Feasibility of Intensive Multimodal Therapy in Infants Affected by Rhabdoid Tumors – Experience of the EU-RHAB registry

Malignant Rhabdoid Tumor of the Kidney in a Child With Xeroderma Pigmentosum: Incidence or Coincidence?

Malignant rhabdoid tumor of the kidney (MRTK) is a rare aggressive malignant rhabdoid tumor that mainly affects children. At the onset of the disease, the usual clinical manifestations are gross hematuria, abdominal pain, and abdominal distension. The prognosis remains poor. Patients with rhabdoid tumors (RT) are treated according to institutional preferences that combine surgery, radiation therapy, and chemotherapy. The authors present the rare case of a child with xeroderma pigmentosum (XP) who presented with an abdominal mass accompanied by hematuria and abdominal pain. The radiological and histological results were congruent with the MRTK. The patient received preoperative chemotherapy but unfortunately died of septic shock. This case highlights the importance of being aware of MRTK and its fatal complications, as well as the increased risk of kidney tumors in patients with XP.

Cardiac Rhabdoid Tumor—A Rare Foe—Case Report and Literature Review

Intracardiac masses are unusual findings in infants, and most of them are benign. Nevertheless, they may be associated with a significant degree of hemodynamic instability and/or arrhythmias. Malignant tumors of the heart rarely occur in children. Rhabdoid tumors are aggressive tumors with a dismal prognosis even when diagnosed early. Although rhabdomyomas are common cardiac tumors in infants, they are mostly benign. The most common sites of involvement are the kidneys and central nervous system, but soft tissues, lungs, and ovaries may also be affected. The diagnosis can be challenging, particularly in sites where they do not usually occur. In the present paper, we report the case of a 2-year-old boy diagnosed with cardiac rhabdoid tumor highlighting the importance of molecular studies and recent genetic discoveries with the purpose of improving the management of such cases. The aim of this educational case report and literature review is to raise awareness of cardiac masses in children and to point out diagnostic hints toward a cardiac tumor on various imaging modalities. Given the rarity of all tumors involving the heart and the lack of symptom specificity, a high degree of suspicion is needed to arrive at the correct diagnosis.

Infants and Newborns with Atypical Teratoid Rhabdoid Tumors (ATRT) and Extracranial Malignant Rhabdoid Tumors (eMRT) in the EU-RHAB Registry: A Unique and Challenging Population

Simple Summary

Malignant rhabdoid tumors (MRT) are deadly tumors that predominantly affect infants and young children. Even when considering the generally young age of these patients, the treatment of infants below the age of six months represents a particular challenge due to the vulnerability of this patient population. The aim of our retrospective study was to assess the available information on prognostic factors, genetics, toxicity of treatment and long-term outcomes of MRT. We confirmed that, in a cohort of homogenously treated infants with MRT, significant predictors of outcome were female sex, localized stage, absence of a GLM and maintenance therapy, and these significantly favorably influence prognosis. Stratification-based biomarker-driven tailored trials may be a key option to improve survival rates.

Abstract

Introduction: Malignant rhabdoid tumors (MRT) predominantly affect infants and young children. Patients below six months of age represent a particularly therapeutically challenging group. Toxicity to developing organ sites limits intensity of treatment. Information on prognostic factors, genetics, toxicity of treatment and long-term outcomes is sparse. Methods: Clinical, genetic, and treatment data of 100 patients (aged below 6 months at diagnosis) from 13 European countries were analyzed (2005–2020). Tumors and matching blood samples were examined for SMARCB1 mutations using FISH, MLPA and Sanger sequencing. DNA methylation subgroups (ATRT-TYR, ATRT-SHH, and ATRT-MYC) were determined using 450 k / 850 k-profiling. Results: A total of 45 patients presented with ATRT, 29 with extracranial, extrarenal (eMRT) and 9 with renal rhabdoid tumors (RTK). Seventeen patients demonstrated synchronous tumors (SYN). Metastases (M+) were present in 27% (26/97) at diagnosis. A germline mutation (GLM) was detected in 55% (47/86). DNA methylation subgrouping was available in 50% (31 / 62) with ATRT or SYN; for eMRT, methylation-based subgrouping was not performed. The 5-year overall (OS) and event free survival (EFS) rates were 23.5 ± 4.6% and 19 ± 4.1%, respectively. Male sex (11 ± 5% vs. 35.8 ± 7.4%), M+ stage (6.1 ± 5.4% vs. 36.2 ± 7.4%), presence of SYN (7.1 ± 6.9% vs. 26.6 ± 5.3%) and GLM (7.7 ± 4.2% vs. 45.7 ± 8.6%) were significant prognostic factors for 5-year OS. Molecular subgrouping and survival analyses confirm a previously described survival advantage for ATRT-TYR. In an adjusted multivariate model, clinical factors that favorably influence the prognosis were female sex, localized stage, absence of a GLM and maintenance therapy. Conclusions: In this cohort of homogenously treated infants with MRT, significant predictors of outcome were sex, M-stage, GLM and maintenance therapy. We confirm the need to stratify which patient groups benefit from multimodal treatment, and which need novel therapeutic strategies. Biomarker-driven tailored trials may be a key option.

Posterior Fossa Tumours in the First Year of Life: A Two-Centre Retrospective Study

Posterior fossa tumours (PFTs) in infants are very rare, and information on these tumours is scarce in the literature. This retrospective study reports their pathological characteristics and describes surgical aspects and treatment outcomes. A two-centre cohort of infants with PFTs treated from 2007 to 2018 was retrospectively reviewed. Patient characteristics, clinical, and treatment data were reviewed. Survival curves for progression-free survival (PFS) and overall survival (OS) were generated. Thirty-three infants were retrieved. There were 11 low grade and 22 high-grade tumours. The most common presenting symptom was intracranial hypertension. Fifteen children out of thirty-three progressed. Five-year PFS was significantly lower in children with high-grade tumours (38.3%) than those with low-grade tumours (69.3%), p = 0.030. High-grade pathology was the only predictor of progression (HR 3.7, 95% CI 1.1–13.31), p = 0.045. Fourteen children with high-grade tumours died, with a 5-year OS of 55.25%. PFTs in children below one year of age still represent a unique challenge. Infants with high-grade tumours display the worst outcomes and the lowest survival, indicating that more effective strategies are needed.

Feasibility of Proton Beam Therapy for Infants with Brain Tumours: Experiences from the Prospective KiProReg Registry Study

AIMS

Proton beam therapy (PBT) has increasingly been applied for the treatment of young children when radiotherapy is needed. The treatment requires intensive multimodality care and is logistically demanding. In this analysis, we evaluated our experiences in treating infants with tumours of the central nervous system with PBT.

MATERIALS AND METHODS

Children younger than 2 years of age treated with PBT for central nervous system tumours enrolled in the prospective registry study KiProReg were retrospectively analysed. Information on patient characteristics, treatment, toxicities and outcome were evaluated. Adverse events were classified according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE V4.0) before, during and after PBT.

RESULTS

Between September 2013 and June 2018, 51 infants were eligible. The median age was 19 months (range 11-23 months) at the time of PBT. Tumour entities were ependymoma (51.0%), atypical teratoid rhabdoid tumour (39.0%), high-grade glioma (6.0%), pineoblastoma (2.0%) and medulloblastoma (2.0%). The prescribed median total dose was 54.0 Gy (range 45.0-59.4 Gy). Most received local radiotherapy. In four patients, craniospinal irradiation followed by a boost to the local tumour bed was applied. The median follow-up time was 42.0 months (range 7.3-86.2 months). The estimated 3-year local control, progression-free survival and overall survival rates for all patients were 62.7, 47.1 and 76.5%, respectively. During radiotherapy, 24 events of higher-grade (CTCAE ≥ °III) toxicities were reported. Interruption of radiotherapy for more than 2 days was due to infection (n = 3) or shunt complication (n = 2). Unexpected hospitalisation during radiotherapy affected 12 patients. Late adverse events attributable to radiotherapy included endocrinopathy (CTCAE °II; 7.8%), new onset of hearing loss (CTCAE °III; 5.8%) and visual impairment (CTCAE °IV; 1.9%). Transient radiation-induced imaging changes occurred in five patients (9.8%).

CONCLUSIONS

Our study indicates that PBT is feasible for very young children with central nervous system tumours, at least in the short term. However, it requires challenging interdisciplinary medical care and high logistical effort. For evaluation of late effects, longer follow-up and evaluation of neurocognitive outcome are desirable. More data have to be gathered to further define the role of radiotherapy in infants over time.

Clinical and genetic risk factors define two risk groups of extracranial malignant rhabdoid tumours (eMRT/RTK)

INTRODUCTION

Extracranial rhabdoid tumours are rare, highly aggressive malignancies primarily affecting young children. The EU-RHAB registry was initiated in 2009 to prospectively collect data of rhabdoid tumour patients treated according to the EU-RHAB therapeutic framework.

METHODS

We evaluated 100 patients recruited within EU-RHAB (2009-2018). Tumours and matching blood samples were examined for SMARCB1 mutations by sequencing and cytogenetics.

RESULTS

A total of 70 patients presented with extracranial, extrarenal tumours (eMRT) and 30 with renal rhabdoid tumours (RTK). Nine patients demonstrated synchronous tumours. Distant metastases at diagnosis (M+) were present in 35% (35/100), localised disease (M0) with (LN+) and without (LN-) loco-regional lymph node involvement in 65% (65/100). SMARCB1 germline mutations (GLM) were detected in 21% (17/81 evaluable) of patients. The 5-year overall survival (OS) and event-free survival (EFS) rates were 45.8 ± 5.4% and 35.2 ± 5.1%, respectively. On univariate analyses, age at diagnosis (≥12 months), M0-stage, absence of synchronous tumours, absence of a GLM, gross total resection (GTR), radiotherapy and achieving a CR were significantly associated with favourable outcomes. In an adjusted multivariate model presence of a GLM, M+ and lack of a GTR were the strongest significant negative predictors of outcome.

CONCLUSIONS

We suggest to stratify patients with localised disease (M0), GTR+ and without proof of a GLM (5-year OS 72.2 ± 9.9%) as 'standard risk'. Patients presenting with one of the features M+ and/or GTR- and/or GLM+ belong to a high risk group (5-year, OS 32.5 ± 6.2%). These patients need novel therapeutic strategies such as combinations of targeted agents with conventional chemotherapy or novel experimental approaches ideally within international phase I/II trials.

Translational genomics of malignant rhabdoid tumours: Current impact and future possibilities

Malignant Rhabdoid Tumours (MRT) are the quintessential example of an epigenetic cancer. Mutation of a single gene, SMARCB1 or more rarely SMARCA4, is capable of causing one of the most aggressive and lethal cancers of early childhood and infancy. SMARCB1 encodes a core subunit of the SWI/SNF complex and its mutation evokes genome-wide downstream effects which may be counteracted therapeutically. Here we review and discuss the use of translational genomics in the study of MRT biology and the ways in which this has impacted clinical practice or may do so in the future. First, the diagnosis and definition of MRT and the transition from a histopathological to a molecular definition. Second, epigenetic and transcriptomic subgroups within MRT, their defining features and potential prognostic or therapeutic significance. Third, functional genomic studies of MRT by mouse modelling and forced re-expression of SMARCB1 in MRT cells. Fourth, studies of underlying epigenetic mechanisms (e.g. EZH2, HDACs) or deregulated kinases (e.g. PDGFR, FGFR1) and the potential therapeutic opportunities these provide. Finally, we discuss likely future directions and proffer opinion on how future translational genomics should be integrated into future biological/clinical studies to select and evaluate the best anti-MRT therapeutic agents.

Childhood Medulloblastoma Revisited

Medulloblastoma is the most common malignant solid tumor in childhood and the most common embryonal neuroepithelial tumor of the central nervous system. Several morphological variants are recognized: classic medulloblastoma, large cell/anaplastic medulloblastoma, desmoplastic/nodular medulloblastoma, and medulloblastoma with extensive nodularity. Recent advances in transcriptome and methylome profiling of these tumors led to a molecular classification that includes 4 major genetically defined groups. Accordingly, the 2016 revision of the World Health Organization's Classification of Tumors of the Central Nervous System recognizes the following medulloblastoma entities: Wingless (WNT)-activated, Sonic hedgehog (SHH)-activated, Group 3, and Group 4. This transcriptionally driven classification constitutes the basis of new risk stratification schemes applied to current therapeutic clinical trials. Because additional layers of molecular tumor heterogeneities are being progressively unveiled, several clinically relevant subgroups within the 4 major groups have already been identified. The purpose of this article is to review the recent basic science and clinical advances in the understanding of "medulloblastomas," and their diagnostic imaging correlates and the implications of those on current neuroimaging practice.

Preclinical drug screen reveals topotecan, actinomycin D, and volasertib as potential new therapeutic candidates for ETMR brain tumor patients

Background

Embryonal tumor with multilayered rosettes (ETMR) is a rare and aggressive embryonal brain tumor that solely occurs in infants and young children and has only recently been recognized as a separate brain tumor entity in the World Health Organization classification for CNS tumors. Patients have a very dismal prognosis with a median survival of 12 months upon diagnosis despite aggressive treatment. The aim of this study was to develop novel treatment regimens in a preclinical drug screen in order to inform potentially more active clinical trial protocols.

Methods

We have carried out an in vitro and in vivo drug screen using the ETMR cell line BT183 and its xenograft model. Furthermore, we have generated the first patient-derived xenograft (PDX) model for ETMR and evaluated our top drug candidates in an in vitro drug screen using this model.

Results

BT183 cells are very sensitive to the topoisomerase inhibitors topotecan and doxorubicin, to the epigenetic agents decitabine and panobinostat, to actinomycin D, and to targeted drugs such as the polo-like kinase 1 (PLK1) inhibitor volasertib, the aurora kinase A inhibitor alisertib, and the mammalian target of rapamycin (mTOR) inhibitor MLN0128. In xenograft mice, monotherapy with topotecan, volasertib, and actinomycin D led to a temporary response in tumor growth and a significant increase in survival. Finally, using multi-agent treatment regimens of topotecan or doxorubicin combined with methotrexate and vincristine, the response in tumor growth and survival was further increased compared with mice receiving single treatments.

Conclusions

We have identified several promising candidates for combination therapies in future clinical trials for ETMR patients.

Pharmacokinetics of Bevacizumab in Three Patients Under the Age of 3 Years with CNS Malignancies

Background

Bevacizumab is a recombinant antibody that is increasingly used in pediatric malignancies. The pharmacokinetics of bevacizumab in pediatric patients have been shown to be influenced by tumor localization and body weight. In this report, we present data on the pharmacokinetics and safety of bevacizumab in children under the age of 3 years with central nervous system (CNS) malignancies.

Methods

Three patients (mean age 22 months) were treated with intravenous bevacizumab 10 mg/kg every 2 weeks. In total, 20 trough and peak bevacizumab concentrations of 10 treatment cycles were obtained at steady state.

Results

Bevacizumab was generally well-tolerated in this age group. The mean trough concentration was 127 ± 29 µg/ml (range 77–155), and the mean peak concentration was 149 ± 13 µg/ml (range 113–157). Trough and peak levels were stable upon repeated treatment cycles in the same patient. In contrast, we determined strong interindividual variations in trough levels. Whereas the plasma concentration of the oldest patient matched the prediction of a previously published model, younger patients showed markedly higher trough levels.

Conclusions

Serum peak concentrations of bevacizumab in children under the age of 3 years with CNS malignancies are in a similar magnitude to that found in older children and adults. Thus, a dosing schedule of bevacizumab 10 mg/kg every 2 weeks can be considered sufficient and safe, even in very young children. We further show that very young children with CNS malignancies show a markedly reduced plasma clearance, possibly related to lower body weight or differences in clearance mechanisms of antibodies.

The extraordinary challenge of treating patients with congenital rhabdoid tumors-a collaborative European effort

BACKGROUND

Congenital rhabdoid tumors are rare and highly aggressive malignancies. In general, patients are considered to be incurable and are often treated using an exclusive, primarily palliative approach.

METHODS

A prospective and retrospective collection of 42 patients from the European Rhabdoid Registry (EU-RHAB), France and Moscow (2006-2016) diagnosed within the first 28 days of life was evaluated. Genetic and clinical reference evaluation included SMARCB1 and/or SMARCA4 (fluorescence-in-situ-hybridization, multiplex ligation-dependent probe amplification, and sequencing) mutation analysis and immunohistochemistry. Forty-eight percent (20/42) of patients were treated according to the EU-RHAB therapy, 7% (3/42) according to the pilot approach Rhabdoid 2007, 33% (14/42) with individual schedules, and 12% (5/42) received no chemotherapy at all.

RESULTS

Forty point five percent (17/42) of patients presented with extracranial rhabdoid tumors, 33.5% (14/42) with rhabdoid tumors of the central nervous system (atypical teratoid/rhabdoid tumor), and the remainder 26% (11/42) demonstrated synchronous tumors. Metastases at diagnosis were present in 52% (22/42) of patients. A germline mutation was detected in 66% (25/38) and was associated with a poor prognosis (4.2 ± 4.1% vs. 48 ± 16.4%, P < 0.00005). A gross total resection (GTR) was realized in 17%. A GTR (42.9 ± 18.7% vs. 4.9 ± 4.3%, P = 0.04), therapy according to a standardized approach (20.9 ± 8.7% vs. 7.1 ± 6.9 %, P = 0.0018), and a complete remission (CR) (23.6 ± 9.8% vs. 1.3 ± 3.6%, P = 0.04) were significant prognostic factors.

CONCLUSIONS

The management of patients with congenital rhabdoid tumors requires a major multidisciplinary effort. In many instances, cure is not possible and a palliative approach is warranted. Our data indicate a positive impact of standardized therapeutic approaches on survival, making a tailored approach toward affected patients and their families mandatory.

Emerging therapeutic targets for the treatment of malignant rhabdoid tumors

INTRODUCTION

Malignant Rhabdoid Tumor (MRT) is a rare and highly aggressive malignancy primarily affecting infants and young children. The most common anatomic locations are the central nervous system (AT/RT), the kidneys (RTK) and other soft tissues (eMRT). The genetic origin of this disease is linked to mutations in SMARCB1, a gene encoding a core subunit of the SWI/SNF chromatin-remodeling complex. Areas covered: Conventional multimodal treatment may offer a significant survival benefit to certain patients. It remains to be determined, however, which patients will prove resistant to chemotherapy and need novel therapeutic approaches. Herein we discuss key signal transduction pathways involved in the pathogenesis of rhabdoid tumors for potential targeted therapy (EZH2, DNMT, HDAC, CDK4/6/Cyclin D1/Rb, AURKA, SHH/GLI1, Wnt/ß-Catenin, immunotherapy). Additional agents currently evaluated in preclinical settings and experimental clinical trials are discussed. Expert opinion: MRTs are genetically homogeneous, but epigenetically distinct malignancies. While there is an abundance of experimental in vitro studies evaluating potential therapeutic avenues, a dearth of clinical trials specifically for this entity persists. In order to improve outcome patients need to be carefully stratified and treated by targeted therapies combined with conventional chemotherapy or with new, less selective experimental agents in phase I/II clinical trials.

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.

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.

Analysis of the antiproliferative effects of 3-deazaneoplanocin A in combination with standard anticancer agents in rhabdoid tumor cell lines

Rhabdoid tumors (RTs) are highly aggressive pediatric malignancies with a rather poor prognosis. New therapeutic approaches and optimization of already established treatment protocols are urgently needed. The histone methyltransferase enhancer of zeste homolog 2 (EZH2) is highly overexpressed in RTs and associated strongly with epigenetic silencing in cancer. EZH2 is involved in aggressive cell growth and stem cell maintenance. Thus, EZH2 is an attractive therapeutic target in RTs. The aim of the study presented here was to analyze the effects of a pharmacological inhibition of EZH2 alone and in combination with other anticancer drugs on RTs cells in vitro. The antitumor activity of the S-adenosyl-homocysteine-hydrolase inhibitor 3-deazaneplanocin A (DZNep) alone and in combination with conventional cytostatic drugs (doxorubicin, etoposide) or epigenetic active compounds [5-Aza-CdR, suberoylanilide hydroxamic acid (SAHA)] was assessed by MTT cell proliferation assays on three RT cell lines (A204, BT16, G401). Combinatorial treatment with DZNep synergistically and significantly enhanced the antiproliferative activity of etoposide, 5-Aza-CdR, and SAHA. In functional analyses, pretreatment with DZNep significantly increased the effects of 5-Aza-CdR and SAHA on apoptosis, cell cycle progression, and clonogenicity. Microarray analyses following sequential treatment with DZNep and 5-Aza-CdR or SAHA showed changes in global gene expression affecting apoptosis, neuronal development, and metabolic processes. In-vitro analyses presented here show that pharmacological inhibition of EZH2 synergistically affects the antitumor activity of the epigenetic active compounds 5-Aza-CdR and SAHA. Sequential treatment with these drugs combined with DZNep may represent a new therapeutic approach in RTs.

Synchronous congenital malignant rhabdoid tumor of the orbit and atypical teratoid/rhabdoid tumor--feasibility and efficacy of multimodal therapy in a long-term survivor

Among infant malignancies, congenital tumors, especially those of the central nervous system (CNS), constitute a rather unique subgroup. Poor survival rates (28% in CNS tumors) may be attributed to the aggressive biology as well as specific therapeutic limitations innate to the young age of affected patients. Our patient developed synchronous congenital tumors: an atypical teratoid/rhabdoid tumor (AT/RT) localized in the right lateral ventricle of the brain and a malignant rhabdoid tumor (MRT) in the soft tissue of the right orbit. A de novo germline chromosomal deletion in 22q encompassing the SMARCB1 gene was detected, prompting the diagnosis of a de novo rhabdoid tumor predisposition syndrome 1 (RTPS1). The patient was reported to the European Rhabdoid Registry (EU-RHAB) and treated according to the Rhabdoid 2007 recommendation. Despite the very young age of the patient, the initially desperate situation of RTPS1, and the synchronous localization of congenital rhabdoid tumors, intensive chemotherapy was well tolerated; the child is still in complete remission 5 years following diagnosis. In conclusion, RTPS1 with congenital synchronous MRTs is not necessarily associated with a detrimental outcome. Intensive multidrug chemotherapy, including high dose chemotherapy, may be feasible and justified.

Clinical and genetic features of rhabdoid tumors of the heart registered with the European Rhabdoid Registry (EU-RHAB)

Rhabdoid tumors are rare but highly aggressive malignancies of infancy and early childhood with a generally unfavorable prognosis. Despite a wide variety of anatomic locations rhabdoid tumors share mutational inactivation of the SWI/SNF (SWItch/Sucrose NonFermentable) core component gene SMARCB1 (also known as INI1, hSNF5 or BAF47) in chromosome 22. As this inactivation usually results in loss of SMARCB1 expression, detectable by an antibody against the SMARCB1 protein, the accurate diagnosis of a rhabdoid tumor may be more distinctly and frequently made. Several reports on rhabdoid tumors presenting in various anatomic sites outside the kidneys and CNS are on record. We report two cases of rhabdoid tumors originating in the heart (cardiac tissue), which were entered into the European Rhabdoid Registry (EU-RHAB). The first case presented with intracardial and -cranial lesions as well as malignant ascites, while the second patient demonstrated an isolated cardiac tumor. This induced a different therapeutic approach and subsequently different clinical course (death 7 weeks after diagnosis in patient 1). Patient 2 presented with a bifocal intracardial tumor without metastases and remains in complete remission for 46 months since diagnosis following multimodal therapy. The second case demonstrates that even in a potentially futile clinical situation early and accurate diagnosis followed by prompt and intensive multimodal therapy may offer prolonged survival, potential cure and improved quality of life.