Survival After Relapse of Medulloblastoma

Mechanistic insights into medulloblastoma relapse

Pediatric brain tumors are the leading cause of cancer-related deaths in children, with medulloblastoma (MB) being the most common type. A better understanding of these malignancies has led to their classification into four major molecular subgroups. This classification not only facilitates the stratification of clinical trials, but also the development of more effective therapies. Despite recent progress, approximately 30% of children diagnosed with MB experience tumor relapse. Recurrent disease in MB is often metastatic and responds poorly to current therapies. As a result, only a small subset of patients with recurrent MB survive beyond one year. Due to its dismal prognosis, novel therapeutic strategies aimed at preventing or managing recurrent disease are urgently needed. In this review, we summarize recent advances in our understanding of the molecular mechanisms behind treatment failure in MB, as well as those characterizing recurrent cases. We also propose avenues for how these findings can be used to better inform personalized medicine approaches for the treatment of newly diagnosed and recurrent MB. Lastly, we discuss the treatments currently being evaluated for MB patients, with special emphasis on those targeting MB by subgroup at diagnosis and relapse.

Disease Evolution Monitored by Serial Cerebrospinal Fluid Liquid Biopsies in Two Cases of Recurrent Medulloblastoma

Medulloblastoma is the most common malignant brain tumor in childhood. Initial treatment generally includes surgery, irradiation, and chemotherapy. Approximately 20-30% of patients will experience a recurrence, which portends a very poor prognosis. The current standard of care for evaluation for relapse includes radiographic surveillance with magnetic resonance imaging at regular intervals. The presence of circulating tumor DNA in the cerebrospinal fluid has been demonstrated to be a predictor of a higher risk of progression in a research setting for patients with medulloblastoma treated on a prospective single institution clinical trial. We have previously published and clinically validated a liquid-biopsy-based genetic assay utilizing low-pass whole genome sequencing to detect copy number alterations in circulating tumor DNA. Here, we present two teenage patients with posterior fossa medulloblastoma with recurrent disease who have been monitored with serial liquid biopsies showing tumor evolution over time, demonstrating the clinical utility of these approaches.

Effective re-induction regimen for children with recurrent medulloblastoma

Background

There is no standard treatment for the recurrence of medulloblastoma, the most common malignant childhood brain tumor, and prognosis remains dismal. In this study, we introduce a regimen that is well-tolerated and effective at inducing remission.

Methods

The primary objectives of this study were to assess tolerability of the regimen and overall response rate (ORR). A retrospective chart review of patients with recurrent medulloblastoma, treated at two institutions with a re-induction regimen of intravenous irinotecan and cyclophosphamide with oral temozolomide and etoposide, was performed. Demographic, clinicopathologic, toxicity, and response data were collected and analyzed.

Results

Nine patients were identified. Median age was 5.75 years. Therapy was well-tolerated with no therapy-limiting toxicities and no toxic deaths. Successful stem cell collection was achieved in all 5 patients in whom it was attempted. ORR after 2 cycles was 78%. Three patients had a complete response, 4 patients had a partial response, 1 patient had stable disease, and 1 patient had progressive disease. Four patients are alive with no evidence of disease (NED), 2 patients are alive with disease, 2 patients have died of disease, and 1 patient died of toxicity related to additional therapy (NED at time of death).

Conclusions

This regimen is well-tolerated and effective. Tumor response was noted in the majority of cases, allowing patients to proceed to additional treatment with no or minimal disease. Further study of this regimen in a clinical trial setting is an important next step.

Intrathecal delivery of nanoparticle PARP inhibitor to the cerebrospinal fluid for the treatment of metastatic medulloblastoma

The morbidity associated with pediatric medulloblastoma, in particular in patients who develop leptomeningeal metastases, remains high in the absence of effective therapies. Administration of substances directly into the cerebrospinal fluid (CSF) is one approach to circumvent the blood-brain barrier and focus delivery of drugs to the site of tumor. However, high rates of CSF turnover prevent adequate drug accumulation and lead to rapid systemic clearance and toxicity. Here, we show that PLA-HPG nanoparticles, made with a single-emulsion, solvent evaporation process, can encapsulate talazoparib, a PARP inhibitor (BMN-673). These degradable polymer nanoparticles improve the therapeutic index when delivered intrathecally and lead to sustained drug retention in the tumor as measured with PET imaging and fluorescence microscopy. We demonstrate that administration of these particles into the CSF, alone or in combination with systemically administered temozolomide, is a highly effective therapy for tumor regression and prevention of leptomeningeal spread in xenograft mouse models of medulloblastoma. These results provide a rationale for harnessing nanoparticles for the delivery of drugs limited by brain penetration and therapeutic index and demonstrate important advantages in tolerability and efficacy for encapsulated drugs delivered locoregionally.

Current Strategies for Management of Medulloblastoma

Medulloblastoma (MB) is the most common malignant central nervous system tumor of childhood, which includes multiple molecular subgroups (4) and subtypes (8 to 12), each with different outcomes and potential therapy options. Long-term survival remains poor for many of the subtypes, with high late mortality risks and poor health-related quality of life. Initial treatment strategies integrate molecular subgroup information with more standard clinical and phenotypic factors to risk stratify newly diagnosed patients. Clinical trials treating relapsed disease, often incurable, now include multiple new approaches in an attempt to improve progression-free and overall survival.

Clinical, Histological, and Molecular Prognostic Factors in Childhood Medulloblastoma: Where Do We Stand?

Medulloblastomas, highly aggressive neoplasms of the central nervous system (CNS) that present significant heterogeneity in clinical presentation, disease course, and treatment outcomes, are common in childhood. Moreover, patients who survive may be diagnosed with subsequent malignancies during their life or could develop treatment-related medical conditions. Genetic and transcriptomic studies have classified MBs into four subgroups: wingless type (WNT), Sonic Hedgehog (SHH), Group 3, and Group 4, with distinct histological and molecular profiles. However, recent molecular findings resulted in the WHO updating their guidelines and stratifying medulloblastomas into further molecular subgroups, changing the clinical stratification and treatment management. In this review, we discuss most of the histological, clinical, and molecular prognostic factors, as well the feasibility of their application, for better characterization, prognostication, and treatment of medulloblastomas.

Current Open Trials and Molecular Update for Pediatric Embryonal Tumors

BACKGROUND

Embryonal tumors are highly malignant cancers of the central nervous system, with a relatively high incidence in infants and young children. Even with intensive multimodal treatment, the prognosis of many types is guarded, and treatment-related toxicity is significant. Recent advances in molecular diagnostics allowed the discovery of novel entities and inter-tumor subgroups, with opportunities for improved risk-stratification and treatment approaches.

SUMMARY

Medulloblastomas separate into four distinct subgroups with distinct clinicopathologic characteristics, and data from recent clinical trials for newly diagnosed medulloblastoma support subgroup-specific treatment approaches. Atypical teratoid rhabdoid tumor (ATRT), embryonal tumor with multilayered rosettes (ETMR), and pineoblastoma, as well as other rare embryonal tumors, can be distinguished from histologically similar tumors by virtue of characteristic molecular findings, with DNA methylation analysis providing a strong adjunct in indeterminate cases. Methylation analysis can also allow further subgrouping of ATRT and pineoblastoma. Despite the dire need to improve outcomes for patients with these tumors, their rarity and lack of actionable targets lead to a paucity of clinical trials and novel therapeutics.

KEY MESSAGES

(1) Embryonal tumors can be accurately diagnosed with pediatric-specific sequencing techniques. (2) Medulloblastoma risk stratification and treatment decisions should take into account molecular subgroups. (3) There is a dire need for a novel collaborative clinical trial design to improve outcomes is rare pediatric embryonal tumors.

Role of Radiotherapy in Patients With Relapsed Medulloblastoma

During the last three decades, the management of medulloblastoma (MBL) has made enormous progress with a multidisciplinary approach, incorporating surgery, radiotherapy (RT), and chemotherapy. Despite this improvement, 20%-30% of patients with MBL remain at risk of disease recurrence, with its relapse being possibly fatal. To date, the salvage treatment for relapse remains challenging, and various approaches have been suggested for the retreatment. In this review, I have described the characteristics of patients with relapsed MBL, patterns of relapse and the most commonly prescribed treatment. Further, I have reviewed the studies on re-irradiation and its associated issues to conclusively suggest the RT recommendations for patients with relapsed MBL.

Current studies and future directions for medulloblastoma: A review from the pacific pediatric neuro-oncology consortium (PNOC) disease working group

Medulloblastoma (MB) is the most common malignant central nervous system tumor of childhood, comprising a heterogenous group of tumors each with distinct biology, clinical behavior, and prognosis. Long-term survival remains unacceptable, and those who do survive face high late mortality risk, new chronic treatment-related medical conditions, neurocognitive impairments, and poor health-related quality of life. Up-front treatment strategies now integrate molecular subgrouping with standard clinico-radiological factors to more actually risk stratify newly-diagnosed patients. To what extent this new stratification will lead to improvements in treatment outcome will be determined in the coming years. In parallel, discovery and appreciation for medulloblastoma's inter- and intra-tumoral heterogeneity continues growing. Clinical trials treating relapsed disease now encompass precision medicine, epigenetic modification, and immune therapy approaches. The Pacific Pediatric Neuro-Oncology (PNOC) Medulloblastoma Working Group is committed to developing clinical trials based on these evolving therapeutic strategies and supports translational efforts by PNOC researchers and the multi-stakeholder medulloblastoma community at large.

Immunohistochemical assessment and clinical, histopathologic, and molecular correlates of membranous somatostatin type-2A receptor expression in high-risk pediatric central nervous system tumors

INTRODUCTION

177Lu-DOTATATE, a radionuclide therapy that binds somatostatin type-2A receptors (SST2A), has demonstrated efficacy in neuroendocrine tumors and evidence of central nervous system (CNS) penetration, supporting potential expansion within pediatric neuro-oncology. Understanding the prevalence of SST2A expression across pediatric CNS tumors is essential to identify patients who may benefit from somatostatin receptor-targeted therapy and to further elucidate the oncogenic role of SST2A.

METHODS

SST2A immunohistochemistry (IHC) was performed on tumor specimens and interpreted by an experienced pathologist (blinded), utilizing semi-quantitative scoring of membranous expression within viable tumor. Immunoreactive cell percentage was visually scored as 0 (none), 1 (<10%), 2 (10-50%), 3 (51-80%), or 4 (>80%). Staining intensity was scored as 0 (none), 1 (weak), 2 (moderate), or 3 (strong). Combined scores for each specimen were calculated by multiplying percent immunoreactivity and staining intensity values (Range: 0-12).

RESULTS

A total of 120 tumor samples from 114 patients were analyzed. Significant differences in SST2A IHC scores were observed across histopathologic diagnoses, with consistently high scores in medulloblastoma (mean ± SD: 7.5 ± 3.6 [n=38]) and meningioma (5.7 ± 3.4 [n=15]), compared to minimal or absent expression in ATRT (0.3 ± 0.6 [n=3]), ETMR (1.0 ± 0 [n=3]), ependymoma (grades I-III; 0.2 ± 0.7 [n=27]), and high-grade glioma (grades III-IV; 0.4 ± 0.7 [n=23]). Pineoblastoma (3.8 ± 1.5 [n=4]) and other embryonal tumors (2.0 ± 4.0 [n=7]) exhibited intermediate, variable expression. Among medulloblastomas, SST2A IHC scores were higher in non-SHH (8.5 ± 3.1) than SHH (5.0 ± 3.3) molecular subgroups (p=0.033). In a subset of paired primary and recurrent specimens from four patients, SST2A IHC scores remained largely unchanged.

DISCUSSION

High membranous SST2A expression was demonstrated in medulloblastoma, meningioma, and some rarer embryonal tumors with potential diagnostic, biologic, and therapeutic implications. Somatostatin receptor-targeted therapy such as 177Lu-DOTATATE deserves further investigation in these highly SST2A-expressing pediatric CNS tumors.

Medulloblastoma in the Modern Era: Review of Contemporary Trials, Molecular Advances, and Updates in Management

Critical discoveries over the past two decades have transformed our understanding of medulloblastoma from a single entity into a clinically and biologically heterogeneous disease composed of at least four molecularly distinct subgroups with prognostically and therapeutically relevant genomic signatures. Contemporary clinical trials also have provided valuable insight guiding appropriate treatment strategies. Despite therapeutic and biological advances, medulloblastoma patients across the age spectrum experience tumor- and treatment-related morbidity and mortality. Using an updated risk stratification approach integrating both clinical and molecular features, ongoing research seeks to (1) cautiously reduce therapy and mitigate toxicity in low-average risk patients, and (2) thoughtfully intensify treatment with incorporation of novel, biologically guided agents for patients with high-risk disease. Herein, we review important historical and contemporary studies, discuss management updates, and summarize current knowledge of the biological landscape across unique pediatric, infant, young adult, and relapsed medulloblastoma populations.

A phase I study of irinotecan and temozolomide with bevacizumab in children with recurrent/refractory central nervous system tumors

PURPOSE

Children with relapsed/refractory central nervous system (CNS) tumors require novel combinations of therapies. Irinotecan and temozolomide (IT) is a frequently used therapy with an established toxicity profile. Bevacizumab is an anti-VEGF monoclonal antibody with demonstrated activity in CNS tumors. Therefore, the combination of these agents has therapeutic potential in CNS tumors. The objective of this study was to determine the maximum tolerated dose (MTD) of escalating dose IT combined with a fixed dose of bevacizumab (BIT) in children with relapsed/refractory CNS tumors.

METHODS

A phase I trial was performed in a 3 + 3 design. Therapy toxicities and radiologic responses to treatment were described.

RESULTS

One hundred eighty cycles of therapy were administered to 26 patients. The MTD of BIT was dose level 1, (bevacizumab 10 mg/kg on days 1 and 15, irinotecan 125 mg/m² on days 1 and 15, and temozolomide 125 mg/m² on days 1-5 of 28-day cycles). The regimen was well tolerated with primarily hematologic toxicity, which was not dose limiting. Among 22 response-evaluable patients, there was 1 complete response (CR), 6 partial responses (PR), and 10 stable diseases (SD) with an overall response rate (ORR: CR + PR) of 31.8%.

CONCLUSION

At the MTD, BIT therapy was well tolerated, and prolonged treatment courses of up to 24 cycles were feasible, with radiographic responses observed. Further evaluation is needed for efficacy in a phase II trial (NCT00876993, registered April 7, 2009, www.

CLINICALTRIALS

gov ).

Loss of H3K27 trimethylation promotes radiotherapy resistance in medulloblastoma and induces an actionable vulnerability to BET inhibition

Medulloblastoma has been categorized into four subgroups based on genetic, epigenetic, and transcriptional profiling. Radiation is used for treating medulloblastoma regardless of the subgroup. A better understanding of the molecular pathways determining radiotherapy response could help improve medulloblastoma treatment. Here, we investigated the role of the EZH2-dependent histone H3K27 trimethylation in radiotherapy response in medulloblastoma. The tumors in 47.2% of group 3 and 4 medulloblastoma patients displayed H3K27me3 deficiency. Loss of H3K27me3 was associated with a radioresistant phenotype, high relapse rates, and poor overall survival. In H3K27me3-deficient medulloblastoma cells, an epigenetic switch from H3K27me3 to H3K27ac occurred at specific genomic loci, altering the transcriptional profile. The resulting upregulation of EPHA2 stimulated excessive activation of the pro-survival AKT signaling pathway, leading to radiotherapy resistance. BET inhibition overcame radiation resistance in H3K27me3-deficient medulloblastoma cells by suppressing H3K27ac levels, blunting EPHA2 overexpression, and mitigating excessive AKT signaling. Additionally, BET inhibition sensitized medulloblastoma cells to radiation by enhancing the apoptotic response through suppression of Bcl-xL and upregulation of Bim. This work demonstrates a novel mechanism of radiation resistance in medulloblastoma and identifies an epigenetic marker predictive of radiotherapy response. Based on these findings, we propose an epigenetically guided treatment approach targeting radiotherapy resistance in medulloblastoma patients.

Conventional Therapies Deplete Brain-Infiltrating Adaptive Immune Cells in a Mouse Model of Group 3 Medulloblastoma Implicating Myeloid Cells as Favorable Immunotherapy Targets

Medulloblastoma is the most common childhood brain cancer. Mainstay treatments of radiation and chemotherapy have not changed in decades and new treatment approaches are crucial for the improvement of clinical outcomes. To date, immunotherapies for medulloblastoma have been unsuccessful, and studies investigating the immune microenvironment of the disease and the impact of current therapies are limited. Preclinical models that recapitulate both the disease and immune environment are essential for understanding immune-tumor interactions and to aid the identification of new and effective immunotherapies. Using an immune-competent mouse model of aggressive Myc-driven medulloblastoma, we characterized the brain immune microenvironment and changes induced in response to craniospinal irradiation, or the medulloblastoma chemotherapies cyclophosphamide or gemcitabine. The role of adaptive immunity in disease progression and treatment response was delineated by comparing survival outcomes in wildtype C57Bl/6J and in mice deficient in Rag1 that lack mature T and B cells. We found medulloblastomas in wildtype and Rag1-deficient mice grew equally fast, and that craniospinal irradiation and chemotherapies extended survival equally in wildtype and Rag1-deficient mice, suggesting that tumor growth and treatment response is independent of T and B cells. Medulloblastomas were myeloid dominant, and in wildtype mice, craniospinal irradiation and cyclophosphamide depleted T and B cells in the brain. Gemcitabine treatment was found to minimally alter the immune populations in the brain, resulting only in a depletion of neutrophils. Intratumorally, we observed an abundance of Iba1⁺ macrophages, and we show that CD45^high cells comprise the majority of immune cells within these medulloblastomas but found that existing markers are insufficient to clearly delineate resident microglia from infiltrating macrophages. Ultimately, brain resident and peripheral macrophages dominate the brain and tumor microenvironment and are not depleted by standard-of-care medulloblastoma therapies. These populations therefore present a favorable target for immunotherapy in combination with front-line treatments.

Opposing Roles of Vascular Endothelial Growth Factor C in Metastatic Dissemination and Resistance to Radio/Chemotherapy: Discussion of Mechanisms and Therapeutic Strategies

Many cancers can be cured by combining surgery with healthy margins, radiation therapy and chemotherapies. However, when the pathology becomes metastatic, cancers can be incurable. The best situation involves "chronicization" of the pathology even for several years. However, most of the time, patients die within a few months. To disseminate throughout the body, cancer cells must enter the vascular network and seed in another organ. However, during the initiation of cancer processes, the tumor is avascular. Later, the production of angiogenic factors causes tumor neovascularization and subsequent growth and spread, and the presence of blood and/or lymphatic vessels is associated with high grade tumors. Moreover, during tumor development, cancer cells enter lymphatic vessels and disseminate via the lymphatic network. Hence, blood and lymphatic vessels are considered as main routes of metastatic dissemination and cancer aggressiveness. Therefore, anti-angiogenic drugs entered in the therapeutic arsenal from 2004. Despite undeniable effects however, they are far from curative and only prolong survival by a few months.Recently, the concepts of angio/lymphangiogenesis were revisited by analyzing the role of blood and lymphatic vessels at the initiation steps of tumor development. During this period, cancer cells enter lymphatic vessels and activate immune cells within lymph nodes to initiate an antitumor immune response. Moreover, the presence of blood vessels at the proximity of the initial nodule allows immune cells to reach the tumor and eliminate cancer cells. Therefore, blood and lymphatic networks have a beneficial role during a defined time window. Considering only their detrimental effects is a concern. Hence, administration of anti-angio/lymphangiogenic therapies should be revisited to avoid the destruction of networks involved in antitumor immune response. This review mainly focuses on one of the main drivers of lymphangiogenesis, the VEGFC and its beneficial and pejorative roles according to the grade of aggressive tumors.

Craniospinal irradiation as part of re-irradiation for children with recurrent medulloblastoma

BACKGROUND

Many studies have demonstrated in the last years that once medulloblastoma has recurred, the probability of regaining tumor control is poor despite salvage therapy. Although re-irradiation has an emerging role in other relapsed brain tumors, there is a lack of strong data on re-irradiation for medulloblastoma.

METHODS

This is a retrospective cohort study of patients aged 18 years or under, treated at least by a second course of external beam for recurrence medulloblastoma at Garrahan Hospital between 2009 and 2020. Twenty-four patients met eligibility criteria for inclusion. All patients received upfront radiotherapy as part of the curative-intent first radiotherapy, either craniospinal irradiation (CSI) followed by posterior fossa boost in 20 patients or focal posterior fossa radiation in 4 infants. The second course of radiation consisted of CSI in 15 and focal in 9. The 3-year post first failure OS (50% vs. 0%; p = 0.0010) was significantly better for children who received re-CSI compared to children who received focal re-irradiation. Similarly, the 3-year post-re-RT PFS (31% vs. 0%; p = 0.0005) and OS (25% vs. 0%; p = 0.0003) was significantly improved for patients who received re-CSI compared to patients who received focal re-irradiation. No symptomatic intratumoral haemorrhagic events or symptomatic radionecrosis were observed. Survivors fell within mild to moderate intellectual disability range, with a median IQ at last assessment of 58 (range 43-69).

CONCLUSIONS

Re-irradiation with CSI is a safe and effective treatment for children with relapsed medulloblastoma; improves disease control and survival compared with focal re-irradiation. However this approach carries a high neurocognitive cost.

Prognostic Value of miR-137 in Children with Medulloblastoma and its Regulatory Effect on Tumor Progression

Medulloblastoma is a malignant tumor with high incidence and poor prognosis in adolescents and children. MicroRNA-137 (miR-137) has been found to be abnormally expressed in cancers such as pancreatic cancer. The purpose of this study is to explore the expression of miR-137 in MB and its role in cell physiological activities to determine the significance of miR-137 in the prognosis of MB. First, the expression of miR-137 in MB tissues and cell lines was analyzed by qRT-PCR. Then the Kaplan-Meier survival curve was used to analyze the significance of miR-137 expression in the prognosis, and the Cox regression model was used to explore the correlation between miR-137 expression and clinical characteristics. The effects of miR-137 on MB cell activities were analyzed by MTT assay, Transwell assays, and flow cytometry. It can be concluded from the results that the expression of miR-137 is down-regulated in MB tissues and cells. The down-regulation of miR-137 was significantly related to the poor prognosis of MB, and significantly related to clinical indicators. Up-regulated miR-137 inhibited cell proliferation, migration, invasion, and cell cycle progression, as well as induced cell apoptosis by targeting KDM1A. This study can conclude that miR-137 may be used as a prognostic biomarker of MB.

Temozolomide with irinotecan versus temozolomide, irinotecan plus bevacizumab for recurrent medulloblastoma of childhood: Report of a COG randomized Phase II screening trial

BACKGROUND

Approximately 30% of children with medulloblastoma (MB) experience recurrence, which is usually incurable. This study compared the overall survival (OS) of patients receiving temozolomide (TMZ) and irinotecan with that of patients receiving TMZ, irinotecan, and bevacizumab for recurrent MB/central nervous system (CNS) primitive neuroectodermal tumor (PNET).

METHODS

Patients with relapsed/refractory MB or CNS PNET were randomly assigned to receive TMZ (150 mg/m² /day PO on days 1-5) and irinotecan (50 mg/m² /day IV on days 1-5) with or without bevacizumab (10 mg/kg IV on days 1 and 15).

RESULTS

One hundred five patients were eligible and treated on study. Median OS was 13 months in the standard arm and 19 months with the addition of bevacizumab; median event-free survival (EFS) was 6 months in the standard arm and 9 months with the addition of bevacizumab. The hazard ratio for death from the stratified relative-risk regression model is 0.63. Overall, 23 patients completed 12 courses of planned protocol therapy, 23% (12/52) in the experimental arm with bevacizumab versus 21% (11/53) in the standard arm. Toxicity profiles were comparable in both treatment arms. The estimate of the incidence of feasibility events associated with the bevacizumab arm is three of 52 (5.8%) (95% CI 1.2-16%). Events included myelosuppression, electrolyte abnormalities, diarrhea, and elevated transaminases. One intracranial hemorrhage event was observed in each arm.

CONCLUSION

The addition of bevacizumab to TMZ/irinotecan significantly reduced the risk of death in children with recurrent MB. The combination was relatively well tolerated in this heavily pretreated cohort. The three-drug regimen demonstrated a sufficient risk reduction to warrant further investigation.

Efficacy of Carboplatin and Isotretinoin in Children With High-risk Medulloblastoma: A Randomized Clinical Trial From the Children's Oncology Group

Importance

Brain tumors are the leading cause of disease-related death in children. Medulloblastoma is the most common malignant embryonal brain tumor, and strategies to increase survival are needed.

Objective

To evaluate therapy intensification with carboplatin as a radiosensitizer and isotretinoin as a proapoptotic agent in children with high-risk medulloblastoma in a randomized clinical trial and, with a correlative biology study, facilitate planned subgroup analysis according to World Health Organization consensus molecular subgroups of medulloblastoma.

Design, Setting, and Participants

A randomized clinical phase 3 trial was conducted from March 2007 to September 2018. Analysis was completed in September 2020. Patients aged 3 to 21 years with newly diagnosed high-risk medulloblastoma from Children's Oncology Group institutions within the US, Canada, Australia, and New Zealand were included. High-risk features included metastasis, residual disease, or diffuse anaplasia.

Interventions

Patients were randomized to receive 36-Gy craniospinal radiation therapy and weekly vincristine with or without daily carboplatin followed by 6 cycles of maintenance chemotherapy with cisplatin, cyclophosphamide, and vincristine with or without 12 cycles of isotretinoin during and following maintenance.

Main Outcomes and Measures

The primary clinical trial end point was event-free survival, using the log-rank test to compare arms. The primary biology study end point was molecular subgroup classification by DNA methylation array.

Results

Of 294 patients with medulloblastoma, 261 were evaluable after central radiologic and pathologic review; median age, 8.6 years (range, 3.3-21.2); 183 (70%) male; 189 (72%) with metastatic disease; 58 (22%) with diffuse anaplasia; and 14 (5%) with greater than 1.5-cm2 residual disease. For all participants, the 5-year event-free survival was 62.9% (95% CI, 55.6%-70.2%) and overall survival was 73.4% (95% CI, 66.7%-80.1%). Isotretinoin randomization was closed early owing to futility. Five-year event-free survival was 66.4% (95% CI, 56.4%-76.4%) with carboplatin vs 59.2% (95% CI, 48.8%-69.6%) without carboplatin (P = .11), with the effect exclusively observed in group 3 subgroup patients: 73.2% (95% CI, 56.9%-89.5%) with carboplatin vs 53.7% (95% CI, 35.3%-72.1%) without (P = .047). Five-year overall survival differed by molecular subgroup (P = .006): WNT pathway activated, 100% (95% CI, 100%-100%); SHH pathway activated, 53.6% (95% CI, 33.0%-74.2%); group 3, 73.7% (95% CI, 61.9%-85.5%); and group 4, 76.9% (95% CI, 67.3%-86.5%).

Conclusions and Relevance

In this randomized clinical trial, therapy intensification with carboplatin improved event-free survival by 19% at 5 years for children with high-risk group 3 medulloblastoma. These findings further support the value of an integrated clinical and molecular risk stratification for medulloblastoma.

Trial Registration

ClinicalTrials.gov Identifier: NCT00392327.

Overview and recent advances in the targeting of medulloblastoma cancer stem cells

Introduction: Medulloblastoma, an embryonal small round blue cell tumor primarily arising in the posterior fossa, is the most common malignancy of the central nervous system in children and requires intensive multi-modality therapy for cure. Overall 5-year survival is approximately 75% in children with primary disease, but outcomes for relapsed disease are very poor. Recent advances have identified molecular subgroups with excellent prognosis, with 5-year overall survival rates >90%, and subgroups with very poor prognosis with overall survival rates <50%. Molecular subtyping has allowed for more sophisticated risk stratification of patients, but new treatments for the highest risk patients have not yet improved outcomes. Targeting cancer stem cells may improve outcomes, and several candidate targets and novel drugs are under investigation.Areas covered: We discuss medulloblastoma epidemiology, biology, treatment modalities, risk stratification, and molecular subgroup analysis, links between subgroup and developmental biology, cancer stem cell biology in medulloblastoma including previously described cancer stem cell markers and proposed targeted treatments in the current literature.Expert opinion: The understanding of cancer stem cells in medulloblastoma will advance therapies targeting the most treatment-resistant cells within the tumor and therefore reduce the incidence of treatment refractory and relapsed disease.

Medulloblastoma recurrence and metastatic spread are independent of colony-stimulating factor 1 receptor signaling and macrophage survival

PURPOSE

Tumor infiltration by immunosuppressive myeloid cells or tumor-associated macrophages (TAMs) contributes to tumor progression and metastasis. In contrast to their adult counterparts, higher TAM signatures do not correlate with aggressive tumor behavior in pediatric brain tumors. While prominent TAM infiltrates exist before and after radiation, the degree to which irradiated macrophages and microglia support progression or leptomeningeal metastasis remains unclear. Patients with medulloblastoma often present with distant metastases and tumor recurrence is largely incurable, making them prime candidates for the study of novel approaches to prevent neuroaxis dissemination and recurrence.

METHODS

Macrophage depletion was achieved using CSF-1 receptor inhibitors (CSF-1Ri), BLZ945 and AFS98, with or without whole brain radiation in a variety of medulloblastoma models, including patient-derived xenografts bearing Group 3 medulloblastoma and a transgenic Sonic Hedgehog (Ptch1^+/-, Trp53^-/-) medulloblastoma model.

RESULTS

Effective reduction of microglia, TAM, and spinal cord macrophage with CSF-1Ri resulted in negligible effects on the rate of local and spinal recurrences or survival following radiation. Results were comparable between medulloblastoma subgroups. While notably few tumor-infiltrating lymphocytes (TILs) were detected, average numbers of CD3+ TILs and FoxP3+ Tregs did not differ between groups following treatment and tumor aggressiveness by Ki67 proliferation index was unaltered.

CONCLUSION

In the absence of other microenvironmental influences, medulloblastoma-educated macrophages do not operate as tumor-supportive cells or promote leptomeningeal recurrence in these models. Our data add to a growing body of literature describing a distinct immunophenotype amid the medulloblastoma microenvironment and highlight the importance of appropriate pediatric modeling prior to clinical translation.

ctDNA-Based Liquid Biopsy of Cerebrospinal Fluid in Brain Cancer

The correct characterisation of central nervous system (CNS) malignancies is crucial for accurate diagnosis and prognosis and also the identification of actionable genomic alterations that can guide the therapeutic strategy. Surgical biopsies are performed to characterise the tumour; however, these procedures are invasive and are not always feasible for all patients. Moreover, they only provide a static snapshot and can miss tumour heterogeneity. Currently, monitoring of CNS cancer is performed by conventional imaging techniques and, in some cases, cytology analysis of the cerebrospinal fluid (CSF); however, these techniques have limited sensitivity. To overcome these limitations, a liquid biopsy of the CSF can be used to obtain information about the tumour in a less invasive manner. The CSF is a source of cell-free circulating tumour DNA (ctDNA), and the analysis of this biomarker can characterise and monitor brain cancer. Recent studies have shown that ctDNA is more abundant in the CSF than plasma for CNS malignancies and that it can be sequenced to reveal tumour heterogeneity and provide diagnostic and prognostic information. Furthermore, analysis of longitudinal samples can aid patient monitoring by detecting residual disease or even tracking tumour evolution at relapse and, therefore, tailoring the therapeutic strategy. In this review, we provide an overview of the potential clinical applications of the analysis of CSF ctDNA and the challenges that need to be overcome in order to translate research findings into a tool for clinical practice.

Clinical Outcomes and Patient-Matched Molecular Composition of Relapsed Medulloblastoma

We sought to investigate clinical outcomes of relapsed medulloblastoma and to compare molecular features between patient-matched diagnostic and relapsed tumors.

Prognostic Clinical and Biologic Features for Overall Survival after Relapse in Childhood Medulloblastoma

Simple Summary

Despite progress in the biology and upfront treatment of childhood medulloblastoma, relapse is almost universally fatal. No standardized treatment has so far been established for these patients. By determining which characteristics are prognostic after relapse, treatment strategies may be optimized for each of these children. We demonstrated that molecular subgroup at diagnosis is a relevant prognostic factor of outcome after relapse. Moreover, we showed that time to relapse and the use of salvage radiotherapy at relapse might have a potential impact on post-relapse survival. Our data suggest that ongoing efforts toward a better understanding of the biology, timing and type of relapse would be important to understand the determinants of tumor behavior at relapse. This could help us address more specific questions on the best surveillance strategies after completion of the treatment and the introduction of risk-stratified second-line treatment strategies.

Abstract

Given the very poor prognosis for children with recurrent medulloblastoma, we aimed to identify prognostic factors for survival post-relapse in children with childhood medulloblastoma. We retrospectively collected clinico-biological data at diagnosis and main clinical characteristics at relapse of children newly diagnosed with a medulloblastoma between 2007 and 2017 at Gustave Roussy and Necker Hospital. At a median follow-up of 6.6 years (range, 0.4–12.3 years), relapse occurred in 48 out 155 patients (31%). The median time from diagnosis to relapse was 14.3 months (range, 1.2–87.2 months). Relapse was local in 9, metastatic in 22 and combined (local and metastatic) in 17 patients. Second-line treatment consisted of chemotherapy in 31 cases, radiotherapy in 9, SHH-inhibitor in four and no treatment in the remaining four. The 1-year overall survival rate post-relapse was 44.8% (CI 95%, 31.5% to 59.0%). While molecular subgrouping at diagnosis was significantly associated with survival post-relapse, the use of radiotherapy at relapse and time to first relapse (>12 months) might also have a potential impact on post-relapse survival.

Pediatric medulloblastoma in the molecular era: what are the surgical implications?

Pediatric brain tumors are the leading cause of childhood cancer mortality with medulloblastoma (MB) representing the most frequent malignant tumor. Although standardization of therapy resulted in a 2-fold reduction in mortality in patients with MB by 2002, it became clear that further improvements in clinical outcome would require a deeper understanding of the biology of MB. Employing the four main molecular MB subgroups (Wnt, Shh, Group 3 and Group 4), a restratification into clinicogenomic risk categories quantified an unacceptable survival for the high-risk group, urging researchers to focus their efforts towards acquiring a greater biological understanding of these children. Advancing in parallel with the molecular characterization and understanding of pediatric MB is the clinicogenomic correlations giving rise to recommendations for neurosurgical care. While unique observations that distinct radiological patterns can be identified to inform the MB molecular subgroup preoperatively, current neurosurgical practice remains maximal safe surgical resection followed by risk-adapted provision of adjuvant therapy in the context of a clinical trial.

Circulating tumour DNA from the cerebrospinal fluid allows the characterisation and monitoring of medulloblastoma

The molecular characterisation of medulloblastoma, the most common paediatric brain tumour, is crucial for the correct management and treatment of this heterogenous disease. However, insufficient tissue sample, the presence of tumour heterogeneity, or disseminated disease can challenge its diagnosis and monitoring. Here, we report that the cerebrospinal fluid (CSF) circulating tumour DNA (ctDNA) recapitulates the genomic alterations of the tumour and facilitates subgrouping and risk stratification, providing valuable information about diagnosis and prognosis. CSF ctDNA also characterises the intra-tumour genomic heterogeneity identifying small subclones. ctDNA is abundant in the CSF but barely present in plasma and longitudinal analysis of CSF ctDNA allows the study of minimal residual disease, genomic evolution and the characterisation of tumours at recurrence. Ultimately, CSF ctDNA analysis could facilitate the clinical management of medulloblastoma patients and help the design of tailored therapeutic strategies, increasing treatment efficacy while reducing excessive treatment to prevent long-term secondary effects.

Thioredoxin System Protein Expression Is Associated with Poor Clinical Outcome in Adult and Paediatric Gliomas and Medulloblastomas

The thioredoxin (Trx) system is an important enzyme family that regulates cellular redox homeostasis. Protein expression of Trx system family members has been assessed in various cancers and linked to various clinicopathological variables, disease progression, treatment response and survival outcomes but information is lacking in brain tumours. Expression of the system was therefore examined, by immunohistochemistry in different brain tumour types, adult and paediatric cases, to determine if expression was of importance to clinical outcome. Trx system proteins were expressed, to variable levels, across all brain tumour types with significant variations in expression between different tumour types/grades/regions. High Trx reductase (TrxR) expression was linked to worse prognosis across all cohorts. High cytoplasmic TrxR expression was significantly associated with adverse overall survival (OS) in adult glioblastoma (P = 0.027) and paediatric low-grade glioma (LGG) patients (P = 0.012). High expression of nuclear TrxR, cytoplasmic and nuclear Trx and Trx-interacting protein (TxNIP) was associated with improved OS in paediatric LGGs (P = 0.031, P < 0.001, P = 0.044 and P = 0.018, respectively). For patients with high-grade gliomas, both high cytoplasmic TrxR and Trx expression were associated with poor OS (P = 0.002 and P = 0.007, respectively). In medulloblastoma, high expression of cytoplasmic TrxR and Trx and nuclear Trx was associated with worse prognosis (P = 0.013, P = 0.033 and P = 0.007, respectively); with cytoplasmic TrxR and nuclear Trx remaining so in multivariate analysis (P = 0.009 and P = 0.013, respectively). The consistent finding that high levels of cytoplasmic TrxR are associated with a worse prognosis across all cohorts suggests that TrxR is an important therapeutic target in brain cancers.

[Dendritic cell vaccines in neurological oncology]

Dendritic cell-based vaccines are an intensively studied active immunotherapy technology. Aim of this article is to review the results of the key clinical studies of such vaccines in the treatment of neuro-oncological diseases. Their effectiveness was studied most widely in the treatment of malignant glial tumors, the study went from experimental work to phase III clinical studies, preliminary results of which indicate some positive results of this immunotherapy method in adults. Currently, emphasis is also being placed on the identification of clinical and immunological correlates of the patient's response to therapy and on the search for new antigens for sensitization of dendritic cells Studies of dendritic cell vaccines also include a number of other neuro-oncological diseases. A separate part of this article is devoted to the treatment of intracerebral tumors in children, for example, medulloblastomas and gliomas of the pons. In addition, the potential use of dendritic cell vaccines for intracerebral metastases is considered.

[Risk factors for recurrence within 2 years in children with medulloblastoma]

OBJECTIVE

To investigate the risk factors for recurrence of medulloblastoma (MB) within 2 years and their influence on progression-free survival (PFS).

METHODS

A retrospective analysis was performed for the clinical data of 123 children with MB who were admitted from January to December, 2017. According to the presence or absence of recurrence, they were divided into recurrence group with 30 children and non-recurrence group with 93 children. The risk factors for recurrence within 2 years were analyzed, and PFS was compared between the children with different risk factors.

RESULTS

Large-cell/anaplastic type and M stage were risk factors for MB recurrence within 2 years. The risk of recurrence in the children with M+ MB was 3.525 times that in those with M0 MB, and the risk of recurrence in the children with large-cell/anaplastic MB was 3.358 times that in those with classic MB (P<0.05). The survival analysis showed that the median PFS time was 20 months in the children with M+ MB, and the 20-month PFS rate was 50% ± 11% in the children with M+ MB and 81% ± 5% in those with M0 MB (P<0.05). The 20-month PFS rate was 80% ± 5% in the children with classic MB, 65% ± 10% in those with desmoplastic/nodular MB, 86% ± 13% in those with MB with extensible nodularity, and 36% ± 20% in those with large-cell/anaplastic MB (P<0.05).

CONCLUSIONS

Recurrence is an important influencing factor for the prognosis of MB, and M+ stage and large-cell/anaplastic MB are risk factors for recurrence. Children with such risk factors tend to have a low PFS rate.

Surgery for recurrent medulloblastoma: A review

INTRODUCTION

Medulloblastoma (MB) is the most common malignant brain tumour in children. Despite significant progress in its management, a proportion of children relapse; tumour recurrence still carries a poor prognosis. While surgery is a mainstay of the management of primary MB, its role in recurrent MB is unclear. The objective of this literature review is to explore current practice and potential benefits of surgery in recurrent MB.

MATERIAL AND METHODS

We reviewed all articles published in PubMed and Scholar from 1990 to 2018 with the following terms: "medulloblastoma" AND "recurrence" AND "neurosurgical procedures". Among 69 articles, 12 were directly relevant.

RESULTS

A total of 581 cases of recurrent MB were identified from published series. Median time from diagnosis to relapse was 20.4months. The majority of relapses involved disseminated craniospinal disease and only one-fifth relapses was located in the posterior fossa. The outcome was consistently poor, with a median survival of 12.4% and a median survival time after relapse of 18.5months. In the HIP-SIOP-PNET4 study, surgery at relapse was performed in 25% of cases and was associated with improved prognosis in solitary posterior fossa recurrence.

CONCLUSION

Recurrent medulloblastoma is often fatal in children who have previously received radiotherapy. The role of surgery in improving survival is unclear, but there is some evidence that resection of a focal single posterior fossa recurrence can bring survival benefit. The value of biopsy lies in the optimisation and selection of appropriate targeted therapy and in excluding a second malignancy.

Salvage Therapy for Childhood Medulloblastoma: A Single Center Experience

INTRODUCTION

Children diagnosed with medulloblastoma (MB) who are refractory to upfront therapy or experience recurrence have very poor prognoses. Although phase I and phase II trials exist, these treatments bear significant treatment-related morbidity and mortality.

METHODS

A retrospective review of children diagnosed with a recurrence of MB from 2002 to 2015 at McMaster University was undertaken.

RESULTS

Recurrent disease in 10 patients involved leptomeningeal dissemination, with 3 experiencing local recurrence. In three recurrent patients the disease significantly progressed, and the children were palliated. The remaining 10 children underwent some form of salvage therapy, including surgical re-resection, radiation, and chemotherapy, either in isolation or in varying combinations. Of the 13 children experiencing treatment-refractory or recurrent disease, 4 are currently alive with a median follow-up of 38.5 months (75.5 months). Of the eight patients with molecular subgrouping data, none of the Wnt MB experienced recurrence.

CONCLUSION

Recurrent MB carried a poor prognosis with a 5-year overall survival (OS) of 18.2% despite the administration of salvage therapy. The upfront therapy received, available treatment, and tolerability of the proposed salvage therapy resulted in significant heterogeneity in the treatment of our recurrent cohort.

Relapse of a group 4 medulloblastoma after 18 years as proven by histology and DNA methylation profiling

BACKGROUND

Recent studies on medulloblastomas (MB) suggest that a large fraction of tumors appearing as late recurrence turn out to be secondary malignancies, e.g., malignant gliomas, after thorough molecular investigation.

RESULTS

Here, we report of a patient with a group 4 MB that developed a distant recurrence after more than 18 years. The recurrent tumor was confirmed by histology and genome-wide DNA methylation profiling.

CONCLUSION

Our case not only illustrates the potential of very late recurrences after seemingly cured group 4 MB, but also illustrates that detailed molecular analyses are indispensable in patients with a history of a previous malignancy.

Molecular genetics of medulloblastoma in children: diagnostic, therapeutic and prognostic implications

Medulloblastoma is the most common embryonal tumor in children. The current standard of care comprises surgical resection, radiation and chemotherapy. Patients are stratified into standard and high risk based on the degree of resection, presence of metastatic disease and histopathology. Cure rates dramatically improved during the past decades reaching 70–80% (high and average risk, respectively). Infant medulloblastoma has a worse outcome as the use of radiation therapy is very limited, a group of patients still has dismal outcome despite appropriate therapy, and the unacceptable long-term therapy side effects in survivors. Advanced molecular techniques have allowed scientists to discover four distinct molecular subgroups and correlate them with multiple factors such as histopathology, clinical behavior and possible therapeutic targets.

Clinical Characteristics and Outcome of Children With Relapsed Medulloblastoma: A Retrospective Study at a Single Center in China

Relapsed medulloblastoma (MB) has a dire prognosis, and chemotherapy remains the main therapeutic option. We retrospectively analyzed the clinical characteristics and survival rates of 60 Chinese children with relapsed MB. The patients received 11 cycles of chemotherapy in sequence, followed by 12 cycles of oral temozolomide and etoposide. Thirty patients were simultaneously administered intrathecal methotrexate (IT-MTX). The Kaplan-Meier method was used to determine survival rates; the patients' median survival time after relapse was 2.8 years, 5-year progression-free survival (PFS) and overall survival (OS) rates were 26.7%±5.7% and 31.6%±6.9%, respectively. There was no significant difference between these rates according to histology or molecular subgroup. Tumor cells were detected in the cerebrospinal fluid of over 40% of patients; such patients had significantly shorter OS and PFS rates. Patients who received IT-MTX showed significantly longer survival than those who did not (3.73 vs. 2.06 y, respectively, P=0.000); the corresponding 5-year PFS and OS rates were 43.3%±9.0% versus 10.0%±5.5% and 49.5%±11.1% versus 14.6%±6.9%, respectively (P=0.000). In addition, tumor cell-positive cerebrospinal fluid and IT-MTX use significantly influenced PFS and OS in relapsed patients. Taken together, our data show that IT-MTX improves the survival of patients with relapsed MB.

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.

Radioimmunotherapy of solid tumors: Approaches on the verge of clinical application

While radioimmunotherapy (RIT) for the treatment of hematological malignancies such as indolent B-cell lymphoma has proven quite successful, clinical results of RIT in solid tumors have only been moderate in the past. The reasons were manifold and can be mostly attributed to the different biological properties of solid tumors vs hematological cancers. Furthermore, the slow clearance of the radiolabelled antibody prevents the use of radiation doses necessary to achieve clinical responses. The long biological half-life of radioimmunoconjugates results in high background levels and is the main reason for radiation related toxicities. In recent years, researchers and clinicians have developed solutions for the successful application of RIT for the treatment of solid tumors. These include compartmental route of administration, neoadjuvant therapies, and pretargeting approaches. In this review, recent developments in RIT for the treatment of solid tumors that address these restrictions as well as future perspectives will be highlighted from a clinical perspective.

Survival Following Tumor Recurrence in Children With Medulloblastoma

Medulloblastoma is the most common malignant brain tumor in children. Published survival rates for this tumor are ∼70%; however, there is limited published information on outcome after disease recurrence. This was an observational study which included all persons under the age of 18 years diagnosed with medulloblastoma from 1990 to 2009 inclusive in Canada. Data collected included date of diagnosis, age at diagnosis, sex, stage, pathology, treatment, recurrence, and current status. Survival rates were determined. In total, 550 cases were ascertained meeting the study criteria. The overall survival rate at 1 year was 83.6%±1.7%, at 3 years 77.2%±1.9%, and at 5 years 72.5%±20%. The progression-free survival rates were 78%±1.9%, 70%±2.1%, and 69±2.1% at 1, 3, and 5 years from initial diagnosis. In total, 173 (31.2%) were reported to have had tumor recurrence and 23 (11.4%) of them were alive at the time of survey with an overall survival rate at 1 year of 38.3%±4%, at 2 years of 16.9%±3.3%, and at 5 years of 12.4%±2.8%. Our data confirm that children with recurrent medulloblastoma have a poor prognosis, supporting the need for novel treatment approaches for this group.

A phase II study of radioimmunotherapy with intraventricular 131 I-3F8 for medulloblastoma

BACKGROUND

High-risk and recurrent medulloblastoma (MB) is associated with significant mortality. The murine monoclonal antibody 3F8 targets the cell-surface disialoganglioside GD2 on MB. We tested the efficacy, toxicity, and dosimetry of compartmental radioimmunotherapy (cRIT) with intraventricular ¹³¹ I-labeled 3F8 in patients with MB on a phase II clinical trial.

METHODS

Patients with histopathologically confirmed high-risk or recurrent MB were eligible for cRIT. After determining adequate cerebrospinal fluid (CSF) flow, patients received 2 mCi (where Ci is Curie) ¹²⁴ I-3F8 or ¹³¹ I-3F8 with nuclear imaging for dosimetry, followed by up to four therapeutic (10 mCi/dose) ¹³¹ I-3F8 injections. Dosimetry estimates were based on serial CSF and blood samplings over 48 hr plus region-of-interest analyses on serial imaging scans. Disease evaluation included pre- and posttherapy brain/spine magnetic resonance imaging approximately every 3 months for the first year after treatment, and every 6-12 months thereafter.

RESULTS

Forty-three patients received a total of 167 injections; 42 patients were evaluable for outcome. No treatment-related deaths occurred. Toxicities related to drug administration included acute bradycardia with somnolence, headache, fatigue, and CSF pleocytosis consistent with chemical meningitis and dystonic reaction. Total CSF absorbed dose was 1,453 cGy (where Gy is Gray; 350.0-2,784). Median overall survival from first dose of cRIT was 24.9 months (95% confidence interval [CI]:16.3-55.8). Patients treated in radiographic and cytologic remission were at a lower risk of death compared to patients with radiographically measurable disease (hazard ratio: 0.40, 95% CI: 0.18-0.88, P = 0.024).

CONCLUSIONS

cRIT with ¹³¹ I-3F8 is safe, has favorable dosimetry to CSF, and when added to salvage therapy using conventional modalities, may have clinical utility in maintaining remission in high-risk or recurrent MB.

Panobinostat, a histone deacetylase inhibitor, suppresses leptomeningeal seeding in a medulloblastoma animal model

Leptomeningeal seeding is a strong negative prognostic factor for medulloblastoma (MB). The mechanism of leptomeningeal seeding is unclear but may involve epigenetic regulation. In this study, we evaluated the feasibility of a histone deacetylase (HDAC) inhibitor, panobinostat, in the suppression of MB leptomeningeal seeding.

Panobinostat decreased the cell viability and proliferation, inducing cell cycle arrest and apoptosis in MB cell lines. The migration and adhesion capabilities were significantly decreased. Panobinostat effectively down-regulated protein expression of CCND1 and ID3 which has been associated with leptomeningeal seeding of MB. After panobinostat treatment, neurophil-like cellular processes developed and expression of synaptophysin and NeuroD1 was increased, indicating neuronal differentiation. In MB leptomeningeal seeding in vivo model, the panobinostat-treated group showed significantly decreased spinal leptomeningeal seeding and a survival benefit.

The findings demonstrate that panobinostat suppresses MB leptomeningeal seeding through the down-regulation of ID3 and the induction of neuronal differentiation. An HDAC inhibitor might be a potent treatment option for the treatment of MB patients with leptomeningeal seeding.