Clinicopathologic prognostic factors in childhood atypical teratoid and rhabdoid tumor of the central nervous system: a multicenter study

Atypical Teratoid/ Rhabdoid Tumor of Brain: a Clinicopathologic Study of Eleven Patients and Review of Literature

Background:

Atypical teratoid/ rhabdoid tumor (AT/RT) is a rare aggressive embryonal central nervous system (CNS) tumor of infancy and early childhood. Majority of the cases arise in the posterior fossa, and remaining in the cerebrum.

Aims:

To analyze the clinicopathologic features of AT/RT on a cohort of cases.

Materials and methods:

All reported cases of AT/RT at the Department of Pathology and Laboratory Medicine, Aga Khan University Hospital (AKUH) from 2007 to 2016 were reviewed for clinical and pathological features. Immunohistochemical stain for INI-1 was performed in all 11 cases. Follow up was obtained.

Results:

A total of 11 cases were identified. Seven patients were males and 4 were females. The ages ranged from 1 month to 48 months (mean 26.6 months). Six tumors were located in the cerebrum and 3 in the posterior fossa. Exact Location was not known in 2 cases. Histologically, rhabdoid cells were present in sheets in variable proportions in five cases, Medulloblastoma and PNET like areas were seen in 2 cases each. Immunohistochemical stains EMA (10/10), vimentin (7/7), CKAE1/AE3 (8/9), and CD99 (3/4), GFAP (6/10), ASMA (3/4) and synaptophysin (3/4) were positive in varying proportions while desmin was negative in all 6 cases in which it was performed. All 11 tumors lacked immunoreactivity for INI-1 protein. Four patients died of disease with a follow up ranging from 5 to 24 months.

Conclusions:

AT/RT is a rare highly aggressive embryonal tumor of CNS. A male predominance was noted in our series. We report the first and largest series from Pakistan.

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 tumors: challenges and search for solutions

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant embryonal central nervous system tumor commonly affecting children <3 years of age. It roughly constitutes 1%-2% of all pediatric central nervous system tumors. Recent data show that it is the most common malignant central nervous system tumor in children <6 months of age. Management of this aggressive tumor is associated with a myriad of diagnostic and therapeutic challenges. On the basis of radiology and histopathology alone, distinction of AT/RT from medulloblastoma or primitive neuroectodermal tumor is difficult, and hence this tumor has been commonly misdiagnosed as primitive neuroectodermal tumor for decades. Presence of a bulky heterogeneous solid-cystic mass with readily visible calcification and intratumor hemorrhage, occurring off-midline in children <3 years of age, should alert the radiologist toward the possibility of AT/RT. Presence of rhabdoid cells on histopathology and polyphenotypic immunopositivity for epithelial, mesenchymal, and neuroectodermal markers along with loss of expression of SMARCB1/INI1 or SMARCA4/BRG1 help in establishing a diagnosis of AT/RT. The optimal management comprises maximal safe resection followed by radiation therapy and multiagent intensive systemic chemotherapy. Gross total excision is difficult to achieve in view of the large tumor size and location and young age at presentation. Leptomeningeal spread is noted in 15%-30% of patients, and hence craniospinal irradiation followed by boost to tumor bed is considered standard in children older than 3 years. However, in younger children, craniospinal irradiation may lead to long-term neurocognitive and neuroendocrine sequel, and hence focal radiation therapy may be a pragmatic approach. In this age group, high-dose chemotherapy with autologous stem cell rescue may also be considered to defer radiation therapy, but this approach is also associated with significant treatment-related morbidity and mortality. Novel small molecule inhibitors hold promise in preclinical studies and should be considered in patients with relapsed or refractory tumor.

Medulloblastoma with epithelioid features in the cerebellar vermis

A 6-year-old girl was admitted with a mass lesion in the cerebellar vermis. She underwent subtotal tumor resection, and on immunohistopathology the tumor consisted of two different parts: typical medulloblastoma (MB) characteristics and atypical teratoid/rhabdoid tumor (AT/RT) features, despite positive integrase interactor 1 expression. The patient was diagnosed with MB with epithelioid features. Chemoradiation therapy was started because of tumor recurrence at the primary site and dissemination to the spinal cord, as determined on magnetic resonance imaging 2 weeks after surgery. The patient died due to tumor progression 13 months after initial diagnosis, although transient partial remission was achieved.

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.

Rapid Diagnosis of an AT/RT by the Detection of a Heterozygous SMARCB1 Germ Line Deletion in an Infant

We report the successful use of multiplex ligation-dependent probe amplification (MLPA) to detect heterozygous loss of SMARCB1/INI1/SNF5 in the germ line of an infant with a huge posterior fossa tumor. MLPA and Sanger sequencing of the SMARCB1 gene in the germ line may be useful for the initial diagnosis in a defined subgroup of infants with rhabdoid tumors, in which biopsies cannot be performed.

Biology and Treatment of Rhabdoid Tumor

Rhabdoid tumor is a rare, highly aggressive malignancy that primarily affects infants and young children. These tumors typically arise in the brain and kidney, although extrarenal, non-central nervous system tumors in almost all soft-tissue sites have been described. SMARCB1 is a member of the SWI/SNF chromatin-remodeling complex and functions as a tumor suppressor in the vast majority of rhabdoid tumors. Patients with germline mutations or deletions affecting SMARCB1 are predisposed to the development of rhabdoid tumors, as well as the genetic disorder schwannomatosis. The current hypothesis is that rhabdoid tumors are driven by epigenetic dysregulation, as opposed to the alteration of a specific biologic pathway. The strategies for novel therapeutic approaches based on what is currently known about rhabdoid tumor biology are presented.

Long-term survival of an infant with an atypical teratoid/rhabdoid tumor following subtotal resection and low-cumulative dose chemotherapy: a case report

INTRODUCTION

Atypical teratoid/rhabdoid tumor (AT/RT) is an aggressive embryonal tumor of the central nervous system with a generally dismal prognosis, especially in patients younger than 12 months.

DISCUSSION

We here describe the unusual case of an infant with AT/RT with long-term survival despite low-cumulative dose chemotherapy after subtotal resection. Due to a poor neurological situation and an unfavorable oncological prognosis, therapy was halted after two partial surgical resections and four of the nine chemotherapy courses recommended by the European Rhabdoid Registry, without the patient receiving either radiotherapy or high-dose chemotherapy. The patient is alive without evidence of disease 52 months after diagnosis.

CONCLUSION

This case report highlights that independent prognostic factors are urgently needed for optimizing treatment stratification and preventing overtreatment.

Improved 6-year overall survival in AT/RT - results of the registry study Rhabdoid 2007

Atypical teratoid rhabdoid tumors (AT/RT) are characterized by mutations and subsequent inactivation of SMARCB1 (INI1, hSNF5), a predilection for very young children and an unfavorable outcome. The European Registry for rhabdoid tumors (EU‐RHAB) was established to generate a common European database and to establish a standardized treatment regimen as the basis for phase I/II trials. Thus, genetic analyses, neuropathologic and radiologic diagnoses, and a consensus treatment regimen were prospectively evaluated. From 2005 to 2009, 31 patients with AT/RT from four countries were recruited into the registry study Rhabdoid 2007 and treated with systemic and intraventricular chemotherapy. Eight patients received high‐dose chemotherapy, 23 radiotherapy, and 17 maintenance therapy. Reference evaluations were performed in 64% (genetic analyses, FISH, MLPA, sequencing) up to 97% (neuropathology, INI1 stain). Germ‐line mutations (GLM) were detected in 6/21 patients. Prolonged overall survival was associated with age above 3 years, radiotherapy and achievement of a complete remission. 6‐year overall and event‐free survival rates were 46% (±0.10) and 45% (±0.09), respectively. Serious adverse events and one treatment‐related death due to insufficiency of a ventriculo peritoneal shunt (VP‐shunt) and consecutive herniation were noted. Acquisition of standardized data including reference diagnosis and a standard treatment schedule improved data quality along with a survival benefit. Treatment was feasible with significant but manageable toxicity. Although our analysis is biased due to heterogeneous adherence to therapy, EU‐RHAB provides the best available basis for phase I/II clinical trials.

Atypical teratoid/rhabdoid tumors-current concepts, advances in biology, and potential future therapies

Atypical teratoid/rhabdoid tumor (AT/RT) is the most common malignant CNS tumor of children below 6 months of age. The majority of AT/RTs demonstrate genomic alterations in SMARCB1 (INI1, SNF5, BAF47) or, to a lesser extent, SMARCA4 (BRG1) of the SWItch/sucrose nonfermentable chromatin remodeling complex. Recent transcription and methylation profiling studies suggest the existence of molecular subgroups. Thus, at the root of these seemingly enigmatic tumors lies a network of factors related to epigenetic regulation, which is not yet completely understood. While conventional-type chemotherapy may have significant survival benefit for certain patients, it remains to be determined which patients will eventually prove resistant to chemotherapy and thus need novel therapeutic strategies. Elucidation of the molecular consequences of a disturbed epigenome has led to the identification of a series of transduction cascades, which may be targeted for therapy. Among these are the pathways of cyclin D1/cyclin-dependent kinases 4 and 6, Hedgehog/GLI1, Wnt/ß-catenin, enhancer of zeste homolog 2, and aurora kinase A, among others. Compounds specifically targeting these pathways or agents that alter the epigenetic state of the cell are currently being evaluated in preclinical settings and in experimental clinical trials for AT/RT.

Generation of a mouse model of atypical teratoid/rhabdoid tumor of the central nervous system through combined deletion of Snf5 and p53

Malignant rhabdoid tumors arise in several anatomic locations and are associated with poor outcomes. In the brain, these tumors are known as atypical teratoid/rhabdoid tumors (AT/RT). While genetically engineered models for malignant rhabdoid tumors exist, none of them recapitulate AT/RT, for which preclinical models remain lacking. In the majority of AT/RT, LOH occurs at the genetic locus SNF5 (Ini1/BAF47/Smarcb1), which functions as a subunit of the SWI/SNF chromatin-remodeling complex and a tumor suppressor in familial and sporadic malignant rhabdoid tumors. Therefore, we generated mice in which Snf5 was ablated specifically in nestin-positive and/or glial fibrillary acid protein (GFAP)-positive progenitor cells of the developing central nervous system (CNS). Snf5 ablation in nestin-positive cells resulted in early lethality that could not be rescued by loss of p53. However, Snf5 ablation in GFAP-positive cells caused a neurodegenerative phenotype exacerbated by p53 loss. Notably, these double mutants exhibited AT/RT development, associated with an earlier failure in granule neuron migration in the cerebellum, reduced neuronal projections in the hippocampus, degeneration of the corpus callosum, and ataxia and seizures. Gene expression analysis confirmed that the tumors that arose in Snf5/p53 mutant mice were distinct from other neural tumors and most closely resembled human AT/RT. Our findings uncover a novel role for Snf5 in oligodendrocyte generation and survival, and they offer evidence of the first genetically engineered mouse model for AT/RT in the CNS.

A case of relapsing spinal atypical teratoid/rhabdoid tumor (AT/RT) responding to vinorelbine, cyclophosphamide, and celecoxib

INTRODUCTION

Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system is a highly aggressive neoplasm which prevalently affects children and is characterized by a severe prognosis.

CASE PRESENTATION

The authors describe an extremely rare case of a primary spinal AT/RT that occurred in a young girl. The patient underwent a wide surgical resection of a lumbar mass, followed by aggressive chemotherapy, myeloablative treatment, and local radiotherapy. After 7 months from the end of the treatment, the patient experienced local recurrence and was treated with surgery and second-line chemotherapy with antiangiogenic purposes, consisting of oral vinorelbine, cyclophosphamide, and celecoxib. Treatment was well tolerated, and patient was still alive 36 months after diagnosis.

CONCLUSION

The peculiarity of this case report is the clinical-radiological response to a metronomic therapy in a case of early-relapsing spinal AT/RT despite previous maximal surgery, chemotherapy, and radiotherapy.

Investigation of the location of atypical teratoid/rhabdoid tumor

INTRODUCTION

The location of a brain tumor is a fundamental characteristic, because various brain tumors develop in relatively specific locations. An atypical teratoid/rhabdoid tumor (AT/RT) is a highly age-specific tumor that occurs in infants and young children. However, AT/RTs develop in a variety of locations in the brain. This study aimed at uncovering the tumor location pattern of AT/RTs to enhance diagnoses.

MATERIAL AND METHODS

Neuroimages from 27 patients with a pathologically proven AT/RT were reviewed, and the specific tumor locations were described and categorized. The association of imaging characteristics and tumor location was analyzed.

RESULTS

The posterior fossa was the most frequent locations accounting for 19 patients (70%), followed by the diencephalon (four patients; 15%), cerebrum (three patients; 11%), and midbrain (one patient; 4%). In the posterior fossa, the superior medullary velum (SMV) and cerebellopontine angle (CPA) areas were the most common sites (eight patients each) and three patients had a tumor in the inferior medullary velum (IMV) region. AT/RTs in the SMV area had a significantly higher chance of no/minimal enhancement compared with tumors in other locations (P = 0.001) and a lower likelihood of leptomeningeal tumor seeding at presentation (P = 0.053).

CONCLUSION

The location spectrum of AT/RT follows a specific pattern, and some of the locations are linked with intriguing clinical characteristics. This information may not only help make correct preoperative diagnosis but also occasionally aid in postoperative pathological diagnosis.

[Molecular methods in diagnosis of poorly differentiated malignant brain tumors in children]

The histological diagnosis of malignant brain tumors in children is a complex process. In some cases, glioblastoma, primitive neuroectodermal tumor of the central nervous system, and atypical teratoid/rhabdoid tumor have a histological type similar to that of small blue round cell malignant tumor. Despite the similar histology, biological properties and approaches to treatment, these neoplasms are completely different and require their own treatment protocols. We retrospectively reviewed the most malignant types of childhood tumors and analyzed our own experience to propose a diagnostic algorithm for intracerebral small blue round cell malignant tumors in children based on the use of immunohistochemistry and fluorescence in situ hybridization.

Molecular subgroups of atypical teratoid rhabdoid tumours in children: an integrated genomic and clinicopathological analysis

BACKGROUND

Rhabdoid brain tumours, also called atypical teratoid rhabdoid tumours, are lethal childhood cancers with characteristic genetic alterations of SMARCB1/hSNF5. Lack of biological understanding of the substantial clinical heterogeneity of these tumours restricts therapeutic advances. We integrated genomic and clinicopathological analyses of a cohort of patients with atypical teratoid rhabdoid tumours to find out the molecular basis for clinical heterogeneity in these tumours.

METHODS

We obtained 259 rhabdoid tumours from 37 international institutions and assessed transcriptional profiles in 43 primary tumours and copy number profiles in 38 primary tumours to discover molecular subgroups of atypical teratoid rhabdoid tumours. We used gene and pathway enrichment analyses to discover group-specific molecular markers and did immunohistochemical analyses on 125 primary tumours to evaluate clinicopathological significance of molecular subgroup and ASCL1-NOTCH signalling.

FINDINGS

Transcriptional analyses identified two atypical teratoid rhabdoid tumour subgroups with differential enrichment of genetic pathways, and distinct clinicopathological and survival features. Expression of ASCL1, a regulator of NOTCH signalling, correlated with supratentorial location (p=0·004) and superior 5-year overall survival (35%, 95% CI 13-57, and 20%, 6-34, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·033) in 70 patients who received multimodal treatment. ASCL1 expression also correlated with superior 5-year overall survival (34%, 7-61, and 9%, 0-21, for ASCL1-positive and ASCL1-negative tumours, respectively; p=0·001) in 39 patients who received only chemotherapy without radiation. Cox hazard ratios for overall survival in patients with differential ASCL1 enrichment treated with chemotherapy with or without radiation were 2·02 (95% CI 1·04-3·85; p=0·038) and 3·98 (1·71-9·26; p=0·001). Integrated analyses of molecular subgroupings with clinical prognostic factors showed three distinct clinical risk groups of tumours with different therapeutic outcomes.

INTERPRETATION

An integration of clinical risk factors and tumour molecular groups can be used to identify patients who are likely to have improved long-term radiation-free survival and might help therapeutic stratification of patients with atypical teratoid rhabdoid tumours.

FUNDING

C17 Research Network, Genome Canada, b.r.a.i.n.child, Mitchell Duckman, Tal Doron and Suri Boon foundations.

Spinal teratoma concomitant with intracranial lipid droplet dissemination

A teratoma is a neoplasm that contains tissues originating from three germ cell layers at ectopic sites. The embryology of teratomas remains unclear. Teratomas are usually composed of cystic and solid components, and they are usually associated with syringomyelia. Cystic lesions of teratomas may rupture in a spontaneous, iatrogenic, or traumatic manner. Lipid droplets in the ventricles and subarachnoid space are rare. We managed a case of a spinal teratoma in the lumbar region in a 67-year-old man. He complained of nocturia, frequent urination, and difficulty in walking for 2 months. Radiographic imaging revealed a lumbar spinal intradural mass. Intracranial lipid droplets dissemination was also existed. The patient underwent surgery, and a diagnosis of mature teratoma was confirmed histopathologically. During the operation, the cystic portion of the intradural mass ruptured. During the hospital stay, the patient's mental status declined. On radiological examination, slightly enlarged ventricle size was observed. Dissemination of lipid droplets within ventricles occurs because of spontaneous, iatrogenic, or traumatic rupture. Additional lipid droplet dissemination to the intracranial space associated with neurologic deterioration after a spinal teratoma surgery should be considered when iatrogenic rupture of the cyst portion occurs.

Atypical teratoid rhabdoid tumour of the spine: report of a case and literature review

Atypical teratoid rhabdoid tumour (ATRT) is a rare and highly aggressive malignant neoplasm of the central nervous system (CNS), which occurs predominantly in children less than 2 years of age. There are less than 50 cases described in adult. We report a case of primary spinal ATRT in a 65-year-old male who presented to us with cauda equina syndrome. To the best of our knowledge, our patient is the (1) second oldest patient to be diagnosed with ATRT and only the third case of adult spinal ATRT report in the literature; (2) first reported case of CNS ATRT occurring in a patient with non-rhabdoid renal cancer; (3) first adult patient of ATRT to present with cauda equina syndrome.

The management of pineal tumors as a model for a multidisciplinary approach in neuro-oncology

The management of pineal tumors is a model for multidisciplinarity. Apart from an emergency situation that requires immediate shunting of cerebrospinal fluid (CSF), the initial discussion should involve at least a radiologist, a surgeon, a neurologist and an oncologist. The initial decision is whether obtaining a histological proof is obligatory. It depends on age and ethnicity, site (mono- or bifocality), presence of markers in serum as well as CSF, and/or of malignant cells in the CSF. In cases of marker elevation indicating a germ cell tumor, front line chemotherapy can avoid dangerous immediate surgery. When histological proof is required, the extent of surgery should be discussed, aiming either only at obtaining tissue or removal. If a germ cell tumor is detected, treatment will include a cisplatin-containing chemotherapy followed by focal or ventricular irradiation. Tumors of the pineal parenchyma will be treated according to grade, either by surgery alone (pinealocytoma) or chemo-radiotherapy (pinealoblastomas). Similarly, gliomas will be treated depending on their grade with several different possible lines in low grade, and usually radio-chemotherapy in high grade. A careful balance between improved survival rates and decreased long-term side effects will guide the decisions of all these specialists.

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.

Intracranial atypical teratoid/rhabdoid tumor presenting as an axillary mass: a case report and review of literature

Atypical teratoid/rhabdoid tumor (AT/RT) is an uncommon, high-grade pediatric malignancy of the central nervous system (CNS) that rarely metastasizes outside the CNS (Chang stage M4). We describe a child with the sole metastasis of an AT/RT to an axillary lymph node and no other site of extra-CNS disease at presentation. The tumor included areas of rhabdoid cells and failed to express the SMARCB1 gene product (INI1). The metastatic site in this patient is unusual for 3 reasons: (1) it is anatomically unexpected for a CNS tumor, (2) no other extra-CNS metastasis or primary tumor outside the CNS was found, and (3) no cardiac septal defect or vascular anomaly was identified. This site as the presenting lesion and sole metastasis of an intracranial AT/RT has not been previously reported. We attempt to explain this phenomenon.

High-dose chemotherapy (HDCT) with auto-SCT in children with atypical teratoid/rhabdoid tumors (AT/RT): a report from the European Rhabdoid Registry (EU-RHAB)

A retrospective analysis of data from the European Rhabdoid Registry (EU-RHAB) was performed to describe the outcome of children with atypical teratoid/rhabdoid tumors (AT/RT) who underwent high-dose chemotherapy (HDCT) with auto-SCT. Nineteen patients (male, n=15; median age at diagnosis 21 months) were identified. Nine patients presented with metastatic disease at diagnosis. A partial or subtotal resection was achieved in 11, a total resection in five and a biopsy in three patients. Patients received a median of six chemotherapy cycles prior to HDCT. Additional radiotherapy was performed in 14 patients (first-line, n=9; following progression, n=5). Six patients underwent tandem auto-SCT. Disease status before HDCT was CR in six, PR in eight, stable disease in two and progressive disease (PD) in two patients (data missing, n=1). With a median follow-up of 16 months, 14 patients progressed. Estimated progression-free and OS at 2 years were 29% (±11%) and 50% (±12%), respectively. At last follow-up, eight patients were alive (first CR, n=4; second CR, n=2; PR, n=1; PD, n=1). Eleven patients died of PD. Median time-to-progression was 14 months. Selected patients with AT/RT might benefit from HDCT with radiotherapy. The definitive impact of this treatment modality has to be evaluated prospectively in a randomized trial.

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.

Case report: long-term survival of an infant syndromic patient affected by atypical teratoid-rhabdoid tumor

Background

Atypical teratoid rhabdoid tumor (ATRT) patients display a dismal median overall survival of less than 1 year. A consistent fraction of cases carries de-novo SMARCB1/INI1 constitutional mutations in the setting of the “rhabdoid tumor predisposition syndrome” and the outcome is worst in infant syndromic ATRT patients.

Case presentation

We here describe a patient affected by mosaic Klinefelter syndrome and by rhabdoid tumor predisposition syndrome caused by constitutional SMARCB1/INI1 heterozygous mutation c.118C>T (Arg40X). Patient’s ATRT primary tumor occurred at 2 years of age concurrent with metastatic lesions. The patient was rendered without evidence of disease by combined surgery, high-dose poli-chemotherapy and craniospinal irradiation, followed by autologous hematopoietic stem cell transplantation. At the onset of a spinal lesion 5.5 years later, both tumors were pathologically and molecularly evaluated at the national central pathology review board and defined as ATRT in a syndromic patient, with strong evidence of a clonal origin of the two lesions. The patient was then treated according to SIOP guidelines and is now alive without evidence of disease 24 months after the detection of metastatic disease and 90 months after the original diagnosis.

Conclusion

The report underscores the current utility of multiple comprehensive approaches for the correct diagnosis and clinical management of patients affected by rare and atypical brain neoplasms. Successful local control of disease and achievement of long-term survival is possible in ATRT patients even in the setting of rhabdoid tumor predisposition syndrome, infant age at diagnosis and metastatic spread of disease, thus justifying the efforts for the management of this severe condition.

High-resolution genomic analysis suggests the absence of recurrent genomic alterations other than SMARCB1 aberrations in atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignant pediatric brain tumor characterized by genetic alterations affecting the SMARCB1 (hSNF5/INI1) locus in chromosome band 22q11.2. To identify potential additional genetic alterations, high-resolution genome-wide analysis was performed using a molecular inversion probe single-nucleotide polymorphism (MIP SNP) assay (Affymetrix OncoScan formalin-fixed paraffin-embedded express) on DNA isolated from 18 formalin-fixed paraffin-embedded archival samples. Alterations affecting the SMARCB1 locus could be demonstrated by MIP SNP in 15 out of 16 evaluable cases (94%). These comprised five tumors with homozygous deletions, six tumors with heterozygous deletions, and four tumors with copy number neutral loss of heterozygosity (LOH) involving chromosome band 22q11.2. Remarkably, MIB SNP analysis did not yield any further recurrent chromosomal gains, losses, or copy neutral LOH. On MIP SNP screening for somatic mutations, the presence of a SMARCB1 mutation (c.472C>T p.R158X) was confirmed, but no recurrent mutations of other cancer relevant genes could be identified. Results of fluorescence in situ hybridization, multiplex ligation-dependent probe amplification, and SMARCB1 sequencing were highly congruent with that of the MIP SNP assay. In conclusion, these data further suggest the absence of recurrent genomic alterations other than SMARCB1 in AT/RT.

Survival analysis for apparent diffusion coefficient measures in children with embryonal brain tumours

Embryonal brain tumors constitute a large and important subgroup of pediatric brain tumors. Apparent diffusion coefficient (ADC) measures have been previously used in the analysis of these tumors. We investigated a newly described ADC-derived parameter, the apparent transient coefficient in tumor (ATCT), a measure of the gradient change of ADC from the peri-tumoral edema into the tumor core, to study whether ATCT correlates with survival outcome. Sixty-one patients with histologically proven embryonal brain tumors and who had diffusion-weighted imaging (DWI) as part of their clinical imaging were enrolled in a retrospective study correlating ADC measures with survival. Kaplan-Meier survival curves were constructed for extent of surgical resection, age <3 years at diagnosis, tumor type, and metastasis at presentation. A multivariate survival analysis was performed that took into consideration ATCT and variables found to be significant in the Kaplan-Meier analysis as covariates. Results from the multivariate analysis showed that ATCT was the only significant covariate (P < .001). Survival analysis using Kaplan-Meier curves, dividing the patients into 4 groups of increasing values of ATCT, showed that more negative values of ATCT were significantly associated with a poorer prognosis (P < .001). A statistically significant difference was observed for survival data with respect to the change in ADC from edema into the tumor volume. Results show that more negative ATCT values are significantly associated with a poorer survival among children with embryonal brain tumors, irrespective of tumor type, extent of resection, age <3 years at diagnosis, and metastasis at presentation.

Multi-tyrosine kinase inhibitors in preclinical studies for pediatric CNS AT/RT: Evidence for synergy with Topoisomerase-I inhibition

BACKGROUND

Currently, Atypical Teratoid Rhabdoid Tumor (AT/RT) constitutes one of the most difficult to treat malignancies in pediatrics. Hence, new knowledge of potential targets for therapeutics and the development of novel treatment approaches are urgently needed. We have evaluated the presence of cytokine pathways and the effects of two clinically available multi-tyrosine kinase inhibitors for cytotoxicity, target modulation and drug combinability against AT/RT cell lines.

RESULTS

AT/RT cell lines expressed measurable quantities of VEGF, FGF, PDGF and SDF-1, although the absolute amounts varied between the cell lines. The targeted receptor tyrosine kinase inhibitor sorafenib inhibited the key signaling molecule Erk, which was activated following the addition of own conditioned media, suggesting the existence of autocrine/paracrine growth stimulatory pathways. The multi-tyrosine kinase inhibitors sorafenib and sunitinib also showed significant growth inhibition of AT/RT cells and their activity was enhanced by combination with the topoisomerase inhibitor, irinotecan. The loss of cytoplasmic NF-kappa-B in response to irinotecan was diminished by sorafenib, providing evidence for a possible benefit for this drug combination.

CONCLUSIONS

In addition to previously described involvement of insulin like growth factor (IGF) family of cytokines, a multitude of other growth factors may contribute to the growth and survival of AT/RT cells. However, consistent with the heterogeneous nature of this tumor, quantitative and qualitative differences may exist among different tumor samples. Multi-tyrosine kinase inhibitors appear to have effective antitumor activity against all cell lines studied. In addition, the target modulation studies and drug combinability data provide the groundwork for additional studies and support the evaluation of these agents in future treatment protocols.