substantial.

Development of the cerebellum: simple steps to make a 'little brain'

The cerebellum is a pre-eminent model for the study of neurogenesis and circuit assembly. Increasing interest in the cerebellum as a participant in higher cognitive processes and as a locus for a range of disorders and diseases make this simple yet elusive structure an important model in a number of fields. In recent years, our understanding of some of the more familiar aspects of cerebellar growth, such as its territorial allocation and the origin of its various cell types, has undergone major recalibration. Furthermore, owing to its stereotyped circuitry across a range of species, insights from a variety of species have contributed to an increasingly rich picture of how this system develops. Here, we review these recent advances and explore three distinct aspects of cerebellar development - allocation of the cerebellar anlage, the significance of transit amplification and the generation of neuronal diversity - each defined by distinct regulatory mechanisms and each with special significance for health and disease.

Design, synthesis, and evaluation of hybrid vitamin D3 side chain analogues as hedgehog pathway inhibitors

Vitamin D3 (VD3) is a moderately potent and non-selective inhibitor of the Hedgehog (Hh) signaling cascade. Previous studies have established that the CD-ring region of VD3 serves as the Hh inhibitory pharmacophore. Subsequently, compound 3, an ester linked aromatic A-ring and CD-ring derivative was identified as an improved and selective Hh inhibitor. Herein, we report modifications of the CD-ring side chain that afford enhancement of selectivity for Hh modulation thereby diminishing the detrimental effects of concomitant vitamin D receptor activation. In general, linear or moderately branched alkyl chains of five or six carbons were optimal for potent and selective inhibition of Hh signaling. Moreover, hybrid VD3 side chain derivative 20 demonstrated 4-fold improvement in Hh antagonistic activity over VD3(IC50=1.1-1.6 μM) while gaining greater than a 1000-fold selectivity for Hh signaling over canonical activation of the vitamin D receptor pathway.

Patterns of Failure Following Multimodal Treatment for Medulloblastoma: Long-Term Follow-up Results at a Single Institution

Purpose

The purpose of this study is to investigate the long-term results and appropriateness of radiation therapy (RT) for medulloblastoma (MB) at a single institution.

Materials and Methods

We analyzed the clinical outcomes of 106 patients with MB who received RT between January 1992 and October 2009. The median age was 7 years (range, 0 to 50 years), and the proportion of M0, M1, M2, and M3 stages was 60.4%, 8.5%, 4.7%, and 22.6%, respectively. The median total craniospinal irradiation (CSI) and posterior fossa tumor bed dose in 102 patients (96.2%) treated with CSI was 36 Gy and 54 Gy, respectively.

Results

The median follow-up period in survivors was 132 months (range, 31 to 248 months). A gradual improvement in survival outcomes was observed, with 5-year overall survival rates of 61.5% in 1990s increasing to 73.6% in 2000s. A total of 29 recurrences (27.4%) developed at the following sites: five (17.2%) in the tumor bed; five (17.2%) in the posterior fossa other than the tumor bed; nine (31%) in the supratentorium; and six (20.7%) in the spinal subarachnoid space only. The four remaining patients showed multiple site recurrences. Among 12 supratentorial recurrences, five cases recurred in the subfrontal areas. Although the frequency of posterior fossa/tumor bed recurrences was significantly high among patients treated with subtotal resection, other site (other intracranial/spinal) recurrences were more common among patients treated with gross tumor removal (p=0.016). There was no case of spinal subarachnoid space relapse from desmoplastic/extensive nodular histological subtypes.

Conclusion

Long-term follow-up results and patterns of failure confirmed the importance of optimal RT dose and field arrangement. More tailored multimodal strategies and proper CSI technique may be the cornerstones for improving treatment outcomes in MB patients.

The BET bromodomain inhibitor I-BET151 acts downstream of smoothened protein to abrogate the growth of hedgehog protein-driven cancers

Epigenetic enzymes modulate signal transduction pathways in different biological contexts. We reasoned that epigenetic regulators might modulate the Hedgehog (HH) signaling pathway, a main driver of cell proliferation in various cancers including medulloblastoma. To test this hypothesis, we performed an unbiased small-molecule screen utilizing an HH-dependent reporter cell line (Light2 cells). We incubated Light2 cells with small molecules targeting different epigenetic modulators and identified four histone deacetylase inhibitors and a bromodomain and extra terminal domain (BET) protein inhibitor (I-BET151) that attenuate HH activity. I-BET151 was also able to inhibit the expression of HH target genes in Sufu(-/-) mouse embryonic fibroblasts, in which constitutive Gli activity is activated in a Smoothened (Smo)-independent fashion, consistent with it acting downstream of Smo. Knockdown of Brd4 (which encodes one of the BET proteins) phenocopies I-BET151 treatment, suggesting that Brd4 is a regulator of the HH signaling pathway. Consistent with this suggestion, Brd4 associates with the proximal promoter region of the Gli1 locus, and does so in a manner that can be reversed by I-BET151. Importantly, I-BET151 also suppressed the HH activity-dependent growth of medulloblastoma cells, in vitro and in vivo. These studies suggest that BET protein modulation may be an attractive therapeutic strategy for attenuating the growth of HH-dependent cancers, such as medulloblastoma.

A novel small molecular STAT3 inhibitor, LY5, inhibits cell viability, cell migration, and angiogenesis in medulloblastoma cells

Signal transducers and activators of transcription 3 (STAT3) signaling is persistently activated and could contribute to tumorigenesis of medulloblastoma. Numerous studies have demonstrated that inhibition of the persistent STAT3 signaling pathway results in decreased proliferation and increased apoptosis in human cancer cells, indicating that STAT3 is a viable molecular target for cancer therapy. In this study, we investigated a novel non-peptide, cell-permeable small molecule, named LY5, to target STAT3 in medulloblastoma cells. LY5 inhibited persistent STAT3 phosphorylation and induced apoptosis in human medulloblastoma cell lines expressing constitutive STAT3 phosphorylation. The inhibition of STAT3 signaling by LY5 was confirmed by down-regulating the expression of the downstream targets of STAT3, including cyclin D1, bcl-XL, survivin, and micro-RNA-21. LY5 also inhibited the induction of STAT3 phosphorylation by interleukin-6 (IL-6), insulin-like growth factor (IGF)-1, IGF-2, and leukemia inhibitory factor in medulloblastoma cells, but did not inhibit STAT1 and STAT5 phosphorylation stimulated by interferon-γ (IFN-γ) and EGF, respectively. In addition, LY5 blocked the STAT3 nuclear localization induced by IL-6, but did not block STAT1 and STAT5 nuclear translocation mediated by IFN-γ and EGF, respectively. A combination of LY5 with cisplatin or x-ray radiation also showed more potent effects than single treatment alone in the inhibition of cell viability in human medulloblastoma cells. Furthermore, LY5 demonstrated a potent inhibitory activity on cell migration and angiogenesis. Taken together, these findings indicate LY5 inhibits persistent and inducible STAT3 phosphorylation and suggest that LY5 is a promising therapeutic drug candidate for medulloblastoma by inhibiting persistent STAT3 signaling.

A comparative study on the risks of radiogenic second cancers and cardiac mortality in a set of pediatric medulloblastoma patients treated with photon or proton craniospinal irradiation

PURPOSE

To compare the risks of radiogenic second cancers and cardiac mortality in 17 pediatric medulloblastoma patients treated with passively scattered proton or field-in-field photon craniospinal irradiation (CSI).

MATERIAL/METHODS

Standard of care photon or proton CSI treatment plans were created for all 17 patients in a commercial treatment planning system (TPS) (Eclipse version 8.9; Varian Medical Systems, Palo Alto, CA) and prescription dose was 23.4 or 23.4 Gy (RBE) to the age specific target volume at 1.8 Gy/fraction. The therapeutic doses from proton and photon CSI plans were estimated from TPS. Stray radiation doses were determined from Monte Carlo simulations for proton CSI and from measurements and TPS for photon CSI. The Biological Effects of Ionization Radiation VII report and a linear model based on childhood cancer survivor data were used for risk predictions of second cancer and cardiac mortality, respectively.

RESULTS

The ratios of lifetime attributable risk (RLARs) (proton/photon) ranged from 0.10 to 0.22 for second cancer incidence and ranged from 0.20 to 0.53 for second cancer mortality, respectively. The ratio of relative risk (RRR) (proton/photon) of cardiac mortality ranged from 0.12 to 0.24. The RLARs of both cancer incidence and mortality decreased with patient's age at exposure (e), while the RRRs of cardiac mortality increased with e. Girls had a significantly higher RLAR of cancer mortality than boys.

CONCLUSION

Passively scattered proton CSI provides superior predicted outcomes by conferring lower predicted risks of second cancer and cardiac mortality than field-in-field photon CSI for all medulloblastoma patients in a large clinically representative sample in the United States, but the magnitude of superiority depends strongly on the patients' anatomical development status.

Developmental and oncogenic radiation effects on neural stem cells and their differentiating progeny in mouse cerebellum

Neural stem cells are highly susceptible to radiogenic DNA damage, however, little is known about their mechanisms of DNA damage response (DDR) and the long-term consequences of genotoxic exposure. Patched1 heterozygous mice (Ptc1(+/-)) provide a powerful model of medulloblastoma (MB), a frequent pediatric tumor of the cerebellum. Irradiation of newborn Ptc1(+/-) mice dramatically increases the frequency and shortens the latency of MB. In this model, we investigated the mechanisms through which multipotent neural progenitors (NSCs) and fate-restricted progenitor cells (PCs) of the cerebellum respond to DNA damage induced by radiation, and the long-term developmental and oncogenic consequences. These responses were assessed in mice exposed to low (0.25 Gy) or high (3 Gy) radiation doses at embryonic day 13.5 (E13.5), when NSCs giving rise to the cerebellum are specified but the external granule layer (EGL) has not yet formed, or at E16.5, during the expansion of granule PCs to form the EGL. We found crucial differences in DDR and apoptosis between NSCs and fate-restricted PCs, including lack of p21 expression in NSCs. NSCs also appear to be resistant to oncogenesis from low-dose radiation exposure but more vulnerable at higher doses. In addition, the pathway to DNA repair and the pattern of oncogenic alterations were strongly dependent on age at exposure, highlighting a differentiation-stage specificity of DNA repair pathways in NSCs and PCs. These findings shed light on the mechanisms used by NSCs and PCs to maintain genome integrity during neurogenesis and may have important implications for radiation risk assessment and for development of targeted therapies against brain tumors.

Cushing's reflex in a rare case of adult medulloblastoma

BACKGROUND

Medulloblastoma is a primitive neuro-ectodermal tumor. It is common in childhood, but rarely seen at adult age, comprising only 1% of primary brain tumors.

METHODS

We treated a 31-year-old man presented to the emergency department (ED) with a chief complaint of nausea and vomiting for one week duration. Immediate frozen section revealed a grade IV medulloblastoma. During the hospital course, the patient was given craniospinal irradiation with chemotherapy.

RESULTS

The patient was eventually discharged from the hospital to an assisted living facility after an uneventful 15-day course with the aid of social work.

CONCLUSIONS

Despite intracranial tumors generally being slow growing masses, this patient demonstrates how quickly one can decompensate, and how important it is to recognize these clinical signs and symptoms of an intracranial lesion. Although these symptoms (i.e. Cushing response) are extremely rare, the ED physician should be aware and appreciate their clinical significance.

Dasatinib suppression of medulloblastoma survival and migration is markedly enhanced by combining treatment with the aurora kinase inhibitor AT9283

Medulloblastoma (MB) expresses Src kinase, while aurora kinase A overexpression correlates with poor survival. We thus investigated novel combination treatment with dasatinib and AT9283, inhibitors of Src and aurora kinase, respectively, on MB growth in vitro and in vivo. Treatment with each drug significantly reduced cell viability and combined treatment markedly potentiated this response. AT9283 induced p53 expression, autophagy, and G2/M cell-cycle arrest, while combined treatment induced S phase arrest. Dasatinib treatment caused tumor regression in vivo. Activated Src was detected in 44% MB analyzed. We conclude that further evaluation of this combination therapy for MB is highly warranted.

Extra-axial medulloblastoma in cerebello-pontine angle: A report of a rare case with literature review

Medulloblastoma is quite uncommon in the adult population and even rarer in extra-axial site in cerebello-pontine (CP) angle. In this report, a 23-year-old male patient with a two month history of deafness, nausea, vomiting and ataxia is presented. Clinical and radiological findings demonstrated a heterogeneously enhanced extra-axial lesion in the right CP angle. Total excision was performed and the histopathological features of medulloblastoma were confirmed. After surgery, the patient had no neurological deficit and the audiometric findings were improved. In addition, he underwent adjuant radiotherapy and no sign of metastatic mass was observed in follow-up spinal cord MRI. Although extremely rare, medulloblastoma must be considered in the differential diagnosis of extra-axial CP angle lesions.

miR-let-7f-1 regulates SPARC mediated cisplatin resistance in medulloblastoma cells

Our previous studies indicate that Secreted Protein Acidic and Rich in Cysteine (SPARC) expression suppressed medulloblastoma tumor growth in vitro and in vivo. Here we sought to determine the effect of SPARC expression in medulloblastoma cells to chemotherapeutic agents. In this study, we show that SPARC expression induces cisplatin resistance in medulloblastoma cells. We also demonstrate that the autophagy was involved in SPARC expression mediated resistance to cisplatin. Suppression of autophagy by either autophagy inhibitor, 3-methyladenosine (3MA) or Atg5 siRNA enhanced cisplatin sensitivity in SPARC expressed cells. Further, SPARC expression suppressed miR-let-7f-1 expression which resulted in disrupted repression of High Mobility Group Box 1 (HMGB1), a critical regulator of autophagy. We also show that HMGB1 is a direct target of miR-let-7f-1 and forced expression of HMGB1 cDNA enhanced cisplatin sensitivity in SPARC expressed cells. In summary, our results suggest that SPARC modulates cisplatin resistance by modulating the Let-7f-1 miRNA/HMGB1 axis in medulloblastoma cells.

Extra-axial medulloblastoma in the cerebellar hemisphere

Extra-axial medulloblastoma is a rare phenomenon. We report a case in a 5-year-old boy who presented with nausea, vomiting, and gait disturbance. He was treated with total removal of the tumor. This is the first case of an extra-axially located medulloblastoma occurring in the cerebellar hemisphere posteriolateral to the cerebellopontine angle in Korea. Although the extra-axial occurrence of medulloblastoma is rare, it should be considered in the differential diagnosis of extra-axial lesions of the posterior fossa in children.

Role of the miR-17∼92 cluster family in cerebellar and medulloblastoma development

The miR-17∼92 cluster family is composed of three members encoding microRNAs that share seed sequences. To assess their role in cerebellar and medulloblastoma (MB) development, we deleted the miR-17∼92 cluster family in Nestin-positive neural progenitors and in mice heterozygous for the Sonic Hedgehog (SHH) receptor Patched 1 (Ptch1(+/-)). We show that mice in which we conditionally deleted the miR-17∼92 cluster (miR-17∼92(floxed/floxed); Nestin-Cre(+)) alone or together with the complete loss of the miR-106b∼25 cluster (miR-106b∼25(-/-)) were born alive but with small brains and reduced cerebellar foliation. Remarkably, deletion of the miR-17∼92 cluster abolished the development of SHH-MB in Ptch1(+/-) mice. Using an orthotopic transplant approach, we showed that granule neuron precursors (GNPs) purified from the cerebella of postnatal day 7 (P7) Ptch1(+/-); miR-106b∼25(-/-) mice and overexpressing Mycn induced MBs in the cortices of naïve recipient mice. In contrast, GNPs purified from the cerebella of P7 Ptch1(+/-); miR-17∼92(floxed/floxed); Nestin-Cre(+) animals and overexpressing Mycn failed to induce tumors in recipient animals. Taken together, our findings demonstrate that the miR-17∼92 cluster is dispensable for cerebellar development, but required for SHH-MB development.

Secreted meningeal chemokines, but not VEGFA, modulate the migratory properties of medulloblastoma cells

Leptomeningeal metastasis is a cause of morbidity and mortality in medulloblastoma, but the understanding of molecular mechanisms driving this process is nascent. In this study, we examined the secretory chemokine profile of medulloblastoma cells (DAOY) and a meningothelial cell line (BMEN1). Conditioned media (CM) of meningothelial cells increased adhesion, spreading and migration of medulloblastoma. VEGFA was identified at elevated levels in the CM from BMEN1 cells (as compared to DAOY CM); however, recombinant VEGFA alone was insufficient to enhance medulloblastoma cell migration. In addition, bevacizumab, the VEGFA scavenging monoclonal antibody, did not block the migratory phenotype induced by the CM. These results reveal that paracrine factors secreted by meningothelial cells can influence migration and adherence of medulloblastoma tumor cells, but VEGFA may not be a specific target for therapeutic intervention in this context.

Zebrafish reporter lines reveal in vivo signaling pathway activities involved in pancreatic cancer

Pancreatic adenocarcinoma, one of the worst malignancies of the exocrine pancreas, is a solid tumor with increasing incidence and mortality in industrialized countries. This condition is usually driven by oncogenic KRAS point mutations and evolves into a highly aggressive metastatic carcinoma due to secondary gene mutations and unbalanced expression of genes involved in the specific signaling pathways. To examine in vivo the effects of KRAS^G12D during pancreatic cancer progression and time correlation with cancer signaling pathway activities, we have generated a zebrafish model of pancreatic adenocarcinoma in which eGFP-KRAS^G12D expression was specifically driven to the pancreatic tissue by using the GAL4/UAS conditional expression system. Outcrossing the inducible oncogenic KRAS^G12D line with transgenic zebrafish reporters, harboring specific signaling responsive elements of transcriptional effectors, we were able to follow TGFβ, Notch, Bmp and Shh activities during tumor development. Zebrafish transgenic lines expressing eGFP-KRAS^G12D showed normal exocrine pancreas development until 3 weeks post fertilization (wpf). From 4 to 24 wpf we observed several degrees of acinar lesions, characterized by an increase in mesenchymal cells and mixed acinar/ductal features, followed by progressive bowel and liver infiltrations and, finally, highly aggressive carcinoma. Moreover, live imaging analysis of the exocrine pancreatic tissue revealed an increasing number of KRAS-positive cells and progressive activation of TGFβ and Notch pathways. Increase in TGFβ, following KRAS^G12D activation, was confirmed in a concomitant model of medulloblastoma (MDB). Notch and Shh signaling activities during tumor onset were different between MDB and pancreatic adenocarcinoma, indicating a tissue-specific regulation of cell signaling pathways. Moreover, our results show that a living model of pancreatic adenocarcinoma joined with cell signaling reporters is a suitable tool for describing in vivo the signaling cascades and molecular mechanisms involved in tumor development and a potential platform to screen for novel oncostatic drugs.

FoxG1 interacts with Bmi1 to regulate self-renewal and tumorigenicity of medulloblastoma stem cells

Brain tumors represent the leading cause of childhood cancer mortality, of which medulloblastoma (MB) is the most frequent malignant tumor. Recent studies have demonstrated the presence of several MB molecular subgroups, each distinct in terms of prognosis and predicted therapeutic response. Groups 1 and 2 are characterized by relatively good clinical outcomes and activation of the Wnt and Shh pathways, respectively. In contrast, groups 3 and 4 ("non-Shh/Wnt MBs") are distinguished by metastatic disease, poor patient outcome, and lack a molecular pathway phenotype. Current gene expression platforms have not detected brain tumor-initiating cell (BTIC) self-renewal genes in groups 3 and 4 MBs as BTICs typically comprise a minority of tumor cells and may therefore go undetected on bulk tumor analyses. Since increasing BTIC frequency has been associated with increasing tumor aggressiveness and poor patient outcome, we investigated the subgroup-specific gene expression profile of candidate stem cell genes within 251 primary human MBs from four nonoverlapping MB transcriptional databases (Amsterdam, Memphis, Toronto, Boston) and 74 NanoString-subgrouped MBs (Vancouver). We assessed the functional relevance of two genes, FoxG1 and Bmi1, which were significantly enriched in non-Shh/Wnt MBs and showed these genes to mediate MB stem cell self-renewal and tumor initiation in mice. We also identified their transcriptional regulation through reciprocal promoter occupancy in CD15+ MB stem cells. Our work demonstrates the application of stem cell data gathered from genomic platforms to guide functional BTIC assays, which may then be used to develop novel BTIC self-renewal mechanisms amenable to therapeutic targeting.

Hyperfractionated Accelerated Radiotherapy (HART) with maintenance chemotherapy for metastatic (M1-3) Medulloblastoma--a safety/feasibility study

BACKGROUND AND PURPOSE

To evaluate feasibility and toxicity of Hyperfractionated Accelerated Radiotherapy (HART) 1.24Gy b.i.d. followed by chemotherapy for M1-3 Medulloblastoma (MB). The aim of HART was to use hyperfractionation to improve therapeutic ratio combined with acceleration to minimise tumour cell repopulation during radiotherapy (RT).

MATERIALS AND METHODS

Between February 2002 and May 2008, 34 eligible patients (22 male, 12 female) aged 3-15years (median 7) with metastatic MB (M1-9; M2-3, M3-22) received HART with a craniospinal radiotherapy (CSRT) dose of 39.68Gy followed by 22.32Gy boost to the whole posterior fossa and 9.92Gy metastatic boosts. The 8th and subsequent patients received vincristine (VCR) 1.5mg/m(2) weekly×8 doses over 8weeks starting during the 1st week of RT. Maintenance chemotherapy comprised 8 six-weekly cycles of VCR 1.5mg/m(2) weekly×3, CCNU 75mg/m(2) and cisplatin 70mg/m(2).

RESULTS

Median duration of HART was 34days (range 31-38). Grade 3-4 toxicities included mucositis (8), nausea (10), anaemia (5), thrombocytopaenia (2), leucopaenia (24). With 4.5-year median follow-up, 3-year EFS and OS were 59% and 71%, respectively. Of 10 relapses, 1 was outside the central nervous system (CNS), 1 posterior fossa alone and 8 leptomeningeal with 3 also associated with posterior fossa.

CONCLUSION

HART with or without VCR was well tolerated and may have a place in the multi-modality management of high-risk MB.

Secondary oligodendroglioma after postoperative irradiation for medulloblastoma: a case report and review of the literature

Medulloblastoma, a malignant, invasive embryonal tumor of the cerebellum, occurs most often in children. It has high metastatic potential and is usually treated by aggressive multimodal therapy, including surgery, chemotherapy and craniospinal irradiation. Multiple secondary tumors have been reported following craniospinal irradiation. It is rare with the occurrence of oligodendroglioma after irradiation. In this report, we described a patient with secondary oligodendroglioma after postoperative craniospinal irradiation for medulloblastoma.

Adaptations of energy metabolism during cerebellar neurogenesis are co-opted in medulloblastoma

Recent studies show that metabolic patterns typical of cancer cells, including aerobic glycolysis and increased lipogenesis, are not unique to malignancy, but rather originate in physiologic development. In the postnatal brain, where sufficient oxygen for energy metabolism is scrupulously maintained, neural progenitors nevertheless metabolize glucose to lactate and prioritize lipid synthesis over fatty acid oxidation. Medulloblastoma, a cancer of neural progenitors that is the most common malignant brain tumor in children, recapitulates the metabolic phenotype of brain progenitor cells. During the physiologic proliferation of neural progenitors, metabolic enzymes generally associated with malignancy, including Hexokinase 2 (Hk2) and Pyruvate kinase M2 (PkM2) configure energy metabolism to support growth. In these non-malignant cells, expression of Hk2 and PkM2 is driven by transcriptional regulators that are typically identified as oncogenes, including N-myc. Importantly, N-myc continues to drive Hk2 and PkM2 in medulloblastoma. Similarly E2F transcription factors and PPARγ function in both progenitors and medulloblastoma to optimize energy metabolism to support proliferation. These findings show that the "metabolic transformation" that is a hallmark of cancer is not specifically limited to cancer. Rather, metabolic transformation represents a co-opting of developmental programs integral to physiologic growth. Despite their physiologic origins, the molecular mechanisms that mediate metabolic transformation may nevertheless present ideal targets for novel anti-tumor therapy.

Salinomycin Suppresses PDGFRβ, MYC, and Notch Signaling in Human Medulloblastoma

Medulloblastoma (MB) is the most common childhood brain tumor. Despite improved therapy and management, approximately 30% of patients die of the disease. To search for a more effective therapeutic strategy, the effects of salinomycin were tested on cell proliferation, cell death, and cell cycle progression in human MB cell lines. The results demonstrated that salinomycin inhibits cell proliferation, induces cell death , and disrupts cell cycle progression in MB cells. Salinomycin was also tested on the expression levels of key genes involved in proliferation and survival signaling and revealed that salinomycin down-regulates the expression of PDGFRβ, MYC, p21 and Bcl-2 as well as up-regulates the expression of cyclin A. In addition, the results reveal that salinomycin suppresses the expression of Hes1 and Hes5 in MB cells. Our data shed light on the potential of using salinomycin as a novel therapeutic agent for patients with MB.

Cerebellar mutism

Cerebellar mutism occurs in about 25% of children following posterior fossa tumor surgery. It is usually accompanied by other neurological and behavioral disturbances. Mutism is transient in nature lasting several days to months and is frequently followed by dysarthria. In addition, impairment of language and other neuropsychological functions can be found after long term follow up in the majority of patients. The pathophysiological background of mutism may be higher speech dysfunction mediated by crossed cerebello-cerebral diaschisis which is frequently found during the mute period. Foremost injury to the bilateral dentatothalamocortical tract appears to be critical for the development of cerebello-cerebral diaschisis and subsequent mutism. Direct cerebellar injury is the likely reason for persisting deficits after the mute period. Minimization of injury to the dentatothalamocortical tract during surgery may be promising in the prevention of mutism. While there is no established treatment of mutism, early speech and rehabilitation therapy is recommended.

Comprehensive high-resolution genomic profiling and cytogenetics of two pediatric and one adult medulloblastoma

Medulloblastoma (WHO grade IV) is a rare, malignant, invasive, embryonal tumor which mainly occurs in children and represents less than 1% of all adult brain tumors. Systematic comprehensive genetic analyses on medulloblastomas are rare but necessary to provide more detailed information. Therefore, we performed comprehensive cytogenetic analyses (blood and tissue) of two pediatric and one adult medulloblastoma, using trypsin-Giemsa staining, spectral karyotyping (tissues only), SNP-arrays, and gene expression analyses. We confirmed frequently detected chromosomal aberrations in medulloblastoma, such as +7q, -8p/q, -9q, -11q, -12q, and +17q and identified novel genetic events. Applying SNP-array, we identified constitutional de novo losses 5q21.1, 15q11.2, 17q21.31, 19p12 (pediatric medulloblastoma), 9p21.1, 19p12, 19q13.3, 21q11.2 (adult medulloblastoma) and gains 16p11.1-16p11.2, 18p11.32, Yq11.223-Yq11.23 (pediatric medulloblastoma), Xp22.31 (adult medulloblastoma) possibly representing inherited causal events for medulloblastoma formation. We show evidence for somatic segmental uniparental disomy in regions 1p36, 6q16.3, 6q24.1, 14q21.2, 17p13.3, and 17q22 not previously described for primary medulloblastoma. Gene expression analysis supported classification of the adult medulloblastoma to the WNT-subgroup and classification of pediatric medulloblastomas to group 3 tumors. Analyses of tumors and matched normal tissues (blood) with a combination of complementary techniques will help to further elucidate potentially causal genetic events for medulloblastomas.

Relapse in medulloblastoma: what can be done after abandoning high-dose chemotherapy? A mono-institutional experience

PURPOSE

We retrospectively report strategies used for medulloblastoma patients progressing after craniospinal irradiation where we aimed for: symptom control, a satisfactory quality of life, accrual in phase 1-2 trials, when available, and the first two conditions could no longer be satisfied by already experienced second-line strategies.

METHODS

Surgery was used in cases of doubtful relapse or when only one site was affected. Radiotherapy was given whenever possible, especially to relieve symptoms. The main chemotherapy regimens were oral temozolomide/etoposide, intravenous (iv.) cisplatin/etoposide, iv. gemcitabine/oxaliplatin, an oral sonic hedgehog pathway inhibitor and oral melphalan.

RESULTS

Between 1998 and 2011, we treated 18 patients relapsed after median 20 months. Nine had relapsed locally, four had dissemination, three single metastases, and two had one synchronous local and metastatic recurrence. Responses to chemotherapy were seen in 32% of cases. The median hospital stay for treatments/complications was 19 days. The 1- and 3-year progression-free survival (PFS) rates were 28 ± 10% and 0%, respectively, for OS, they were 44 ± 12% and 22 ± 10% but no patient was cured. The median PFS after a first relapse was 7 months (range 1-29); the median OS was 7 months (range 4-44). No patients died due to treatment toxicity. Late recurrence (more than 1-2 years after diagnosis) and involvement of single sites were favorable prognostic factors.

CONCLUSIONS

Without succeeding in patients cure, we ensured them further treatment with short hospital stay thus affording low personal and social costs. The chances of cure may emerge from tailored therapies according to genetic stratification.

Natural history of a medulloblastoma: 30 months of wait and see in a child with a cerebellar incidentaloma

INTRODUCTION

With the increasing use of neuroimaging studies, the discovery of incidental neoplastic lesions is becoming more frequent. However, standard procedures are lacking, and little is known about their optimal management.

CASE REPORT

We here present the case of a boy with a cerebellar mass incidentally discovered on a CT scan performed after head trauma. In another scan performed after another incident of head trauma 14 months earlier, the lesion could be seen after retrospective examination. In view of the asymptomatic clinical and stable radiological status and the presumed diagnosis of a low-grade glioma, a watch-and-wait strategy was elected. After clinical and radiological progression was observed, the tumour was resected, 2½ years after the initial imaging study. Histological evaluation revealed a WNT pathway-activated classical medulloblastoma.

DISCUSSION

To our knowledge, this is the first description of such a long natural history and pre-symptomatic period of a medulloblastoma. The long period of stability followed by a period of accelerated tumour growth is compatible with increasing biological aggressiveness, possibly related to the stepwise accumulation of genetic changes.

Medulloblastoma in a patient with the PTPN11 p.Thr468Met mutation

Medulloblastoma is the commonest brain tumor in childhood and in a minority of patients is associated with an underlying genetic disorder such as Gorlin syndrome or familial adenomatous polyposis. Increased susceptibility to certain tumors, including neuroblastoma and some hematological malignancies, is recognized in disorders caused by mutations in genes encoding components of the RAS signaling pathway which include Noonan syndrome, Noonan syndrome with multiple lentigines (NSML; formerly called LEOPARD syndrome), Costello syndrome, Cardiofaciocutaneous syndrome, Legius syndrome, and Neurofibromatosis type 1 (NF1), collectively termed RASopathies. Although an association between medulloblastoma and NF1 has been reported, this tumor has not previously been reported in other RASopathies. We present a patient with NSML caused by the recurrent PTPN11 mutation c.1403C > T (p.Thr468Met) in whom medulloblastoma was diagnosed at age 10 years. Medulloblastoma could therefore be part of the tumor spectrum associated with this disorder.

Medulloblastoma expresses CD1d and can be targeted for immunotherapy with NKT cells

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. Current therapies are toxic and not always curative that necessitates development of targeted immunotherapy. However, little is known about immunobiology of this tumor. In this study, we show that MB cells in 9 of 20 primary tumors express CD1d, an antigen-presenting molecule for Natural Killer T cells (NKTs). Quantitative RT-PCR analysis of 61 primary tumors revealed an elevated level of CD1d mRNA expression in a molecular subgroup characterized by an overactivation of Sonic Hedgehog (SHH) oncogene compared with Group 4. CD1d-positive MB cells cross-presented glycolipid antigens to activate NKT-cell cytotoxicity. Intracranial injection of NKTs resulted in regression of orthotopic MB xenografts in NOD/SCID mice. Importantly, the numbers and function of peripheral blood type-I NKTs were preserved in MB patients. Therefore, CD1d is expressed on tumor cells in a subset of MB patients and represents a novel target for immunotherapy.

Signaling pathway and molecular subgroups of medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children. Although multimodality treatment regimens including surgery, radiotherapy and chemotherapy have greatly improved disease outcome, about one-third of MB patient remains incurable, and many long-term survivors are suffered from deleterious effects due to aggressive treatment. Understanding the signaling pathways and the genetic mechanisms contributed to MB development would be the key to develop novel therapeutic treatment strategies for improving survival and outcome of MB. In this review, we discuss the biological signaling pathways involved in MB pathogenesis. We also go through the current international consensus of four core MB subgroups namely, SHH, WNT, Group 3, and Group 4. This is adopted based on the knowledge of genomic complexity of MB as analyzed by recent high-throughput genomic technology. We talk about immunohistochemistry assays established to determine molecular subgroup affiliation. In the last part of review, we discuss how identification of molecular subgroups is going to change our routine disease diagnosis and clinical management.

Signals that regulate the oncogenic fate of neural stem cells and progenitors

Brain tumors have frequently been associated with a neural stem cell (NSC) origin and contain stem-like tumor cells, so-called brain tumor stem cells (BTSCs) that share many features with normal NSCs. A stem cell state of BTSCs confers resistance to radiotherapy and treatment with alkylating agents. It is also a hallmark of aggressive brain tumors and is maintained by transcriptional networks that are also active in embryonic stem cells. Advances in reprogramming of somatic cells into induced pluripotent stem (iPS) cells have further identified genes that drive stemness. In this review, we will highlight the possible drivers of stemness in medulloblastoma and glioma, the most frequent types of primary malignant brain cancer in children and adults, respectively. Signals that drive expansion of developmentally defined neural precursor cells are also active in corresponding brain tumors. Transcriptomal subgroups of human medulloblastoma and glioma match features of NSCs but also more restricted progenitors. Lessons from genetically-engineered mouse (GEM) models show that temporally and regionally defined NSCs can give rise to distinct subgroups of medulloblastoma and glioma. We will further discuss how acquisition of stem cell features may drive brain tumorigenesis from a non-NSC origin. Genetic alterations, signaling pathways, and therapy-induced changes in the tumor microenvironment can drive reprogramming networks and induce stemness in brain tumors. Finally, we propose a model where dysregulation of microRNAs (miRNAs) that normally provide barriers against reprogramming plays an integral role in promoting stemness in brain tumors.

Thickened area of external granular layer and Ki-67 positive focus are early events of medulloblastoma in Ptch1⁺/⁻ mice

Patched1 (Ptch1) encodes a receptor for Sonic hedgehog (Shh) and is major gene related to human medulloblastoma (MB) in the Shh subgroup. MB is thought to arise from residual granule cell precursors (GCPs) located in the external granular layer (EGL) of the developing cerebellum. As the detailed preneoplastic changes of MB remain obscure, we immunohistochemically clarified the derived cell, early events of MBs, and the cerebellar developmental processes of Ptch1(+/-) (Ptch1) mice, an animal model of human MB of the Shh subgroup. In Ptch1 mice, the earliest proliferative lesions were detected at PND10 as focal thickened areas of outer layer of the EGL. This area was composed of GCP-like cells with atypia and nuclei disarrangement. In the latter cerebellar developmental period, GCP-like cell foci were detected at high incidence in the outermost area of the cerebellum. Their localization and morphological similarities indicated that the foci were derived from GCPs in the EGL. There were two types of the foci. A Ki-67-positive focus was found in Ptch1 mice only. This type resembled the GCPs in the outer layer of EGL characterized by having proliferating activity and a lack of neuronal differentiation. Another type of focus, Ki-67-negative, was observed in both genotypes and exhibited many of the same features of mature internal granule cells, suggesting that the focus had no preneoplastic potential. Due to morphological, immunohistochemical characteristics, our results indicate that the focal thickened area of EGL and Ki-67-positive foci are preneoplastic lesions of MB.

Hexokinase-2-mediated aerobic glycolysis is integral to cerebellar neurogenesis and pathogenesis of medulloblastoma

Background

While aerobic glycolysis is linked to unconstrained proliferation in cancer, less is known about its physiological role. Why this metabolic program that promotes tumor growth is preserved in the genome has thus been unresolved. We tested the hypothesis that aerobic glycolysis derives from developmental processes that regulate rapid proliferation.

Methods

We performed an integrated analysis of metabolism and gene expression in cerebellar granule neuron progenitors (CGNPs) with and without Sonic Hedgehog (Shh), their endogenous mitogen. Because our analysis highlighted Hexokinase-2 (Hk2) as a key metabolic regulator induced by Shh, we studied the effect of conditional genetic Hk2 deletion in CGNP development. We then crossed Hk2 conditional knockout mice with transgenic SmoM2 mice that develop spontaneous medulloblastoma and determined changes in SmoM2-driven tumorigenesis.

Results

We show that Shh and phosphoinositide 3-kinase (PI3K) signaling combine to induce an Hk2-dependent glycolytic phenotype in CGNPs. This phenotype is recapitulated in medulloblastoma, a malignant tumor of CGNP origin. Importantly, cre-mediated ablation of Hk2 abrogated aerobic glycolysis, disrupting CGNP development and Smoothened-induced tumorigenesis. Comparing tumorigenesis in medulloblastoma-prone SmoM2 mice with and without functional Hk2, we demonstrate that loss of aerobic glycolysis reduces the aggressiveness of medulloblastoma, causing tumors to grow as indolent lesions and allowing long-term survival of tumor bearing mice.

Conclusions

Our investigations demonstrate that aerobic glycolysis in cancer derives from developmental mechanisms that persist in tumorigenesis. Moreover, we demonstrate in a primary tumor model the anti-cancer potential of blocking aerobic glycolysis by targeting Hk2.

See commentary article:http://www.biomedcentral.com/1741-7007/11/3

The role of stem cells and progenitors in the genesis of medulloblastoma

Cancer results from dysregulation of growth and survival pathways in normal stem cells and progenitors. Identifying the cells from which a tumor arises can facilitate the development of animal models and point to novel targets for therapy. Medulloblastoma is an aggressive tumor of the cerebellum that occurs predominantly in children. Recent genomic studies suggest that medulloblastoma consists of 4 major subgroups, each with distinct mutations and signaling pathway deregulations, and each potentially arising from distinct populations of stem cells and progenitors. Here we review the major types of progenitor cells in the cerebellum and discuss their role in the genesis of medulloblastoma.

Update on molecular and genetic alterations in adult medulloblastoma

Medulloblastoma encompasses a group of aggressively growing cancers that arise either in the cerebellum or brain stem. They present primarily in children, with 80-85 % of medulloblastomas being diagnosed in patients of 16 years and younger. In adults, medulloblastomas are rare and account for less than 1 % of intracranial malignancies. Due to the low incidence of medulloblastoma in adults, the biology and genetics of adult medulloblastomas have long been poorly understood. Many centers therefore still treat adults either by radiotherapy only or by using glioblastoma protocols (both often noncurative), or with standard pediatric medulloblastoma regimes (often associated with dose-limiting toxicity).Current clinical staging systems discriminate between standard-risk or high-risk patients based on clinical and histological parameters. However, clinico-pathological features often fail to accurately predict treatment response. In children, molecularly defined risk assessment has become important to improve survival of high-risk patients and to decrease treatment-related toxicity and long-term sequelae in standard-risk patients. However, several recent studies have shown that adult and pediatric medulloblastomas are genetically distinct and may require different algorithms for molecular risk stratification. Moreover, four subtypes of medulloblastoma have been identified that appear at different frequencies in children and adults and that have a different prognostic impact depending on age. Molecular markers such as chromosome 10q and chromosome 17 statuses can be used for molecular risk stratification of adult medulloblastoma, but only in a subgroup-specific context. Here we present an overview of the current knowledge of the genomics of adult medulloblastoma and how these tumors differ from their pediatric counterparts.

Medulloblastoma stem cells: modeling tumor heterogeneity

Brain tumors represent the leading cause of childhood cancer mortality, with medulloblastoma (MB) being the most frequent malignant tumor. In this review we discuss the morphological and molecular heterogeneity of this malignant childhood brain tumor and how this key feature has implicated the presence of a MB stem cell. We focus on evidence from cerebellar development, histopathological and molecular subtypes of MB, the recent identification of brain tumor-initiating cells (BTICs, also referred to as MB stem cells), and the current limitations in studying the interplay between MB stem cells and tumor heterogeneity.

A rare presentation of medulloblastoma in adults as primary leptomeningeal involvement

Medulloblastoma is one of the most common primary tumors of the central nervous system of children but it is uncommon in adult age. We report a case of young male presented with a history of generalized headache that was found to have medulloblastoma with diffuse leptomeningeal involvement without prominent mass lesion. To our knowledge, our patient is the second reported case of medulloblastoma in adults identified with primary leptomeningeal involvement without a prominent mass lesion. The clinical, radiological and pathologic features of this entity are described.

Medulloblastoma in childhood-King Edward Memorial hospital surgical experience and review: Comparative analysis of the case series of 365 patients

AIM

Medulloblastoma is one of the most common posterior fossa tumors in childhood. The treatment-related side effects as well as predictive outcome still remain as a major challenge. The improved understanding of the disease and advances in molecular biology is changing the treatment paradigms from Chang's staging system to molecular risk stratification. However, surgery still remains as an important mainstay of therapy and is formidable. The role of radical surgery has always been a crucial factor in the outcome of these patients, the best survival being reported in patients who had total excision of the tumor and with no metastasis.

PATIENT AND METHODS

An analysis of 365 patients (age<18 years) of medulloblastoma who underwent treatment at the Seth G.S. Medical College and King Edward VII Memorial hospital (KEM), Mumbai over a 25- year period (1985-2000 and 2001-2010) is presented. The clinical profile, radiological features, pathology and surgical nuances are discussed.

RESULTS

The most common age group affected was between 3 and 12 years. 75.3% presented with headaches, vomiting and 63.2% with papilledema. Sitting position was used in majority of cases. A total of 8 patients underwent shunting; all of them were in the postoperative period (5.19%). 92.2% (142 cases) had classical medulloblastoma, 5.1% (8 cases) had desmoplastic variant, 1.9% (3 cases) had anaplastic changes and 0.6% (1 case) had glial differentiation. The 5-year and 10-year progression free survival rate was 73 and 41% for average risk disease while for high risk disease rate it was 34%. The mortality rate was 2%. The quality of life was enhanced in patients who survived 5-10 years after treatment.

CONCLUSION

Surgery for medulloblastoma is formidable. The option of sitting position for medulloblastoma surgery is still viable. A vigilant neuroanesthesiologist and a safe surgery are necessary to achieve a good postoperative result. Radiological characteristics are helpful adjuncts for determining effective surgical strategy. Permanent CSF drainage can be avoided in majority of patients and can be definitively considered in progressive symptomatic hydrocephalus. A safe maximal resection and a good Karnofsky score are paramount to ensure compliance with adjuvant therapy and contribute to an overall survival advantage.

Medulloblastoma in infants: the critical issues of the dilemma

Brain tumours have now become the leading cause of cancer death in children under the age of 18 [...]

Medulloblastoma manifesting as sudden sensorineural hearing loss

We present a rare case of medulloblastoma which presented with unilateral sudden sensorineural hearing loss as an initial symptom. A 19-year-old man was admitted to our hospital with a chief complaint of dizziness and facial numbness on the right side. His illness had begun two years previously with sudden hearing loss on the right side, for which he had been treated as an idiopathic sudden hearing loss. Magnetic resonance imaging demonstrated abnormal signals located mainly in the right middle cerebellar peduncle. We performed partial resection of the tumor by suboccipital craniotomy. The histopathological diagnosis was medulloblastoma. Intrinsic brain tumor is an extremely rare cause of sudden sensorineural hearing loss and is therefore easily overlooked as was in the present case. The present case highlights not only the need to evaluate patients with sudden sensorineural hearing loss by magnetic resonance imaging but also the importance of paying attention to intrinsic lesions involving the brainstem. Although this condition like the presented case might be rare, intrinsic brain tumor should be considered as a potential cause of sudden sensorineural hearing loss, as it may be easily missed leading to a delay in appropriate treatment.

Frozen Section Diagnosis of Pediatric Brain Tumors

Brain tumors represent a significant group of tumors seen in the pediatric population. Intraoperative consultation represents a critical and integral component of the management of these tumors. Since the prevalence, frequency, and location of the different histologic types of brain tumors vary significantly between children and adults, it is reasonable to expect that diagnoses entertained during intraoperative consultation will also differ, influencing the aggressiveness of surgical resection and course of management. It is, therefore, imperative for surgical pathologists responsible for pediatric patients to become familiar with these entities and the diagnostic challenges they pose during the course of surgery.

Efficacy of high-dose chemotherapy and autologous stem cell transplantation in patients with relapsed medulloblastoma: a report on the Korean Society for Pediatric Neuro-Oncology (KSPNO)-S-053 study

The efficacy and toxicity of high-dose chemotherapy and autologous stem cell transplantation (HDCT/ASCT) were investigated for improving the outcomes of patients with relapsed medulloblastoma. A total of 15 patients with relapsed medulloblastoma were enrolled in the KSPNO-S-053 study from May 2005 to May 2007. All patients received approximately 4 cycles of salvage chemotherapy after relapse. Thirteen underwent HDCT/ASCT; CTE and CM regimen were employed for the first HDCT (HDCT1) and second HDCT (HDCT2), respectively, and 7 underwent HDCT2. One transplant related mortality (TRM) due to veno-occlusive disease (VOD) occurred during HDCT1 but HDCT2 was tolerable with no further TRM. The 3-yr overall survival probability and event-free survival rates +/-95% confidence intervals (CI) were 33.3+/-12.2% and 26.7% +/-11.4%, respectively. When analysis was confined to only patients who had a complete response (CR) or partial response (PR) prior to HDCT, the probability of 3-yr overall survival rates +/-95% CI was 40.0+/-15.5%. No patients with stable disease (SD) or progressive disease (PD) survived. Survival rates from protocol KSPNO-S-053 are encouraging and show that tumor status prior to HDCT/ASCT is an important factor to consider for improving survival rates of patients with relapsed medulloblastoma.

Reduced-dose craniospinal radiotherapy followed by high-dose chemotherapy and autologous stem cell rescue for children with newly diagnosed high-risk medulloblastoma or supratentorial primitive neuroectodermal tumor

Background

In this study, we investigated the effects of reduced-dose craniospinal radiotherapy (CSRT) followed by tandem high-dose chemotherapy (HDCT) with autologous stem cell rescue (ASCR) in children with a newly diagnosed high-risk medulloblastoma (MB) or supratentorial primitive neuroectodermal tumor (sPNET).

Methods

Between March 2005 and April 2007, patients older than 3 years with a newly diagnosed high-risk MB or sPNET were enrolled. The patients received two cycles of pre-RT chemotherapy consisting of cisplatin, etoposide, vincristine, and cyclophosphamide (cycle A), and carboplatin, etoposide, vincristine, and ifosphamide (cycle B), followed by CSRT with 23.4 Gy and local RT with 30.6 Gy. After four cycles of post-RT chemotherapy (cycles A, B, A, and B), tandem double HDCT with ASCR was performed.

Results

A total of 13 patients (MB=11, sPNET=2) were enrolled. Of these, one patient progressed, one patient died of septic shock after the second cycle of B, and one patient relapsed after the third cycle of B. The 3-year event-free survival (EFS) rate of the patients intended for HDCT was 76.9%, whereas the 3-year EFS rate of the patients who received HDCT was 100%. No treatment-related mortality occurred during HDCT.

Conclusion

Although the follow-up period was short and the patient cohort was small in size, the results of this study are encouraging. The limited toxicity and favorable EFS rate observed in children treated with reduced-dose CSRT followed by HDCT and ASCR warrant further exploration in a larger study population.

Binding and Internalization of Iron Oxide Nanoparticles Targeted to Nuclear Oncoprotein

A targeted nanoconjugate is being developed for non-invasive detection of gene expression in cells expressing the JC virus oncoprotein, T-antigen, which has been associated with medulloblastoma and other cancers. JC virus T-antigen localizes predominantly to the nucleus via a classical monopartite nuclear localization signal (NLS). An antibody fragment which recognizes JC virus T-antigen was attached to cross-linked dextran coated iron oxide nanoparticles. Radiolabeled conjugates were added to mouse medulloblastoma cells expressing the target T-antigen to test their ability to bind to tumor cells and be internalized by the cells. All conjugates containing targeting antibody bound to cells and were internalized, with increasing levels over time. There was no difference in cell binding or internalization among conjugates containing 2, 4, 6 or 8 antibody fragments per nanoparticle. Conjugates with only nonspecific antibody on nanoparticles, or unconjugated nonspecific antibody, had significantly lower total binding and internalization than conjugates with targeting antibody. Unconjugated targeting antibody had equivalent or lower cell uptake compared with targeted nanoparticle conjugates. Specificity of uptake was demonstrated by >80% reduction of nanoconjugate uptake in the presence of 100 fold excess of unconjugated antibody. The presence of a membrane translocation peptide (Tat) on the nanoparticles in addition to targeting antibody did not improve nanoconjugate internalization over the internalization caused by the antibody alone. This antibody nanoconjugate demonstrates feasibility of targeting a nuclear protein and suggests that a minimum number of antibody fragments per nanoparticle are sufficient for achieving binding specificity and efficient uptake into living cells.