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

ESTRO-SIOPE guideline: Clinical management of radiotherapy in atypical teratoid/rhabdoid tumors (AT/RTs)

BACKGROUND AND PURPOSE

Treatment of patients with atypical teratoid/rhabdoid (AT/RT) is challenging, especially when very young (below the age of three years). Radiotherapy (RT) is part of a complex trimodality therapy. The purpose of this guideline is to provide appropriate recommendations for RT in the clinical management of patients not enrolled in clinical trials.

MATERIALS AND METHODS

Nine European experts were nominated to form a European Society for Radiotherapy and Oncology (ESTRO) guideline committee. A systematic literature search was conducted in PubMed/MEDLINE and Web of Science. They discussed and analyzed the evidence concerning the role of RT in the clinical management of AT/RT.

RESULTS

Recommendations on diagnostic imaging, therapeutic principles, RT considerations regarding timing, dose, techniques, target volume definitions, dose constraints of radiation-sensitive organs at risk, concomitant chemotherapy, and follow-up were considered. Treating children with AT/RT within the framework of prospective trials or prospective registries is of utmost importance.

CONCLUSION

The present guideline summarizes the evidence and clinical-based recommendations for RT in patients with AT/RT. Prospective clinical trials and international, large registries evaluating modern treatment approaches will contribute to a better understanding of the best treatment for these children in future.

Rhabdoid tumor predisposition syndrome: A historical review of treatments and outcomes for associated pediatric malignancies

Rhabdoid tumor predisposition syndrome (RTPS) is a rare disorder associated with malignant rhabdoid tumor of the kidney (RTK), atypical teratoid rhabdoid tumor (ATRT), and/or other extracranial, extrarenal rhabdoid tumors (EERT), and these pediatric malignancies are difficult to treat. Presently, most of the information regarding clinical manifestations, treatment, and outcomes of rhabdoid tumors comes from large data registries and case series. Our current understanding of treatments for patients with rhabdoid tumors may inform how we approach patients with RTPS. In this manuscript, we review the genetic and clinical features of RTPS and, using known registry data and clinical reports, review associated tumor types ATRT, RTK, and EERT, closing with potential new approaches to treatment. We propose collaborative international efforts to study the use of SMARC (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin)-targeting agents, high-dose consolidative therapy, and age-based irradiation of disease sites in RTPS.

Central nervous system embryonal tumors with EWSR1-PLAGL1 rearrangements reclassified as INI-1 deficient tumors at relapse

PURPOSE

Central nervous system (CNS) embryonal tumors are a diverse group of malignant tumors typically affecting pediatric patients that recently have been better defined, and this paper describes evolution of a unique type of embryonal tumor at relapse.

METHODS

Two pediatric patients with CNS embryonal tumors with EWSR1-PLAGL1 rearrangements treated at Arkansas Children's Hospital with histopathologic and molecular data are described.

RESULTS

These two patients at diagnosis were classified as CNS embryonal tumors with EWSR1-PLAGL1 rearrangements based on histologic appearance and molecular data. At relapse both patient's disease was reclassified as atypical teratoid rhabdoid tumor (ATRT) based on loss of INI-1, presence of SMARCB1 alterations, and methylation profiling results.

CONCLUSION

CNS embryonal tumors with EWSR1-PLAGL1 rearrangements acquire or include a population of cells with SMARCB1 alterations that are the component that predominate at relapse, suggesting treatment aimed at this disease component at diagnosis should be considered.

Synergistic Antitumor Activity of Talazoparib and Temozolomide in Malignant Rhabdoid Tumors

Malignant rhabdoid tumors (MRTs) are among the most aggressive and treatment-resistant malignancies affecting infants, originating in the kidney, brain, liver, and soft tissues. The 5-year event-free survival rate for these cancers is a mere 20%. In nearly all cases of MRT, the SMARCB1 gene (occasionally SMARCA4)-a pivotal component of the SWI/SNF chromatin remodeling complex-is homozygously deleted, although the precise etiology of these tumors remains unknown. While young patients with localized MRT generally show improved outcomes, especially those who are older and have early-stage disease, the overall prognosis remains poor despite optimal standard treatments. This highlights the urgent need for more effective treatment strategies. We investigated the antitumor activity of a PARP1 inhibitor (talazoparib, TLZ) combined with a DNA alkylating agent (temozolomide, TMZ) in MRT xenograft models. PARP1 is a widely targeted molecule in cancer treatment and, beyond its role in DNA repair, it participates in transcriptional regulation by recruiting chromatin remodeling complexes to modulate DNA accessibility for RNA polymerases. To widen the therapeutic window of the drug combination, we employed PEGylated TLZ (PEG~TLZ), which has been reported to reduce systemic toxicity through slow drug release. Remarkably, our findings indicate that five out of six MRT xenografts exhibited an objective response to PEG~TLZ+TMZ therapy. Significantly, the loss of SMARCB1 was found to confer a protective effect, correlating with higher expression levels of DNA damage and repair proteins in SMARCB1-deficient MRT cells. Additionally, we identified MGMT as a potential biomarker indicative of in vivo MRT response to PEG~TLZ+TMZ therapy. Moreover, our analysis revealed alterations in signaling pathways associated with the observed antitumor efficacy. This study presents a novel and efficacious therapeutic approach for MRT, along with a promising candidate biomarker for predicting tumor response.

Doxycycline hydrochloride inhibits the progress of malignant rhabdoid tumor of kidney by targeting MMP17 and MMP1 through PI3K-Akt signaling pathway

OBJECTIVE

To identify therapeutic targets for malignant rhabdoid tumors of kidney (MRTK) and to investigate the effects and underlying mechanism of doxycycline hydrochloride on these tumors.

METHODS

Gene expression and clinical data of MRTK were retrieved from the TARGET database. Differentially expressed genes (DEGs) and prognostic-related genes (PRGs) were selected through a combination of statistical analyses. The functional roles of MMP17 and MMP1 were elucidated through RNA overexpression and intervention experiments. Furthermore, in vitro and in vivo studies provided evidence for the inhibitory effect of doxycycline hydrochloride on MRTK. Additionally, transcriptome sequencing was employed to investigate the underlying molecular mechanisms.

RESULTS

3507 DEGs and 690 PRGs in MRTK were identified. Among these, we focused on 41 highly expressed genes associated with poor prognosis and revealed their involvement in extracellular matrix regulatory pathways. Notably, MMP17 and MMP1 stood out as particularly influential genes. When these genes were knocked out, a significant inhibition of proliferation, invasion and migration was observed in G401 cells. Furthermore, our study explored the impact of the matrix metalloproteinase inhibitor, doxycycline hydrochloride, on the malignant progression of G401 both in vitro and in vivo. Combined with sequencing data, the results indicated that doxycycline hydrochloride effectively inhibited MRTK progression, due to its ability to suppress the expression of MMP17 and MMP1 through the PI3K-Akt signaling pathway.

CONCLUSION

Doxycycline hydrochloride inhibits the expression of MMP17 and MMP1 through the PI3K-Akt signaling pathway, thereby inhibiting the malignant progression of MRTK in vivo and in vitro.

Survival Benefit from Multimodal Treatment for Patients with Atypical Teratoid Rhabdoid Tumor in a Surveillance, Epidemiology, and End Results Database Analysis

INTRODUCTION

Atypical teratoid rhabdoid tumor (ATRT) is among the most aggressive central nervous system malignancies. Although rare, this tumor typically afflicts young children and results in mortality within months. Here, we aim to determine key clinical features and treatment options that impact the survival of patients with ATRT.

METHODS

From the year 2000 to 2019, 363 patients with ATRT were identified from the Surveillance, Epidemiology, and End Results database. Univariate analysis was used to identify variables that had a significant impact on the primary endpoint of overall survival (OS). Multivariable analysis was then used to identify independent predictors of survival.

RESULTS

The median OS of the entire cohort was 13 months. Univariate analysis identified ages between 1 and 3 years, ages between 4 and 17 years, years of diagnosis between 2010 and 2019, and the receipt of treatment to have a significant impact on survival. In multivariable analysis, ages between 1 and 3 years and receipt of treatment were the only significant independent predictors of survival. The median OS was significantly greater in patients who received surgical treatment, chemotherapy, or radiation when compared to those who did not receive any treatment. In general, the receipt of any combination of therapies improved the median OS significantly. The receipt of triple therapy had the greatest impact on survival.

DISCUSSION

This study highlights the survival benefit of a multimodal approach in the treatment of ATRT. The use of triple therapy, including surgery, radiation, and chemotherapy, was found to have the greatest survival benefit for patients. Overall, these findings may guide future care for patients with ATRT.

Spinal atypical teratoid rhabdoid tumor-narrative review and report of a rare case managed with multimodality approach

BACKGROUND

Spinal atypical teratoid rhabdoid tumor (AT/RT) is an extremely rare tumor and represents less than 2% of all AT/RTs.

METHODS

Available medical literature on spinal AT/RT in English was retrieved from PubMed and comprehensively reviewed. Clinical presentation, diagnosis, management, prognosis, and outcome in patients with spinal AT/RT have been elucidated by citing a case of extradural AT/RT of the cervicodorsal spine.

RESULTS

The age at presentation is usually less than 3 years. The most common site is the cervicodorsal spine. The most frequent tumor location is intradural extramedullary. A contrast-enhanced magnetic resonance imaging (MRI) of the entire neuraxis is the imaging modality of choice. The incidence of leptomeningeal dissemination is high (15-30%). Histopathological examination shows an admixture of primitive neuroectodermal, mesenchymal, and epithelial elements along with rhabdoid cells. Loss of SMARCB1/INI1 is considered pathognomonic of AT/RT. Maximal safe resection of tumor is the initial management of choice. Thereafter focal radiotherapy for localized tumor or craniospinal irradiation for leptomeningeal dissemination should be considered. Post-operative intensive polychemotherapy including intrathecal and high-dose chemotherapy (with autologous stem cell rescue) is usually considered to optimize survival. Typically, the time to recurrence and overall survival are less than 6 and 12 months, respectively. However, with judicious multimodality management long-term survivors are increasingly being recognized. The illustrative patient was a 18-month-old girl diagnosed with extradural AT/RT of the cervicodorsal spine (C3-D1), who was managed with maximal safe resection of tumor, multiagent chemotherapy (ICE-ifosfamide, carboplatin, etoposide) and focal RT to the tumor bed-50.4 Gy/28 fractions/5.5 weeks. At the last follow-up visit, 30 months after surgery, she had complete clinicoradiological response.

CONCLUSION

Multimodal treatment comprising maximal safe resection of tumor, multiagent chemotherapy (ICE), and focal RT can lead to successful outcome in patients with localized spinal AT/RT, under the age of 3 years.

Effect of Autograft CD34+ Dose on Outcome in Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors

Consolidation with autologous hematopoietic stem cell transplantation (HSCT) has improved survival for patients with central nervous system tumors (CNSTs). The impact of the autologous graft CD34+ dose on patient outcomes is unknown. We wanted to analyze the relationship between CD34+ dose, total nucleated cell (TNC) dose, and clinical outcomes, including overall survival (OS), progression-free survival (PFS), relapse, non-relapse mortality (NRM), endothelial-injury complications (EIC), and time to neutrophil engraftment in children undergoing autologous HSCT for CNSTs. A retrospective analysis of the CIBMTR database was performed. Children aged <10 years who underwent autologous HSCT between 2008 to 2018 for an indication of CNST were included. An optimal cut point was identified for patient age, CD34+ cell dose, and TNC, using the maximum likelihood method and PFS as an endpoint. Univariable analysis for PFS, OS, and relapse was described using the Kaplan-Meier estimator. Cox models were fitted for PFS and OS outcomes. Cause-specific hazards models were fitted for relapse and NRM. One hundred fifteen patients met the inclusion criteria. A statistically significant association was identified between autograft CD34+ content and clinical outcomes. Children receiving >3.6×106/kg CD34+ cells experienced superior PFS (p = .04) and OS (p = .04) compared to children receiving ≤3.6 × 106/kg. Relapse rates were lower in patients receiving >3.6 × 106/kg CD34+ cells (p = .05). Higher CD34+ doses were not associated with increased NRM (p = .59). Stratification of CD34+ dose by quartile did not reveal any statistically significant differences between quartiles for 3-year PFS (p = .66), OS (p = .29), risk of relapse (p = .57), or EIC (p = .87). There were no significant differences in patient outcomes based on TNC, and those receiving a TNC >4.4 × 108/kg did not experience superior PFS (p = .26), superior OS (p = .14), reduced risk of relapse (p = .37), or reduced NRM (p = .25). Children with medulloblastoma had superior PFS (p < .001), OS (p = .01), and relapse rates (p = .001) compared to those with other CNS tumor types. Median time to neutrophil engraftment was 10 days versus 12 days in the highest and lowest infused CD34+ quartiles, respectively. For children undergoing autologous HSCT for CNSTs, increasing CD34+ cell dose was associated with significantly improved OS and PFS, and lower relapse rates, without increased NRM or EICs.

Radiotherapy for Atypical Teratoid/=Rhabdoid Tumor (ATRT) on the Pediatric Proton/Photon Consortium Registry (PPCR)

PURPOSE

Atypical teratoid/rhabdoid tumors (ATRT) of the central nervous system (CNS) are rare tumors with a poor prognosis and variable use of either focal or craniospinal (CSI) radiotherapy (RT). Outcomes on the prospective Pediatric Proton/Photon Consortium Registry (PPCR) were evaluated according to RT delivered.

METHODS

Pediatric patients receiving RT were prospectively enrolled on PPCR to collect initial patient, disease, and treatment factors as well as provide follow-up for patient outcomes. All ATRT patients with evaluable data were included. Kaplan-Meier analyses with log-rank p-values and cox proportional hazards regression were performed.

RESULTS

The PPCR ATRT cohort includes 68 evaluable ATRT patients (median age 2.6 years, range 0.71-15.40) from 2012 to 2021. Median follow-up was 40.8 months (range 3.4-107.7). Treatment included surgery (65% initial gross total resection or GTR), chemotherapy (60% with myeloablative therapy including stem cell rescue) and RT. For patients with M0 stage (n = 60), 50 (83%) had focal RT and 10 (17%) had CSI. Among patients with M + stage (n = 8), 3 had focal RT and 5 had CSI. Four-year overall survival (OS, n = 68) was 56% with no differences observed between M0 and M + stage patients (p = 0.848). Local Control (LC) at 4 years did not show a difference for lower primary dose (50-53.9 Gy) compared to ≥ 54 Gy (73.3% vs 74.7%, p = 0.83). For patients with M0 disease, four-year OS for focal RT was 54.6% and for CSI was 60% (Hazard Ratio 1.04, p = 0.95. Four-year event free survival (EFS) among M0 patients for focal RT was 45.6% and for CSI was 60% (Hazard Ratio 0.71, p = 0.519). For all patients, the 4-year OS comparing focal RT with CSI was 54.4% vs 60% respectively (p = 0.944), and the 4-year EFS for focal RT or CSI was 42.8% vs 51.4% respectively (p = 0.610).

CONCLUSION

The PPCR ATRT cohort found no differences in outcomes according to receipt of either higher primary dose or larger RT field (CSI). However, most patients were M0 and received focal RT. A lower primary dose (50.4 Gy), regardless of patient age, is appealing for further study as part of multi-modality therapy.

Recent progress and novel approaches to treating atypical teratoid rhabdoid tumor

Atypical teratoid rhabdoid tumors (AT/RT) are malignant central nervous system (CNS) tumors that occur mostly in young children and have historically carried a very poor prognosis. While recent clinical trial results show that this tumor is curable, outcomes are still poor compared to other central nervous system embryonal tumors. We here review prior AT/RT clinical trials and highlight promising pre-clinical results that may inform novel clinical approaches to this aggressive cancer.

High-dose thiotepa, in conjunction with melphalan, followed by autologous hematopoietic stem cell transplantation in patients with pediatric solid tumors, including brain tumors

Among pediatric malignancies, solid tumors, particularly within the central nervous system (CNS), are common. Thiotepa, a myeloablative, high-dose chemotherapeutic (HDT) treatment administered prior to autologous hematopoietic stem cell transplantation (HSCT), can cross the blood-brain barrier and rapidly penetrate the CNS. We evaluated thiotepa HDT in conjunction with melphalan in Japanese patients with pediatric CNS/non-CNS solid tumors in a multicenter, open-label, non-comparative study. Thiotepa (200 mg/m²/day) was administered intravenously (IV) over 24 h on days -12, -11, -5, and -4 before scheduled HSCT. Melphalan (70 mg/m²/day) was administered IV over 1 h on days -11, -5, and -4. The safety analysis population comprised 41 patients, of whom 16 (39.0%) had solid tumors and 25 (61.0%) had brain tumors. The most frequently reported adverse events were diarrhea (40/41 [97.6%] patients) and febrile neutropenia (34/41 [82.9%]). No unexpected safety events were observed, and no events resulted in death or treatment discontinuation. All patients experienced bone marrow suppression and 39/41 (95.1%) achieved engraftment (neutrophil count ≥500/mm³ for 3 consecutive days after HSCT). The survival rate at day 100 post-autologous HSCT was 100%. These data confirm the safety of IV thiotepa plus melphalan HDT prior to autologous HSCT for patients with pediatric CNS/non-CNS solid tumors. Trial registration: JapicCTI-173654.

Relapsing cerebral atypical teratoid/rhabdoid tumor after trimodality therapy: A case report

INTRODUCTION

Atypical teratoid rhabdoid tumor (AT/RT) is a high-grade embryonal malignant neoplasm of the central nervous system. It is rare and most often diagnosed in children <4 years of age. The biological manifestations of AT/RTs are highly malignant and have a very poor prognosis. Here, we present the case of a 16-year-old boy with AT/RT in the right parietal lobe and with a dismal outcome.

PATIENT CONCERNS

A 16-year-old male boy presented with a headache after waking up for 1 year without obvious cause. The pain was persistent and dull, mainly in the right orbital, and was slightly relieved after pressing the orbital. Occasionally, nausea and vomiting occurred, and the vomiting was gastric contents. Examination and head computed tomography performed at a local hospital revealed a space-occupying lesion in the right parietal lobe. The patient was then transferred to our hospital for further diagnosis and treatment.

DIAGNOSIS

The patient underwent craniotomy and gross total excision of the tumor. Further histologic examination of the tumor was identified (space-occupying lesion in the right parietal lobe) AT/RT, World Health Organization grade IV.

INTERVENTIONS

The patient was transferred to the oncology department for radiotherapy and chemotherapy after surgery recovery.

OUTCOMES

The patient did not comply with the advice for adjuvant chemotherapy regularly and the tumor recurred rapidly. Finally, the patient died after 18 months after the definitive surgery.

CONCLUSION

In conclusion, in the presence of a tumor with peripheral cystic components or hemorrhage in young children, a diagnosis of AT/RT must always be considered. Patients must follow the doctor's advice for active treatment. All relevant data are within the paper and its Supporting Information files.

Circulating Lymphocyte Counts Early During Radiation Therapy Are Associated With Recurrence in Pediatric Medulloblastoma

PURPOSE

Decreased peripheral lymphocyte counts are associated with survival after radiation therapy (RT) in several solid tumors, although they appear late during or after the radiation course and often correlate with other clinical factors. Here we investigate if absolute lymphocyte counts (ALCs) are independently associated with recurrence in pediatric medulloblastoma early during RT.

METHODS AND MATERIALS

We assessed 202 patients with medulloblastoma treated between 2000 and 2016 and analyzed ALC throughout therapy, focusing on both early markers (ALC during week 1 - ALCwk1; grade 3+ Lymphopenia during week 2 - Lymphopeniawk2) and late markers (ALC nadir). Uni- and multivariable regressions were used to assess association of clinical and treatment variables with ALC and of ALC with recurrence.

RESULTS

Thirty-six recurrences were observed, with a median time to recurrence of 1.6 years (range, 0.2-10.3) and 7.1 years median follow-up. ALC during RT was associated with induction chemotherapy (P < .001), concurrent carboplatin (P = .009), age (P = .01), and high-risk status (P = .05). On univariable analysis, high-risk disease (hazard ratio = 2.0 [1.06-3.9]; P = .03) and M stage≥1 (hazard ratio = 2.2 [1.1-4.4]) were associated with recurrence risk, as was lower ALC early during RT (ALCwk1, hazard ratio = 0.28 [0.12-0.65]; P = .003; Lymphopeniawk2, hazard ratio = 2.27 [1.1-4.6]; P = .02). Neither baseline ALC nor nadir correlated with outcome. These associations persisted when excluding carboplatin and pre-RT chemotherapy patients, and in the multivariable analysis accounting for confounders lymphocyte counts remained significant (ALCwk1, hazard-ratio = 0.23 [0.09-0.57]; P = .002; Lymphopeniawk2, hazard-ratio = 2.3 [1.1-4.8]; P = .03).

CONCLUSIONS

ALC during weeks 1 and 2 of RT was associated with recurrence, and low ALC is an independent prognostic factor in medulloblastoma. Strategies to mitigate the risk of radiation-induced lymphopenia should be considered.

Brain tumors: Medulloblastoma, ATRT, ependymoma

Children with medulloblastoma, atypical teratoid rhabdoid tumor (ATRT), and ependymoma are treated with a multidisciplinary approach including surgery, radiotherapy, and chemotherapy. Lower doses of craniospinal irradiation and tumor bed boost together with chemotherapy are the current standard of care for average-risk medulloblastoma in the Children's Oncology Group (COG). The International Society of Pediatric Oncology (SIOP) is examining the role of hyperfractionated craniospinal irradiation and chemotherapy in high-risk patients. The recent stratification of medulloblastoma into specific molecular risk groups has prompted both COG and SIOP to reexamine the role of these modalities in these different risk groups to maximize cure rates and minimize long-term complications. Proton therapy has shown lower rates of neurocognitive and endocrine complications compared with photons. Ependymomas are treated with maximal surgical resection and adjuvant radiation therapy. The role of chemotherapy in ependymoma is currently being studied in both COG and SIOP. Likewise, for ATRT the role of different high-dose chemotherapy regimens together with local radiation therapy in infants, or craniospinal radiation in older children, is the current focus of research.

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.

Relevance of Molecular Groups in Children with Newly Diagnosed Atypical Teratoid Rhabdoid Tumor: Results from Prospective St. Jude Multi-institutional Trials

PURPOSE

Report relevance of molecular groups to clinicopathologic features, germline SMARCB1/SMARCA4 alterations (GLA), and survival of children with atypical teratoid rhabdoid tumor (ATRT) treated in two multi-institutional clinical trials.

MATERIALS AND METHODS

Seventy-four participants with newly diagnosed ATRT were treated in two trials: infants (SJYC07: age < 3 years; n = 52) and children (SJMB03: age 3-21 years; n = 22), using surgery, conventional chemotherapy (infants), or dose-dense chemotherapy with autologous stem cell rescue (children), and age- and risk-adapted radiotherapy [focal (infants) and craniospinal (CSI; children)]. Molecular groups ATRT-MYC (MYC), ATRT-SHH (SHH), and ATRT-TYR (TYR) were determined from tumor DNA methylation profiles.

RESULTS

Twenty-four participants (32%) were alive at time of analysis at a median follow-up of 8.4 years (range, 3.1-14.1 years). Methylation profiling classified 64 ATRTs as TYR (n = 21), SHH (n = 30), and MYC (n = 13), SHH group being associated with metastatic disease. Among infants, TYR group had the best overall survival (OS; P = 0.02). However, outcomes did not differ by molecular groups among infants with nonmetastatic (M0) disease. Children with M0 disease and <1.5 cm² residual tumor had a 5-year progression-free survival (PFS) of 72.7 ± 12.7% and OS of 81.8 ± 11%. Infants with M0 disease had a 5-year PFS of 39.1 ± 11.5% and OS of 51.8 ± 12%. Those with metastases fared poorly [5-year OS 25 ± 12.5% (children) and 0% (infants)]. SMARCB1 GLAs were not associated with PFS.

CONCLUSIONS

Among infants, those with ATRT-TYR had the best OS. ATRT-SHH was associated with metastases and consequently with inferior outcomes. Children with nonmetastatic ATRT benefit from postoperative CSI and adjuvant chemotherapy.

Atypical Teratoid/Rhabdoid Tumor of the Central Nervous System in Children under the Age of 3 Years

Purpose

Atypical teratoid/rhabdoid tumor (ATRT) is a highly aggressive malignancy with peak incidence in children aged less than 3 years. Standard treatment for central nervous system ATRT in children under the age of 3 years have not been established yet. The objective of this study was to analyze characteristics and clinical outcomes of ATRT in children aged less than 3 years.

Materials and Methods

A search of medical records from seven centers was performed between January 2005 and December 2016.

Results

Forty-three patients were enrolled. With a median follow-up of 90 months, 27 patients (64.3%) showed at least one episode of disease progression (PD). The first date of PD was at 160 days after diagnosis. The 1- and 3-year progression-free survivals (PFS) were 51.2% and 28.5%, respectively. The 1- and 3-year overall survivals were 61.9% and 38.1%, respectively. The 3-year PFS was improved from 0% in pre-2011 to 47.4% in post-2011. Excluding one patient who did not receive any further therapy after surgery, 27 patients died due to PD (n=21), treatment-related toxicity (n=5), or unknown cause (n=1). In univariate analysis, factors associated with higher 3-year PFS were no metastases, diagnosis after 2011, early adjuvant radiotherapy, and high-dose chemotherapy (HDCT). In multivariate analysis, the use of HDCT and adjuvant radiotherapy remained significant prognostic factors for PFS (both p < 0.01).

Conclusion

Aggressive therapy including early adjuvant radiotherapy and HDCT could be considered to improve outcomes of ATRT in children under the age of 3 years.

Atypical teratoid rhabdoid tumor: molecular insights and translation to novel therapeutics

INTRODUCTION

Atypical teratoid rhabdoid tumor (ATRT) is a rare, often lethal brain tumor of childhood characterized by a complex epigenetic landscape amongst a simple genetic background. Recent molecular studies have defined key biologic events that contribute to tumorigenesis and molecular subtypes of ATRT.

METHODS

Seminal studies on ATRT are reviewed with an emphasis on molecular pathogenesis and its relevance to novel therapeutics.

RESULTS

In this review, we summarize the key clinicopathologic and molecular features of ATRT, completed and ongoing clinical trials and outline the translational potential of novel insights into the molecular pathogenesis of this tumor.

CONCLUSIONS

SMARCB1 loss is the key genetic event in ATRT pathogenesis that leads to widespread epigenetic dysregulation and loss of lineage-specific enhancers. Current work is defining subtype-specific treatments that target underlying molecular derangements that drive tumorigenesis.

Successful Stem Cell Apheresis Using Spectra Optia in a 6 kg Child With Atypical Teratoid/Rhabdoid Tumor

Peripheral blood stem cell apheresis has become a routine procedure for the collection of peripheral blood stem cells to enable high-dose chemotherapy followed by autologous stem cell transplantation in high-risk pediatric malignancies. However, the procedure remains challenging in very low-weight infants due to high extracorporeal blood volume and citrate toxicity. Our case report demonstrates in detail a successful and complication-free large-volume leukapheresis in a very small infant weighing 6 kg using a Spectra Optia apheresis system after placing a femoral double-lumen Shaldon catheter. Anticoagulation was achieved by citrate dextrose solution without the use of heparin. The total amount of blood being processed during the procedure equaled almost 4 times the total blood volume of the patient. The final apheresis product contained 14.0×10 CD34 cells/kg body weight. The infant was diagnosed with an atypical teratoid/rhabdoid tumor of the thalamus and third ventricle at the age of 3 months and had a history of epileptic seizures.

CAR T Cell Therapy for Pediatric Brain Tumors

Chimeric Antigen Receptor (CAR) T cell therapy has recently begun to be used for solid tumors such as glioblastoma multiforme. Many children with pediatric malignant brain tumors develop extensive long-term morbidity of intensive multimodal curative treatment. Others with certain diagnoses and relapsed disease continue to have limited therapies and a dismal prognosis. Novel treatments such as CAR T cells could potentially improve outcomes and ameliorate the toxicity of current treatment. In this review, we discuss the potential of using CAR therapy for pediatric brain tumors. The emerging insights on the molecular subtypes and tumor microenvironment of these tumors provide avenues to devise strategies for CAR T cell therapy. Unique characteristics of these brain tumors, such as location and associated morbid treatment induced neuro-inflammation, are novel challenges not commonly encountered in adult brain tumors. Despite these considerations, CAR T cell therapy has the potential to be integrated into treatment schema for aggressive pediatric malignant brain tumors in the future.

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.

Neuropsychological outcomes on Head Start III: a prospective, multi-institutional clinical trial for young children diagnosed with malignant brain tumors

BACKGROUND

Current pediatric brain tumor treatment focuses on titrating toxicity based on risk factors while simultaneously improving survivorship. The Head Start (HS) protocols I to IV (1991-present) use high-dose chemotherapy (HDCTx) with an aim of reducing or eliminating cranial irradiation in very young children, the most vulnerable to its effects.

METHODS

We examined estimated Full Scale IQ, overall Adaptive Functioning, Working Memory, Processing Speed, and Verbal and Nonverbal Memory outcome data for 43 HS III patients diagnosed between ages 2 months and 7 years from 15 institutions in the United States and Canada.

RESULTS

At a mean of 5.12 years postdiagnosis, the HS III patients performed within the average to low-average ranges across these variables; however, individual variability was noted with scores ranging from superior to impaired, and the sample as a whole performed lower than age expectations. Performance did not significantly differ by sex or ethnicity, diagnosis, or for those treated with an intravenous methotrexate dose of 400 mg/kg vs 270 mg/kg. Additionally, performance did not significantly differ by age at diagnosis or length of follow-up.

CONCLUSIONS

The results, indicating overall average to low-average neurocognitive functioning, are encouraging, though significant individual variability was noted. Those who were younger at diagnosis, received more intensive methotrexate, and were further out from treatment were not at significantly increased risk of cognitive decline within our sample, suggesting a strategy of using HDCTx and autologous hematopoietic progenitor cell rescue to reduce or eliminate irradiation may allow for continued CNS development in young children treated for a brain tumor.

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.

Pediatric embryonal brain tumors in the molecular era

Introduction: Embryonal brain tumors (EBTs) are highly aggressive malignancies predominantly affecting children. They include medulloblastoma (MB), atypical rhabdoid/teratoid tumors (ATRT), pineoblastoma (PB), embryonal tumor multiple rosettes (ETMR)/C19MC-altered tumors, and newly recognized embryonal tumors with FOXR2 activation or BCOR alteration.Areas covered: This review will provide a comprehensive overview and updated of the literature on each of these EBTs. The evolution from location- and histopathology-based diagnosis to more specific and robust molecular-based classification schemes, as well as treatment modalities, will be discussed.Expert commentary: The subgrouping of EBTs with multi-omic profiling has had important implications for risk stratification and discovery of targetable driver pathways. However, these innovations are unlikely to significantly improve survival among high-risk patients until robust preclinical studies are conducted, followed by validation in biology-informed clinical 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.

Subgroup-specific outcomes of children with malignant childhood brain tumors treated with an irradiation-sparing protocol

PURPOSE

Molecular subgroups of pediatric brain tumors associated with divergent biological, clinical, and prognostic features have been identified. However, data regarding the impact of subgroup affiliation on the outcome of children with malignant brain tumors treated with radiation-sparing protocol is limited. We report long-term clinical outcomes and the molecular subgroups of malignant brain tumors in young children whose first-line treatment was high-dose chemotherapy without irradiation.

METHODS

Tumor subclassification was performed using the Illumina HumanMethylation450 BeadChip (450k) genome-wide methylation array profiling platform. Clinical information was obtained from chart review.

RESULTS

Methylation array profiling yielded information on molecular subgroups in 22 children. Median age at surgery was 26 months (range 1-119 months). Among medulloblastomas (MB), all 6 children in the infant sonic hedgehog (SHH) subgroup were long-term survivors, whereas all 4 children in subgroup 3 MB died. There was one long-term survivor in subgroup 4 MB. One out of five children with ependymoma was a long-term survivor (RELPOS). Both children with primitive neuroectodermal tumors died. One child with ATRT TYR and one child with choroid plexus carcinoma were long-term survivors.

CONCLUSIONS

The efficacy of high-dose chemotherapy radiation-sparing treatment appears to be confined to favorable molecular subgroups of pediatric brain tumors, such as infant SHH MB. Identification of molecular subgroups that benefit from radiation-sparing therapy will aid in the design of prospective, "precision medicine"-driven clinical trials.

Clinical characteristics, treatment, and survival outcome in pediatric patients with atypical teratoid/rhabdoid tumors: a retrospective study by the Japan Children's Cancer Group

OBJECTIVE

The prognosis of atypical teratoid/rhabdoid tumors (ATRTs) has improved in recent years with the use of multimodal therapy, mainly in cases not involving metastatic disease. The authors wanted to obtain historical control data and evaluate the suitable treatments in Japanese children with ATRTs that were proven negative for INI-1 immunostaining.

METHODS

The authors retrospectively collected clinical information on 38 pediatric patients with ATRTs treated from 2005 to 2016 and analyzed the data for this series.

RESULTS

The median age of the patient population was 1.3 years, and the male/female ratio was approximately 2:1. Twenty-three patients (60.5%) had metastases. The effects of treatment on prognosis were analyzed for 34 patients after exclusion of 4 patients who could not receive curative treatment. At a median follow-up of 40.9 months, the mean (± SD) progression-free survival (PFS) and overall survival (OS) were 66.6% ± 8.3% and 45.9% ± 8.7% at 2 years and 44.2% ± 9.9% and 34.2% ± 8.9% at 5 years, respectively. The metastasis stage at diagnosis (M0-1 vs M2-4) (HR 2.68, 95% CI 1.08-6.65; p = 0.0338) and gross tumor resection (yes vs no) (HR 3.49, 95% CI 1.01-12.1; p = 0.0481) were prognostic factors for PFS but not for OS. Postoperative chemotherapy was performed in all 34 cases. High-dose chemotherapy was performed in 19 (55.8%) of 34 patients and showed a positive impact on OS (HR 0.31, 95% CI 0.11-0.86; p = 0.0254); the most commonly used regimen was a double-conditioning regimen of thiotepa plus melphalan. Local radiotherapy had a positive impact on both PFS and OS; however, craniospinal irradiation (CSI) performed in 12 patients as the primary therapy was associated with a poor outcome. Disseminated recurrence within 12 months from diagnosis was the most common pattern of treatment failure regardless of CSI.

CONCLUSIONS

There has been an improvement in outcomes for pediatric ATRT patients since the introduction of multimodal therapy in Japan, mainly in patients without metastases. Even if selection bias is taken into consideration, CSI did not contribute to an improved prognosis. Novel treatment approaches are required for pediatric ATRT patients with metastases.

Tandem high-dose chemotherapy with topotecan-thiotepa-carboplatin and melphalan-etoposide-carboplatin regimens for pediatric high-risk brain tumors

BACKGROUND

High-dose chemotherapy (HDC) and autologous stem-cell transplantation (auto-SCT) are used to improve the survival of children with high-risk brain tumors who have a poor outcome with the standard treatment. This study aims to evaluate the outcome of HDC/auto-SCT with topotecan-thiotepa-carboplatin and melphalan-etoposide-carboplatin (TTC/MEC) regimens in pediatric brain tumors.

METHODS

We retrospectively analyzed the data of 33 children (median age 6 years) who underwent HDC/auto-SCT (18 tandem and 15 single) with uniform conditioning regimens.

RESULTS

Eleven patients aged < 3 years at diagnosis were eligible for HDC/auto-SCT to avoid or defer radiotherapy. In addition, nine patients with high-risk medulloblastoma (presence of metastasis and/or postoperative residual tumor ≥ 1.5 cm²), eight with other high-risk brain tumor (six CNS primitive neuroectodermal tumor, one CNS atypical teratoid/rhabdoid tumor, and one pineoblastoma), and five with relapsed brain tumors were enrolled. There were three toxic deaths, and two of which were due to pulmonary complications. The main reason for not performing tandem auto-SCT was due to toxicities and patient refusal. The event-free survival (EFS) and overall survival (OS) rates of all patients were 59.4% and 80.0% at a median follow-up with 49.1 months from the first HDC/auto-SCT, respectively. The EFS/OS rates of patients aged < 3 years at diagnosis, high-risk medulloblastoma, other high-risk brain tumor, and relapsed tumors were 50.0/81.8%, 87.5/85.7%, 66.7/88.9%, and 20.0/60.0%, respectively.

CONCLUSIONS

Although tandem HDC/auto-SCT with TTC/MEC regimens showed promising survival rates, treatment modifications are warranted to reduce toxicities. The survival rates with relapsed brain tumors were unsatisfactory despite HDC/auto-SCT, and further study is needed.

Role of early and aggressive post-operative radiation therapy in improving outcome for pediatric central nervous system atypical teratoid/rhabdoid tumor

PURPOSE

The purpose of the study is to evaluate possible prognostic factors and optimal management for pediatric atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS).

METHODS

Twenty-eight pediatric patients with CNS AT/RT who were treated with radiation therapy (RT) as part of multimodality treatment regimens at a single institution (1996-2015) were reviewed. Survival outcomes were analyzed in relation to possible prognostic factors.

RESULTS

The 28 patients analyzed were followed up for a median 48-month period. Median progression-free survival (PFS) was 11 months, and overall survival (OS) was 57 months. Patients < 3 years old had RT delayed for a longer period after surgery (p = 0.04), and the mean RT dose to tumor bed was lower (p < 0.01) than in patients ≥ 3 years old. In multivariate analysis, a higher primary tumor bed RT dose was identified as a favorable prognostic factor for both PFS (hazard ratio [HR] = 0.85 per gray, p < 0.01) and OS (HR = 0.92 per gray, p = 0.02). In addition, an interval between surgery and RT initiation > 2 months, with disease progression observed before RT, as compared with an interval ≤ 2 months without disease progression prior to RT, was associated with worse PFS (HR = 8.50, p < 0.01) and OS (HR = 5.27, p < 0.01).

CONCLUSIONS

Early and aggressive RT after surgery is critical for successful disease control in AT/RT patients. Conversely, a delay in RT until disease progression is observed that leads to unfavorable outcomes.

The impact on outcomes by using thiotepa in tandem transplant for pediatric high-risk embryonal brain tumors

BACKGROUND

Despite aggressive treatment including surgery, radiotherapy, and adjuvant chemotherapy, the outcome of pediatric high-risk embryonal brain tumors remains poor; especially in young children, in whom early radiotherapy inevitably brings significant long-term morbidities. Single or tandem autologous stem cell transplant has been reported to improve outcomes; but optimal use is not well defined.

METHODS

Pediatric patients with high-risk embryonal brain tumors who underwent tandem transplant as consolidation from August 2011 to December 2017 were included. We performed a retrospective chart review and analyzed the outcomes to identify possible prognostic factors.

RESULTS

Eleven pediatric patients with high-risk embryonal brain tumors were enrolled. They received double or triple autologous transplant at complete response in 5 patients and at partial response in 6 for a total of 24 transplants. There were five atypical teratoid rhabdoid tumors, four medulloblastoma, one primitive neuroectodermal tumors, and one pineoblastoma. Median age at diagnosis was 1.8 years (range, 0.6-11.2 years) and at transplant was 2.2 years (range, 1.2-11.9 years). Thiotepa-based regimens were used in 13 cycles of conditioning. All patients achieved successful engraftment. No transplant-related mortality was identified. With a median follow-up of 21.2 months (range, 6.9-51.8 months), seven patients had disease progression. Disease entity and the use of one or more cycles of thiotepa-based regimen during tandem transplant had statistically significant impact on both progression-free survival and overall survival.

CONCLUSION

With successful engraftment and manageable toxicity, tandem transplant in pediatric patients with high-risk embryonal brain tumor is feasible and safe. Patients receiving tandem transplant with one or more cycles of thiotepa-based regimen might have better outcome than those without. In combination with salvage radiotherapy, a favorable 2-year overall survival could be achieved in the majority of patients.

The Clonal Evolution of Metastatic Osteosarcoma as Shaped by Cisplatin Treatment

To investigate the genomic evolution of metastatic pediatric osteosarcoma, we performed whole-genome and targeted deep sequencing on 14 osteosarcoma metastases and two primary tumors from four patients (two to eight samples per patient). All four patients harbored ancestral (truncal) somatic variants resulting in TP53 inactivation and cell-cycle aberrations, followed by divergence into relapse-specific lineages exhibiting a cisplatin-induced mutation signature. In three of the four patients, the cisplatin signature accounted for >40% of mutations detected in the metastatic samples. Mutations potentially acquired during cisplatin treatment included NF1 missense mutations of uncertain significance in two patients and a KIT G565R activating mutation in one patient. Three of four patients demonstrated widespread ploidy differences between samples from the sample patient. Single-cell seeding of metastasis was detected in most metastatic samples. Cross-seeding between metastatic sites was observed in one patient, whereas in another patient a minor clone from the primary tumor seeded both metastases analyzed. These results reveal extensive clonal heterogeneity in metastatic osteosarcoma, much of which is likely cisplatin-induced. IMPLICATIONS: The extent and consequences of chemotherapy-induced damage in pediatric cancers is unknown. We found that cisplatin treatment can potentially double the mutational burden in osteosarcoma, which has implications for optimizing therapy for recurrent, chemotherapy-resistant disease.

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.

Surveillance imaging for high-grade childhood brain tumors: What to do 10 years after completion of treatment?

Brain tumors are the second most common childhood cancer. Treatment protocols for high-grade pediatric brain tumors recommend regular follow-up imaging for up to 10 years. We review maximal time to recurrence and minimal time to radiologically detectable long-term sequelae such as secondary malignancies, vascular complications, and white matter disease. No tumors recurred after the 10-year point, but radiological long-term sequelae grew more common as the treatment completion date receded. We do not recommend regular imaging more than 10 years after treatment has ended, unless there are clinical symptoms.

Case-based review: atypical teratoid/rhabdoid tumor

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare CNS cancer that typically occurs in children younger than 3 years of age. Histologically, AT/RTs are embryonal tumors that contain a rhabdoid component as well as areas with primitive neuroectodermal, mesenchymal, and epithelial features. Compared to other CNS tumors of childhood, AT/RTs are characterized by their rapid growth, short symptomatic prodrome, and large size upon presentation, often leading to brain compression and intracranial hypertension requiring urgent intervention. For decades, the mainstay of care has been a combination of maximal safe surgical resection followed by adjuvant chemotherapy and radiotherapy. Despite advances in each of these modalities, the relative paucity of data on these tumors, their inherently aggressive course, and a lack of molecular data have limited advances in treatment over the past 3 decades. Recent large-scale, multicenter interdisciplinary studies, however, have significantly advanced our understanding of the molecular pathogenesis of these tumors. Multiple clinical trials testing molecularly targeted therapies are underway, offering hope for patients with AT/RT and their families.

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.

Radiotherapy after high-dose chemotherapy with autologous hematopoietic cell rescue: Quality assessment of Head Start III

BACKGROUND

The use of high-dose chemotherapy with autologous hematopoietic cell rescue (AuHCR) in Head Start III is a potentially curative approach for the management of young children with central nervous system neoplasms. We report the potential influence of quality and timing of radiation therapy on the survival of patients treated on the study.

PROCEDURE

Between 2003 and 2009, 220 children with newly diagnosed central nervous system neoplasms were enrolled on the study. Radiation therapy was indicated following AuHCR for children between 6 and 10 years old or those younger than 6 years with residual tumor preconsolidation. Records were received for 42 patients and reviewed to determine adherence to protocol treatment volume and dose guidelines. Of these patients, seven were irradiated prior to consolidation, and additional four patients who initially avoided radiation therapy after AuHCR were subsequently treated at relapse.

RESULTS

Of the 31 patients who were fully evaluable, 2 refused radiation therapy until recurrence and 4 progressed between recovery from AuHCR and radiation therapy. Of the remaining 25 patients, 8 had violations in their indication, dose, or treatment volume. All violations occurred in patients under 6 years of age. Two patients could have avoided radiation therapy. There were 6 violations in the 23 patients who received radiation therapy for guideline indications.

CONCLUSION

All protocol violations occurred in patients under 6 years of age and were associated with decreased overall survival as was the time to start radiotherapy of greater than 11 weeks. When indicated, starting radiation therapy soon after neutrophil and platelet recovery may improve the outcome for these high-risk children.

BRD9 Inhibition, Alone or in Combination with Cytostatic Compounds as a Therapeutic Approach in Rhabdoid Tumors

Rhabdoid tumors (RT) are malignant neoplasms of early childhood. Despite intensive therapy, survival is poor and new treatment approaches are required. The only recurrent mutations in these tumors affect SMARCB1 and less commonly SMARCA4, both subunits of the chromatin remodeling complex SWItch/Sucrose Non-Fermentable (SWI/SNF). Loss of these two core subunits alters the function of the SWI/SNF complex, resulting in tumor development. We hypothesized that inhibition of aberrant SWI/SNF function by selective blockade of the BRD9 subunit of the SWI/SNF complex would reduce tumor cell proliferation. The cytotoxic and anti-proliferative effects of two specific chemical probes (I-BRD9 and BI-9564) which target the bromodomain of SWI/SNF protein BRD9 were evaluated in 5 RT cell lines. Combinatorial effects of I-BRD9 and cytotoxic drugs on cell proliferation were evaluated by cytotoxicity assays. Single compound treatment of RT cells with I-BRD9 and BI-9564 resulted in decreased cell proliferation, G1-arrest and apoptosis. Combined treatment of doxorubicin or carboplatin with I-BRD9 resulted in additive to synergistic inhibitory effects on cell proliferation. In contrast, the combination of I-BRD9 with vincristine demonstrated the antagonistic effects of these two compounds. We conclude that the BRD9 bromodomain is an attractive target for novel therapies in this cancer.

Overexpression of TEAD4 in atypical teratoid/rhabdoid tumor: New insight to the pathophysiology of an aggressive brain tumor

BACKGROUND

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant embryonal brain tumor that occurs mainly in early childhood. Although most of the tumors are characterized by inactivating mutations of the tumor suppressor gene, SMARCB1, the biological basis of its tumorigenesis and aggressiveness is still unknown.

PROCEDURE

We performed high-throughput copy number variation analysis of primary cell lines generated from primary and relapsed tumors from one of our patients to identify new genes involved in AT/RT biology. The expression of the identified gene was validated in 29 AT/RT samples by gene expression profiling, quantitative real-time polymerase chain reaction, and immunohistochemistry (IHC). Furthermore, we investigated the function of this gene by mutating it in rhabdoid tumor cells.

RESULTS

TEAD4 amplification was detected in the primary cell lines and its overexpression was confirmed at mRNA and protein levels in an independent cohort of AT/RT samples. TEAD4's co-activator, YAP1, and the downstream targets, MYC and CCND1, were also found to be upregulated in AT/RT when compared to medulloblastoma. IHC showed TEAD4 and YAP1 overexpression in all samples. Cell proliferation and migration were significantly reduced in TEAD4-mutated cells.

CONCLUSIONS

We report the overexpression of TEAD4 in AT/RT, which is a key component of Hippo pathway. Recent reports revealed that dysregulation of the Hippo pathway is implicated in tumorigenesis and poor prognosis of several human cancers. Our results suggest that TEAD4 plays a role in the pathophysiology of AT/RT, which represents a new insight into the biology of this aggressive tumor.

The under reporting of recruitment strategies in research with children with life-threatening illnesses: A systematic review

BACKGROUND

Researchers report difficulties in conducting research with children and young people with life-limiting conditions or life-threatening illnesses and their families. Recruitment is challenged by barriers including ethical, logistical and clinical considerations.

AIM

To explore how children and young people (aged 0-25 years) with life-limiting conditions or life-threatening illnesses and their families were identified, invited and consented to research published in the last 5 years.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE, PsycINFO, Web of Science, Sciences Citation Index and SCOPUS were searched for original English language research published between 2009 and 2014, recruiting children and young people with life-limiting conditions or life-threatening illness and their families.

RESULTS

A total of 215 studies - 152 qualitative, 54 quantitative and 9 mixed methods - were included. Limited recruitment information but a range of strategies and difficulties were provided. The proportion of eligible participants from those screened could not be calculated in 80% of studies. Recruitment rates could not be calculated in 77%. A total of 31% of studies recruited less than 50% of eligible participants. Reasons given for non-invitation included missing clinical or contact data, or clinician judgements of participant unsuitability. Reasons for non-participation included lack of interest and participants' perceptions of potential burdens.

CONCLUSION

All stages of recruitment were under reported. Transparency in reporting of participant identification, invitation and consent is needed to enable researchers to understand research implications, bias risk and to whom results apply. Research is needed to explore why consenting participants decide to take part or not and their experiences of research recruitment.

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.

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.

Adaptation of vacuum-assisted mouthpiece head immobilization system for precision infant brain radiation therapy

PURPOSE

Our purpose was to describe an adaptation of a commercially available mouthpiece for vacuum-assisted mouthpiece immobilization for radiation therapy in infants.

METHODS AND MATERIALS

An infant diagnosed with a brain tumor required radiation therapy. After reviewing dental literature about obturators, we designed a modification for the smallest commercially available mouthpiece tray.

RESULTS

The patient was simulated with the adapted mouthpiece tray. We achieved excellent immobilization and had small daily image guided treatment position shifts. Our patient tolerated treatment well without injury to oral cavity or mucosa.

CONCLUSIONS

Head immobilization with a vacuum-assisted modified mouthpiece has not been described in infants. Our modification is a novel and safe and permits effective and accurate immobilization for infants for radiation therapy. New manufacturing technologies may allow creation of individualized mouthpieces.

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.