Outcome for patients with metastatic (M2–3) medulloblastoma treated with SIOP/UKCCSG PNET-3 chemotherapy

Drivers Underlying Metastasis and Relapse in Medulloblastoma and Targeting Strategies

Medulloblastomas comprise a molecularly diverse set of malignant pediatric brain tumors in which patients are stratified according to different prognostic risk groups that span from very good to very poor. Metastasis at diagnosis is most often a marker of poor prognosis and the relapse incidence is higher in these children. Medulloblastoma relapse is almost always fatal and recurring cells have, apart from resistance to standard of care, acquired genetic and epigenetic changes that correlate with an increased dormancy state, cell state reprogramming and immune escape. Here, we review means to carefully study metastasis and relapse in preclinical models, in light of recently described molecular subgroups. We will exemplify how therapy resistance develops at the cellular level, in a specific niche or from therapy-induced secondary mutations. We further describe underlying molecular mechanisms on how tumors acquire the ability to promote leptomeningeal dissemination and discuss how they can establish therapy-resistant cell clones. Finally, we describe some of the ongoing clinical trials of high-risk medulloblastoma and suggest or discuss more individualized treatments that could be of benefit to specific subgroups.

Long-term Outcomes of Protocol-Based Treatment for Newly Diagnosed Medulloblastoma

PURPOSE

The Korean Society of Pediatric Neuro-Oncology (KSPNO) conducted treatment strategies for children with medulloblastoma (MB) by using alkylating agents for maintenance chemotherapy or tandem high-dose chemotherapy (HDC) with autologous stem cell rescue (ASCR) according to the risk stratification. The purpose of the study was to assess treatment outcomes and complications based on risk-adapted treatment and HDC.

MATERIALS AND METHODS

Fifty-nine patients diagnosed with MB were enrolled in this study. Patients in the standard-risk (SR) group received radiotherapy (RT) after surgery and chemotherapy using the KSPNO M051 regimen. Patients in the high-risk (HR) group received two and four chemotherapy cycles according to the KSPNO S081 protocol before and after reduced RT for age following surgery and two cycles of tandem HDC with ASCR consolidation treatment.

RESULTS

In the SR group, 24 patients showed 5-year event-free survival (EFS) and overall survival (OS) estimates of 86.7% (95% confidence interval [CI], 73.6 to 100) and 95.8% (95% CI, 88.2 to 100), respectively. In the HR group, more infectious complications and mortality occurred during the second HDC than during the first. In the HR group, the 5-year EFS and OS estimates were 65.5% (95% CI, 51.4 to 83.4) and 72.3% (95% CI, 58.4 to 89.6), respectively.

CONCLUSION

High intensity of alkylating agents for SR resulted in similar outcomes but with a high incidence of hematologic toxicity. Tandem HDC with ASCR for HR induced favorable EFS and OS estimates compared to those reported previously. However, infectious complications and treatment-related mortalities suggest that a reduced chemotherapy dose is necessary, especially for the second HDC.

Evolution of neurosurgical advances and nuances in medulloblastoma therapy

Medulloblastoma, the most common malignant brain tumor in children, presents a complex treatment challenge due to its propensity for infiltrative growth within the posterior fossa and its potential attachment to critical anatomical structures. Central to the management of medulloblastoma is the surgical resection of the tumor, which is a key determinant of patient prognosis. However, the extent of surgical resection (EOR), ranging from gross total resection (GTR) to subtotal resection (STR) or even biopsy, has been the subject of extensive debate and investigation within the medical community. Today, the impact of neurosurgical EOR on the prognosis of medulloblastoma patients remains a complex and evolving area of investigation. The conflicting findings in the literature, the challenges posed by critical surrounding anatomical structures, the potential for surgical complications and neurologic morbidity, and the nuanced interactions with molecular subgroups all contribute to the complexity of this issue. As the field continues to advance, the imperative to strike a delicate balance between maximizing resection and preserving quality of life remains central to the management of medulloblastoma patients.

Childhood and Adolescent Central Nervous System Tumours in Spain: Incidence and Survival over 20 Years: A Historical Baseline for Current Assessment

BACKGROUND

Central nervous system (CNS) neoplasms are highly frequent solid tumours in children and adolescents. While some studies have shown a rise in their incidence in Europe, others have not. Survival remains limited. We addressed two questions about these tumours in Spain: (1) Is incidence increasing? and (2) Has survival improved?

METHODS

This population-based study included 1635 children and 328 adolescents from 11 population-based cancer registries with International Classification of Childhood Cancer Group III tumours, incident in 1983-2007. Age-specific and age-standardised (world population) incidence rates (ASRws) were calculated. Incidence time trends were characterised using annual percent change (APC) obtained with Joinpoint. Cases from 1991 to 2005 (1171) were included in Kaplan-Meier survival analyses, and the results were evaluated with log-rank and log-rank for trend tests. Children's survival was age-standardised using: (1) the age distribution of cases and the corresponding trends assessed with Joinpoint; and (2) European weights for comparison with Europe.

RESULTS

ASRw 1983-2007: children: 32.7 cases/106; adolescents: 23.5 cases/106. The overall incidence of all tumours increased across 1983-2007 in children and adolescents. Considering change points, the APCs were: (1) children: 1983-1993, 4.3%^ (1.1; 7.7); 1993-2007, -0.2% (-1.9; 1.6); (2) adolescents: 1983-2004: 2.9%^ (0.9; 4.9); 2004-2007: -7.7% (-40; 41.9). For malignant tumours, the trends were not significant. 5-year survival was 65% (1991-2005), with no significant trends (except for non-malignant tumours).

CONCLUSIONS

CNS tumour incidence in Spain was found to be similar to that in Europe. Rises in incidence may be mostly attributable to changes in the registration of non-malignant tumours. The overall malignant CNS tumour trend was compatible with reports for Southern Europe. Survival was lower than in Europe, without improvement over time. We provide a baseline for assessing current paediatric oncology achievements and incidence in respect of childhood and adolescent CNS tumours.

Chemotherapy in pediatric brain tumor and the challenge of the blood-brain barrier

BACKGROUND

Pediatric brain tumors (PBT) stand as the leading cause of cancer-related deaths in children. Chemoradiation protocols have improved survival rates, even for non-resectable tumors. Nonetheless, radiation therapy carries the risk of numerous adverse effects that can have long-lasting, detrimental effects on the quality of life for survivors. The pursuit of chemotherapeutics that could obviate the need for radiotherapy remains ongoing. Several anti-tumor agents, including sunitinib, valproic acid, carboplatin, and panobinostat, have shown effectiveness in various malignancies but have not proven effective in treating PBT. The presence of the blood-brain barrier (BBB) plays a pivotal role in maintaining suboptimal concentrations of anti-cancer drugs in the central nervous system (CNS). Ongoing research aims to modulate the integrity of the BBB to attain clinically effective drug concentrations in the CNS. However, current findings on the interaction of exogenous chemical agents with the BBB remain limited and do not provide a comprehensive explanation for the ineffectiveness of established anti-cancer drugs in PBT.

METHODS

We conducted our search for chemotherapeutic agents associated with the blood-brain barrier (BBB) using the following keywords: Chemotherapy in Cancer, Chemotherapy in Brain Cancer, Chemotherapy in PBT, BBB Inhibition of Drugs into CNS, Suboptimal Concentration of CNS Drugs, PBT Drugs and BBB, and Potential PBT Drugs. We reviewed each relevant article before compiling the information in our manuscript. For the generation of figures, we utilized BioRender software.

FOCUS

We focused our article search on chemical agents for PBT and subsequently investigated the role of the BBB in this context. Our search criteria included clinical trials, both randomized and non-randomized studies, preclinical research, review articles, and research papers.

FINDING

Our research suggests that, despite the availability of potent chemotherapeutic agents for several types of cancer, the effectiveness of these chemical agents in treating PBT has not been comprehensively explored. Additionally, there is a scarcity of studies examining the role of the BBB in the suboptimal outcomes of PBT treatment, despite the effectiveness of these drugs for other types of tumors.

Treatment Outcomes of Childhood Medulloblastoma with the SIOP/UKCCSG PNET-3 Protocol

OBJECTIVES

To retrospectively compare the overall and event-free survival rates of patients with standard and high risk medulloblastoma who received postoperative radiotherapy (RT) followed by maintenance chemotherapy.

METHODS

The study included 48 patients with medulloblastoma who were treated and followed-up between 2005 and 2021. Patients were classified according to the Chang classification because no molecular analysis was done. Immediately after surgery all patients received postoperative RT followed by eight cycles of chemotherapy (SIOP/UKCCSG PNET-3 protocol); if thrombocytopenia developed, carboplatin was replaced by cisplatin to avoid treatment delay. The clinical characteristics, risk categories and treatment outcomes of all patients were analyzed.

RESULTS

The mean age of the 48 patients (26 males, 22 females) at diagnosis was 7.27±4.21 y. The median start time of RT after surgery was 37 (range 19-80) d. The median follow-up was 56 (3-216) mo. The 5-year event-free survival was 61.2±10% in the high-risk group and 82.5±11.5% in the standard-risk group. The 5-year overall survival was 73.2±7.1%; it was 61.2±10% and 92.9±6.9% for high- and standard-risk patients, respectively (p = 0.026).

CONCLUSIONS

The outcomes of patients who were started on the modified SIOP/UKCCSG PNET-3 chemotherapy protocol, in which RT was begun as soon as possible after surgery, were comparable to those of current treatment protocols. Although a definitive conclusion is difficult, given the limited number of patients in the present study, authors suggest that their treatment protocol is a viable option for centers with limited facilities (such as an inability to perform molecular analysis).

An effective kinase inhibition strategy for metastatic recurrent childhood medulloblastoma

PURPOSE

Medulloblastomas (MBs) constitute the most common malignant brain tumor in children and adolescents. MYC-amplified Group 3 MBs are characterized by disease recurrence, specifically in the leptomeninges, whereby patients with these metastatic tumors have a mortality rate nearing 100%. Despite limited research on such tumors, studies on MB metastases at diagnosis suggest targeting kinases to be beneficial.

METHODS

To identify kinase inhibitors that eradicate cells driving therapy evasion and tumor dissemination, we utilized our established patient-derived xenograft (PDX) mouse-adapted therapy platform that models human MB metastatic recurrences following standard chemoradiotherapy. High-throughput screens of 640 kinase inhibitors were conducted against cells isolated from mouse spines in the PDX model and human fetal neural stem cells to reveal compounds that targeted these treatment-refractory, metastatic cells, whilst sparing healthy cells. Blood-brain barrier permeability assays and additional in vitro experimentation helped select top candidates for in vivo studies.

RESULTS

Recurrent Group 3 MB PDX spine cells were therapeutically vulnerable to a selective checkpoint kinase 1 (CHK1) inhibitor and small molecular inhibitor of platelet-derived growth factor receptor beta (PDGFRβ). Inhibitor-treated cells showed a significant reduction in MB stem cell properties associated with treatment failure. Mice also demonstrated survival advantage when treated with a CHK1 inhibitor ex vivo.

CONCLUSION

We identified CHK1 and PDGFRβ inhibitors that effectively target MB cells fueling treatment-refractory metastases. With limited research on effective therapies for Group 3 MB metastatic recurrences, this work highlights promising therapeutic options to treat these aggressive tumors. Additional studies are warranted to investigate these inhibitors' mechanisms and recommended in vivo administration.

Questions and answers in the management of children with medulloblastoma over the time. How did we get here? A systematic review

Introduction

Treatment of children with medulloblastoma (MB) includes surgery, radiation therapy (RT) and chemotherapy (CT). Several treatment protocols and clinical trials have been developed over the time to maximize survival and minimize side effects.

Methods

We performed a systematic literature search in May 2023 using PubMed. We selected all clinical trials articles and multicenter studies focusing on MB. We excluded studies focusing exclusively on infants, adults, supratentorial PNETs or refractory/relapsed tumors, studies involving different tumors or different types of PNETs without differentiating survival, studies including <10 cases of MB, solely retrospective studies and those without reference to outcome and/or side effects after a defined treatment.

Results

1. The main poor-prognosis factors are: metastatic disease, anaplasia, MYC amplification, age younger than 36 months and some molecular subgroups. The postoperative residual tumor size is controversial.2. MB is a collection of diseases.3. MB is a curable disease at diagnosis, but survival is scarce upon relapse.4. Children should be treated by experienced neurosurgeons and in advanced centers.5. RT is an essential treatment for MB. It should be administered craniospinal, early and without interruptions.6. Craniospinal RT dose could be lowered in some low-risk patients, but these reductions should be done with caution to avoid relapses.7. Irradiation of the tumor area instead of the entire posterior fossa is safe enough.8. Hyperfractionated RT is not superior to conventional RT9. Both photon and proton RT are effective.10. CT increases survival, especially in high-risk patients.11. There are multiple drugs effective in MB. The combination of different drugs is appropriate management.12. CT should be administered after RT.13. The specific benefit of concomitant CT to RT is unknown.14. Intensified CT with stem cell rescue has no benefit compared to standard CT regimens.15. The efficacy of intraventricular/intrathecal CT is controversial.16. We should start to think about incorporating targeted therapies in front-line treatment.17. Survivors of MB still have significant side effects.

Conclusion

Survival rates of MB improved greatly from 1940-1970, but since then the improvement has been smaller. We should consider introducing targeted therapy as front-line therapy.

Medulloblastomas in Pediatric and Adults

Medulloblastoma is the primary malignant embryonic tumor of the cerebellum and the most common malignant tumor of childhood, accounting up to 25% of all CNS tumors in children, but is extremely rare in adults. Despite the fact that medulloblastomas are one of the most malignant human tumors, it is worthy to note that a great breakthrough has been achieved in our understanding of oncogenesis and the development of real methods of treatment. The main objective of surgical treatment is a maximum resection of tumor with minimal impairment of neurological functions, in order to reduce the volume, remove tumor tissue, get the biopsy, and restore the cerebrospinal fluid flow. The progress of surgical techniques (using a microscope, ultrasound suction), anesthesiology, and intensive care has significantly decreased surgical mortality and increased radicality of tumor removal. Postoperative mortality is less than one percent in most studies, while neurological complications have been reported between 5-10%. Radiotherapy is the main method of treatment in patients older than 3 years, which dramatically improved the recurrence-free survival. Nevertheless, the radiation therapy without systemic chemotherapy leads to a high risk of systemic metastases. After the role of chemotherapy was statistically proven, investigations of the optimal combination of different chemotherapy regimens continued around the world. Currently, 80% of patients can already be cured, however, the quality of life of patients in the long-term period remains quite low, which depends on many factors including endocrinological, cognitive, neurological, and otoneurologic aspects. Thus, the main strategic goal of the development of neuro-oncology is to reduce the doses of radiation therapy to the CNS and the main task of international research is to optimize existing protocols and develop fundamentally new ones based on molecular genetic research in order to improve the quality of life.

Medulloblastoma: Current Perspectives and Recent Advances

Medulloblastoma is the most common embryonal tumor of the central nervous system in childhood. Combined multimodality approaches, including surgery, radiation, and chemotherapy, have improved the outcome of medulloblastoma. Advances in genomic research have shown that medulloblastoma is not a biologically or clinically discrete entity. Previously, the risk was divided according to histology, presence of metastasis, degree of resection, and age at diagnosis. Through the development of integrated genomics, new biology-based risk stratification methods have recently been proposed. It is also important to understand the genetic predisposition of patients with medulloblastoma. Therefore, treatment goal aimed to improve the survival rate with minimal additional adverse effects and reduced long-term sequelae. It is necessary to incorporate genetic findings into the standard of care, and clinical trials that reflect this need to be conducted.

Meta of classical chemotherapy compared with high-dose chemotherapy and autologous stem cell rescue in newly diagnosed medulloblastoma after radiotherapy

BACKGROUND

High-dose chemotherapy combined with autologous stem cell rescue (HDCT + ASCR) has been used to treat newly diagnosed medulloblastoma, but there was no high-level evidence to support its efficacy.

METHODS

Databases were retrieved, and patients were divided into 2 groups: group A was radiotherapy combined with HCDT + ASCR, and group B was classical radiotherapy and chemotherapy. The clinical benefit rate, progression-free survival (PFS), overall survival (OS) and toxicities data were extracted.

RESULTS

22 clinical trials met the inclusion criteria, 416 in group A and 2331 in group B. There was no difference in CBR between 2 groups (80.0% vs 71.5%, P.262). The 3-year PFS (3-y PFS) of group A was significantly better than group B (79.0% vs 69.5%, P = .004). The analysis found that there was no difference between the 2 groups of the standard risk group or the high-risk group. In the standard risk group, the 5-y PFS of group A was significantly better than group B (83.6% vs75.6%, P = .004). Comparison of 3-y OS and 5-y OS between 2 groups of all MB patients showed no difference (P = .086; P = .507), stratified analysis was the same result. The gastrointestinal toxicity in group A was significantly higher than that in group B (P = .016), and the level 3/4 ototoxicity in high-risk group A was higher than that in group B (P = .001).

CONCLUSIONS

HDCT + ASCR can prolong 3-year PFS significantly, and prolong 5-y PFS significantly in the standard risk group, but increase gastrointestinal toxicity significantly for newly diagnosed medulloblastoma.

High-Dose Chemotherapy in Children with Newly Diagnosed Medulloblastoma

Simple Summary

Medulloblastoma is the most common malignant central nervous system tumor in the pediatric population. Treatment modalities are stratified by age, extent of resection, metastatic status, histology, and more recently, tumor biology. Maximal surgical resection followed by risk-adapted craniospinal irradiation and adjuvant chemotherapy have produced the best survival for medulloblastoma. Although survival is, in general, quite high, some caveats and drawbacks argue for continuous adaptations of this treatment strategy. Clearly, for children with metastatic disease, there is no established standard chemotherapy regimen, even if there is a consensus that chemotherapy brings additional benefit. The treatment of infants and very young children is particularly challenging, as irradiation of the developing brain leads to substantial neurocognitive impairment. Some clinical trials have explored the possible efficacy of high-dose chemotherapy in childhood medulloblastoma, and here we have focused on clinical trials for infants and children with newly diagnosed medulloblastoma.

Abstract

High-dose chemotherapy with stem cell rescue has been used as an adjuvant therapy or as salvage therapy to treat pediatric patients with brain tumors, and to avoid deleterious side effects of radiotherapy in infants and very young children. Here, we present the most recent trials using high-dose chemotherapy regimens for medulloblastoma in children, and we discuss their contribution to improved survival and describe their toxicity profile and limitations.

Discovery of HDAC6-Selective Inhibitor NN-390 with in Vitro Efficacy in Group 3 Medulloblastoma

Histone deacetylase 6 (HDAC6) has been targeted in clinical studies for anticancer effects due to its role in oncogenic transformation and metastasis. Through a second-generation structure-activity relationship (SAR) study, the design, and biological evaluation of the selective HDAC6 inhibitor NN-390 is reported. With nanomolar HDAC6 potency, >200-550-fold selectivity for HDAC6 in analogous HDAC isoform functional assays, potent intracellular target engagement, and robust cellular efficacy in cancer cell lines, NN-390 is the first HDAC6-selective inhibitor to show therapeutic potential in metastatic Group 3 medulloblastoma (MB), an aggressive pediatric brain tumor often associated with leptomeningeal metastases and therapy resistance. MB stem cells contribute to these patients' poor clinical outcomes. NN-390 selectively targets this cell population with a 44.3-fold therapeutic margin between patient-derived Group 3 MB cells in comparison to healthy neural stem cells. NN-390 demonstrated a 45-fold increased potency over HDAC6-selective clinical candidate citarinostat. In summary, HDAC6-selective molecules demonstrated in vitro therapeutic potential against Group 3 MB.

Clinical Trials in High-Risk Medulloblastoma: Evolution of the SIOP-Europe HR-MB Trial

Medulloblastoma patients receive adapted therapies stratified according to their risk-profile. Favourable, standard, and high disease-risk groups are each defined by the status of clinical and pathological risk factors, alongside an evolving repertoire of diagnostic and prognostic biomarkers. Medulloblastoma clinical trials in Europe are coordinated by the International Society for Paediatric Oncology (SIOP-Europe) brain tumour group. Favourable and standard-risk patients are eligible for the SIOP-PNET5-MB clinical trial protocol. In contrast, therapies for high-risk disease worldwide have, to date, encompassed a range of different treatment philosophies, with no clear consensus on approach. Higher radiotherapy doses are typically deployed, delivered either conventionally or in hyper-fractionated/accelerated regimens. Similarly, both standard and high-dose chemotherapies were assessed. However, trials to date in high-risk medulloblastoma have commonly been institutional or national, based on modest cohort sizes, and have not evaluated the relative performance of different strategies in a randomised fashion. We describe the concepts and design of the SIOP-E high-risk medulloblastoma clinical trial (SIOP-HR-MB), the first international biomarker-driven, randomised, clinical trial for high-risk medulloblastoma. SIOP-HR-MB is programmed to recruit >800 patients in 16 countries across Europe; its primary objectives are to assess the relative efficacies of the alternative established regimens. The HR-MB patient population is molecularly and clinically defined, and upfront assessments incorporate a standardised central review of molecular pathology, radiology, and radiotherapy quality assurance. Secondary objectives include the assessment of (i) novel therapies within an upfront 'window' and (ii) therapy-associated neuropsychology, toxicity, and late effects, alongside (iii) the collection of materials for comprehensive integrated studies of biological determinants within the SIOP-HR-MB cohort.

Radiotherapy in Medulloblastoma-Evolution of Treatment, Current Concepts and Future Perspectives

Simple Summary

Craniospinal irradiation (CSI) is the backbone of medulloblastoma treatment and the first treatment to achieve a cure in many patients. Within the last decades, significant efforts have been made to enhance efficacy in combination with chemotherapy. With this approach, a majority of low- and standard-risk patients can be cured. In parallel, many clinical trials have dealt with CSI-dose reduction and reduction of boost volume in order to decrease long-term toxicity, particularly neurotoxicity. Within these trials, standardized quality assurance has helped to increase the accuracy of treatment and improve prognosis. More recently, advances of radiotherapy techniques such as proton treatment allowed for better sparing of healthy tissue in order to further diminish detrimental long-term effects. Major future challenges are the adaption of radiotherapy regimens to different molecularly defined disease groups alone or together with new targeted agents. Moreover, and even more importantly, innovative combinatorial treatments are needed in high- and very-high risk situations.

Abstract

Medulloblastoma is the most frequent malignant brain tumor in children. During the last decades, the therapeutic landscape has changed significantly with craniospinal irradiation as the backbone of treatment. Survival times have increased and treatments were stratified according to clinical and later molecular risk factors. In this review, current evidence regarding the efficacy and toxicity of radiotherapy in medulloblastoma is summarized and discussed mainly based on data of controlled trials. Current concepts and future perspectives based on current risk classification are outlined. With the introduction of CSI, medulloblastoma has become a curable disease. Due to combination with chemotherapy, survival rates have increased significantly, allowing for a reduction in radiation dose and a decrease of toxicity in low- and standard-risk patients. Furthermore, modern radiotherapy techniques are able to avoid side effects in a fragile patient population. However, high-risk patients remain with relevant mortality and many patients still suffer from treatment related toxicity. Treatment needs to be continually refined with regard to more efficacious combinatorial treatment in the future.

What does a non-response to induction chemotherapy imply in high-risk medulloblastomas?

PURPOSE

High-risk medulloblastomas (HR-MB) may not respond to induction chemotherapy, with either post-induction stable (SD) or progressive disease (PD). There is no consensus regarding their optimal management.

METHODS

A retrospective, multicentre study investigated patients with non-responder HR-MB treated according to the PNET HR + 5 protocol (NCT00936156) between 01/01/2009 and 31/12/2018. After two courses of etoposide and carboplatin (induction), patients with SD or PD were analyzed. Upon clinician's decision, the PNET HR + 5 protocol was either pursued with tandem high-dose chemotherapy (HDCT) and craniospinal irradiation (CSI) (continuation group) or it was modified (switched group).

RESULTS

Forty-nine patients were identified. After induction, 37 patients had SD and 12 had PD. The outcomes were better for the SD group: the 5-y PFS and OS were 52% (95% CI 35-67) and 70% (95% CI 51-83), respectively, in the SD group while the 2-y PFS and OS were 17% (95% CI 3-41) and 25% (95% CI 6-50), respectively, in the PD group (p < 0.0001). The PNET HR + 5 strategy was pursued for 3 patients in the PD group, of whom only one survived. In the SD group, it was pursued for 24/37 patients whereas 13 patients received miscellaneous treatments including a 36 Gy CSI in 12 cases. Despite that continuation and switched group were well-balanced for factors impacting the outcomes, the latter were better in the continuation group than in the switched group: the 5-y PFS were 78% (95% CI 54-90) versus 0% (p < 0.001), and the 5-y OS were 78% (95% CI 54-90) versus 56% (95% CI 23-79) (p = 0.0618) respectively. In the SD group, multivariate analysis revealed that MYC amplification, molecular group 3, and a switched strategy were independent prognostic factors for progression.

CONCLUSION

Patients with post-induction SD may benefit from HDCT and CSI, whereas patients with early PD will require new therapeutic approaches.

ABCB1 inhibition provides a novel therapeutic target to block TWIST1-induced migration in medulloblastoma

Background

Therapeutic intervention in metastatic medulloblastoma is dependent on elucidating the underlying metastatic mechanism. We investigated whether an epithelial–mesenchymal transition (EMT)-like pathway could drive medulloblastoma metastasis.

Methods

A 3D Basement Membrane Extract (3D-BME) model was used to investigate medulloblastoma cell migration. Cell line growth was quantified with AlamarBlue metabolic assays and the morphology assessed by time-lapse imaging. Gene expression was analyzed by qRT-PCR and protein expression by immunohistochemistry of patient tissue microarrays and mouse orthotopic xenografts. Chromatin immunoprecipitation was used to determine whether the EMT transcription factor TWIST1 bound to the promoter of the multidrug pump ABCB1. TWIST1 was overexpressed in MED6 cells by lentiviral transduction (MED6-TWIST1). Inhibition of ABCB1 was mediated by vardenafil, and TWIST1 expression was reduced by either Harmine or shRNA.

Results

Metastatic cells migrated to form large metabolically active aggregates, whereas non-tumorigenic/non-metastatic cells formed small aggregates with decreasing metabolic activity. TWIST1 expression was upregulated in the 3D-BME model. TWIST1 and ABCB1 were significantly associated with metastasis in patients (P = .041 and P = .04, respectively). High nuclear TWIST1 expression was observed in the invasive edge of the MED1 orthotopic model, and TWIST1 knockdown in cell lines was associated with reduced cell migration (P < .05). TWIST1 bound to the ABCB1 promoter (P = .03) and induced cell aggregation in metastatic and TWIST1-overexpressing, non-metastatic (MED6-TWIST1) cells, which was significantly attenuated by vardenafil (P < .05).

Conclusions

In this study, we identified a TWIST1–ABCB1 signaling axis during medulloblastoma migration, which can be therapeutically targeted with the clinically approved ABCB1 inhibitor, vardenafil.

Transition of Care for Children with High-Grade Central Nervous System Tumors

The increase in survival rates of children with high-grade central nervous system tumors has highlighted the necessity for and challenges associated with transition of care as these children grow into adult life. Late recurrence and treatment effects are some of the conditions that require care after transition. Several models of transition have been proposed in the literature. An effective transition will not only ensure adequate continuity of care but will also include assessment of effectiveness of the transition by health care personnel and the patient/patient's family themselves.

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.

Medulloblastoma: an Old Diagnosis with New Promises

PURPOSE OF REVIEW

Molecular subtyping in medulloblastoma (MB) has diagnostic and prognostic values which impact therapy. This paper provides guidance for the clinician caring for pediatric and adult patients with medulloblastoma in the modern era.

RECENT FINDINGS

Medulloblastoma comprises four molecularly distinct subgroups: wingless activated (WNT), sonic hedgehog activated (SHH), group 3, and group 4. Risk stratification before and after the discovery of molecular subgroups aims at minimizing toxicity by reducing radiation and chemotherapy doses in low-risk patients while maintaining favorable overall survival (OS). The mainstay of newly diagnosed medulloblastoma treatment is surgery, radiation therapy, and chemotherapy, except for children under 6 years of age, where high-dose chemotherapy with autologous stem cell rescue is used to avoid or delay radiotherapy, preventing neurocognitive sequelae. Management of recurrent/refractory medulloblastoma remains a challenge with immunotherapy and small-molecule inhibitors forming the backbone of novel strategies. Recent innovations in medulloblastoma research allow us to better understand pathogenesis and molecular characteristics resulting in advanced risk stratification models, new therapeutic approaches, and overall improved survival and quality of life.

Promising survival rate but high incidence of treatment-related mortality after reduced-dose craniospinal radiotherapy and tandem high-dose chemotherapy in patients with high-risk medulloblastoma

BACKGROUND

In this study, we report the follow-up results of reduced dose of craniospinal radiotherapy (CSRT) followed by tandem high-dose chemotherapy (HDCT) in patients with high-risk medulloblastoma (MB).

METHODS

Newly diagnosed high-risk MB patients (metastatic disease, postoperative residual tumor >1.5 cm² , or large cell/anaplastic histology) over 3 years of age were enrolled in this study. Two cycles of pre-RT chemotherapy, radiotherapy (RT) including reduced-dose CSRT (23.4 or 30.6 Gy), four cycles of post-RT chemotherapy, and tandem HDCT were administered. NanoString and DNA sequencing were performed using archival tissues.

RESULTS

In all, 40 patients were enrolled, and molecular subgrouping was possible in 21 patients (2 wingless, 3 sonic hedgehog, 8 Group 3, and 8 group 4). All patients including two patients who experienced progression during the induction chemotherapy underwent HDCT. Relapse/progression occurred only in four patients (5-year cumulative incidence [CI] 10.4 ± 0.3%). However, six patients died from treatment-related mortality (TRM) (four acute TRMs and two late TRMs) resulting in 18.5 ± 0.5% of 5-year CI. Taken together, the 5-year event-free survival and overall survival were 71.1 ± 8.0% and 73.2 ± 7.9%, respectively. Late effects were evaluated in 25 patients and high-tone hearing loss, endocrine dysfunction, dyslipidemia, and growth retardation were common.

CONCLUSIONS

The strategy using tandem HDCT following reduced-dose CSRT showed promising results in terms of low relapse/progression rate; however, the high TRM rate indicates that modification of HDCT regimen and careful selection of patients who can benefit from HDCT will be needed in the future study.

Strategy to minimize radiation burden in infants and high-risk medulloblastoma using intrathecal methotrexate and high-dose chemotherapy: A prospective registry study in Japan

BACKGROUND

Most childhood medulloblastoma (MB) cases are curable using multimodal treatment, including craniospinal irradiation (CSI). However, late effects are a serious problem for survivors. This prospective registry study evaluated Japanese patients to determine whether a reduced radiation dose was feasible.

PATIENTS AND METHODS

Patients with MB were classified as an infant group (<3 years old) and a high-risk (HR) group (≥3 years old with metastasis). The HR group received intrathecal methotrexate (IT-MTX) and high-dose chemotherapy (HDC) using thiotepa and melphalan, as well as concomitant radiotherapy with a recommended CSI dose of 18 Gy and a total local dose of 50 Gy. Radiotherapy was only considered for infants if residual tumors were present after the HDC.

RESULTS

Between 1997 and 2006, we identified 28 HR patients (M1: 9, M2/3: 19) and 17 infant patients (M0: 11, M1: 3, M2/3: 3). During the median follow-up of 9.4 years for the entire HR group, the 5-year progression-free survival (PFS) rate was 82.1 ± 7.2% and the 5-year overall survival (OS) rate was 85.7 ± 6.6%. Subanalyses of the patients who received the recommended treatment revealed that the 5-year PFS and OS rates were both 90.5 ± 6.4%. In the infant group, the 5-year PFS rate was 52.9 ± 12.1% and the 5-year OS rate was 51.8 ± 12.4%. There were no serious adverse events associated with the IT-MTX and HDC treatments.

CONCLUSION

Intensified chemotherapy using HDC and IT-MTX might allow for a reduced prophylactic radiation dose in patients with MB with metastases. Further studies are needed to validate these findings.

Medulloblastomas in cerebellopontine angle: Epidemiology, clinical manifestations, imaging features, molecular analysis and surgical outcome

Cerebellopontine angle (CPA) medulloblastoma is rare and short of system description. We attempted to clarify its epidemiology, clinical manifestations, imaging features, pathological and molecular types, and surgical outcomes. 8 patients from 7 to 52 years old were enrolled in this retrospective study, with mean age 21.6 ± 16.4 years. The most frequent symptoms were raised intracranial pressure (100%), followed by cerebellar signs (50%), decreased hearing (50%), facial paralysis (50%), abducent paralysis (50%), and facial paresthesia (37.5%). MRI demonstrated a solid CPA lesion with heterogeneously weak or significant enhancement after gadolinium administration, accompanied with peritumoral oedema (75%), cystic change (62.5%) and dural tail sign (50%), while CT showed petrous bone and internal auditory canal intact. All cases received tumor excision, with 6 (75%) cases undergoing gross total resection, and the remaining (25%) getting partial excision. Pathological examination confirmed 5 (62.5%) classic, 2 (25%) desmoplastic, and 1 (12.5%) anaplastic. Further molecular analysis identified 5 (62.5%) WNT and 3 (37.5%) SHH. Immediately after the primary surgery, 7 (87.5%) cases gained improvement of the symptoms and signs and 1 (12.5%) kept the preoperative status stable. Follow up was available ranged from 5 to 34 months, during that period 5 cases kept symptom free and 3 cases recurred/progressed. In conclusion, CPA medulloblastoma is rare and lacking of special clinical manifestations and radiological features, and should be considered in the differential diagnosis of CPA lesions. In this series the most frequent pathological and molecular type is classic and WNT. Microsurgery excision is effective to prevent progressive decline of neurological status.

Management of high-risk medulloblastoma

Medulloblastoma is the most common malignant brain tumors in children. Current management combines surgery, radiotherapy, and chemotherapy. Current treatment of medulloblastoma is based on a clinical risk-stratification system that takes into account age, extent of resection and metastatic status. High-risk medulloblastoma patients are defined by the presence of metastatic disease and/or an incomplete resection with a residual amount of tumour>1.5 cm². This review describes the evolution in the management of high-risk medulloblastoma patients during recent 4 decades and recent changes in the definition of high-risk patients as a result of major advances in the understanding of the molecular heterogeneity of medulloblastomas.

Medulloblastomas in adolescents and adults - Can the pediatric experience be extrapolated?

Adult medulloblastomas are orphan diseases that differ from their pediatric counterpart. Most are classified as classic or desmoplastic and fall in the SHH subgroup, mainly with loss-of-function mutations in PTCH1 and some by TP53-mutation due to underlying germline mutation. Activation of the WNT pathway is sporadic, although underlying Turcot syndrome may be present. One-third of tumors are issued from group 4. Most adult studies are small non-randomized retrospective heterogeneous studies performed at a single center with short follow-up. Standard craniospinal irradiation followed by maintenance chemotherapy (CCNU, cisplatin-vincristine) results in a 4-year event-free survival (EFS) and overall survival (OS) of 68% and 89% respectively in standard-risk adults, and in a 4-year EFS and OS of 50% and 90%, respectively in high-risk adults. Several pooled analyses point out the potential role of chemotherapy in adults. The feasibility of pediatric protocols in adults is sometimes hampered because of blood and peripheral nerve toxicity. In the near future, subgroups of medulloblastomas may be treated by personalized therapies. With prolonged follow-up, adults fare worse. Long-term sequelae and second line treatment are not well defined in adults. Prospective studies are ongoing to define optimal first-line and relapse treatments.

Reproducibility of the NanoString 22-gene molecular subgroup assay for improved prognostic prediction of medulloblastoma

Medulloblastoma is the most frequent malignant brain tumor in children. Four medulloblastoma molecular subgroups, MB_SHH , MB_WNT , MB_GRP3 and MB_GRP4 , have been identified by integrated high-throughput platforms. Recently, a 22-gene panel NanoString-based assay was developed for medulloblastoma molecular subgrouping, but the robustness of this assay has not been widely evaluated. Mutations in the gene for human telomerase reverse transcriptase (hTERT) have been found in medulloblastomas and are associated with distinct molecular subtypes. This study aimed to implement the 22-gene panel in a Brazilian context, and to associate the molecular profile with patients' clinical-pathological features. Formalin-fixed, paraffin-embedded (FFPE) medulloblastoma samples (n = 104) from three Brazilian centers were evaluated. Expression profiling of the 22-gene panel was performed by NanoString and a Canadian series (n = 240) was applied for training phase. hTERT mutations were analyzed by PCR followed by direct Sanger sequencing and the molecular profile was associated with patients' clinicopathological features. Overall, 65% of the patients were male, average age at diagnosis was 18 years and 7% of the patients presented metastasis at diagnosis. The molecular classification was attained in 100% of the cases, with the following frequencies: MB_SHH (n = 51), MB_WNT (n = 19), MB_GRP4 (n = 19) and MB_GRP3 (n = 15). The MB_SHH and MB_GRP3 subgroups were associated with older and younger patients, respectively. The MB_GRP4 subgroup exhibited the lowest 5-year cancer-specific overall survival (OS), yet in the multivariate analysis, only metastasis at diagnosis and surgical resection were associated with OS. hTERT mutations were detected in 29% of the cases and were associated with older patients, increased hTERT expression and MB_SHH subgroup. The 22-gene panel provides a reproducible assay for molecular subgrouping of medulloblastoma FFPE samples in a routine setting and is well-suited for future clinical trials.

UAB30, a novel RXR agonist, decreases tumorigenesis and leptomeningeal disease in group 3 medulloblastoma patient-derived xenografts

BACKGROUND

Group 3 tumors account for approximately 25-30% of medulloblastomas and have the worst prognosis. UAB30 is a novel synthetic rexinoid shown to have limited toxicities in humans and significant efficacy in the pediatric neuroectodermal tumor, neuroblastoma. We hypothesized that treatment with UAB30 would decrease tumorigenicity in medulloblastoma patient-derived xenografts (PDXs).

METHODS

Three group 3 medulloblastoma PDXs (D341, D384 and D425) were utilized. Cell viability, proliferation, migration and invasion assays were performed after treatment with UAB30 or 13-cis-retinoic acid (RA). Cell cycle analysis was completed using flow cytometry. A flank model, a cerebellar model, and a model of leptomeningeal metastasis using human medulloblastoma PDX cells was used to assess the in vivo effects of UAB30 and RA.

RESULTS

UAB30 treatment led to cell differentiation and decreased medulloblastoma PDX cell viability, proliferation, migration and invasion and G1 cell cycle arrest in all three PDXs similar to RA. UAB30 and RA treatment of mice bearing medulloblastoma PDX tumors resulted in a significant decrease in tumor growth and metastasis compared to vehicle treated animals.

CONCLUSIONS

UAB30 decreased viability, proliferation, and motility in group 3 medulloblastoma PDX cells and significantly decreased tumor growth in vivo in a fashion similar to RA, suggesting that further investigations into the potential therapeutic application of UAB30 for medulloblastoma are warranted.

Targeting inhibitors of apoptosis proteins suppresses medulloblastoma cell proliferation via G2/M phase arrest and attenuated neddylation of p21

Medulloblastoma (MB) is the most common type of malignant childhood brain tumor. We previously showed that inhibitors of apoptosis proteins (IAP) small‐molecule inhibitors (LCL161 or LBW242) combined with chemotherapy have synergistic antiproliferative effects on MB cells. The synergistic antitumor effects of combination treatments happen through induction of autophagy and caspase‐3/7‐activated apoptosis. Here, we investigated the effects of IAP inhibitors or silencing IAP on cell cycle regulation. We discovered that treatment with IAP inhibitors or their combination with conventional chemotherapy (vincristine or cisplatin), as well as RNAi knockdown of cIAP1/2 or XIAP arrested MB cells in the G2/M phase through downregulation of cyclin B1‐CDK1 and cyclin A‐CDK1/2. Among these three IAPs, only silencing cIAP1 expression enhanced p21 dependent‐G2/M phase accumulation. IAP inhibitors reduced cIAP1 expression and increased p21 expression in time course experiments. Furthermore, cIAP1 can govern p21 proteasomal degradation via neddylation in lieu of ubiquitination. Inhibition of IAPs significantly abrogated cIAP1‐mediated p21 degradation. We also observed an inverse correlation between nuclear cIAP1 and nuclear p21 expressions in MB tumor tissues. These findings provide new mechanistic evidence of the influence of IAP inhibitors on MB cell proliferation through disruption of the cell cycle.

Tandem High-dose Chemotherapy and Autologous Stem Cell Transplantation in Children with Brain Tumors : Review of Single Center Experience

The prognosis of brain tumors in children has improved for last a few decades. However, the prognosis remains dismal in patients with recurrent brain tumors. The outcome for infants and young children in whom the use of radiotherapy (RT) is very limited because of unacceptable long-term adverse effect of RT remains poor. The prognosis is also not satisfactory when a large residual tumor remains after surgery or when leptomeningeal seeding is present at diagnosis. In this context, a strategy using high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT) has been explored to improve the prognosis of recurrent or high-risk brain tumors. This strategy is based on the hypothesis that chemotherapy dose escalation might result in improvement in survival rates. Recently, the efficacy of tandem HDCT/auto-SCT has been evaluated in further improving the outcome. This strategy is based on the hypothesis that further dose escalation might result in further improvement in survival rates. At present, the number of studies employing tandem HDCT/auto-SCT for brain tumors is limited. However, results of these pilot studies suggest that tandem HDCT/auto-SCT may further improve the outcome. In this review, we will summarize our single center experience with tandem HDCT/auto-SCT for recurrent or high-risk brain tumors.

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.

Medulloblastoma in the Molecular Era

Medulloblastoma is the most common malignant brain tumor of childhood and remains a major cause of cancer related mortality in children. Significant scientific advancements have transformed the understanding of medulloblastoma, leading to the recognition of four distinct clinical and molecular subgroups, namely wingless (WNT), sonic hedgehog, group 3, and group 4. Subgroup classification combined with the recognition of subgroup specific molecular alterations has also led to major changes in risk stratification of medulloblastoma patients and these changes have begun to alter clinical trial design, in which the newly recognized subgroups are being incorporated as individualized treatment arms. Despite these recent advancements, identification of effective targeted therapies remains a challenge for several reasons. First, significant molecular heterogeneity exists within the four subgroups, meaning this classification system alone may not be sufficient to predict response to a particular therapy. Second, the majority of novel agents are currently tested at the time of recurrence, after which significant selective pressures have been exerted by radiation and chemotherapy. Recent studies demonstrate selection of tumor sub-clones that exhibit genetic divergence from the primary tumor, exist within metastatic and recurrent tumor populations. Therefore, tumor resampling at the time of recurrence may become necessary to accurately select patients for personalized therapy.

Survival and Prognostic Factors in Pediatric Patients with Medulloblastoma in Southern Thailand

BACKGROUND

The current prognosis of medulloblastoma in children is better because of technological advancements and improvements in treatment strategies and genetic investigations. However, there is a lack of studies that focus on medulloblastoma in Thailand. The aims of our study were to conduct a survival analysis and to identify the prognostic factors of pediatric medulloblastoma.

MATERIALS AND METHODS

Fifty-five children, with medulloblastoma, were eligible for analysis between 1991 and 2015. We retrospectively reviewed both the clinical and the histological data. Survival curves were constructed using the Kaplan-Meier method. For comparisons of dichotomous factors, between groups, the log-rank test was used to determine survival. The Cox proportional hazard regression model was used to identify the univariate and multivariate survival predictors.

RESULTS

The mortality rate was 49.1% in this study. The median follow-up time was 68.8 months (range: 1-294 months). The 5-year overall survival rate and median survival time were 53.8% (95% CI 38.7-66.7) and 80 months (95% CI 23-230), respectively. Univariate analysis revealed children <3 years of age, hemispheric tumor location, high risk according to risk stratification, and patients who did not receive radiation therapy affected the prognosis. In multivariable analysis, hemispheric tumors (hazard ratio [HR] 2.54 [95% CI 1.11-5.80]; P = 0.01)and high risk groups (HR 3.86 [95% CI 1.28-11.60]; P = 0.01) influenced death. Finally, using conditional inference trees, the study showed that hemispheric tumor locations are truly aggressive in behavior, whereas risk stratification is associated with the prognosis of midline tumors.

CONCLUSIONS

Hemispheric medulloblastoma and high-risk groups according to risk stratification were associated with poor prognosis.

MRI Characteristics of Primary Tumors and Metastatic Lesions in Molecular Subgroups of Pediatric Medulloblastoma: A Single-Center Study

BACKGROUND AND PURPOSE

Molecular grouping of medulloblastoma correlates with prognosis and supports the therapeutic strategy. We provide our experience with the imaging features of primary and metastatic disease in relation to the molecular groups.

MATERIALS AND METHODS

One hundred nineteen consecutive patients (mean age, 7.3 ± 3.8 years at diagnosis; male, 79 [66.4%]) with a confirmed diagnosis of medulloblastoma and interpretable pretreatment MRIs were retrieved from our data base from January 2000 to December 2016. Each patient was assigned to wingless, sonic hedgehog, group 3, or group 4 molecular groups. Then, we determined the imaging features of both primary and metastatic/recurrent disease predictive of molecular groups.

RESULTS

In addition to recently reported predictors based on primary tumor, including cerebellar peripheral location for sonic hedgehog (adjusted odds ratio = 9, P < .0001), minimal enhancement of primary group 4 tumor (adjusted odds ratio = 5.2, P < .0001), and cerebellopontine angle location for wingless (adjusted odds ratio = 1.4, P = .03), ependymal metastasis with diffusion restriction and minimal postcontrast enhancement ("mismatching pattern") (adjusted odds ratio = 2.8, P = .001) for group 4 and spinal metastasis for group 3 (adjusted odds ratio = 1.9, P = .01) also emerged as independent predictors of medulloblastoma molecular groups. Specifically, the presence of a metastasis in the third ventricular infundibular recess showing a mismatching pattern was significantly associated with group 4 (P = .02).

CONCLUSIONS

In addition to imaging features of primary tumors, some imaging patterns of metastatic dissemination in medulloblastoma seem characteristic, perhaps even specific to certain groups. This finding could further help in differentiating molecular groups, specifically groups 3 and 4, when the characteristics of the primary tumor overlap.

Impact of induction chemotherapy, hyperfractionated accelerated radiotherapy and high-dose thiotepa on brain volume loss and functional status of children with primitive neuroectodermal tumour

BACKGROUND

The introduction of aggressive chemo-radiotherapy regimens has improved overall survival in children with primitive neuroectodermal tumours (PNET). However, these combinations may result in neurotoxicity. Previously reported magnetic resonance imaging abnormalities in children receiving intensive sequential chemotherapy, hyperfractionated accelerated radiotherapy (HART) and high-dose thiotepa prompted us to investigate the degree of brain volume loss and patients' functional status after therapy.

METHODS

We retrospectively reviewed clinico-radiological data of children with PNET treated in this way at our centre.

RESULTS

We studied 14 children treated between December 2009 and April 2013. Data were not complete for one child. Performance status was severely restricted in four children, and mildly to moderately impaired in 7 of the 13 children. Eleven of 13 children showed mild-to-severe generalised neuroparenchymal atrophy, in 7 of whom neuroparenchymal volume loss was moderate to severe. Of these seven, six had received high-dose thiotepa. There was no correlation between brain volume loss and Lansky performance status. However, unexpected neurotoxicities, such as symptoms of transverse myelitis, were observed.

CONCLUSION

Measurement of brain volume loss in patients treated with HART and high-dose thiotepa may not be sufficient to predict function. However, correlation of brain volume loss due to late neurotoxicity with performance decline may be more obvious over longer period of follow-up. The combination of HART and myeloablative courses of thiotepa is associated with severe neurotoxicity and subsequent decline in performance status in a significant proportion of patients.

Outcome for children treated for medulloblastoma and supratentorial primitive neuroectodermal tumor (CNS-PNET) - a retrospective analysis spanning 40 years of treatment

BACKGROUND

Medulloblastoma (MB) and supratentorial primitive neuroectodermal tumor of the central nervous system (CNS-PNET) are among the most common pediatric brain tumors. The diagnosis, treatment, and outcome of MB/CNS-PNET patients treated during the last four decades at Oslo University Hospital (OUH) are described.

MATERIAL AND METHODS

All patients younger than 20 years of age diagnosed and treated for MB/CNS-PNET at OUH between 1 January 1974 and 31 December 2013 were identified.

RESULTS

We found 175 patients. In 13 of them, the diagnosis was changed upon histopathological review and in 4 patients part of the treatment was administered at other hospitals. Thus, 158 patients were included for further analysis. Eight patients did not receive adjuvant therapy because of a dismal clinical condition. The overall 5-year survival rate for MB and CNS-PNET was 54%, for MB 57%, and for CNS-PNET 41%. Gross total resection (GTR) was achieved in 118 patients and 5-year overall survival for patients with GTR versus those with non-GTR differed significantly with 64% versus 22%. Cytological examination of the cerebrospinal fluid was performed in 52 patients. A total of 126 patients received radiotherapy as part of the primary treatment and 24 did not due to young age. Median time from surgery to start of radiotherapy was 33 days. Duration of radiotherapy was more than 48 days in 22% of patients. At the time of analysis, 63 patients were alive and disease-free, one alive with disease, and 94 patients were deceased; 84 of these due to MB/CNS-PNET and 10 due to supposed late effects from the treatment.

CONCLUSIONS

Survival was comparable to data from other population-based studies. The importance of GTR for survival was corroborated. Reporting real-world data remains crucial to know the true outcome of patients treated outside clinical trials.

Treatment of Children and Adolescents With Metastatic Medulloblastoma and Prognostic Relevance of Clinical and Biologic Parameters

Purpose To assess an intensified treatment in the context of clinical and biologic risk factors in metastatic medulloblastoma. Patients and Methods Patients (4 to 21 years old, diagnosed between 2001 and 2007) received induction chemotherapy, dose-escalated hyperfractionated craniospinal radiotherapy, and maintenance chemotherapy. Subgroup status and other biologic parameters were assessed. Results In 123 eligible patients (median age, 8.2 years old; median follow-up, 5.38 years), 5-year event-free survival (EFS) and overall survival (OS) were 62% (95% CI, 52 to 72) and 74% (95% CI, 66 to 82), respectively. OS was superior compared with the precedent HIT '91 trial. The 5-year EFS and OS were both 89% (95% CI, 67 to 100) for desmoplastic/nodular (n = 11), 61% (95% CI, 51 to 71) and 75% (95% CI, 65 to 85) for classic (n = 107), and 20% (95% CI, 0 to 55) and 40% (95% CI, 0 to 83) for large-cell/anaplastic (n = 5) medulloblastoma ( P < .001 for EFS; P = .001 for OS). Histology (hazard ratio, 0.19 for desmoplastic/nodular and 45.97 for large-cell/anaplastic medulloblastoma) and nonresponse to the first chemotherapy cycle (hazard ratio, 1.97) were independent risk factors (EFS). Among 81 (66%) patients with tumor material, 5-year EFS and OS differed between low-risk (wingless [WNT], n = 4; both 100%), high-risk ( MYCC/ MYCN amplification; n = 5, both 20%), and intermediate-risk patients (neither; n = 72, 63% and 73%, respectively). Survival rates were different between molecular subgroups (WNT, n = 4; sonic hedgehog [SHH; n = 4]; group 4 [n = 41]; group 3 with [n = 3] or without [n = 17] MYCC/MYCN amplification; P < .001). All cases showed p53 immuno-negativity. There was no association between patients with nonresponding tumors to induction chemotherapy and WNT ( P = .143) or MYCC/MYCN status ( P = .075), histologic subtype ( P = .814), or molecular subtype ( P = .383), as assessed by Fisher's exact test. Conclusion This regimen was feasible and conferred overall favorable survival. Our data confirm the relevance of subgroup status and biologic parameters (WNT/ MYCC/ MYCN status) in a homogeneous prospective trial population, and show that metastatic group 3 patients do not uniformly have poor outcomes. Biologic subgroup, MYCC/ MYCN status, response to induction chemotherapy, and histologic subtype may serve for improved treatment stratification.

Survival after chemotherapy and stem cell transplant followed by delayed craniospinal irradiation is comparable to upfront craniospinal irradiation in pediatric embryonal brain tumor patients

Pediatric embryonal brain tumor patients treated with craniospinal irradiation (CSI) are at risk for adverse effects, with greater severity in younger patients. Here we compare outcomes of CSI vs. high-dose chemotherapy (HD), stem cell transplant (SCT) and delayed CSI in newly diagnosed patients. Two hundred one consecutive patients treated for medulloblastoma (72 %), supratentorial primitive neuroectodermal tumor (sPNET; 18 %) or pineoblastoma (10 %) at two institutions between 1988 and 2014 were retrospectively identified. Progression free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method and compared by log-rank tests. Adjuvant CSI regimens were used for 56 % of patients (upfront-CSI), and HD/SCT regimens were used in 32 % of patients. HD/SCT patients were significantly younger than those receiving upfront-CSI (2.9 vs. 7.8 years; P < 0.0001). There were no differences in metastases, extent of resection, or CSI dose between upfront-CSI and HD/SCT patients, but median follow-up was shorter in the HD/SCT group (6.2 vs. 3.9 years; P = 0.007). There were no significant outcome differences between upfront-CSI and HD/SCT patients who received CSI as a prophylaxis or following relapse (OS 66 % vs. 61 %, P = 0.13; PFS 67 % vs. 62 %, P = 0.12). Outcomes were equivalent when restricting analyses to HD/SCT patients who received prophylactic CSI prior to relapse (OS 66 % vs. 65 %, P = 0.5; PFS 67 % vs. 74 %, P = 0.8). At last follow-up, 48 % of HD/SCT patients had received neither definitive nor salvage radiotherapy. In this retrospective cohort, outcomes with adjuvant HD/SCT followed by delayed CSI are comparable to upfront-CSI for carefully surveyed pediatric embryonal brain tumor patients. Future prospective studies are required to validate this finding, and also to assess the impact of delayed CSI on neurocognitive outcomes.

Medulloblastoma

Medulloblastoma accounts for nearly 10% of all childhood brain tumors. These tumors occur exclusively in the posterior fossa and have the potential for leptomeningeal spread. Treatment includes a combination of surgery, radiation therapy (in patients >3 years old). Patients >3 years old are stratified based on the volume of postoperative residual tumor and the presence or absence of metastases into "standard risk" and "high risk" categories with long-term survival rates of approximately 85% and 70%, respectively. Outcomes are inferior in infants and children younger than 3 years with exception of those patients with the medulloblastoma with extensive nodularity histologic subtype. Treatment for medulloblastoma is associated with significant morbidity, especially in the youngest patients. Recent molecular subclassification of medulloblastoma has potential prognostic and therapeutic implications. Future incorporation of molecular subgroups into treatment protocols will hopefully improve both survival outcomes and posttreatment quality of life.

High Incidence of Veno-Occlusive Disease With Myeloablative Chemotherapy Following Craniospinal Irradiation in Children With Newly Diagnosed High-Risk CNS Embryonal Tumors: A Report From the Children's Oncology Group (CCG-99702)

BACKGROUND

The outcomes with high-risk central nervous system (CNS) embryonal tumors remain relatively poor despite aggressive treatment. The purposes of this study using postirradiation myeloablative chemotherapy with autologous hematopoietic stem cell rescue (ASCR) were to document feasibility and describe toxicities of the regimen, establish the appropriate dose of thiotepa, and estimate the overall survival (OS) and event-free survival (EFS).

PROCEDURE

The Children's Cancer Group conducted this pilot study in children and adolescents with CNS embryonal tumors. The treatment consisted of induction chemotherapy to mobilize hematopoietic stem cells, chemoradiotherapy, and myeloablative consolidation chemotherapy with ASCR.

RESULTS

The study accrued 25 subjects in 40 months and was closed early due to toxicity, namely, veno-occlusive disease (VOD) of the liver, more recently termed sinusoidal obstructive syndrome (SOS). Of 24 eligible subjects, three of 11 (27%) receiving thiotepa Dose Level 1 (150 mg/m(2) /day × 3 days) and three of 12 (25%) receiving de-escalated Dose Level 0 (100 mg/m(2) /day × 3 days) experienced VOD/SOS. One additional subject experienced toxic death attributed to septic shock; postmortem examination revealed clinically undiagnosed VOD/SOS. The 2-year EFS and OS were 54 ± 10% and 71 ± 9%, respectively. The 5-year EFS and OS were 46 ± 11% and 50 ± 11%.

CONCLUSIONS

The treatment regimen was deemed to have an unacceptable rate of VOD/SOS. There was complete recovery in all six cases. The overall therapeutic strategy using a regimen less likely to cause VOD/SOS may merit further evaluation for the highest risk patients.

Blockade of Inhibitors of Apoptosis Proteins in Combination with Conventional Chemotherapy Leads to Synergistic Antitumor Activity in Medulloblastoma and Cancer Stem-Like Cells

Background

Medulloblastoma (MB) is the most common pediatric primary malignant brain tumor. Approximately one-third of MB patients succumb to treatment failure and some survivors suffer detrimental side effects. Hence, the purpose of this study is to explore new therapeutic regimens to overcome chemotherapeutic agent resistance or reduce chemotherapy-induced toxicity.

Methods

We detected the expression of inhibitors of apoptosis proteins (IAPs) in MB and CD133+ MB cell lines and MB tissues using immunoblotting and immunohistochemical staining. The antitumor effects of inhibitors against IAPs on MB or CD133+ MB cells were evaluated by MTT assay, Annexin V/PI analysis, and caspase-3/7 activity. Autophagy was assessed by the conversion of light chain (LC) 3-I to LC3-II and Cyto-ID autophagy detection kit.

Results

MB cells showed higher expression of IAPs compared to normal astrocytes and normal brain tissues. Conventional chemotherapeutic agents combined with small-molecule IAP inhibitors (LCL161 or LBW242) showed a synergistic effect in MB cells. Combined treatments triggered apoptosis in MB cells through activation of caspase-3/7 and autophagic flux simultaneously. In addition, we found that CD133+ MB cells with features of cancer stem cells displayed higher levels of X-linked inhibitor of apoptosis (XIAP) and cellular inhibitor of apoptosis 1/2 (cIAP1/2), and were hypersensitive to treatment with IAP inhibitors.

Conclusions

These results shed light on the biological effects of combination therapy on MB cells and illustrate that IAP inhibitors are more effective for CD133+ stem-like MB cells.

Childhood medulloblastoma

Medulloblastoma accounts for 15-20% of childhood nervous system tumours. The risk of dying was reduced by 30% in the last twenty years. Patients are divided in risk strata according to post-surgical disease, dissemination, histology and some molecular features such as WNT subgroup and MYC status. Sixty to 70% of patients older than 3 years are assigned to the average-risk group. High-risk patients include those with disseminated and/or residual disease, large cell and/or anaplastic histotypes, MYC genes amplification. Current and currently planned clinical trials will: (1) evaluate the feasibility of reducing both the dose of craniospinal irradiation and the volume of the posterior fossa radiotherapy (RT) for those patients at low biologic risk, commonly identified as those having a medulloblastoma of the WNT subgroup; (2) determine whether intensification of chemotherapy (CT) or irradiation can improve outcome in patients with high-risk disease; (3) find target therapies allowing tailored therapies especially for relapsing patients and those with higher biological risk.

Risk stratification of childhood medulloblastoma in the molecular era: the current consensus

Historical risk stratification criteria for medulloblastoma rely primarily on clinicopathological variables pertaining to age, presence of metastases, extent of resection, histological subtypes and in some instances individual genetic aberrations such as MYC and MYCN amplification. In 2010, an international panel of experts established consensus defining four main subgroups of medulloblastoma (WNT, SHH, Group 3 and Group 4) delineated by transcriptional profiling. This has led to the current generation of biomarker-driven clinical trials assigning WNT tumors to a favorable prognosis group in addition to clinicopathological criteria including MYC and MYCN gene amplifications. However, outcome prediction of non-WNT subgroups is a challenge due to inconsistent survival reports. In 2015, a consensus conference was convened in Heidelberg with the objective to further refine the risk stratification in the context of subgroups and agree on a definition of risk groups of non-infant, childhood medulloblastoma (ages 3-17). Published and unpublished data over the past 5 years were reviewed, and a consensus was reached regarding the level of evidence for currently available biomarkers. The following risk groups were defined based on current survival rates: low risk (>90 % survival), average (standard) risk (75-90 % survival), high risk (50-75 % survival) and very high risk (<50 % survival) disease. The WNT subgroup and non-metastatic Group 4 tumors with whole chromosome 11 loss or whole chromosome 17 gain were recognized as low-risk tumors that may qualify for reduced therapy. High-risk strata were defined as patients with metastatic SHH or Group 4 tumors, or MYCN-amplified SHH medulloblastomas. Very high-risk patients are Group 3 with metastases or SHH with TP53 mutation. In addition, a number of consensus points were reached that should be standardized across future clinical trials. Although we anticipate new data will emerge from currently ongoing and recently completed clinical trials, this consensus can serve as an outline for prioritization of certain molecular subsets of tumors to define and validate risk groups as a basis for future clinical trials.

[Pediatric medulloblastoma: Retrospective series of 52 patients]

PURPOSE

Retrospective analysis of the results of 52 children irradiated for a medulloblastoma.

PATIENTS AND METHODS

Between 1974 and 2012, 52 children with an average age of 6 years and a half (11 months-17 years and a half) were treated with surgery then with radiotherapy at the Comprehensive Cancer Centre of Strasbourg (France). For 44 children, the treatment consisted of a chemotherapy.

RESULTS

After a mean follow-up of 106.6 months (7-446 months), 13 relapses and 24 deaths were observed. Overall survival at 5 years and 10 years were 62% and 57%, respectively. Disease-free survival at 5 years and 10 years were 80% and 63%, respectively. Univariate analysis found the following adverse prognostic factors: the existence of a postoperative residue, the positivity of the cerebrospinal fluid, the metastatic status and medulloblastoma of high-risk. Positivity of the cerebrospinal fluid remains a negative factor in multivariate analysis.

CONCLUSION

These results confirm the survival rate obtained by a conventional approach (surgery then irradiation). Insufficiency of results and rarity of medulloblastoma require the establishment of international protocols.

The UK Experience of a Treatment Strategy for Pediatric Metastatic Medulloblastoma Comprising Intensive Induction Chemotherapy, Hyperfractionated Accelerated Radiotherapy and Response Directed High Dose Myeloablative Chemotherapy or Maintenance Chemotherapy (Milan Strategy)

BACKGROUND

Historically, the 5-year overall survival (OS) for metastatic medulloblastoma (MMB) was less than 40%. The strategy of post-operative induction chemotherapy (IC) followed by hyperfractionated accelerated radiotherapy (HART) and response directed high dose chemotherapy (HDC) was reported in a single center study to improve 5-year OS to 73%. We report outcomes of this strategy in UK.

METHODS

Questionnaires were sent to all 20 UK pediatric oncology primary treatment centers to collect retrospective data on delivered treatment, toxicity and survival with this strategy in children aged 3-19 years with MMB.

RESULTS

Between February 2009 and October 2011, 34 patients fulfilled the entry criteria of the original study. The median age was 7 years (range 3-15). Median interval from surgery to HART was 109 versus 85 days in the original series. The incidence of grade 3 or 4 hematological toxicities with IC and HDC was 83-100%. All 16 patients who achieved complete response by the end of the regimen remain in remission but only three of 18 patients with lesser responses are still alive (P < 0.0001). With a median follow-up of 45 months for survivors, the estimated 3-year OS is 56% (95% CI 38, 71). This result is outside the 95% CI of the original study results and encompasses the historical survival result of 40%.

CONCLUSION

Within the limits of statistical significance, we did not replicate the improved survival results reported in the original series. The reasons include differences in patient sub-groups and protocol administration. International randomized phase III studies are needed.