The RE1 Silencing Transcription Factor (REST) is a repressor of neuronal differentiation and its elevated expression in neural cells blocks neuronal differentiation. In the present study, we demonstrate a role for REST in the control of proliferation of medulloblastoma cells. REST expression decreased the levels of CDKNIB/p27, a cyclin-dependent kinase inhibitor and a brake of cell proliferation in these cells. The reciprocal relationship between REST and p27 was validated in human tumor samples. REST knockdown in medulloblastoma cells derepessed a novel REST-target gene encoding the deubiquitylase ubiquitin-specific peptidase 37 (USP37). Ectopically expressed wild type USP37 formed a complex with p27, promoted its deubiquitination and stabilization and blocked cell proliferation. Knockdown of REST and USP37 prevented p27 stabilization and blocked the diminution in proliferative potential that normally accompanied REST loss. Unexpectedly, wild type USP37 expression also induced the expression of REST-target neuronal differentiation genes even though REST levels were unaffected. In contrast, a mutant of USP37 carrying a site-directed change in a conserved cysteine failed to rescue REST-mediated p27 destabilization, maintenance of cell proliferation and blockade to neuronal differentiation. Consistent with these findings, a significant correlation between USP37 and p27 was observed in patient tumors. Collectively, these findings provide a novel connection between REST and the proteasomal machinery in the control of p27 and cell proliferation in medulloblastoma cells.
REST; proliferation; p27; USP37; deubiquitylase
Medulloblastoma is a malignant pediatric brain tumor. Current treatment following patient stratification into standard and high-risk groups using clinical features, has improved survival. However, a subset of patients with standard-risk features have unanticipated aggressive disease, underscoring the need for a better understanding of tumor biology and development of novel treatments. Poor differentiation, a hallmark of medulloblastomas is associated with elevated expression levels of the repressor of neuronal differentiation REST. Here, we assessed if elevated REST expression levels had prognostic significance and if its pharmacological manipulation would promote neurogenesis and block tumor cell growth. REST levels in patient tumors were measured by immunohistochemistry (IHC) and stratified into low/moderate- (+/++/+++) and high-REST (+++++) groups. Kaplan-Meier curves revealed that patients with high-REST tumors had worse overall and event-free survival compared to patients with REST-negative or REST-low tumors. Since histone deacetylases (HDACs), are required for REST-dependent repression of neurogenesis, we evaluated a panel of HDAC inhibitors (HDACIs) for their effects on growth and differentiation of established and primary REST-positive cell lines. MS-275, trichostatin-A (TSA), valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA) upregulated expression of the REST-target neuronal differentiation gene, Syn1, suggesting a potential effect of these HDACIs on REST function. Interestingly, VPA and TSA substantially increased histone acetylation at the REST promoter and activated its transcription, whereas SAHA unexpectedly promoted its proteasomal degradation. A REST-dependent decrease in cell growth was also observed following SAHA treatment. Thus, our studies suggest that HDACIs may have therapeutic potential for patients with REST-positive tumors. This warrants further investigation.
REST; medulloblastoma; HDAC inhibitor; prognosis; differentiation
A pilot study to investigate the feasibility of the addition of intrathecal (IT) mafosfamide to a regimen of concomitant multi-agent systemic chemotherapy followed by conformal radiation therapy (RT) for children <3 years with newly diagnosed embryonal CNS tumors was performed.
Patients and Methods
Ninety-three newly diagnosed infants and children (<3 years) with embryonal CNS tumors were enrolled. Twenty weeks of systemic multi-agent chemotherapy commenced within 35 days of surgery. Patients without CSF flow obstruction (n=71) received IT mafosfamide (14 mg) with chemotherapy. Localized (M0) patients with SD or better subsequently received RT followed by 20 additional weeks of chemotherapy. Second look surgery was encouraged prior to RT if there was an incomplete surgical resection at diagnosis.
71 evaluable patients with normal CSF flow received IT Mafosfamide with systemic chemotherapy; patients with M+ disease were removed from protocol therapy at 20 weeks and those with PD at the time of progression. One and 5-year progression free survival (PFS) and overall survival (OS) for the cohort of 71 evaluable patients were 52±6.5% and 33±13%, and 67±6.2% and 51±11%, respectively. The 1-year Progression Free Survival (PFS) for M0 patients with medulloblastoma (MB, n=20), supratentorial primitive neuroectodermal tumor (PNET, n=9), and atypical teratoid rhabdoid tumor (ATRT, n=12) was 80±7%, 67±15% and 27±13% and 5-year PFS was 65± 19%, 37±29%, and 0±0%, respectively.
The addition of IT mafosfamide to systemic chemotherapy in infants with embryonal CNS tumors was feasible. The PFS for M0 patients appears comparable to or better than most prior historical comparisons and was excellent for those receiving conformal radiotherapy.
mafosfamide; intrathecal; infant brain tumor; embryonal CNS tumor; conformal radiation therapy
To estimate the sustained (≥8 weeks) objective response rate in pediatric patients with recurrent or progressive high-grade gliomas (HGG, Stratum A) or brainstem gliomas (BSG, Stratum B) treated with the combination of O6-benzylguanine (O6BG) and temozolomide® (TMZ).
Patients and Methods
Patients received O6BG 120 mg/m2/d IV followed by TMZ 75 mg/m2/d orally daily for 5 consecutive days of each 28-day course. The target objective response rate to consider the combination active was 17%. A two-stage design was employed.
Forty-three patients were enrolled; 41 were evaluable for response, including 25 patients with HGG and 16 patients with BSG. The combination of O6BG and TMZ was tolerable, and the primary toxicities were myelosuppression and gastrointestinal symptoms. One sustained (≥8 weeks) partial response was observed in the HGG cohort; no sustained objective responses were observed in the BSG cohort. Long-term (≥6 courses) stable disease (SD) was observed in 4 patients in Stratum A and 1 patient in Stratum B. Of the 5 patients with objective response or long-term SD, 3 underwent central review with 2 reclassified as low-grade gliomas.
The combination of O6BG and TMZ did not achieve the target response rate for activity in pediatric patients with recurrent or progressive HGG and BSG.
glioma; pediatric; resistance; alkylating agent; brainstem glioma; AGT; MGMT
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.
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.
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.
Objective The purpose of this study is to report the reliability, validity, and clinical utility of a parent-report perceived cognitive function (pedsPCF) item bank. Methods From the U.S. general population, 1,409 parents of children aged 7–17 years completed 45 pedsPCF items. Their psychometric properties were evaluated using Item Response Theory (IRT) approaches. Receiver operating characteristic (ROC) curves and discriminant function analysis were used to predict clinical problems on child behavior checklist (CBCL) scales. A computerized adaptive testing (CAT) simulation was used to evaluate clinical utility. Results The final 43-item pedsPCF item bank demonstrates no item bias, has acceptable IRT parameters, and provides good prediction of related clinical problems. CAT simulation resulted in correlations of 0.98 between CAT and the full-length pedsPCF. Conclusions The pedsPCF has sound psychometric properties, U.S. general population norms, and a brief-yet-precise CAT version is available. Future work will evaluate pedsPCF in other clinical populations in which cognitive function is important.
assessment; cancer and oncology; cognitive assessment; computer applications/eHealth; neuropsychology; quality of life
Although ionizing radiation induces germline mutations in animals, human studies of radiation-exposed populations have not detected an effect. We conducted a case-control study of sporadic bilateral retinoblastoma, which results from a new germline RB1 mutation, to investigate gonadal radiation exposure of parents from medical sources before their child's conception. Parents of 206 cases from 9 North American institutions and 269 controls participated; fathers of 184 cases and 223 friend and relative controls and mothers of 204 cases and 260 controls provided information in telephone interviews on their medical radiation exposure. Cases provided DNA for RB1 mutation testing. Of common procedures, lower GI series conferred the highest estimated dose to testes and ovaries. Paternal history of lower GI series was associated with increased risk of retinoblastoma in the child (matched odds ratio (OR)=3.6, 95% confidence interval (CI) 1.2, 11.2, 2-sided P=0.02), as was estimated total testicular dose from all procedures combined (OR for highest dose=3.9, 95% CI 1.2, 14.4, P =0.02). Maternal history of lower GI series was also associated with increased risk (OR=7.6, 95% CI 2.8, 20.7, P <0.001) as was estimated total dose (OR for highest dose=3.0, 95% CI 1.4, 7.0, P =0.005). The RB1 mutation spectrum in cases of exposed parents did not differ from that of other cases. Some animal and human data support our findings of an association of gonadal radiation exposure in men and women with new germline RB1 mutation detectable in their children, although bias, confounding, and/or chance may also explain the results.
germline mutation; ionizing radiation; retinoblastoma; case-control studies; pediatric cancer
A phase I trial of lenalidomide was performed in children with recurrent, refractory, or progressive primary CNS tumors to estimate the maximum-tolerated dose (MTD) and to describe the toxicity profile and pharmacokinetics.
Patients and Methods
Lenalidomide was administered by mouth daily for 21 days, repeated every 28 days. The starting dose was 15 mg/m2/d orally, and the dose was escalated according to a modified continuous reassessment method. Correlative studies included pharmacokinetics obtained from consenting patients on course 1, day 1, and at steady-state (between days 7 and 21).
Fifty-one patients (median age, 10 years; range, 2 to 21 years) were enrolled. Forty-four patients were evaluable for dose finding, and 49 patients were evaluable for toxicity. The primary toxicity was myelosuppression, but the MTD was not defined because doses up to 116 mg/m2/d were well-tolerated during the dose-finding period. Two objective responses were observed (one in thalamic juvenile pilocytic astrocytoma and one in optic pathway glioma) at dose levels of 88 and 116 mg/m2/d. Twenty-three patients, representing all dose levels, received ≥ six cycles of therapy. Pharmacokinetic analysis demonstrated that the lenalidomide area under the concentration-time curve from 0 to 24 hours and maximum plasma concentration increased with dosage over the range studied.
Lenalidomide was tolerable in children with CNS tumors at doses of 116 mg/m2/d during the initial dose-finding period. The primary toxicity is myelosuppression. Antitumor activity, defined by both objective responses and long-term stable disease, was observed, primarily in patients with low-grade gliomas.
We have examined expression of microRNAs (miRNAs) in ependymomas to identify molecular markers of value for clinical management. miRNAs are non-coding RNAs that can block mRNA translation and affect mRNA stability. Changes in the expression of miRNAs have been correlated with many human cancers.
Materials and Methods
We have utilized TaqMan Low Density Arrays to evaluate the expression of 365 miRNAs in ependymomas and normal brain tissue. We first demonstrated the similarity of expression profiles of paired frozen tissue (FT) and paraffin-embedded specimens (FFPE). We compared the miRNA expression profiles of 34 FFPE ependymoma samples with 8 microdissected normal brain tissue specimens enriched for ependymal cells. miRNA expression profiles were then correlated with tumor location, histology and other clinicopathological features.
We have identified miRNAs that are over-expressed in ependymomas, such as miR-135a and miR-17-5p, and down-regulated, such as miR-383 and miR-485-5p. We have also uncovered associations between expression of specific miRNAs which portend a worse prognosis. For example, we have identified a cluster of miRNAs on human chromosome 14q32 that is associated with time to relapse. We also found that miR-203 is an independent marker for relapse compared to the parameters that are currently used. Additionally, we have identified three miRNAs (let-7d, miR-596 and miR-367) that strongly correlate to overall survival.
We have identified miRNAs that are differentially expressed in ependymomas compared with normal ependymal tissue. We have also uncovered significant associations of miRNAs with clinical behavior. This is the first report of clinically relevant miRNAs in ependymomas.
Recurrent medulloblastoma is highly lethal in previously irradiated patients. Previously irradiated patients with M-0–M-3 recurrences who achieved a minimal disease state prior to protocol enrollment received carboplatin (Calvert formula with area under the curve = 7 mg/mL min, maximum 500 mg/m2/day) on days −8 to −6, and thiotepa (300 mg/m2/day) and etoposide (250 mg/m2/day) on days −5 to −3, followed by autologous stem cell rescue (ASCR) on day 0. Twenty-five patients, aged 7.6–44.7 years (median 13.8 years) at ASCR, were treated. Three (12%) died of treatment-related toxicities within 30 days of ASCR, due to multiorgan system failure (n = 2) and aspergillus infection with veno-occlusive disease (n = 1). Tumor recurred in 16 at a median of 8.5 months (range 2.3–58.5 months). Six are event-free survivors at a median of 151.2 months post-ASCR (range 127.2–201.6 months). The Kaplan–Meier estimate of median overall survival is 26.8 months (95% CI: 11.9–51.1 months) and of event-free survival (EFS) and overall survival are both 24% (95% CI: 9.8%–41.7%) at 10 years post-ASCR. M-0 (vs M-1 + ) recurrence prior to protocol, lack of tissue confirmation of relapse, and initial therapy of radiation therapy (RT) alone (vs RT + chemotherapy) were not significantly associated with better EFS (P = .33, .34, and .27, respectively). Trends toward better EFS were noted in patients (n = 5) who received additional RT as part of their retrieval therapy (P = .07) and whose recurrent disease was demonstrated to be sensitive to reinduction chemotherapy (P = .09). This retrieval strategy provides long-term EFS for some patients with previously irradiated recurrent medulloblastoma. The use of additional RT may be associated with better outcome.
chemotherapy; hematopoietic stem cell transplantation; medulloblastoma
Genomic DNA methylation contributes substantively to transcriptional regulations that underlie mammalian development and cellular differentiation. Much effort has been made to decipher the molecular mechanisms governing the establishment and maintenance of DNA methylation patterns. However, little is known about genome-wide variation of DNA methylation patterns. In this study, we introduced the concept of methylation entropy, a measure of the randomness of DNA methylation patterns in a cell population, and exploited it to assess the variability in DNA methylation patterns of Alu repeats and promoters. A few interesting observations were made: (i) within a cell population, methylation entropy varies among genomic loci; (ii) among cell populations, the methylation entropies of most genomic loci remain constant; (iii) compared to normal tissue controls, some tumors exhibit greater methylation entropies; (iv) Alu elements with high methylation entropy are associated with high GC content but depletion of CpG dinucleotides and (v) Alu elements in the intronic regions or far from CpG islands are associated with low methylation entropy. We further identified 12 putative allelic-specific methylated genomic loci, including four Alu elements and eight promoters. Lastly, using subcloned normal fibroblast cells, we demonstrated the highly variable methylation patterns are resulted from low fidelity of DNA methylation inheritance.
The identification of molecular signatures predictive of clinical behavior and outcome in brain tumors has been the focus of many studies in the recent years. Despite the wealth of data that are available in the public domain on alterations in the genome, epigenome and transcriptome of brain tumors, the underlying molecular mechanisms leading to tumor initiation and progression remain largely unknown. Unfortunately, most of these data are scattered in multiple databases and supplementary materials of publications, thus making their retrieval, evaluation, comparison and visualization a rather arduous task. Here we report the development and implementation of an open access database (BTECH), a community resource for the deposition of a wide range of molecular data derived from brain tumor studies. This comprehensive database integrates multiple datasets, including transcript profiles, epigenomic CpG methylation data, DNA copy number alterations and structural chromosomal rearrangements, tumor-associated gene lists, SNPs, genomic features concerning Alu repeats and general genomic annotations. A genome browser has also been developed that allows for the simultaneous visualization of the different datasets and the various annotated features. Besides enabling an integrative view of diverse datasets through the genome browser, we also provide links to the original references for users to have a more accurate understanding of each specific dataset. This integrated platform will facilitate uncovering interactions among genetic and epigenetic factors associated with brain tumor development. BTECH is freely available at http://cmbteg.childrensmemorial.org/.
Electronic supplementary material
The online version of this article (doi:10.1007/s12021-010-9091-9) contains supplementary material, which is available to authorized users.
Database; Brain tumor; Genome browser; Genomics; Epigenomics; DNA methylation; Gene expression
To determine the efficacy and safety of clofarabine in pediatric patients with refractory or relapsed acute myeloid leukemia (AML).
Patients and Methods
A phase II, open-label, multicenter study was conducted with single-agent clofarabine in pediatric patients with refractory or relapsed AML. Clofarabine was administered intravenously over 2 hours at the pediatric maximum-tolerated dose (MTD) of 52 mg/m2 daily for 5 consecutive days. Cycles were repeated every 2 to 6 weeks. Responses determined by an independent response review panel.
The 42 patients treated on the study had a median age of 13 years (range, 2 to 22 years) and had received a median number of two (range, one to five) prior regimens. The response rate was 26% and included one complete response without platelet recovery and 10 partial responses. The median duration of response was 20 weeks (range, 2 to ≥ 156 weeks). Six of 28 patients who were refractory to the immediately preceding therapy achieved response. Thirteen patients (31%), including seven responders, proceeded to hematopoietic stem-cell transplantation (HSCT) after treatment with clofarabine and survived between 24 to ≥ 160 weeks. Five patients (12%) remain alive post-transplantation at ≥ 63, ≥ 71, ≥ 86, ≥ 114, and ≥ 130 weeks. The most common grade 3 or greater adverse events without regard to causality were febrile neutropenia, catheter-related infection, epistaxis, hypotension, nausea, and fever. Transient elevation of liver enzymes and hypokalemia occurred frequently. Five patients died within 30 days of clofarabine administration secondary to progressive disease, and another five died as a result of an adverse event.
Clofarabine is active in pediatric patients with multiply relapsed or refractory AML. Responses allowed several refractory patients to proceed to HSCT. The toxicity profile was expected in this patient population.
Children and adolescents with malignant astrocytomas recurring after initial treatment have a dismal prognosis, with only rare patients surviving one year beyond recurrence. The purpose of this study was to attempt to improve their survival.
Twenty-seven children and adolescents with malignant astrocytomas (17 glioblastoma multiforme and 10 anaplastic astrocytoma) following initial tumor progression, received myeloablative chemotherapy followed by autologous marrow rescue with one of three thiotepa and etoposide-based chemotherapy regimens, administered alone (n=11) or combined with carmustine (n=5) or carboplatin (n=11). Time to progression and death following myeloablative chemotherapy for these patients was compared non-randomly with outcome of a contemporaneously treated cohort of similar patients who received only conventional chemotherapy following initial tumor progression. The two cohorts were compared for age, histology, prior therapies, extent of surgical resection at progression and time from initial diagnosis to progression.
Five of 27 children (two with glioblastoma multiforme and three with anaplastic astrocytoma) survive event-free from 8.3 to 13.3 years (median of 11.1 years) following myeloablative chemotherapy. Of 56 children with recurrent malignant astrocytoma who received conventional chemotherapy following initial progression, no patient survives. Differences in distributions of survival were not significant when stratified by surgical debulking (p=0.39). However, for patients who were surgically debulked, the survival distributions are significantly different (p=0.017).
Myeloablative chemotherapy with autologous marrow rescue can produce durable remissions in children and young adults with recurrent malignant gliomas, in the setting of minimal residual tumor burden achieved surgically.
Myeloablative chemotherapy; autologous bone marrow rescue; recurrent malignant astrocytoma
SU5416 is a novel small molecule tyrosine kinase inhibitor of the VEGF receptors 1 and 2. A phase I dose escalation study stratified by concurrent use (stratum II) or absence (Stratum I) of enzyme-inducing anticonvulsant drugs was undertaken to estimate the maximum-tolerated dose (MTD) and to describe the toxicity profile of SU5416 in pediatric patients with refractory brain tumors. Dose escalations were conducted independently for stratum I starting at 110mg/m2 while stratum II started at 48mg/m2. Thirty-three eligible patients were treated on stratum I (n=23) and stratum II (n=10). Tumor types included 23 glial tumors, 4 neural tumors, 4 ependymomas and 2 choroid plexus carcinomas. The MTD in Stratum I was initially estimated to be 110mg/m2. The protocol was amended to determine the MTD after excluding transient AST elevation. Re-estimation of the MTD began at the 145mg/m2 dose level but due to development of SU5416 being stopped by the sponsor, the trial was closed before completion. The most serious drug-related toxicities were grade 3 liver enzyme abnormalities, arthralgia and hallucinations. The plasma pharmacokinetics of SU5416 was not significantly affected by the concurrent administration of enzyme-inducing anticonvulsant drugs. Mean values of the total body clearance, apparent volume of distribution, and terminal phase half-life of SU5416 for the 19 patients in Stratum I were 26.1 ± 12.5 liter/h/m2, 41.9 ± 21.4 liter/m2, and 1.11 ± 0.41 h, respectively. The plasma pharmacokinetics of SU5416 in children was similar to previously reported findings in adult cancer patients. Prolonged disease stabilization was observed in 4 of 16 stratum 1 patients.
VEGF; Anti-angiogenesis; Brain tumor; SU5416
Atypical teratoid rhabdoid tumor (ATRT) of the CNS is a highly malignant neoplasm primarily affecting young children, with a historic median survival ranging from 6 to 11 months. Based on a previous pilot series, a prospective multi-institutional trial was conducted for patients with newly diagnosed CNS ATRT.
Patients and Methods
Treatment was divided into five phases: preirradiation, chemoradiation, consolidation, maintenance, and continuation therapy. Intrathecal chemotherapy was administered, alternating intralumbar and intraventricular routes. Radiation therapy (RT) was prescribed, either focal (54 Gy) or craniospinal (36 Gy, plus primary boost), depending on age and extent of disease at diagnosis.
Between 2004 and 2006, 25 patients were enrolled; 20 were eligible for evaluation. Median age at diagnosis was 26 months (range, 2.4 months to 19.5 years). Gross total resection of the primary tumor was achieved in 11 patients. Fourteen patients had M0 disease at diagnosis, one patient had M2 disease, and five patients had M3 disease. Fifteen patients received radiation therapy: 11 focal and four craniospinal. Significant toxicities, in addition to the expected, included radiation recall (n = 2) and transverse myelitis (n = 1). There was one toxic death. Of the 12 patients who were assessable for chemotherapeutic response (pre-RT), the objective response rate was 58%. The objective response rate observed after RT was 38%. The 2-year progression-free and overall survival rates are 53% ± 13% and 70% ± 10%, respectively. Median overall survival has not yet been reached.
This intensive multimodality regimen has resulted in a significant improvement in time to progression and overall survival for patients with this previously poor-prognosis tumor.
DNA methylation, the only known covalent modification of mammalian DNA, occurs primarily in CpG dinucleotides. 51% of CpGs in the human genome reside within repeats, and 25% within Alu elements. Despite that, no method has been reported for large-scale ascertainment of CpG methylation in repeats. Here we describe a sequencing-based strategy for parallel determination of the CpG-methylation status of thousands of Alu repeats, and a computation algorithm to design primers that enable their specific amplification from bisulfite converted genomic DNA. Using a single primer pair, we generated amplicons of high sequence complexity, and derived CpG-methylation data from 31 178 Alu elements and their 5′ flanking sequences, altogether representing over 4 Mb of a human cerebellum epigenome. The analysis of the Alu methylome revealed that the methylation level of Alu elements is high in the intronic and intergenic regions, but low in the regions close to transcription start sites. Several hypomethylated Alu elements were identified and their hypomethylated status verified by pyrosequencing. Interestingly, some Alu elements exhibited a strikingly tissue-specific pattern of methylation. We anticipate the amplicons herein described to prove invaluable as epigenome representations, to monitor epigenomic alterations during normal development, in aging and in diseases such as cancer.
This study estimated the maximum tolerated dose (MTD) of imatinib with irradiation in children with newly diagnosed brainstem gliomas, and those with recurrent malignant intracranial gliomas, stratified according to use of enzyme-inducing anticonvulsant drugs (EIACDs). In the brainstem glioma stratum, imatinib was initially administered twice daily during irradiation, but because of possible association with intratumoral hemorrhage (ITH) was subsequently started two weeks after irradiation. The protocol was also amended to exclude children with prior hemorrhage. Twenty-four evaluable patients received therapy before the amendment, and three of six with a brainstem tumor experienced dose-limiting toxicity (DLT): one had asymptomatic ITH, one had grade 4 neutropenia and, one had renal insufficiency. None of 18 patients with recurrent glioma experienced DLT. After protocol amendment, 3 of 16 patients with brainstem glioma and 2 of 11 patients with recurrent glioma who were not receiving EIACDs experienced ITH DLTs, with three patients being symptomatic. In addition to the six patients with hemorrhages during the DLT monitoring period, 10 experienced ITH (eight patients were symptomatic) thereafter. The recommended phase II dose for brainstem gliomas was 265 mg/m2. Three of 27 patients with brainstem gliomas with imaging before and after irradiation, prior to receiving imatinib, had new hemorrhage, excluding their receiving imatinib. The MTD for recurrent high-grade gliomas without EIACDs was 465 mg/m2, but the MTD was not established with EIACDs, with no DLTs at 800 mg/m2. In summary, recommended phase II imatinib doses were determined for children with newly diagnosed brainstem glioma and recurrent high-grade glioma who were not receiving EIACDs. Imatinib may increase the risk of ITH, although the incidence of spontaneous hemorrhages in brainstem glioma is sufficiently high that this should be considered in studies of agents in which hemorrhage is a concern.
brainstem; children; dose-limiting toxicity; enzyme-inducing anticonvulsant drugs; imatinib mesylate; intratumoral hemorrhage; malignant glioma; maximum tolerated dose; phase I trial
We report a case of bloodstream infection caused by Candida thermophila, a yeast not previously associated with human disease. The infection occurred in a 13-year-old boy with medulloblastoma who presented with 1 day of fever. Multiple blood cultures were positive for yeast. Removal of the catheter resulted in prompt resolution of the fever and sterilization of the blood cultures. The species was identified by sequencing domains 1 and 2 of the large subunit rRNA gene. Antifungal susceptibility testing was also performed.