Atypical teratoid rhabdoid tumors (ATRTs): the British Columbia's Children's Hospital's experience, 1986-2006

Behavioral Improvements following Lesion Resection for Pediatric Epilepsy: Pediatric Psychosurgery?

INTRODUCTION

Resection of brain lesions associated with refractory epilepsy to achieve seizure control is well accepted. However, concurrent behavioral effects of these lesions such as changes in mood, personality, and cognition and the effects of surgery on behavior have not been well characterized. We describe 5 such children with epileptogenic lesions and significant behavioral abnormalities which improved after surgery.

CASE DESCRIPTIONS

Five children (ages 3-14 years) with major behavioral abnormalities and lesional epilepsy were identified and treated at our center. Behavioral problems included academic impairment, impulsivity, self-injurious behavior, and decreased social interaction with diagnoses of ADHD, oppositional defiant disorder, and autism. Pre-operative neuropsychiatric testing was performed in 4/5 patients and revealed low-average cognitive and intellectual abilities for their age, attentional difficulties, and poor memory. Lesions were located in the temporal (2 gangliogliomas, 1 JPA, 1 cavernoma) and parietal (1 DNET) lobes. Gross total resection was achieved in all cases. At mean 1-year follow-up, seizure freedom (Engel 1a in 3 patients, Engel 1c in 2 patients) and significant behavioral improvements (academic performance, attention, socialization, and aggression) were achieved in all. Two patients manifested violence pre-operatively; one had extreme behavior with violence toward teachers and peers despite low seizure burden. Since surgery, his behavior has normalized.

CONCLUSION

We identified 5 patients with severe behavioral disorders in the setting of lesional epilepsy, all of whom demonstrated improvement after surgery. The degree of behavioral abnormality was disproportionate to epilepsy severity, suggesting a more complicated mechanism by which lesional epilepsy impacts behavior. We propose a novel paradigm in which lesionectomy may offer behavioral benefit even when seizures are not refractory. Thus, behavioral improvement may be an important novel goal for neurosurgical resection in children with epileptic brain lesions.

Immunotherapy for Pediatric Brain and Spine Tumors: Current State and Future Directions

BACKGROUND

Brain tumors are the most common solid tumors and the leading cause of cancer-related deaths in children. Incidence in the USA has been on the rise for the last 2 decades. While therapeutic advances in diagnosis and treatment have improved survival and quality of life in many children, prognosis remains poor and current treatments have significant long-term sequelae.

SUMMARY

There is a substantial need for the development of new therapeutic approaches, and since the introduction of immunotherapy by immune checkpoint inhibitors, there has been an exponential increase in clinical trials to adopt these and other immunotherapy approaches in children with brain tumors. In this review, we summarize the current immunotherapy landscape for various pediatric brain tumor types including choroid plexus tumors, embryonal tumors (medulloblastoma, AT/RT, PNETs), ependymoma, germ cell tumors, gliomas, glioneuronal and neuronal tumors, and mesenchymal tumors. We discuss the latest clinical trials and noteworthy preclinical studies to treat these pediatric brain tumors using checkpoint inhibitors, cellular therapies (CAR-T, NK, T cell), oncolytic virotherapy, radioimmunotherapy, tumor vaccines, immunomodulators, and other targeted therapies.

KEY MESSAGES

The current landscape for immunotherapy in pediatric brain tumors is still emerging, but results in certain tumors have been promising. In the age of targeted therapy, genetic tumor profiling, and many ongoing clinical trials, immunotherapy will likely become an increasingly effective tool in the neuro-oncologist armamentarium.

Case report: Atypical teratoid/rhabdoid tumor of the lateral ventricle in a male adolescent (case-based review and diagnostic challenges in developing countries)

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare and highly malignant central nervous system (CNS) embryonal neoplasm: it accounts for <2% of all pediatric CNS tumors and occurs mainly in infants and young children. The primary site of this tumor is usually the posterior cranial fossa. Supratentorial and, in detail, latero-ventricular location is extremely uncommon, especially in adolescents. This tumor is characterized by rapid growth and spread in cerebrospinal fluid and, therefore, it is characterized by a poor prognosis. Neurological signs and symptoms are related the location of the tumor. The radiological features of AT/RT are nonspecific. Immunohistochemical staining for loss of nuclear integrase interactor 1 (INI1) expression is considered a reliable criterion for the diagnosis of this type of tumor. AT/RT has been linked to mutations of SMARCB1 or, rarely, SMARCA4 genes, which function as tumor suppressor genes. Currently, there is no validated protocol of treatment for children with AT/RT, and multimodality treatment (consisting of surgery, chemotherapy, and radiation therapy) is considered. In this case report, we describe a 15-year-old adolescent with an AT/RT of the left lateral ventricle. Despite the late diagnosis, the multimodal therapeutic approach provided a good outcome for our patient at 21 months' follow-up. Based on our case-based review, early diagnosis and a multimodal approach to treatment play a key role in improving the survival of patients with this diagnosis. Implementing a system supporting pathological and molecular analyses for developing countries and, in general, for non-academic centers is of primary importance to timely diagnose and treat rare tumors, such as AT/RT.

Targeting of cyclin-dependent kinases in atypical teratoid rhabdoid tumors with multikinase inhibitor TG02

OBJECTIVE

Atypical teratoid rhabdoid tumors (ATRTs) are aggressive pediatric brain tumors with no current standard of care and an estimated median patient survival of 12 to 18 months. Previous genetic analyses have implicated cyclin D1 and enhancer of zeste homolog 2 (EZH2), a histone methyltransferase that is implicated in many cancers, as key drivers of tumorigenicity in ATRTs. Since the effects of EZH2 and cyclin D1 are facilitated by a host of cyclin-dependent kinases (CDKs), the authors sought to investigate the potential therapeutic effects of targeting CDKs in ATRTs with the multi-CDK inhibitor, TG02.

METHODS

Human ATRT cell lines BT12, BT37, CHLA05, and CHLA06 were selected for investigation. The effects of TG02 on cell viability, proliferation, clonogenicity, and apoptosis were assessed via Cell Counting Kit-8 assays, cell counting, clonogenic assays, and flow cytometry, respectively. Similar methods were used to determine the effects of TG02 combined with radiation therapy (RT) or cisplatin. Synergism indices for TG02-cisplatin combination therapy were calculated using CompuSyn software.

RESULTS

TG02 was observed to significantly impair ATRT cell growth in vitro by limiting cell proliferation and clonogenicity, and by inducing apoptosis. TG02 inhibited ATRT cell proliferation and decreased cell viability in a dose-dependent manner with nanomolar half maximal effective concentration (EC50) values (BT12, 207.0 nM; BT37, 127.8 nM; CHLA05, 29.7 nM; CHLA06, 18.7 nM). TG02 (150 nM) dramatically increased the proportion of apoptotic ATRT cells 72 hours posttreatment (TG02 8.50% vs control 1.52% apoptotic cells in BT12, p < 0.0001; TG02 70.07% vs control 15.36%, p < 0.0001). Combination therapy studies revealed that TG02 acted as a potent radiosensitizer in ATRT cells (BT12 surviving fraction, RT 51.2% vs RT + TG02 21.7%). Finally, CompuSyn analysis demonstrated that TG02 acted synergistically with cisplatin against ATRT cells at virtually all therapeutic doses. These findings were consistent in cell lines that cover all three molecular subgroups of ATRTs.

CONCLUSIONS

The results of this investigation have established that TG02 is an effective therapeutic against ATRTs in vitro. Given the lack of standard therapy for ATRTs, these findings help fill an unmet need and support further study of TG02 as a potential therapeutic option for patients with this deadly disease.

Differential and Common Signatures of miRNA Expression and Methylation in Childhood Central Nervous System Malignancies: An Experimental and Computational Approach

Epigenetic modifications are considered of utmost significance for tumor ontogenesis and progression. Especially, it has been found that miRNA expression, as well as DNA methylation plays a significant role in central nervous system tumors during childhood. A total of 49 resected brain tumors from children were used for further analysis. DNA methylation was identified with methylation-specific MLPA and, in particular, for the tumor suppressor genes CASP8, RASSF1, MGMT, MSH6, GATA5, ATM1, TP53, and CADM1. miRNAs were identified with microarray screening, as well as selected samples, were tested for their mRNA expression levels. CASP8, RASSF1 were the most frequently methylated genes in all tumor samples. Simultaneous methylation of genes manifested significant results with respect to tumor staging, tumor type, and the differentiation of tumor and control samples. There was no significant dependence observed with the methylation of one gene promoter, rather with the simultaneous presence of all detected methylated genes' promoters. miRNA expression was found to be correlated to gene methylation. Epigenetic regulation appears to be of major importance in tumor progression and pathophysiology, making it an imperative field of study.

Cerebrospinal fluid cytology in a toddler with a posterior fossa space-occupying lesion

An atypical teratoid rhabdoid tumour (AT/RT) is an extremely rare malignant neoplasm. Cerebrospinal fluid (CSF) involvement at presentation indicates intracranial dissemination and is associated with an aggressive course and worse outcomes. We present the characteristic cytomorphological features of AT/RT in the cerebrospinal fluid from a toddler presenting with a posterior fossa space-occupying lesion.

Meta-Analysis of Treatment Modalities in Metastatic Atypical Teratoid/Rhabdoid Tumors in Children

BACKGROUND

Metastatic atypical teratoid/rhabdoid tumors (AT/RTs) are aggressive central nervous system tumors that present during infancy and are associated with dismal outcomes. Patients receive multimodal treatment including surgical resection, systemic chemotherapy, and one or more of intrathecal chemotherapy (IT), marrow-ablative chemotherapy with autologous hematopoietic cell rescue (AuHCR) and radiation therapy (XRT). While data regarding treatment modalities for AT/RT patients exist, no comprehensive data have been published regarding the metastatic patients.

METHODS

We performed a meta-analysis of 1578 articles published through September 2018, including 44 studies with a total of 123 subjects. In addition, seven patients were included through chart review of patients treated at Nationwide Children's Hospital.

RESULTS

Analysis of 130 patients revealed a 3-year overall survival (OS) of 25%. Age at diagnosis had a significant effect on survival (P = 0.0355); 3-year OS for infants less than 18 months was 21%, 18 to 36 months was 26%, and greater than 36 months was 36%. Location of the primary tumor, metastatic stage, and extent of surgical resection did not have a significant impact on OS. On univariate analysis, XRT (P < 0.0001), IT (P = 0.01), and AuHCR (P < 0.0001) were found to significantly improve survival. The most substantial effect was noted in patients who received AuHCR (3-year OS of 60% vs 9% in those who did not). On multivariable analysis, XRT (P = 0.0006), IT (P = 0.0124), and AuHCR (P < 0.0001) were independently associated with reduced risk of death.

CONCLUSIONS

Although more research is warranted to make generalizable conclusions, these results suggest that treatment regimens for patients with metastatic AT/RTs should include AuHCR, XRT, and IT.

ATRT of lateral ventricle in a child: A Rare Tumor at a Very Rare Location

Atypical teratoid/rhabdoid tumors (AT/RTs) of infancy are highly malignant central nervous system neoplasms that are most commonly seen during the first 2 years of life with limited therapeutic options. To date, only two cases have been described in the lateral ventricle. A 4-year-old boy presented with a 4-month history of increased intracranial pressure. Cerebral magnetic resonance imaging (MRI) revealed a huge intraventricular tumor, occupying the entire temporal horn and the body of the left lateral ventricle. The boy was operated through a left temporal transventricular approach with gross total removal of the lesion. The histopathological diagnosis was an AT/RT. The infant underwent adjuvant chemotherapy and radiation therapy. The 1-year MRI of control showed a local recurrence of the tumor. Then after, Gamma Knife radiosurgery was performed because of the small volume and the deep location of the lesion. At the 3-month follow-up, the MRI showed a significant growth of the tumor volume, and the child was given additional adjuvant chemotherapy. Unfortunately, he died 9 months later. AT/RT of the lateral ventricle is a very rare tumor in children, associated with a poor prognosis in spite of multimodal treatment. Gamma knife surgery (GKS) was rarely reported as a treatment modality of AT/RT. The aim of this work is to discuss about the rarity of this tumor and the best treatment strategy to improve prognosis.

Precision Medicine in Pediatric Neurooncology: A Review

Central nervous system tumors are the leading cause of cancer related death in children. Despite much progress in the field of pediatric neurooncology, modern combination treatment regimens often result in significant late effects, such as neurocognitive deficits, endocrine dysfunction, secondary malignancies, and a host of other chronic health problems. Precision medicine strategies applied to pediatric neurooncology target specific characteristics of individual patients' tumors to achieve maximal killing of neoplastic cells while minimizing unwanted adverse effects. Here, we review emerging trends and the current literature that have guided the development of new molecularly based classification schemas, promising diagnostic techniques, targeted therapies, and delivery platforms for the treatment of pediatric central nervous system tumors.

Ribavirin as a potential therapeutic for atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive, malignant tumors and are the most common malignant brain tumor in children under 6 months of age. Currently, there is no standard treatment for AT/RT. Recent studies have reported potential anti-tumoral properties of ribavirin, a guanosine analog and anti-viral molecule approved by the Food and Drug Administration for treatment of hepatitis C. We previously demonstrated that ribavirin inhibited glioma cell growth in vitro and in vivo. Based on these results and the fact that no pre-clinical model of ribavirin in AT/RT exists, we decided to investigate the effect of ribavirin on several human AT/RT cell lines (BT12, BT16, and BT37) both in vitro and in vivo. We provide evidence that ribavirin has a significant impact on AT/RT cell growth and increases cell cycle arrest and cell death, potentially through modulation of the eIF4E and/or EZH2 pathways. Interestingly, using scratch wound and transwell Boyden chamber assays, we observed that ribavirin also impairs AT/RT cell migration, invasion, and adhesion. Finally, we demonstrate that ribavirin significantly improves the survival of mice orthotopically implanted with BT12 cells. Our work establishes that ribavirin is effective against AT/RT by decreasing tumoral cell growth and dissemination and could represent a new therapeutic option for children with this deadly disease.

SMARCB1-deficient Tumors of Childhood: A Practical Guide

The SMARCB1 gene ( INI1, BAF47) is a member of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complex, involved in the epigenetic regulation of gene transcription. SMARCB1 acts as a tumor suppressor gene, and loss of function of both alleles gives rise to SMARCB1-deficient tumors. The prototypical SMARCB1-deficient tumor is the malignant rhabdoid tumor (MRT) which was first described in the kidney but also occurs in soft tissue, viscera, and the brain (where it is referred to as atypical teratoid rhabdoid tumor or AT/RT). These are overwhelmingly tumors of the very young, and most follow an aggressive and ultimately lethal course. Morphologically, most but not all contain a population of "rhabdoid" cells, which are large cells with abundant cytoplasm, perinuclear spherical inclusions, and eccentric vesicular nuclei with large inclusion-like nucleoli. MRT immunohistochemistry reveals complete loss of SMARCB1 nuclear expression, and molecular analysis confirms biallelic SMARCB1 inactivation in the vast majority. Rare AT/RTs have loss of SMARCA4, another SWI/SNF member, rather than SMARCB1. With the widespread adoption of SMARCB1 immunohistochemistry, an increasing number of SMARCB1-deficient tumors outside of the MRT-AT/RT spectrum have been described. In addition to MRT and AT/RT, pediatric tumors with complete loss of SMARCB1 expression include cribriform neuroepithelial tumor, renal medullary carcinoma, and epithelioid sarcoma. Tumors with variable loss of SMARCB1 expression include subsets of epithelioid malignant peripheral nerve sheath tumor, schwannomas arising in schwannomatosis, subsets of chordomas, myoepithelial carcinomas, and sinonasal carcinomas. Variable and reduced expression of SMARCB1 is characteristic of synovial sarcoma. In this review, the historical background, clinical characteristics, morphology, immunohistochemical features, and molecular genetics most germane to these tumors are summarized. In addition, familial occurrence of these tumors (the rhabdoid tumor predisposition syndrome) is discussed. It is hoped that this review may provide practical guidance to pathologists encountering tumors that have altered expression of SMARCB1.

Atypical Teratoid/Rhabdoid Tumor of the Spinal Cord in a Child: Case Report and Comprehensive Review of the Literature

INTRODUCTION

Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system is characterized by SMARCB1/INI deletion or mutation in the long arm of chromosome 22 11(22q11.2), also resulting in loss of nuclear expression of INI1 protein immunohistochemically. AT/RT tumors usually occur in children below 3 years. The tumor is usually seen in the cerebellum or the cerebrum, with an extremely rare incidence in the spinal cord.

MATERIALS AND METHODS

We report a rare case of AT/RT in a 6-year-old boy who had a primary spinal cord lesion in the thoracolumbar junction. Pathology revealed loss of nuclear staining of INI1 immunohistochemically. This is the first case reported with mixed intraspinal lesion (intra- and extramedullary). The patient underwent two surgeries and received radiotherapy and chemotherapy; however, he died 16 months after the initial presentation.

RESULTS AND DISCUSSION

We reviewed the literature on all children with spinal cord AT/RT. The review showed that the cervical region is the most common location of origin, especially in younger children. Reported cases were treated with a combination of surgery, systemic and intrathecal chemotherapy, and radiation therapy, and a survival time of 18 months represented the best outcome. Overall mean survival time was 10 months.

Atypical teratoid rhabdoid tumor in the first year of life: the Canadian ATRT registry experience and review of the literature

While 2/3 of patients with ATRT are less than 3 years at diagnosis, the literature suggests younger children present with more aggressive disease and poorer outcome. However, little data exist on characteristics and outcome of patients diagnosed with ATRT in the first year of life. In particular, it is unclear whether they access similar treatments as do older children. We compared the cohort of patients ≤12 months from the Canadian ATRT registry to all cases extracted from the literature reported between 1996 and 2014 to describe their clinical and treatment characteristics, and potential prognostic factors. Twenty-six (33.7%) patients from the Canadian registry were ≤12 months at diagnosis as were 120 cases identified in the literature. Post-operatively, 46% of the registry's patients underwent palliation as opposed to 10.8% in the literature cohort. Palliative patients were significantly younger than those who received active therapy (3.3 vs. 6.6 months). While the use of high-dose chemotherapy (HDC) was relatively similar in both cohorts (42.9 and 35.5% respectively), radiotherapy (RT) use was significantly lower in the Canadian cohort (14.3 vs 44.9%). Children ≤6 months, who received active therapy, had a worst outcome than older ones. Gross total resection, HDC and adjuvant RT were associated with better outcomes. Eighty percent of the tested patients had evidence of germline mutation of INI1. While 1/3 of ATRT occurs within the first year of life, a large proportion only received palliative therapy. Even when actively treated, children ≤6 months fare worse. Some selected patients benefit from HDC.

Atypical teratoid/rhabdoid tumours: clinicopathological characteristics, prognostic factors and outcomes of 22 children from 2010 to 2015 in China

Atypical teratoid/rhabdoid tumours (AT/RTs) are rare, highly malignant tumours of the central nervous system (CNS) with poor prognosis that usually affect young children. The aim of this study was to assess the clinicopathological features and prognostic factors of AT/RTs. Here, we describe the clinicopathological and immunohistochemical characteristics, along with the treatments and outcomes, of 22 patients with AT/RTs treated in our hospital from 2010 to 2015. Morphologically, cytoplasmic vacuoles, the most common characteristic in our cases, were observed in 68% of the cases. Similarly, vesicular nuclei were detected in 68% of the cases. However, rhabdoid cells were found in only 59.1% of the cases and were not observed in 40.9% of the cases. Immunohistochemical analysis revealed loss of nuclear INI1 expression in all 22 cases. Age, surgical resection and adjuvant therapy, but not tumour location, were associated with AT/RTs patient prognosis. Our results showed that cells with cytoplasmic vacuoles or with vesicular nuclei are more common than rhabdoid cells in patients with AT/RTs and that a lack of INI1 protein expression is the most useful marker for the differential diagnosis of AT/RTs. Young age is a negative prognostic factor, whereas gross total surgical resection and adjuvant therapy are positive prognostic factors for AT/RT patients.

Malignant brainstem tumors in children, excluding diffuse intrinsic pontine gliomas

OBJECT Malignant tumors of the brainstem, excluding classic diffuse intrinsic pontine gliomas (DIPGs), are a very rare, heterogeneous group of neoplasms that have been infrequently described in the literature. In this paper, the authors present their experiences with treating these unique cancers. METHODS A retrospective chart review was conducted to identify eligible cases over a 15-year period. All tumors involving the pons were, by consensus, felt not to be DIPGs based on their neuroimaging features. Demographic information, pathological specimens, neuroimaging characteristics, surgical and nonsurgical management plans, and survival data were gathered for analysis. RESULTS Between January 2000 and December 2014, 29 patients were identified. The mean age at diagnosis was 8.4 years (range 2 months to 25 years), and 17 (59%) patients were male. The most common presenting signs and symptoms were cranial neuropathies (n = 24; 83%), hemiparesis (n = 12; 41%), and ataxia or gait disturbance (n = 10; 34%). There were 18 glial and 11 embryonal tumors. Of the glial tumors, 5 were radiation-induced and 1 was a malignant transformation of a previously known low-grade tumor. Surgical intervention consisted of biopsy alone in 12 patients and some degree of resection in another 15 patients. Two tumors were diagnosed postmortem. The median overall survival for all patients was 196 days (range 15 to 3999 days). There are currently 5 (17%) patients who are still alive: 1 with an anaplastic astrocytoma and the remaining with embryonal tumors. CONCLUSIONS In general, malignant non-DIPG tumors of the brainstem carry a poor prognosis. However, maximal cytoreductive surgery may be an option for select patients with focal tumors. Long-term survival is possible in patients with nonmetastatic embryonal tumors after multimodal treatment, most importantly maximal resection.

Atypical teratoid/ rhabdoid tumor, an immunohistochemical study of potential diagnostic and prognostic markers

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare tumor of the CNS mostly seen in infants and is often associated with a dismal outcome. Despite the heterogeneous morphology and/or immunoprofile, its diagnosis nowadays relies on the negative INI-1/BAF47 nuclear immunostain in tumor cells. We aim to investigate a number of immunohistochemical antibodies as potential diagnostic and prognostic markers. All AT/RT cases in patients younger than 18 years of age were included. Demographics, clinical features and outcome were collected. Immunostains tested included SALL-4, OCT3/4, CD99, FLI-1, cyclin-D1, β-catenin, P53, P16, CDX2 and WT-1. Nineteen cases (10 males) were identified at our center between 2004-2013 with a median age of 24 months. Ten (52.6%) cases were supratentorial. Six (42.9%) cases showed metastasis at time of presentation. Chemotherapy was administered to 10 (62.5%) and radiotherapy to seven (43.8%). The median overall survival was 11 months. A single long-term survival of 104 months was identified. Pathologically, most cases showed an admixture of rhabdoid cells and/or small cells and/or pale cells in variable proportions. Of all tested antibodies, only positivity for FLI-1 was associated with improved survival (P = 0.0012), while positivity for cyclin-D1 showed a trend toward improved survival (P = 0.0547). CDX2 was positive only in the single long-term survival. Interestingly, two cases showed co-expression of CD99 and FLI-1, and some were positive for SALL-4. In conclusion, FLI-1 and cyclin-D1 are potential prognostic markers associated with better outcome. Occasional AT/RT cases might co-express CD99 and FLI-1 as well as SALL-4, a potential diagnostic pitfall with Ewing sarcoma/ primitive neuroectodermal tumors and germ cell tumors, respectively.

The descriptive epidemiology of atypical teratoid/rhabdoid tumors in the United States, 2001-2010

BACKGROUND

Atypical teratoid/rhabdoid tumor is a rare malignant CNS tumor that most often affects children ≤ 3 years old. The Central Brain Tumor Registry of the United States contains the largest aggregation of population-based incidence data for primary CNS tumors in the US. Its data were used to describe the incidence, associated trends, and relative survival after diagnosis of atypical teratoid/rhabdoid tumor.

METHODS

Using data from 50 cancer registries between 2001 and 2010, age-adjusted incidence rates per 100 000 and 95% CIs were calculated by sex, race, Hispanic ethnicity, age at diagnosis, and location of tumor in the CNS for children aged 0 to 19 years. Relative survival rates and 95% CIs were also calculated.

RESULTS

The average annual age-adjusted incidence rate was 0.07 (95% CI: 0.07, 0.08). Incidence rates did not significantly vary by sex, race, or ethnicity. Age had a strong effect on incidence rate, with highest incidence among children <1 year, and decreasing incidence with increasing age. The 6-month, 1-year, and 5-year relative survival rates for all ages were 65.0%, 46.8%, and 28.3%, respectively. Atypical teratoid/rhabdoid tumor can occur anywhere in the CNS, but supratentorial tumors were more common with increasing age.

CONCLUSION

We confirm differences in survival by age at diagnosis, treatment pattern, and location of tumor in the brain. This contributes to our understanding of these tumors and may stimulate research leading to improved treatment of this devastating childhood disease.

Rhabdoid tumors: clinical approaches and molecular targets for innovative therapy

Rhabdoid tumors are rare but highly aggressive tumors with a predilection for infants and young children. The majority of these tumors harbor biallelic mutations in SMARCB1/INI1/hSNF5. Rather rare cases with mutations in other SWI/SNF core members such as BRG1 are on record. Rhabdoid tumors have only recently been registered and treated according to specifically designed treatment recommendations and in the framework of clinical trials. Within the last decade, prognosis has improved significantly but at least 50% of patients still relapse and subsequently almost inevitably succumb to their disease. This review summarizes past and current clinical approaches and presents an overview of the rationales for targeted therapy with potential for future clinical treatment trials for rhabdoid tumors.

The histone deacetylase inhibitor SAHA acts in synergism with fenretinide and doxorubicin to control growth of rhabdoid tumor cells

BACKGROUND

Rhabdoid tumors are highly aggressive malignancies affecting infants and very young children. In many instances these tumors are resistant to conventional type chemotherapy necessitating alternative approaches.

METHODS

Proliferation assays (MTT), apoptosis (propidium iodide/annexin V) and cell cycle analysis (DAPI), RNA expression microarrays and western blots were used to identify synergism of the HDAC (histone deacetylase) inhibitor SAHA with fenretinide, tamoxifen and doxorubicin in rhabdoidtumor cell lines.

RESULTS

HDAC1 and HDAC2 are overexpressed in primary rhabdoid tumors and rhabdoid tumor cell lines. Targeting HDACs in rhabdoid tumors induces cell cycle arrest and apoptosis. On the other hand HDAC inhibition induces deregulated gene programs (MYCC-, RB program and the stem cell program) in rhabdoid tumors. These programs are in general associated with cell cycle progression. Targeting these activated pro-proliferative genes by combined approaches of HDAC-inhibitors plus fenretinide, which inhibits cyclinD1, exhibit strong synergistic effects on induction of apoptosis. Furthermore, HDAC inhibition sensitizes rhabdoid tumor cell lines to cell death induced by chemotherapy.

CONCLUSION

Our data demonstrate that HDAC inhibitor treatment in combination with fenretinide or conventional chemotherapy is a promising tool for the treatment of chemoresistant rhabdoid tumors.