Tandem high-dose chemotherapy and autologous stem cell transplantation in young children with atypical teratoid/rhabdoid tumor of the central nervous system

Atypical Teratoid/Rhabdoid Tumor of the Central Nervous System in Children: Case Reports and Literature Review

Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system is a highly malignant tumor that mainly occurs in children under the age of 3 and has only been rarely described in adults. The fact that AT/RT patients have such a terrible prognosis is even more regrettable. Herein, we reported two special cases of AT/RT, both of which were under 3 years. Symptoms at presentation included increased intracranial pressure and cerebellar symptoms such as headache, altered gait, and ataxia. As for the tumor location, one was infratentorial in the posterior fossa, and the other was the right lateral ventricle. Preoperative magnetic resonance imaging scans showed calcification and heterogeneous contrast enhancement in the lesions. The mass was excised surgically for the progression of symptoms. Postoperative pathologies of the tumors, combined with immunohistochemistry, revealed AT/RT. AT/RTs are often misdiagnosed as other types of brain tumors due to the lack of specific radiological features and other key characteristics. To improve awareness of AT/RT on the differential diagnosis of intracranial lesions among clinicians, we present this report and briefly summarize previous cases.

Advancing biology-based therapeutic approaches for atypical teratoid rhabdoid tumors

Atypical teratoid rhabdoid tumor (ATRT) is a rare, highly malignant central nervous system cancer arising in infants and younger children, historically considered to be homogeneous, monogenic, and incurable. Recent use of intensified therapies has modestly improved survival for ATRT; however, a majority of patients will still succumb to their disease. While ATRTs almost universally exhibit loss of SMARCB1 (BAF47/INI1/SNF5), recent whole genome, transcriptome, and epigenomic analyses of large cohorts reveal previously underappreciated molecular heterogeneity. These discoveries provide novel insights into how SMARCB1 loss drives oncogenesis and confer specific therapeutic vulnerabilities, raising exciting prospects for molecularly stratified treatment for patients with ATRT.

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.

Effect of early radiotherapy initiation and high-dose chemotherapy on the prognosis of pediatric atypical teratoid rhabdoid tumors in different age groups

PURPOSE

The optimal treatment strategy for pediatric atypical teratoid rhabdoid tumor (ATRT) is inconclusive. This study evaluated the prognostic value of early radiotherapy (RT) and high-dose chemotherapy with autologous stem cell rescue (HDC/ASCR) in pediatric ATRT.

METHODS

This pooled analysis included ATRT patients treated at our institution and from other studies who were identified by a search of the PubMed electronic database. The effect of patient demographics and treatment profiles on progression-free survival (PFS) and overall survival (OS) were analyzed using Cox regression.

RESULTS

Overall, 34 patients from our institution and 436 patients from 35 published studies were included. In multivariable analysis, patients with gross total resection (GTR), early RT (time to RT interval < 2 months), and HDC/ASCR had both better PFS [hazard ratio (HR) 0.46, p[Formula: see text] 0.001; HR 0.64, p = 0.011; and HR 0.51, p = 0.005, respectively] and OS (HR 0.55, p = 0.002; HR 0.48, p = 0.004; and HR 0.42, p < 0.001, respectively). For patients aged < 3 years, both RT and HDC/ASCR were significant favorable factors for PFS (HR 0.32 and 0.46, respectively) and OS (HR 0.40 and 0.36, respectively), while early RT was not prognostic. For patients aged ≥ 3 years, early RT was significantly associated with better PFS (HR 0.51) and HDC/ASCR did not affect PFS, and neither was related to OS.

CONCLUSION

Both early RT initiation and HDC/ASCR were important components in the treatment of pediatric ATRT. However, the optimal treatment strategies might differ by age.

Trimodality therapy for atypical teratoid/rhabdoid tumor is associated with improved overall survival: A surveillance, epidemiology, and end results analysis

BACKGROUND

Atypical teratoid/rhabdoid tumors (AT/RTs) are rare aggressive central nervous system tumors. The use of radiation therapy (RT) remains controversial, especially for patients younger than three years of age. The purpose of the current investigation is to robustly analyze the impact of RT among pediatric AT/RT patients using the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

SEER 18 Custom Data registries were queried for AT/RT (ICD-0-3 9508/3). A total of 190 pediatric AT/RT patients were identified, of whom 102 underwent surgery + chemotherapy and 88 underwent trimodality therapy. Univariate and multivariable analyses using Kaplan-Meier and Cox proportional hazards regression modeling were performed. Propensity-score matched analysis with inverse probability of treatment weighting was performed to account for indication bias. The landmark method was used to account for immortal time bias.

RESULTS

The majority of patients were <3 years old (75.8%). Patients <3 were more likely to be treated without RT as compared with older patients (62% vs 38%). Doubly robust MVA identified distant disease as a negative prognostic factor (HR 2.1, P = 0.003), whereas trimodality therapy was strongly protective (HR 0.39, P < 0.001). Infants (<1), toddlers (1-2), and older children (3+) all benefited from trimodality therapy, with largest benefit for infants (HR 0.34, P = 0.02) and toddlers (HR 0.31, P < 0.001).

CONCLUSION

The current study provides further evidence that trimodality therapy improves clinical outcomes among patients with AT/RT. This finding was most pronounced for younger patients; therefore, further studies are needed to confirm this finding in this vulnerable population.

Overall Survival of Primary Intracranial Atypical Teratoid Rhabdoid Tumor Following Multimodal Treatment: A Pooled Analysis of Individual Patient Data

No standard treatment protocol to guide the management of the primary central nervous system atypical teratoid rhabdoid tumors (ATRTs). To evaluate the efficacy of GTR (gross total resection), RT (radiotherapy), CCMT (conventional chemotherapy), or intensified chemotherapy (ICMT) and verify the optimal treatment strategy. A total of 501 cases (18 cases from our center and 483 cases from published literature) were eligible for analysis. Clinical characteristics were reviewed, and overall survival (OS) of each combined treatment modality was compared. These prior publication data were processed according to PRISMA guidelines. This study included 265 (52.9%) males and 216 (43.1%) females. The median age of the cohort was 2.2 years with 295 (58.9%) cases younger than 3 years. GTR was achieved in 217 (43.3%) patients. Initial adjuvant CCMT, CCMT plus intrathecal chemotherapy (ITCMT), CCMT plus high-dose chemotherapy (HDCMT), and CCMT plus ITCMT and HDCMT were administered in 228 (45.5%), 78 (15.6%), 55 (11.0%), and 24 (4.8%) patients, respectively. Radiotherapy (RT) was prescribed in 266 (53.1%) patients. Fewer patients younger than 3 years old received RT (21.9% vs 33.0%, p < 0.001, chi-square test). The OS of the entire cohort at 1, 3, and 5 years were 56.6, 35.9, and 30.8%, respectively. After adjusting for age and sex, GTR (HR 0.630; p < 0.001), RT (HR = 0.295; p < 0.001), CCMT (HR = 0.382; p < 0.001), and ICMT (HR = 0.209; p < 0.001) were independent prognostic factors. The 3-year OS of surgery alone, surgery plus CCMT, surgery plus RT, surgery plus ICMT, surgery plus CCMT and RT, and surgery plus ICMT and RT were 8.9, 13.4, 23.7, 37.4, 48.3, and 68.5%, respectively. When taking into consideration the extent of tumor resection (n = 462), GTR followed by RT, CCMT, intrathecal chemotherapy, and high-dose chemotherapy provided the best OS (5-year OS 88.2%). In younger children, adjuvant ICMT had a greater 3-year OS than adjuvant RT alone (34.0% vs 0%, p = .001). This study identified independent favorable predictors for OS of ATRTs and distinguished significantly different OS following various treatment modalities. If tolerable, intensive treatment with GTR followed by adjuvant RT and ICMT is recommended. Intensified CCMT could be an alternative to avoid radiological radiotoxicity for younger children CRD42018098841.

Repositioning disulfiram as a radiosensitizer against atypical teratoid/rhabdoid tumor

Background

Atypical teratoid/rhabdoid tumor (AT/RT) is one of the most common malignant brain tumors in infants. Although cancer stem cells of AT/RT express aldehyde dehydrogenase (ALDH), effective chemotherapies against AT/RT have not been established. Here, we examined radiosensitizing effects of disulfiram (DSF), an irreversible inhibitor of ALDH against AT/RT for a novel therapeutic method.

Methods

Patient-derived primary cultured AT/RT cells (SNU.AT/RT-5 and SNU.AT/RT-6) and established AT/RT cell lines (BT-12 and BT-16) were used to assess therapeutic effects of combining DSF with radiation treatment (RT). Survival fraction by clonogenic assay, protein expression, immunofluorescence, and autophagy analysis were evaluated in vitro. Antitumor effects of combining DSF with RT were verified by bioluminescence imaging, tumor volume, and survival analysis in vivo.

Results

The results demonstrated that DSF at low concentration enhanced the radiosensitivity of AT/RT cells with reduction of survival fraction to 1.21‒1.58. DSF increased DNA double-strand break (γ-H2AX, p-DNA-PKcs, and p-ATM), apoptosis (cleaved caspase-3), autophagy (LC3B), and cell cycle arrest (p21) in irradiated AT/RT cells, while it decreased anti-apoptosis (nuclear factor-kappaB, Survivin, and B-cell lymphoma 2 [Bcl2]). In vivo, DSF and RT combined treatment significantly reduced tumor volumes and prolonged the survival of AT/RT mouse models compared with single treatments. The combined treatment also increased γ-H2AX, cleaved caspase-3, and LC3B expression and decreased ALDH1, Survivin, and Bcl2 expression in vivo.

Conclusions

DSF and RT combination therapy has additive therapeutic effects on AT/RT by potentiating programmed cell death, including apoptosis and autophagy of AT/RT cells. We suggest that DSF can be applied as a radiosensitizer in AT/RT treatment.

Radiation Therapy against Pediatric Malignant Central Nervous System Tumors : Embryonal Tumors and Proton Beam Therapy

Radiation therapy is highly effective for the management of pediatric malignant central nervous system (CNS) tumors including embryonal tumors. With the increment of long-term survivors from malignant CNS tumors, the radiation-related toxicities have become a major concern and we need to improve the treatment strategies to reduce the late complications without compromising the treatment outcomes. One of such strategies is to reduce the radiation dose to craniospinal axis or radiation volume and to avoid or defer radiation therapy until after the age of three. Another strategy is using particle beam therapy such as proton beams instead of photon beams. Proton beams have distinct physiologic advantages over photon beams and greater precision in radiation delivery to the tumor while preserving the surrounding healthy tissues. In this review, I provide the treatment principles of pediatric CNS embryonal tumors and the strategic improvements of radiation therapy to reduce treatment-related late toxicities, and finally introduce the increasing availability of proton beam therapy for pediatric CNS embryonal tumors compared with photon beam therapy.

Atypical Teratoid Rhabdoid Tumour : From Tumours to Therapies

Atypical teratoid rhabdoid tumours (ATRTs) are the most common malignant central nervous system tumours in children ≤1 year of age and represent approximately 1–2% of all pediatric brain tumours. ATRT is a primarily monogenic disease characterized by the bi-allelic loss of the SMARCB1 gene, which encodes the hSNF5 subunit of the SWI/SNF chromatin remodeling complex. Though conventional dose chemotherapy is not effective in most ATRT patients, high dose chemotherapy with autologous stem cell transplant, radiotherapy and/or intrathecal chemotherapy all show significant potential to improve patient survival. Recent epigenetic and transcriptional studies highlight three subgroups of ATRT, each with distinct clinical and molecular characteristics with corresponding therapeutic sensitivities, including epigenetic targeting, and inhibition of tyrosine kinases or growth/lineage specific pathways.

Atypical teratoid/rhabdoid tumors in children treated with multimodal therapies: The necessity of upfront radiotherapy after surgery

BACKGROUND

Atypical teratoid/rhabdoid tumor (ATRT) is a rare malignant pediatric brain tumor with a dismal prognosis. We evaluated the efficacy of multimodal therapy in children with ATRT.

PROCEDURE

Nine children diagnosed with cranial ATRT, who received multimodal therapy between 2005 and 2014, including surgical resection followed by radiotherapy (RT), systemic chemotherapy (CT), and high-dose chemotherapy/stem cell transplantation (HDCT/SCT), were analyzed retrospectively. The median age at diagnosis was 32 months. Initial treatment included surgery in eight patients (88%), CT in all (100%), RT in eight (88%), and HDCT/SCT in seven (78%).

RESULTS

The median follow-up period for survivors was 21 months. The 2-year progression-free rate was 66.7%. Two patients had progression 4 and 17 months after diagnosis. One received multimodal treatment, including surgery and upfront CT with delayed RT; the other underwent surgery and upfront CT without RT. The 2-year event-free survival and overall survival rates were 46.7% and 62.2%, respectively. Hematologic toxicity of grade 3 or more was observed in six patients treated with HDCT/SCT and two who underwent craniospinal irradiation. Deaths were attributed to progressive disease (n = 2) and treatment-related toxicity (n = 2) from sepsis and acute respiratory failure after CT and HDCT/SCT.

CONCLUSIONS

Maximal safe resection in conjunction with upfront RT is a reasonable multimodal treatment in patients with ATRT for prolonging progression-free survival. Further research may help determine the optimal parameters for reducing treatment toxicity, such as intensity of HDCT/SCT and the RT field.

Rare Primary Central Nervous System Tumors Encountered in Pediatrics

As part of the special issue on Pediatric Neuro-Oncology, this article will focus on 4 of the rarer tumors in this spectrum, including atypical teratoid rhabdoid tumors, embryonal tumors with multilayered rosettes, choroid plexus tumors, and pleomorphic xanthoastrocytoma. Incidence and current understanding of the molecular pathogenesis of these tumors are discussed, and avenues of therapy both current and prospective are explored.

Long-term survival following additive radiotherapy in patients with atypical teratoid rhabdoid tumors

BACKGROUND

Atypical teratoid rhabdoid tumor (ATRT) is a highly aggressive disease of embryonic origin accounting for <5% of all pediatric central nervous system (CNS) tumors.

PATIENTS AND METHODS

We describe a series of five cases of CNS ATRT. The first three patients underwent subtotal tumor resection. Gross total resection of the tumor was achieved in the fourth and fifth patients. Only 4 patients received chemotherapy, whereas all 5 patients received additive radiotherapy (RT). The latter included three dimensional (3D) conformal RT or intensity modulated RT (IMRT) with a median dose of 54 Gy (range 50.4-59.0 Gy) applied in daily fractions of 1.8 Gy. The median interval between surgery and RT was 5 months (range 2-11 months).

RESULTS

Two months after completion of RT, 4 patients had achieved complete radiologic remission. The median event-free survival period was 46 months (range 10-90 months). However, the first patient died 17 months after developing an out-of-field recurrence. The third patient developed a recurrence 11 months after salvage RT. The other 3 patients (cases 2, 4, and 5) remain alive with no evidence of disease 59, 46 and 90 months after therapy, respectively.

CONCLUSION

Overall, the 5 patients survived for a median of 48 months (range 25-90 months) from the time of initial diagnosis and they tolerated the RT well, without severe acute or late onset toxicities. The results imply a potential survival gain after irradiation at acceptable toxicity level.

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.

Tandem High-Dose Chemotherapy and Autologous Stem Cell Transplantation for Atypical Teratoid/Rhabdoid Tumor

Purpose

We prospectively evaluated the effectiveness of tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT) in improving the survival of patients with atypical teratoid/rhabdoid tumors while reducing the risks of late adverse effects from radiotherapy (RT).

Materials and Methods

For young children (< 3 years old), tandem HDCT/auto-SCT was administered after six cycles of induction chemotherapy. RT was deferred until after 3 years of age unless the tumor showed relapse or progression. For older patients (> 3 years old), RT including reduced-dose craniospinal RT (23.4 or 30.6 Gy) was administered either after two cycles of induction chemotherapy or after surgery, and tandem HDCT/auto-SCT was administered after six cycles of induction chemotherapy.

Results

A total of 13 patients (five young and eight older) were enrolled from November 2004 to June 2012. Eight patients, including all five young patients, had metastatic disease at diagnosis. Six patients (four young and two older) experienced progression before initiation of RT, and seven were able to proceed to HDCT/auto-SCT without progression during induction treatment. Three of six patients who experienced progression during induction treatment underwent HDCT/auto-SCT as salvage treatment. All five young patients died from disease progression. However, four of the eight older patients remain progression-freewith a median follow-up period of 64 months (range, 39 to 108 months). Treatment-related late toxicities were acceptable.

Conclusion

The required dose of craniospinal RT might be reduced in older patients if the intensity of chemotherapy is increased. However, early administration of RT should be considered to prevent early progression in young patients.

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.

Atypical teratoid/rhabdoid tumor (AT/RT) arising from the acoustic nerve in a young adult: a case report and a review of literature

Atypical teratoid/rhabdoid tumors (AT/RTs) are rare, highly malignant central nervous system tumors that predominantly occur in young children. A 22-year-old woman presented with a 4-year history of relapsing tinnitus and gradual hearing loss. Neuroimaging revealed an enhanced intrinsic left internal auditory canal mass. The patient underwent radiotherapy treatment. Three years later, the tumor size continued to increase, as observed by imaging, and ultimately evolved into the left cerebellopontine angle. As a consequence, a total tumor resection was performed, and a pathological diagnosis of AT/RT was made. Aggressive radiotherapy and chemotherapy treatment continued; however, the tumor recurred within 11 months after the total tumor resection. The patient died within 4 months of the second operation. Histopathologically, the tumor contained characteristic rhabdoid cells with areas that resembled a classical primitive neuroectodermal tumor. Immunostaining showed loss of INI1 protein expression in tumor cells, and fluorescence in situ hybridization showed a hemizygous deletion of the hSNF5/INI1 gene region on 22q11.2. This is the first report of an AT/RT that arised from the acoustic nerve in a young adult. Despite manifold diagnostic and therapeutic advances, the prognosis of patients with AT/RT remains poor.

Adult-onset sellar and suprasellar atypical teratoid rhabdoid tumor treated with a multimodal approach: a case report

We report a very rare case of sellar and suprasellar atypical teratoid rhabdoid tumor (ATRT) in a 42-year-old female patient. The tumor was removed subtotally with a transsphenoidal approach. Histopathologic study showed rhabdoid cells with prominent nucleoli and abundant cytoplasm. Immunohistochemistry for INI1 was completely negative in the tumor cells, consistent with ATRT. After surgery, she received radiotherapy including spinal irradiation with proton beam therapy and subsequent chemotherapy, with no evidence of recurrence for more than 2 years. Up to date, this is the 8th case of an adult-onset ATRT in the sellar or suprasellar region. Despite its rarity, ATRTs should be considered in the differential diagnosis of an unclear malignant sellar or suprasellar lesion in adult patients and the treatment strategies for adult ATRT patients could be differentiated from those of pediatric ATRT patients.

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.

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.

Intensive induction chemotherapy followed by myeloablative chemotherapy with autologous hematopoietic progenitor cell rescue for young children newly-diagnosed with central nervous system atypical teratoid/rhabdoid tumors: the Head Start III experience

BACKGROUND

Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS) is a rare embryonal neoplasm of early childhood with dismal outcome and no current uniformly accepted treatment. Given its highly aggressive nature and predilection for dissemination at diagnosis, intensive multimodal therapy is required.

MATERIALS AND METHODS

Nineteen children with newly diagnosed CNS AT/RT were treated on the head start (HS) III protocol. Treatment consisted of surgical resection, 5 cycles of induction chemotherapy, followed by consolidation with myeloablative chemotherapy and autologous hematopoietic progenitor cell rescue (AuHCR). Irradiation was given following recovery from consolidation based on patient age, disease extent at diagnosis, and treatment response to induction.

RESULTS

Nineteen children (median age of 14 months) were treated on HS III between 2003 and 2009. Only four finished induction and three proceeded to consolidation. There are presently four survivors at 40, 42, 46, and 79 months from study enrollment. Eleven patients experienced tumor progression at a median time to progression of 4.1 months of whom 10 died with a median time from progression to death of 2.6 months. Five toxic deaths occurred, three of them while on the study. The 3-year event-free survival (EFS) and overall survival (OS) for the whole group was 21 ± 9% and 26 ± 10%, respectively. Five patients received irradiation at progression with only one long-term survivor.

CONCLUSION

A minority of children with CNS AT/RT treated on HS III may be long-term survivors without irradiation. More effective therapies are desperately needed.

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.

Atypical teratoid rhabdoid tumor: current therapy and future directions

Atypical teratoid rhabdoid tumors (ATRTs) are rare central nervous system tumors that comprise approximately 1-2% of all pediatric brain tumors; however, in patients less than 3 years of age this tumor accounts for up to 20% of cases. ATRT is characterized by loss of the long arm of chromosome 22 which results in loss of the hSNF5/INI-1 gene. INI1, a member of the SWI/SNF chromatin remodeling complex, is important in maintenance of the mitotic spindle and cell cycle control. Overall survival in ATRT is poor with median survival around 17 months. Radiation is an effective component of therapy but is avoided in patients younger than 3 years of age due to long term neurocognitive sequelae. Most long term survivors undergo radiation therapy as a part of their upfront or salvage therapy, and there is a suggestion that sequencing the radiation earlier in therapy may improve outcome. There is no standard curative chemotherapeutic regimen, but anecdotal reports advocate the use of intensive therapy with alkylating agents, high-dose methotrexate, or therapy that includes high-dose chemotherapy with stem cell rescue. Due to the rarity of this tumor and the lack of randomized controlled trials it has been challenging to define optimal therapy and advance treatment. Recent laboratory investigations have identified aberrant function and/or regulation of cyclin D1, aurora kinase, and insulin-like growth factor pathways in ATRT. There has been significant interest in identifying and testing therapeutic agents that target these pathways.