Summary

Medulloblastoma is a malignant childhood brain tumour comprising four discrete subgroups. To identify mutations that drive medulloblastoma we sequenced the entire genomes of 37 tumours and matched normal blood. One hundred and thirty-six genes harbouring somatic mutations in this discovery set were sequenced in an additional 56 medulloblastomas. Recurrent mutations were detected in 41 genes not yet implicated in medulloblastoma: several target distinct components of the epigenetic machinery in different disease subgroups, e.g., regulators of H3K27 and H3K4 trimethylation in subgroup-3 and 4 (e.g., KDM6A and ZMYM3), and CTNNB1-associated chromatin remodellers in WNT-subgroup tumours (e.g., SMARCA4 and CREBBP). Modelling of mutations in mouse lower rhombic lip progenitors that generate WNT-subgroup tumours, identified genes that maintain this cell lineage (DDX3X) as well as mutated genes that initiate (CDH1) or cooperate (PIK3CA) in tumourigenesis. These data provide important new insights into the pathogenesis of medulloblastoma subgroups and highlight targets for therapeutic development.

Background

Dysembryoplastic neuroepithelial tumors (DNETs) are benign glioneuronal tumors that occur in children. These tumors are characterized by seizures, lack of neurologic deficits, and a seemingly benign course after resection.

Methods

We conducted a retrospective review of data relating to 11 children diagnosed with DNET between January 1988 and December 2007 at St. Jude Children's Research Hospital. This report documents the clinical features, neurocognitive function, and treatment outcomes in our institutional series.

Results

Our patient cohort included 8 boys and 3 girls (median age at diagnosis, 10 years); all patients presented with seizures: 4 complex partial, 3 generalized tonic clonic, 2 absence, 1 partial simple, and 1 not classified. Of the 11 patients, 1 died of cardiac fibrosis, and tumors recurred or progressed in 4 (36%). Seizure control was achieved in all patients but 1. Of the 9 patients who completed neuropsychologic testing, only 3 (23%) functioned at or above the expected level of same-age peers.

Conclusion

The high recurrence and progression rates of DNETs and the high rate of abnormal neurocognitive test results in this study highlight the need for regular follow-up and appropriate academic counseling of children with these tumors.

Background

Young adult survivors of childhood brain tumors (BT) may have late-effects that compromise physical performance and everyday task participation.

Objective

To evaluate muscle strength, fitness, physical performance, and task participation among adult survivors of childhood BT.

Design/Method

In-home evaluations and interviews were conducted for 156 participants (54% male). Results on measures of muscle strength, fitness, physical performance, and participation were compared between survivors and population-group members with chi-squared statistics and two-sample t-tests. Associations between late effects and physical performance, and physical performance and participation, were evaluated in regression models.

Results

BT survivors were a median age of 22 (18–58), and 14.7 (6.5–45.9) years from diagnosis. Survivors had lower estimates of grip strength (Female: 24.7±9.2 vs. 31.5±5.8, Male: 39.0±12.2 vs. 53.0±10.1 kilograms), knee extension strength (Female: 246.6±95.5 vs. 331.5±5.8, Male: 304.7±116.4 vs. 466.6±92.1 Newtons) and peak oxygen uptake (Female: 25.1±8.8 vs. 31.3±5.1, Male: 24.6±9.5 vs. 33.2±3.4 milliliters/kilogram/minute) than population-group members. Physical performance was lower among survivors and associated with not living independently (OR=5.0, 95% CI=2.0–12.2) and not attending college (OR=2.3, 95% CI 1.2–4.4).

Conclusion

Muscle strength and fitness values among BT survivors are similar to those among persons 60+ years, and are associated with physical performance limitations. Physical performance limitations are associated with poor outcomes in home and school environments. These data indicate an opportunity for interventions targeted at improving long-term physical function in this survivor population.

Purpose

The current study reports longitudinal coping responses among parents of children diagnosed with an embryonal brain tumor.

Patients and Methods

Patients (n=219) were enrolled on a treatment protocol for a pediatric embryonal brain tumor. Their parents (n=251) completed the Coping Response Inventory at time of their child’s diagnosis and yearly thereafter, resulting in 502 observations. Outcomes were examined with patient and parent age at diagnosis, patient risk, parent gender and education as covariates.

Results

At the time of diagnosis, the highest observed coping method was seeking guidance with well above average scores (T=61.6). Over time, younger parents were found to seek guidance at a significantly higher rate than older parents (p=.016) and the use of acceptance resignation and seeking alternative results by all parents significantly increased (p=.011 and p<.0001 respectively). The use of emotional discharge was also observed above average at time of diagnosis (T= 55.4) with younger fathers being more likely to exhibit emotional discharge than older fathers (p=.002). Differences in coping according to age of the patient and parent education level are also discussed.

Discussion

Results show a high need for guidance, and above average emotional discharge, especially among younger parents. It is imperative for the healthcare team to lead with accurate information so that these parents may make informed decisions about the care of their child. This need remains high years after diagnosis. Therefore it is critical to continue a consistent level of effective communication and support, even following treatment.

Purpose

Children treated with cranial irradiation for brain tumors have reduced white matter volume and deficits in reading ability. This study prospectively examined the relationship between reading and white matter integrity within this patient group.

Methods

Patients (n=54) were treated with post-surgical radiation followed by 4 cycles of high-dose chemotherapy with stem cell support. At 12 months post-diagnosis, all patients completed a neuropsychology evaluation and a diffusion tensor imaging (DTI) exam. White matter integrity was determined through measures of fractional anisotropy (FA).

Results

Significant group differences in FA were found between above average readers and below average readers within the left and right posterior limb of the internal capsule, and right knee of the internal capsule with a trend within the left temporal-occipital region.

Conclusions

The integrity of the white matter in these regions may affect communication among visual, auditory, and language cortical areas that are engaged during reading.

Purpose

Long-term survival for children with diffuse intrinsic pontine glioma (DIPG) is less than 10%, and new therapeutic targets are urgently required. We evaluated a large cohort of DIPGs to identify recurrent genomic abnormalities and gene expression signatures underlying DIPG.

Patients and Methods

Single-nucleotide polymorphism arrays were used to compare the frequencies of genomic copy number abnormalities in 43 DIPGs and eight low-grade brainstem gliomas with data from adult and pediatric (non-DIPG) glioblastomas, and expression profiles were evaluated using gene expression arrays for 27 DIPGs, six low-grade brainstem gliomas, and 66 nonbrainstem low-grade gliomas.

Results

Frequencies of specific large-scale and focal imbalances varied significantly between DIPGs and nonbrainstem pediatric glioblastomas. Focal amplifications of genes within the receptor tyrosine kinase–Ras–phosphoinositide 3-kinase signaling pathway were found in 47% of DIPGs, the most common of which involved PDGFRA and MET. Thirty percent of DIPGs contained focal amplifications of cell-cycle regulatory genes controlling retinoblastoma protein (RB) phosphorylation, and 21% had concurrent amplification of genes from both pathways. Some tumors showed heterogeneity in amplification patterns. DIPGs showed distinct gene expression signatures related to developmental processes compared with nonbrainstem pediatric high-grade gliomas, whereas expression signatures of low-grade brainstem and nonbrainstem gliomas were similar.

Conclusion

DIPGs comprise a molecularly related but distinct subgroup of pediatric gliomas. Genomic studies suggest that targeted inhibition of receptor tyrosine kinases and RB regulatory proteins may be useful therapies for DIPG.

Summary

Using a mouse model of ependymoma—a chemoresistant brain tumor—we combined multi-cell high-throughput screening (HTS), kinome-wide binding assays, and in vivo efficacy studies, to identify potential treatments with predicted toxicity against neural stem cells (NSC). We identified kinases within the insulin signaling pathway and centrosome cycle as regulators of ependymoma cell proliferation, and their corresponding inhibitors as potential therapies. FDA approved drugs not currently used to treat ependymoma were also identified that posses selective toxicity against ependymoma cells relative to normal NSCs both in vitro and in vivo e.g., 5-fluoruracil. Our comprehensive approach advances understanding of the biology and treatment of ependymoma including the discovery of several treatment leads for immediate clinical translation.

Purpose

To estimate the maximum-tolerated dose (MTD), describe dose-limiting toxicities (DLTs), and characterize pharmacokinetic properties of MK-0752, a gamma secretase inhibitor, in children with refractory or recurrent CNS malignancies.

Patients and Methods

MK-0752 was administered once daily for 3 consecutive days of every 7 days at escalating dosages starting at 200 mg/m2. The modified continual reassessment method was used to estimate the MTD. A course was 28 days in duration. Pharmacokinetic analysis was performed during the first course. Expression of NOTCH and hairy enhancer of split (HES) proteins was assessed in peripheral-blood mononuclear cells (PBMCs) before and following treatment with MK-0752.

Results

Twenty-three eligible patients were enrolled: 10 males (median age, 8.1 years; range, 2.6 to 17.7 years) with diagnoses of brainstem glioma (n = 6), ependymoma (n = 8), medulloblastoma/primitive neuroectodermal tumor (n = 4), glioblastoma multiforme (n = 2), atypical teratoid/rhabdoid tumor (n = 1), malignant glioma (n = 1), and choroid plexus carcinoma, (n = 1). Seventeen patients were fully evaluable for toxicity. No DLTs occurred in the three patients enrolled at 200 mg/m2/dose. At 260 mg/m2/dose, DLTs occurred in two of six patients, both of whom experienced grade 3 ALT and AST. There were no grade 4 toxicities; non–dose-limiting grade 3 toxicities included hypokalemia and lymphopenia. Population pharmacokinetic values (% coefficient of variation) for MK-0752 were apparent oral clearance, 0.444 (38%) L/h/m2; apparent volume of distribution, 7.36 (24%) L/m2; and ka, 0.358 (99%) hr−1.

Conclusion

MK-0752 is well-tolerated in children with recurrent CNS malignancies. The recommended phase II dose using the 3 days on followed by 4 days off schedule is 260 mg/m2/dose once daily.

To identify somatic mutations in paediatric diffuse intrinsic pontine gliomas (DIPGs), we performed whole genome sequencing of 7 DIPGs and matched germline DNA, and targeted sequencing of an additional 43 DIPGs and 36 non-brainstem paediatric glioblastomas (non-BS-PGs). 78% of DIPGs and 22% of non-BS-PGs contained p.K27M mutation in H3F3A, encoding histone H3.3, or the related HIST1H3B, encoding histone H3.1. An additional 14% of non-BS-PGs had somatic p.G34R H3F3A mutations.

SUMMARY

We discovered a high-level amplicon involving the chr19q13.41 microRNA (miRNA) cluster (C19MC) in 11/45(~25%) primary CNS-PNET which results in striking over-expression of miR-517c and 520g. Constitutive expression of miR-517c or 520g promotes in vitro and in vivo oncogenicity, modulates cell survival and robustly enhances growth of untransformed human neural stem cells (hNSCs) in part by upregulating WNT pathway signaling and restricting differentiation of hNSCs. Remarkably, the C19MC amplicon, which is very rare in other brain tumors (1/263), identify an aggressive sub-group of CNS-PNET with distinct gene expression profiles, characteristic histology and dismal survival. Our data implicate miR-517c and 520g as oncogenes and promising biological markers for CNS-PNET and provide important insights into oncogenic properties of the C19MC locus.

Little is known about brain tumors in early infancy. We reviewed the records of 27 patients (12 boys and 15 girls) diagnosed within 120 days of birth. The median age was 66 days (range, 0–110 days) at diagnosis. All patients underwent surgery; 18 received adjuvant chemotherapy, and 3 received adjuvant chemotherapy and radiation therapy. The median follow-up was 2.1 years (range, 0.2–21.6 years). At last encounter, 15 patients were alive, and 11 had no evidence of disease. Ten patients died of progressive disease, and 2 died of treatment-related complications. All survivors experienced late effects, including endocrine, neurologic, and cognitive deficits. Of the 13 patients who completed neurocognitive assessments, 7 had an IQ score less than 70. Children in whom brain tumors arise during early infancy can be cured with conventional therapy; however, contemporary approaches can adversely affect long-term function, and families need to be aware when making therapeutic decisions.

Purpose

Medulloblastomas are heterogeneous tumors that collectively represent the most common malignant brain tumor in children. To understand the molecular characteristics underlying their heterogeneity and to identify whether such characteristics represent risk factors for patients with this disease, we performed an integrated genomic analysis of a large series of primary tumors.

Patients and Methods

We profiled the mRNA transcriptome of 194 medulloblastomas and performed high-density single nucleotide polymorphism array and miRNA analysis on 115 and 98 of these, respectively. Non-negative matrix factorization–based clustering of mRNA expression data was used to identify molecular subgroups of medulloblastoma; DNA copy number, miRNA profiles, and clinical outcomes were analyzed for each. We additionally validated our findings in three previously published independent medulloblastoma data sets.

Results

Identified are six molecular subgroups of medulloblastoma, each with a unique combination of numerical and structural chromosomal aberrations that globally influence mRNA and miRNA expression. We reveal the relative contribution of each subgroup to clinical outcome as a whole and show that a previously unidentified molecular subgroup, characterized genetically by c-MYC copy number gains and transcriptionally by enrichment of photoreceptor pathways and increased miR-183∼96∼182 expression, is associated with significantly lower rates of event-free and overall survivals.

Conclusion

Our results detail the complex genomic heterogeneity of medulloblastomas and identify a previously unrecognized molecular subgroup with poor clinical outcome for which more effective therapeutic strategies should be developed.

Improvements in protocol-driven clinical trials and supportive care for children and adolescents with cancer have reduced mortality rates by more than 50% over the past three decades. Overall, the 5-year survival rate for pediatric cancer patients has increased to approximately 80%. Recognition of the biological heterogeneity within specific subtypes of cancer, the discovery of genetic lesions that drive malignant transformation and cancer progression, and improved understanding of the basis of drug resistance will undoubtedly catalyze further advances in risk-directed treatments and the development of targeted therapies, boosting the cure rates further. Emerging new treatments include novel formulations of existing chemotherapeutic agents, monoclonal antibodies against cancer-associated antigens, and molecular therapies that target genetic lesions and their associated signaling pathways. Recent findings that link pharmacogenomic variations with drug exposure, adverse effects, and efficacy should accelerate efforts to develop personalized therapy for individual patients. Finally, palliative care should be included as an essential part of cancer management to prevent and relieve the suffering and to improve the quality of life of patients and their families.

Long-term morbidity for children with low-grade glioma (LGG) requires exposure-specific characterization. Overall survival (OS) and progression-free survival (PFS) were estimated for 361 children diagnosed with LGG between 1985 and 2007 at a single institution. Five-year survivors (n = 240) received risk-based clinical assessment. Cumulative incidence of late effects 15 years from diagnosis were estimated. Risk factors for adverse health were identified using Fine and Gray's approach to Cox's proportional hazards model, accounting for death as a competing risk. OS at 15 years was 86% (95% confidence interval [CI] 82%–90%), and PFS was 55% (95% CI 51%–58%). Among the 240 5-year survivors, the 5-, 10-, and 15-year cumulative incidence of adverse outcomes included blindness: 10%, 13%, and 18%, respectively; hearing loss: 8%, 14%, and 22%; obesity/overweight: 18%, 35%, and 53%; hyperinsulinism: 1%, 5%, and 24%; growth hormone deficiency: 13%, 27%, and 29%;thyroid hormone deficiency: 16%, 28%, and 33%; and adrenocorticotropic hormone (ACTH) deficiency: 12%, 22%, and 26%. Multivariable models demonstrated radiation therapy to be a significant independent predictor of hearing loss, growth hormone deficiency, abnormal thyroid function, and ACTH deficiency. Diencephalic location was a statistically significant independent risk factor for blindness, growth hormone deficiency, abnormal thyroid function, and ACTH deficiency. Among the 182 5-year survivors assessed for intellectual function, 34% had an intelligence quotient (IQ) below average (<85), associated with younger age at diagnosis, epilepsy, and shunt placement. Survivors of childhood LGG experience substantial long-term adverse effects that continue to increase well beyond the 5-year survival time point.

Atypical teratoid rhabdoid tumors (ATRTs) are rare central nervous system tumors that comprise approximately 1–2% of all pediatric brain tumors; however, in patients less than 3 years of age this tumor accounts for up to 20% of cases. ATRT is characterized by loss of the long arm of chromosome 22 which results in loss of the hSNF5/INI-1 gene. INI1, a member of the SWI/SNF chromatin remodeling complex, is important in maintenance of the mitotic spindle and cell cycle control. Overall survival in ATRT is poor with median survival around 17 months. Radiation is an effective component of therapy but is avoided in patients younger than 3 years of age due to long term neurocognitive sequelae. Most long term survivors undergo radiation therapy as a part of their upfront or salvage therapy, and there is a suggestion that sequencing the radiation earlier in therapy may improve outcome. There is no standard curative chemotherapeutic regimen, but anecdotal reports advocate the use of intensive therapy with alkylating agents, high-dose methotrexate, or therapy that includes high-dose chemotherapy with stem cell rescue. Due to the rarity of this tumor and the lack of randomized controlled trials it has been challenging to define optimal therapy and advance treatment. Recent laboratory investigations have identified aberrant function and/or regulation of cyclin D1, aurora kinase, and insulin-like growth factor pathways in ATRT. There has been significant interest in identifying and testing therapeutic agents that target these pathways.

Purpose: Associations of radiation therapy (RT) deviations and outcomes in medulloblastoma have not been defined well, particularly in the era of reduced-dose craniospinal irradiation and chemotherapy. The aim of this study is to evaluate the quality of RT on Children’s Cancer Group/Pediatric Oncology Group 9961 and analyze associations of RT deviations with outcome. Materials and Methods: Major volume deviations were assessed based on the distance from specified anatomical region to field edge. We investigated associations of RT deviations with progression-free survival (PFS), overall survival (OS), and explored associations with demographics and clinical variables. Results: Of the 308 patients who were evaluable for volume deviations, 101 patients (33%) did not have any. Of the remaining 207 patients, 50% had only minor deviations, 29% had only major deviations, and 21% had both minor and major deviations. Of the patients with major deviations, 73% had a single major deviation. The most common major deviation was in the cribriform plate region, followed by the posterior fossa (PF); PF deviations resulted from treating less than whole PF. There were no significant differences in PFS or OS between patients with deviations and those without. There was no evidence of associations of deviations with patient age. Conclusions: Approximately one-third of patients had major volume deviations. There was no evidence of a significant association between these and outcome. This lack of correlation likely reflects the current high quality of RT delivered in Children’s Oncology Group institutions, our strict definition of volume deviations, and the relatively few instances of multiple major deviations in individual patients. In is noteworthy that the types of PF volume deviations observed in this study were not adversely associated with outcome. As we move forward, quality assurance will continue to play an important role to ensure that deviations on study do not influence study outcome.

Medulloblastoma, a small blue cell malignancy of the cerebellum, is a major cause of morbidity and mortality in pediatric oncology. Current mechanisms for clinical prognostication and stratification include clinical factors (age, presence of metastases, and extent of resection) as well as histological subgrouping (classic, desmoplastic, and large cell/anaplastic histology). Transcriptional profiling studies of medulloblastoma cohorts from several research groups around the globe have suggested the existence of multiple distinct molecular subgroups that differ in their demographics, transcriptomes, somatic genetic events, and clinical outcomes. Variations in the number, composition, and nature of the subgroups between studies brought about a consensus conference in Boston in the fall of 2010. Discussants at the conference came to a consensus that the evidence supported the existence of four main subgroups of medulloblastoma (Wnt, Shh, Group 3, and Group 4). Participants outlined the demographic, transcriptional, genetic, and clinical differences between the four subgroups. While it is anticipated that the molecular classification of medulloblastoma will continue to evolve and diversify in the future as larger cohorts are studied at greater depth, herein we outline the current consensus nomenclature, and the differences between the medulloblastoma subgroups.

The aim is to prospectively assess early neurocognitive outcome of children who developed cerebellar mutism syndrome (CMS) following surgical resection of a posterior fossa embryonal tumor, compared with carefully matched control patients. Children who were enrolled on an ongoing IRB-approved protocol for treatment of embryonal tumors, were diagnosed with postoperative CMS, and had completed prospectively planned neuropsychological evaluation at 12 months postdiagnosis were considered eligible. The cognitive outcomes of these patients were examined in comparison to patients without CMS from the same treatment protocol and matched with regard to primary diagnosis, age at diagnosis, and risk/corresponding treatment (n = 22 pairs). Seventeen were also matched according to gender, and 14 were also matched according to race. High-risk patients received 36–39.6 Gy CSI and 3D conformal boost to the primary site to 55.8–59.4 Gy. Average-risk patients received 23.4 Gy CSI and 3D conformal boost to the primary site to 55.8 Gy. Significant group differences were found on multiple cognitive outcomes. While the matched control patients exhibited performance in the average range, patients who developed CMS postsurgery were found to have significantly lower performance in processing speed, attention, working memory, executive processes, cognitive efficiency, reading, spelling, and math. Patients treated for medulloblastoma who experience postoperative CMS show an increased risk for neurocognitive impairment, evident as early as 12 months following diagnosis. This study highlights the need for careful follow-up with neuropsychological evaluation and for obtaining critical support for patients and their families.

Recent studies of genetic abnormalities in pediatric low-grade gliomas (LGGs) have focused on activation of the ERK/MAPK pathway by KIAA1549-BRAF gene fusions in the majority of pilocytic astrocytomas (PAs) and by rare mutations in elements of the pathway across histopathologically diverse LGGs. This study reports that MYB, an oncogene not previously implicated in gliomagenesis, is activated in a diverse subset of pediatric LGGs. The study cohort comprised 57 pediatric LGGs and a comparative cohort of 59 pediatric high-grade gliomas (HGGs). The LGG cohort included 34 PAs and 23 diffuse gliomas; fibrillary astrocytomas (n=14), oligodendroglial tumors (n=7), and angiocentric gliomas (n=2). MYB copy number abnormalities were disclosed using Affymetrix 6.0 SNP arrays and confirmed using interphase fluorescence in situ hybridization. Novel MYB amplifications that upregulate MYB RNA and protein expression were demonstrated in 2/14 diffuse astrocytomas. In addition, focal deletion of the terminal region of MYB was seen in 1 of 2 angiocentric gliomas (AGs). Increased expression of MYB was demonstrated by quantitative RT-PCR and immunohistochemistry. MYB upregulation at the protein level was demonstrated in a proportion of diffuse LGGs (60%), pilocytic astrocytomas (41%), and HGGs (19%), but abnormalities at the genomic level were only a feature of diffuse gliomas. Our data suggest that MYB may have a role in a subset of pediatric gliomas, through a variety of mechanisms in addition to MYB amplification and deletion.

Purpose

To evaluate the safety, maximum-tolerated dose, pharmacokinetics, and pharmacodynamics of vandetanib, an oral vascular endothelial growth factor receptor 2 (VEGFR2) and epidermal growth factor receptor inhibitor, administered once daily during and after radiotherapy in children with newly diagnosed diffuse intrinsic pontine glioma.

Patients and Methods

Radiotherapy was administered as 1.8-Gy fractions (total cumulative dose of 54 Gy). Vandetanib was administered concurrently with radiotherapy for a maximum of 2 years. Dose-limiting toxicities (DLTs) were evaluated during the first 6 weeks of therapy. Pharmacokinetic studies were obtained for all patients. Plasma angiogenic factors and VEGFR2 phosphorylation in mononuclear cells were analyzed before and during therapy.

Results

Twenty-one patients were administered 50 (n = 3), 65 (n = 3), 85 (n = 3), 110 (n = 6), and 145 mg/m2 (n = 6) of vandetanib. Only one patient developed DLT (grade 3 diarrhea) at dosage level 5. An expanded cohort of patients were treated at dosage levels 4 (n = 10) and 5 (n = 4); two patients developed grade 4 hypertension and posterior reversible encephalopathy syndrome while also receiving high-dose dexamethasone. Despite significant interpatient variability, exposure to vandetanib increased with higher dosage levels. The bivariable analysis of vascular endothelial growth factor (VEGF) before and during therapy showed that patients with higher levels of VEGF before therapy had a longer progression-free survival (PFS; P = .022), whereas patients with increases in VEGF during treatment had a shorter PFS (P = .0015). VEGFR2 phosphorylation was inhibited on day 8 or 29 of therapy compared with baseline (P = .039).

Conclusion

The recommended phase II dose of vandetanib in children is 145 mg/m2 per day. Close monitoring and management of hypertension is required, particularly for patients receiving corticosteroids.

BACKGROUND

Brain tissue obtained at autopsy has been used in research for non-oncological disorders. However, this tool has never been systematically used in large investigational studies for cancer. We conducted a prospective, multicenter study to assess the feasibility of tissue collection at autopsy and its suitability for molecular analyses in children with diffuse intrinsic pontine glioma.

METHODS

Tumor tissue was collected at diagnosis, if clinically indicated, or at autopsy. Normal brain tissue was also collected at autopsy. The integrity of DNA and RNA was evaluated in all samples. Logistical data about autopsies were recorded. The feasibility of tissue collection at autopsy was assessed for patients treated at a single institution over a 43-month period.

RESULTS

Tumor samples were collected at diagnosis (n=3) or at autopsy (n=38) at 29 centers across the US; samples were obtained at diagnosis and autopsy in two cases. The median interval from death to autopsy was 7.7 hours. DNA and RNA with minimal or partial degradation, which were suitable for genome-wide analysis, were obtained from 100% and 63% of tumor samples, respectively. At the coordinating institution, approximately 40% of parents consented to autopsy and 40% declined. During the study period, 12 autopsies were obtained from patients who did not receive therapy at the coordinating center.

CONCLUSIONS

Multicenter, biological studies based on tissue obtained at autopsy are feasible in children with brain cancer. Our experience established a new paradigm for brain tissue collection which may increase the potential for research studies in patients with cancer.

Purpose

To estimate the maximum-tolerated dose, dose-limiting toxicities (DLTs), and pharmacokinetic properties of lapatinib, a selective epidermal growth factor receptor (EGFR) and ERBB2 inhibitor, in children with refractory or recurrent CNS malignancies.

Patients and Methods

Lapatinib was administered orally twice daily at escalating doses starting at 300 mg/m2 to patients who were not (stratum I) or were (stratum II) receiving steroids. Pharmacokinetic studies were performed during the first two courses. Expression of the four ERBB receptors and downstream signaling elements in tumor tissue was evaluated by immunohistochemistry.

Results

Fifty-nine patients were enrolled (stratum I, n = 32; stratum II, n = 27). Of 29 patients evaluable for toxicity in stratum I, one experienced a DLT (diarrhea) at 520 mg/m2 twice daily, and all three receiving 1,150 mg/m2 twice daily experienced DLTs (one each of rash, diarrhea, and fatigue). Two of 21 patients evaluable for toxicity in stratum II experienced DLTs of rash at 900 mg/m2 twice daily. Lapatinib dosage was related linearly to area under the [concentration-time] curve from start time to 12 hours later (AUC0-12) and dose-normalized maximum serum concentration and AUC values for patients in stratum II were both significantly higher (P = .001) than those for patients in stratum I. Frequent, high-level expression of activated (phosphorylated) EGFR and ERBB2 receptors and downstream signal intermediates were observed in tumors, particularly in ependymomas that displayed prolonged stable disease on lapatinib therapy.

Conclusion

Lapatinib is well tolerated in children with recurrent CNS malignancies, with rash, diarrhea, and fatigue identified as DLTs. The recommended phase II dose, regardless of steroid use, is 900 mg/m2 twice daily.

Trilateral retinoblastoma is characterized by the presence of retinoblastoma with an intracranial tumor. The incidence is low and prognosis poor. Due to the paucity of information regarding successful treatment, we report the case of a 6 month old female referred for leukocoria and found to have an associated suprasellar tumor and pineal enhancement. The patient, treated with standard infant brain tumor therapy, remains alive without signs of active disease 35 months after diagnosis; no surgery or irradiation was used. Early diagnosis of trilateral retinoblastoma may facilitate the use of less intensive therapeutic approaches and result in excellent outcomes in these patients.

Medulloblastoma encompasses a collection of clinically and molecularly diverse tumor subtypes that together comprise the most common malignant childhood brain tumor1–4. These tumors are thought to arise within the cerebellum, with approximately 25% originating from granule neuron precursor cells (GNPCs) following aberrant activation of the Sonic Hedgehog pathway (hereafter, SHH-subtype)3–8. The pathological processes that drive heterogeneity among the other medulloblastoma subtypes are not known, hindering the development of much needed new therapies. Here, we provide evidence that a discrete subtype of medulloblastoma that contains activating mutations in the WNT pathway effector CTNNB1 (hereafter, WNT-subtype)1,3,4, arises outside the cerebellum from cells of the dorsal brainstem. We found that genes marking human WNT-subtype medulloblastomas are more frequently expressed in the lower rhombic lip (LRL) and embryonic dorsal brainstem than in the upper rhombic lip (URL) and developing cerebellum. Magnetic resonance imaging (MRI) and intra-operative reports showed that human WNT-subtype tumors infiltrate the dorsal brainstem, while SHH-subtype tumors are located within the cerebellar hemispheres. Activating mutations in Ctnnb1 had little impact on progenitor cell populations in the cerebellum, but caused the abnormal accumulation of cells on the embryonic dorsal brainstem that included aberrantly proliferating Zic1+ precursor cells. These lesions persisted in all mutant adult mice and in 15% of cases in which Tp53 was concurrently deleted, progressed to form medulloblastomas that recapitulated the anatomy and gene expression profiles of human WNT-subtype medulloblastoma. We provide the first evidence that subtypes of medulloblastoma have distinct cellular origins. Our data provide an explanation for the marked molecular and clinical differences between SHH and WNT-subtype medulloblastomas and have profound implications for future research and treatment of this important childhood cancer.

Purpose

To define copy number alterations and gene expression signatures underlying pediatric high-grade glioma (HGG).

Patients and Methods

We conducted a high-resolution analysis of genomic imbalances in 78 de novo pediatric HGGs, including seven diffuse intrinsic pontine gliomas, and 10 HGGs arising in children who received cranial irradiation for a previous cancer using single nucleotide polymorphism microarray analysis. Gene expression was analyzed with gene expression microarrays for 53 tumors. Results were compared with publicly available data from adult tumors.

Results

Significant differences in copy number alterations distinguish childhood and adult glioblastoma. PDGFRA was the predominant target of focal amplification in childhood HGG, including diffuse intrinsic pontine gliomas, and gene expression analyses supported an important role for deregulated PDGFRα signaling in pediatric HGG. No IDH1 hotspot mutations were found in pediatric tumors, highlighting molecular differences with adult secondary glioblastoma. Pediatric and adult glioblastomas were clearly distinguished by frequent gain of chromosome 1q (30% v 9%, respectively) and lower frequency of chromosome 7 gain (13% v 74%, respectively) and 10q loss (35% v 80%, respectively). PDGFRA amplification and 1q gain occurred at significantly higher frequency in irradiation-induced tumors, suggesting that these are initiating events in childhood gliomagenesis. A subset of pediatric HGGs showed minimal copy number changes.

Conclusion

Integrated molecular profiling showed substantial differences in the molecular features underlying pediatric and adult HGG, indicating that findings in adult tumors cannot be simply extrapolated to younger patients. PDGFRα may be a useful target for pediatric HGG, including diffuse pontine gliomas.