Favorable outcome with conservative treatment for children with low grade brainstem tumors

BACKGROUND

Pediatric brainstem tumors (BST) comprise a heterogeneous group of entities. Data regarding treatment options and outcome of BST, specifically brainstem low grade tumors (BSLGT) are limited. In order to better define risk groups and evaluate treatment options for pediatric BST, we performed a comprehensive analysis of all BST patients treated in our hospital during the MRI era.

PROCEDURES

We retrospectively analyzed clinical, imaging, and pathology data at presentation, treatment, and outcome of all BST patients followed at the Hospital for Sick Children in Toronto over the last 25 years.

RESULTS

Of 1,801 children with brain tumors, 223 (12%) had a brainstem primary location. Tumors without pontine involvement were BSLGT in 98.3%, whereas 75% of tumors involving the pons were high grade (P = 0.0001). Patients with BSLGT had 5-year progression-free survival (PFS) and overall survival (OS) of 57 ± 3% and 89 ± 5%, respectively. Upfront observation of tumor residual conferred no survival disadvantage with 5-year PFS and OS of 57 ± 5% and 93 ± 3%, respectively. In the group of patients requiring further treatment, 5-year PFS and OS were comparable between chemotherapy and radiotherapy with 53 ± 12% and 93 ± 4% and 66 ± 11% and 83 ± 6%, respectively (P = 0.26 and 0.3, respectively).

CONCLUSION

BST without pontine involvement are almost invariably BSLGT. Children with BSLGT have an excellent outcome even with careful initial observation. No clear benefit was observed for radiotherapy over chemotherapy when adjuvant treatment was needed. A conservative approach may be warranted for children with non-pontine brainstem lesions.

Genome sequencing of pediatric medulloblastoma links catastrophic DNA rearrangements with TP53 mutations

Genomic rearrangements are thought to occur progressively during tumor development. Recent findings, however, suggest an alternative mechanism, involving massive chromosome rearrangements in a one-step catastrophic event termed chromothripsis. We report the whole-genome sequencing-based analysis of a Sonic-Hedgehog medulloblastoma (SHH-MB) brain tumor from a patient with a germline TP53 mutation (Li-Fraumeni syndrome), uncovering massive, complex chromosome rearrangements. Integrating TP53 status with microarray and deep sequencing-based DNA rearrangement data in additional patients reveals a striking association between TP53 mutation and chromothripsis in SHH-MBs. Analysis of additional tumor entities substantiates a link between TP53 mutation and chromothripsis, and indicates a context-specific role for p53 in catastrophic DNA rearrangements. Among these, we observed a strong association between somatic TP53 mutations and chromothripsis in acute myeloid leukemia. These findings connect p53 status and chromothripsis in specific tumor types, providing a genetic basis for understanding particularly aggressive subtypes of cancer.

Driver mutations in histone H3.3 and chromatin remodelling genes in paediatric glioblastoma

Glioblastoma multiforme (GBM) is a lethal brain tumour in adults and children. However, DNA copy number and gene expression signatures indicate differences between adult and paediatric cases. To explore the genetic events underlying this distinction, we sequenced the exomes of 48 paediatric GBM samples. Somatic mutations in the H3.3-ATRX-DAXX chromatin remodelling pathway were identified in 44% of tumours (21/48). Recurrent mutations in H3F3A, which encodes the replication-independent histone 3 variant H3.3, were observed in 31% of tumours, and led to amino acid substitutions at two critical positions within the histone tail (K27M, G34R/G34V) involved in key regulatory post-translational modifications. Mutations in ATRX (α-thalassaemia/mental retardation syndrome X-linked) and DAXX (death-domain associated protein), encoding two subunits of a chromatin remodelling complex required for H3.3 incorporation at pericentric heterochromatin and telomeres, were identified in 31% of samples overall, and in 100% of tumours harbouring a G34R or G34V H3.3 mutation. Somatic TP53 mutations were identified in 54% of all cases, and in 86% of samples with H3F3A and/or ATRX mutations. Screening of a large cohort of gliomas of various grades and histologies (n = 784) showed H3F3A mutations to be specific to GBM and highly prevalent in children and young adults. Furthermore, the presence of H3F3A/ATRX-DAXX/TP53 mutations was strongly associated with alternative lengthening of telomeres and specific gene expression profiles. This is, to our knowledge, the first report to highlight recurrent mutations in a regulatory histone in humans, and our data suggest that defects of the chromatin architecture underlie paediatric and young adult GBM pathogenesis.

Monoallelic expression determines oncogenic progression and outcome in benign and malignant brain tumors

Although monoallelic expression (MAE) is a frequent genomic event in normal tissues, its role in tumorigenesis remains unclear. Here we carried out single-nucleotide polymorphism arrays on DNA and RNA from a large cohort of pediatric and adult brain tumor tissues to determine the genome-wide rate of MAE, its role in specific cancer-related genes, and the clinical consequences of MAE in brain tumors. We also used targeted genotyping to examine the role of tumor-related genes in brain tumor development and specifically examined the clinical consequences of MAE at TP53 and IDH1. The genome-wide rate of tumor MAE was higher than in previously described normal tissue and increased with specific tumor grade. Oncogenes, but not tumor suppressors, exhibited significantly higher MAE in high-grade compared with low-grade tumors. This method identified nine novel genes highly associated with MAE. Within cancer-related genes, MAE was gene specific; hTERT was most significantly affected, with a higher frequency of MAE in adult and advanced tumors. Clinically, MAE at TP53 exists only in mutated tumors and increases with tumor aggressiveness. MAE toward the normal allele at IDH1 conferred worse survival even in IDH1 mutated tumors. Taken together, our findings suggest that MAE is tumor and gene specific, frequent in brain tumor subtypes, and may be associated with tumor progression/aggressiveness. Further exploration of MAE at relevant genes may contribute to better understanding of tumor development and determine survival in brain tumor patients.

Neural tumor-initiating cells have distinct telomere maintenance and can be safely targeted for telomerase inhibition

PURPOSE

Cancer recurrence is one of the major setbacks in oncology. Maintaining telomeres is essential for sustaining the limitless replicative potential of such cancers. Because telomerase is thought to be active in all tumor cells and normal stem cells, telomerase inhibition may be nonspecific and have detrimental effects on tissue maintenance and development by affecting normal stem cell self-renewal.

METHODS

We examined telomerase activity, telomere maintenance, and stem cell maturation in tumor subpopulations from freshly resected gliomas, long-term, primary, neural tumor-initiating cells (TIC) and corresponding normal stem cell lines. We then tested the efficacy of the telomerase inhibitor Imetelstat on propagation and self-renewal capacity of TIC and normal stem cells in vitro and in vivo.

RESULTS

Telomerase was undetectable in the majority of tumor cells and specific to the TIC subpopulation that possessed critically short telomeres. In contrast, normal tissue stem cells had longer telomeres and undetectable telomerase activity and were insensitive to telomerase inhibition, which results in proliferation arrest, cell maturation, and DNA damage in neural TIC. Significant survival benefit and late tumor growth arrest of neuroblastoma TIC were observed in a xenograft model (P = 0.02). Furthermore, neural TIC exhibited irreversible loss of self-renewal and stem cell capabilities even after cessation of treatment in vitro and in vivo.

CONCLUSIONS

TIC exhaustion with telomerase inhibition and lack of telomerase dependency in normal stem cells add new dimensions to the telomere hypothesis and suggest that targeting TIC with telomerase inhibitors may represent a specific and safe therapeutic approach for tumors of neural origin.

Primary Ewing's sarcoma affecting the central nervous system: a review and proposed prognostic considerations

Ewing's sarcoma (ES) is a part of a larger family of round blue cell tumors, which occasionally manifest as osseous or extraosseous lesions adjacent to or within the central nervous system (CNS). While a large body of literature exists on ES of bone, data are lacking on tumors with cranial or spinal components that affect the CNS. Here, we perform a systematic review of the literature and summarize the best available evidence on diagnosis, treatment and outcomes of ES affecting the CNS with emphasis on the breadth of clinical presentations, diagnostic tools and emerging management options for these rare and challenging lesions. We include a review of known prognostic factors and propose several new considerations for prognostication of ES affecting the CNS.

Delineation of two clinically and molecularly distinct subgroups of posterior fossa ependymoma

Despite the histological similarity of ependymomas from throughout the neuroaxis, the disease likely comprises multiple independent entities, each with a distinct molecular pathogenesis. Transcriptional profiling of two large independent cohorts of ependymoma reveals the existence of two demographically, transcriptionally, genetically, and clinically distinct groups of posterior fossa (PF) ependymomas. Group A patients are younger, have laterally located tumors with a balanced genome, and are much more likely to exhibit recurrence, metastasis at recurrence, and death compared with Group B patients. Identification and optimization of immunohistochemical (IHC) markers for PF ependymoma subgroups allowed validation of our findings on a third independent cohort, using a human ependymoma tissue microarray, and provides a tool for prospective prognostication and stratification of PF ependymoma patients.

Feasibility and efficacy of repeated chemotherapy for progressive pediatric low-grade gliomas

BACKGROUND

Chemotherapy is widely accepted as first-line therapy for pediatric low-grade gliomas (LGG). Treatment modalities for further progression are not clearly established. The aim of the study was to determine the feasibility and long-term outcome of repeated chemotherapy for children with recurrent LGG.

METHODS

The study group consisted of patients who received a second line of chemotherapy at progression of their LGG. We compared toxicity, progression-free survival (PFS), and overall survival (OS) of patients treated with chemotherapy at the time of initial diagnosis and patients who received another treatment with chemotherapy at further progression.

RESULTS

Between 1985 and 2009, 118 patients received chemotherapy as primary treatment for LGG, 38 had repeated chemotherapy at further progression. Chemotherapy was tolerated extremely well. Ninety-two percent of patients completed their second line protocol and toxicity was comparable between initial and second line chemotherapy. Five-year OS and PFS were 86 ± 6% and 37 ± 8%, respectively, which were similar to first-line chemotherapy (P = 0.14). Repeated chemotherapy courses were not associated with worsening of visual, neuroendocrine, or other long-term organ sequelae.

CONCLUSION

This study demonstrates high feasibility and low mortality of repeated chemotherapy treatment for progressive LGG. The chronic nature of LGG concerning tumor progression justifies consideration of non-toxic second-line treatment regimens at the time of recurrence. Prospective studies focusing on toxicity and long-term outcome are needed to substantiate this approach.

Genetic aberrations leading to MAPK pathway activation mediate oncogene-induced senescence in sporadic pilocytic astrocytomas

PURPOSE

Oncogenic BRAF/Ras or NF1 loss can potentially trigger oncogene-induced senescence (OIS) through activation of the mitogen-activated protein kinase (MAPK) pathway. Somatic genetic abnormalities affecting this pathway occur in the majority of pilocytic astrocytomas (PA), the most prevalent brain neoplasm in children. We investigated whether OIS is induced in PA.

EXPERIMENTAL DESIGN

We tested expression of established senescence markers in three independent cohorts of sporadic PA. We also assessed for OIS in vitro, using forced expression of wild-type and V600E-mutant BRAF in two astrocytic cell lines: human telomerase reverse transcriptase (hTERT)-immortalized astrocytes and fetal astrocytes.

RESULTS

Our results indicate that PAs are senescent as evidenced by marked senescence-associated acidic β-galactosidase activity, low KI-67 index, and induction of p16(INK4a) but not p53 in the majority of 52 PA samples (46 of 52; 88.5%). Overexpression of a number of senescence-associated genes [CDKN2A (p16), CDKN1A (p21), CEBPB, GADD45A, and IGFBP7] was shown at the mRNA level in two independent PA tumor series. In vitro, sustained activation of wild-type or mutant BRAF induced OIS in both astrocytic cell lines. Loss of p16(INK4a) in immortalized astrocytes abrogated OIS, indicative of the role of this pathway in mediating this phenomenon in astrocytes. OIS is a mechanism of tumor suppression that restricts the progression of benign tumors. We show that it is triggered in PAs through p16(INK4a) pathway induction following aberrant MAPK activation.

CONCLUSIONS

OIS may account for the slow growth pattern in PA, the lack of progression to higher-grade astrocytomas, and the high overall survival of affected patients.

BRAF-KIAA1549 fusion predicts better clinical outcome in pediatric low-grade astrocytoma

PURPOSE

Recent studies have revealed that the majority of pediatric low-grade astrocytomas (PLGA) harbor the BRAF-KIAA1549 (B-K) fusion gene resulting in constitutive activation of the RAS/MAPK pathway. However, the clinical significance of this genetic alteration is yet to be determined. We aimed to test the prognostic role of the B-K fusion in progression of incompletely resected PLGA.

EXPERIMENTAL DESIGN

We retrospectively identified 70 consecutive patients with incompletely resected "clinically relevant" PLGA. We added 76 tumors diagnosed at our institution between 1985 and 2010 as controls. We examined BRAF alterations by reverse transcriptase PCR, FISH, and single-nucleotide polymorphism array analysis and correlated that with progression-free survival (PFS).

RESULTS

Overall, 60% of tumors were B-K fusion positive. All patients with B-K fused PLGA are still alive. Five-year PFS was 61% ± 8% and 18% ± 8% for fusion positive and negative patients, respectively (P = 0.0004). B-K fusion resulted in similarly significant favorable PFS for patients who received chemotherapy. Multivariate analysis revealed that B-K fusion was the most significant favorable prognostic factor in incompletely resected PLGA and was independent of location, pathology, and age. In vitro, BRAF overexpression resulted in growth arrest associated with DNA damage (γH2AX expression). Five-year PFS was 68% ± 15% and 0% for patients with B-K fused and γH2AX-expressing PLGA versus negative tumors (P = 0.001).

CONCLUSION

These data suggest that B-K fusion confers a less aggressive clinical phenotype on PLGA and may explain their tendency to growth arrest. Combined analysis of B-K fusion and γH2AX expression can determine prognosis and may be a powerful tool to tailor therapy for these patients.

Biochemical and imaging surveillance in germline TP53 mutation carriers with Li-Fraumeni syndrome: a prospective observational study

BACKGROUND

Individuals with Li-Fraumeni syndrome have a high lifetime risk of developing cancer. We assessed the feasibility and potential clinical effect of a comprehensive surveillance protocol in asymptomatic TP53 mutation carriers in families with this syndrome.

METHODS

We implemented a clinical surveillance protocol, using frequent biochemical and imaging studies, for asymptomatic TP53 mutation carriers on Jan 1, 2004, and did a prospective observational study of members of eight families with Li-Fraumeni syndrome who either chose to undergo surveillance or chose not to undergo surveillance. The primary outcome measure was detection of new cancers. The secondary outcome measure was overall survival.

FINDINGS

As of Nov 1, 2010, 33 TP53 mutation carriers were identified, 18 of whom underwent surveillance. The surveillance protocol detected ten asymptomatic tumours in seven patients, including small, high-grade tumours and low-grade or premalignant tumours. All seven mutation carriers were alive after a median follow-up of 24 months (IQR 22-65 months). 12 high-grade, high-stage tumours developed in 10 individuals in the non-surveillance group, two of whom (20%) were alive at the end of follow-up (p=0·0417 for comparison with survival in the surveillance group). 3-year overall survival was 100% in the surveillance group and 21% (95% CI 4-48%) in the non-surveillance group (p=0·0155).

INTERPRETATION

Our findings show the feasibility of a clinical surveillance protocol for the detection of asymptomatic neoplasms in individuals with germline TP53 mutations. This strategy offers a management option for affected individuals, and its benefits lend support to the use of early genetic testing of at-risk individuals and families.

FUNDING

Canadian Cancer Society Research Institute, Canadian Institutes of Health Research, SickKids Foundation, and Soccer for Hope.

Early aging in adult survivors of childhood medulloblastoma: long-term neurocognitive, functional, and physical outcomes

Treatment for medulloblastoma during childhood impairs neurocognitive function in survivors. While those diagnosed at younger ages are most vulnerable, little is known about the long-term neurocognitive, functional, and physical outcomes in survivors as they approach middle age. In this retrospective cohort study, we assessed 20 adults who were treated with surgery and radiotherapy for medulloblastoma during childhood (median age at assessment, 21.9 years [range, 18-47 years]; median time since diagnosis, 15.5 years [range, 6.5-42.2 years]). Nine patients also underwent chemotherapy. Cross-sectional analyses of current neurocognitive, functional, and physical status were conducted. Data from prior neuropsychological assessments were available for 18 subjects; longitudinal analyses were used to model individual change over time for those subjects. The group was well below average across multiple neurocognitive domains, and 90% had required accommodations at school for learning disorders. Longer time since diagnosis, but not age at diagnosis, was associated with continued decline in working memory, a common sign of aging. Younger age at diagnosis was associated with lower intelligence quotient and academic achievement scores, even many years after treatment had been completed. The most common health complications in survivors were hearing impairment, second cancers, diabetes, hypertension, and endocrine deficiencies. Adult survivors of childhood medulloblastoma exhibit signs of early aging regardless of how young they were at diagnosis. As survival rates for brain tumors continue to improve, these neurocognitive and physical sequelae may become evident in survivors diagnosed at different ages across the lifespan. It will become increasingly important to identify factors that contribute to risk and resilience in this growing population.

Abstract 3455: Comparison of expression profiles of pediatric high and low grade brainstem gliomas to pediatric supratentorial high grade astrocytomas

Diffuse intrinsic pontine gliomas (DIPG) are one of the most devastating pediatric malignancies and currently the number one cause of brain tumor related death in children with a 10-12 month median survival. Despite this very little is understood about the biology of these tumors. We have already shown potential novel therapeutic targets for DIPG using high-resolution SNP-based analysis. We performed high resolution genetic analysis using whole-genome single-nucleotide polymorphism (SNP) arrays (Affymetrix 500K and 6.0) on post mortem tumor with matched normal brain samples (n=9) and surgical samples (n=2) for a series of DIPG patients as well as pediatric supratentorial high grade astrocytomas (sHGA, n=20). Here we extend our initial study to include expression array analysis, amalgamating the datasets to generate a more complete understanding of the genetic alterations underlying brainstem gliomas. Expression profiling using Illumina HumanHT-12 arrays was conducted on 26 high grade brainstem gliomas, including 23 DIPGs, 51 low grade brainstem gliomas and 30 supratentorial high grade astrocytomas. Expression profiles highlighted the distinctiveness of DIPGs when compared to high grade supratentorial astrocytomas. Analysis resulted in two groups of DIPGs when clustering based on most significant differentially expressed genes (p < 0.005) with one group being more similar to pediatric low grade brainstem gliomas and the other distinct from both the supratentorial high grade tumors and other brainstem gliomas. This data will increase our understanding of brainstem glioma biology, information crucial to the development of agents targeted more specifically towards this devastating disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3455. doi:10.1158/1538-7445.AM2011-3455

Abstract 3460: Genome-wide copy number analysis reveals novel somatic mutations associated with choroid plexus tumorigenesis

Choroid plexus carcinomas (CPCs) are aggressive pediatric neoplasms accounting for less than 1% of brain tumors, but representing more than 10% of brain tumors in children under 1 year of age. CPCs are frequently observed in the context of the Li-Fraumeni Syndrome (LFS), yet this association has not been fully elucidated. The genetic mechanisms leading to this disease are poorly understood; however, we have recently demonstrated that TP53 status and total structural variation are correlated with tumor subtype and clinical outcome in choroid plexus tumor (CPT) patients, distinguishing between individuals with CPC and choroid plexus papilloma (CPP), a benign tumor with a more favorable prognosis. We set out to characterize genomic regions in which copy number variation and gene expression changes are uniquely associated with CPC tumors in order to identify genes that may serve as markers in tumor diagnosis and prognosis.

DNA and RNA from 59 choroid plexus tumors (CPC, n=29 and CPP, n=30) and two samples of normal choroid plexus tissue were obtained from a multi-institutional tissue and clinical database. We conducted high-resolution copy number alteration (CNA) and gene expression analysis for each tumor sample using highly dense microarrays (Affymetrix SNP 6.0 and Exon 1.0 ST array, respectively). DNA microarray data was segmented using a Hidden Markov Model (HMM) approach. Statistical analysis was carried out using Partek Genomics Suite in which CNAs and gene expression changes between CPC, CPP, and normal choroid plexus samples were contrasted. We identified 14 CPC-unique loci harboring CNAs with corresponding gene expression changes (p>0.05). We observed that CNAs were found at loci where cancer genes with well-characterized oncogenic functions have been previously identified (1p13.2, 1p13.3, 1p21.3, 1p22.1 and 5q13.3). Furthermore, more than 90% of tumors with copy number alterations and expression changes at these five loci also harbored mutant TP53.

These observations suggest involvement of several genes in the malignant progression of CPCs, which may help elucidate the aggressiveness and poor clinical outcome of this tumor subtype compared to the more favorable CPP. Further analysis of CNAs and expression at these loci in the context of TP53 mutations, will provide a more refined genetic profile that will facilitate diagnosis of CPTs and aid in predicting patient outcome.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3460. doi:10.1158/1538-7445.AM2011-3460

TP53 Mutation Is Frequently Associated With CTNNB1 Mutation or MYCN Amplification and Is Compatible With Long-Term Survival in Medulloblastoma

Purpose

The role of TP53 mutations in the tumorigenesis of sporadic medulloblastoma (MB) and the value of TP53 mutation status as a prognostic marker are not yet definitely elucidated. A recent report identified TP53 mutations in MB as an adverse prognostic marker. Hence, the current study was conducted to validate the prognostic role of TP53 mutation in MB and to understand its contribution to tumorigenesis.

Methods

A comprehensive genetic analysis of 310 MB samples was performed by screening for TP53 mutations and further relating the TP53 mutation status to p53 immunostaining, cytogenetic aberrations, and clinical variables.

Results

Mutation analysis of TP53 revealed mutations in 21 (6.8%) of 310 samples. Germline TP53 mutations were found in two patients with a history suggestive of a hereditary cancer syndrome. TP53 mutation status was not associated with unfavorable prognosis (P = .63) and was not linked to 17p allelic loss but was over-represented in the prognostically favorable WNT subgroup of MB as defined by CTNNB1 mutation (seven of 35 TP53-mutated tumors v 14 of 271 TP53 wild-type tumors; P = .005) and in tumors carrying high-level MYCN amplification (seven of 21 TP53-mutated tumors v 14 of 282 TP53 wild-type tumors; P = .001).

Conclusion

The contradictory results in the recent literature concerning the prognostic value of TP53 mutation might be explained by different frequencies of WNT MBs, different frequencies of patients with Li-Fraumeni syndrome, and different cumulative doses of alkylating drugs applied in these studies.

Vincristine and carboplatin chemotherapy for unresectable and/or recurrent low-grade astrocytoma of the brainstem

BACKGROUND

Radiotherapy remains a widely accepted postoperative treatment modality for unresectable or recurrent low-grade glioma (LGG). However, there is increasing evidence to suggest that chemotherapy can delay and may obviate the need for radiotherapy in progressive/recurrent LGG. The majority of the published experience is in children with hypothalamic/optic chiasmatic lesions and little information is available regarding its use in LGG of the brainstem.

PROCEDURE

We describe clinical characteristics and course of children with LGG of the brainstem who received carboplatin-based chemotherapy in two institutions over 10 years (1996-2006). This was a retrospective review of consecutively treated children with LGG of the brainstem (midbrain, pons, medulla, and upper cervical cord). Vincristine and carboplatin were first-line chemotherapy regimen used in all patients.

RESULTS

In this series, there were 16 children (9 males) with median age at diagnosis of 4.2 years (range 0.5-8). Eight children were treated at diagnosis while the remaining eight received chemotherapy after either radiological progression or clinical deterioration. After a median follow-up of 57 months (range 20-136) from initiation of chemotherapy all children are alive and 11 remain progression free (1 complete response, 8 with partial response + minor response, and 2 stable diseases).

CONCLUSIONS

The efficacy of this chemotherapy regimen in this series supports its role in children with progressive unresectable LGG of brainstem.

Use of ifosfamide, carboplatin, and etoposide chemotherapy in choroid plexus carcinoma

OBJECT

Choroid plexus carcinomas (CPCs) are rare pediatric tumors with a generally poor prognosis. Although the role of surgery is well recognized, the role of adjuvant chemotherapy and radiation therapy remains unclear. In this paper, the authors' goal was to assess the role of second-look surgery and neoadjuvant ifosfamide, carboplatin, etoposide (ICE) chemotherapy in the management of CPC and to study neurocognitive outcome.

METHODS

The authors performed an institutional retrospective review of patients in whom CPC was diagnosed between 1985 and 2006 at the Hospital for Sick Children in Toronto. Fourteen patients (7 boys and 7 girls) were included. The median age at diagnosis was 18.6 months (range 1.1-65.3 months). Four patients had evidence of metastatic disease at diagnosis. Two of the 14 patients underwent gross-total resection during initial surgery; 12 of the patients received neoadjuvant chemotherapy, 10 of whom underwent second surgery. In total, of 12 patients who received chemotherapy with a curative intent, 11 underwent a greater than 95% resection. Neoadjuvant ICE chemotherapy was given prior to second surgery (median 4 cycles, range 2-5 cycles) and was continued after second resection for a median total of 7 cycles (range 4-16 cycles).

RESULTS

No tumor progression was observed during chemotherapy prior to second surgery. Five patients subsequently experienced tumor progression/relapse. At a median follow-up of 6.9 years (range 1.9-18.5 years), 8 patients are alive. None of the survivors received radiation therapy. However, 6 of 8 display significant neurocognitive and/or sensorial deficit.

CONCLUSIONS

In this experience, second surgery following neoadjuvant ICE chemotherapy led to a high rate of complete or near-complete resection. Chemotherapy appears to facilitate second-look surgery, in particular through a reduction of intraoperative blood loss. Despite radiation avoidance, the majority of survivors experienced significant neurocognitive impairment.

TP53 alterations determine clinical subgroups and survival of patients with choroid plexus tumors

PURPOSE Choroid plexus carcinomas are pediatric tumors with poor survival rates and a strong, but poorly understood, association with Li-Fraumeni syndrome (LFS). Currently, with lack of biologic predictors, most children are treated with aggressive chemoradiation protocols. PATIENTS AND METHODS We established a multi-institutional tissue and clinical database, which enabled the analysis of specific alterations of the TP53 tumor suppressor and its modifiers in choroid plexus tumors (CPTs). We conducted high-resolution copy-number analysis to correlate these genetic parameters with family history and outcome. Results We studied 64 patients with CPTs. All individuals with germline TP53 mutations fulfilled LFS criteria, whereas all patients not meeting these criteria harbored wild-type TP53 (P < .001). TP53 mutations were found in 50% of choroid plexus carcinomas (CPCs). Additionally, two sequence variants known to confer TP53 dysfunction, TP53 codon72 and MDM2 SNP309, coexisted in the majority of TP53 wild-type CPCs (92%) and not in TP53 mutated CPC (P = .04), which suggests a complementary mechanism of TP53 dysfunction in the absence of a TP53 mutation. High-resolution single nucleotide polymorphism (SNP) array analysis revealed extremely high total structural variation (TSV) in TP53-mutated CPC tumor genomes compared with TP53 wild-type tumors and choroid plexus papillomas (CPPs; P = .006 and .004, respectively). Moreover, high TSV was associated with significant risk of progression (P < .001). Five-year survival rates for patients with TP53-immunopositive and -immunonegative CPCs were 0% and 82 (+/- 9%), respectively (P < .001). Furthermore, 14 of 16 patients with TP53 wild-type CPCs are alive without having received radiation therapy. CONCLUSION Patients with CPC who have low tumor TSV and absence of TP53 dysfunction have a favorable prognosis and can be successfully treated without radiation therapy.