High-risk Medulloblastoma Patients Research Articles

GD2-Targeting CAR T-cell Therapy for Patients with GD2+ Medulloblastoma.

Medulloblastoma (MB), the most common childhood malignant brain tumor, has a poor prognosis in about 30% of patients. The current standard of care, which includes surgery, radiation, and chemotherapy, is often responsible for cognitive, neurologic, and endocrine side effects. We investigated whether chimeric antigen receptor (CAR) T cells directed toward the disialoganglioside GD2 can represent a potentially more effective treatment with reduced long-term side effects. GD2 expression was evaluated on primary tumor biopsies of MB children by flow cytometry. GD2 expression in MB cells was also evaluated in response to an EZH2 inhibitor (tazemetostat). In in vitro and in vivo models, GD2+ MB cells were targeted by a CAR-GD2.CD28.4-1BBζ (CAR.GD2)-T construct, including the suicide gene inducible caspase-9. GD2 was expressed in 82.68% of MB tumors. The SHH and G3-G4 subtypes expressed the highest levels of GD2, whereas the WNT subtype expressed the lowest. In in vitro coculture assays, CAR.GD2 T cells were able to kill GD2+ MB cells. Pretreatment with tazemetostat upregulated GD2 expression, sensitizing GD2dimMB cells to CAR.GD2 T cells cytotoxic activity. In orthotopic mouse models of MB, intravenously injected CAR.GD2 T cells significantly controlled tumor growth, prolonging the overall survival of treated mice. Moreover, the dimerizing drug AP1903 was able to cross the murine blood-brain barrier and to eliminate both blood-circulating and tumor-infiltrating CAR.GD2 T cells. Our experimental data indicate the potential efficacy of CAR.GD2 T-cell therapy. A phase I/II clinical trial is ongoing in our center (NCT05298995) to evaluate the safety and therapeutic efficacy of CAR.GD2 therapy in high-risk MB patients.

Metabolic rewiring in MYC-driven medulloblastoma by BET-bromodomain inhibition

Medulloblastoma (MB) is the most common malignant brain tumour in children. High-risk MB patients harbouring MYC amplification or overexpression exhibit a very poor prognosis. Aberrant activation of MYC markedly reprograms cell metabolism to sustain tumorigenesis, yet how metabolism is dysregulated in MYC-driven MB is not well understood. Growing evidence unveiled the potential of BET-bromodomain inhibitors (BETis) as next generation agents for treating MYC-driven MB, but whether and how BETis may affect tumour cell metabolism to exert their anticancer activities remains unknown. In this study, we explore the metabolic features characterising MYC-driven MB and examine how these are altered by BET-bromodomain inhibition. To this end, we employed an NMR-based metabolomics approach applied to the MYC-driven MB D283 and D458 cell lines before and after the treatment with the BETi OTX-015. We found that OTX-015 triggers a metabolic shift in both cell lines resulting in increased levels of myo-inositol, glycerophosphocholine, UDP-N-acetylglucosamine, glycine, serine, pantothenate and phosphocholine. Moreover, we show that OTX-015 alters ascorbate and aldarate metabolism, inositol phosphate metabolism, phosphatidylinositol signalling system, glycerophospholipid metabolism, ether lipid metabolism, aminoacyl-tRNA biosynthesis, and glycine, serine and threonine metabolism pathways in both cell lines. These insights provide a metabolic characterisation of MYC-driven childhood MB cell lines, which could pave the way for the discovery of novel druggable pathways. Importantly, these findings will also contribute to understand the downstream effects of BETis on MYC-driven MB, potentially aiding the development of new therapeutic strategies to combat medulloblastoma.

MBCL-28. LONG-TERM FOLLOW-UP RESULTS OF REDUCED DOSE CRANIOSPINAL RADIOTHERAPY AND TANDEM HIGH-DOSE CHEMOTHERAPY IN PATIENTS WITH HIGH-RISK MEDULLOBLASTOMA

BACKGROUNDIn 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).METHODSNewly 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, RT including reduced-dose CSRT (23.4 or 30.6 Gy), 4 cycles of post-RT chemotherapy and tandem HDCT were given. NanoString and DNA sequencing were done with archival tissues.RESULTSForty patients were enrolled, and molecular subgrouping was possible in 21 patients (2 WNT, 3 SHH, 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 (10-year cumulative incidence 10.4 ± 0.3%). However, six patients died from treatment-related mortality (TRM) (4 acute TRMs and 2 late TRMs) resulting in 18.5 ± 0.5% of 10-year cumulative incidence. Taken together, the 10-year event-free survival and overall survival were 71.1 ± 8.0% and 68.9 ± 8.5%, respectively. Late effects were evaluated in 25 patients and high-tone hearing loss, endocrine dysfunction, dyslipidemia, and growth retardation were common.CONCLUSIONSStrategy 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 have benefit from HDCT will be needed in the future study.

Targeting cyclin-dependent kinase 9 sensitizes medulloblastoma cells to chemotherapy

Medulloblastoma (MB) is a highly aggressive, malignant brain tumor in children with poor prognosis. Cyclin-dependent kinase 9 (CDK9), a serine-threonine kinase, is widely implicated in the control of basal gene expression by phosphorylating Serine 2 (Ser2) of the heptad repeat in the RNA Polymerase II (RNA Pol II) C-terminal domain (CTD). Although CDK9 plays a pathogenic role in various cancers, its function in MB remains unknown. Here, we show that CDK9 is highly expressed in MB tumors and increased CDK9 expression is correlated with high risk MB patients. CDK9 expression along with phospho-Ser2 RNA Pol II (pRNA Pol II ser2) and bromodomain-binding protein 4 (BRD4), which recruits CDK9, were elevated in multiple MB cell lines and in MB tumors originated spontaneously from Ptch1+/−p53−/− mice. Inhibition of CDK9 with LDC067 suppressed MB cell growth, reduced pRNA Pol II ser2 level and expression of oncogenic markers, including MYC. Moreover, LDC067 treatment synergistically sensitizes MB cells to chemotherapeutic agent cisplatin. Further, LDC067 in combination with BRD4 inhibitor decreased MB cells growth, delayed cell migration and attenuated pRNA Pol II ser2 occupancy to CCND1 and BCL2 gene promoters as revealed by chromatin immunoprecipitation assay (ChIP). Together, these findings highlight the importance of CDK9 in MB pathogenesis and suggest that it may serve as a promising therapeutic target for the treatment of MB.

416P - Meta of classical chemotherapy compared with high-dose chemotherapy combined with autologous stem cell transplantation in newly diagnosed medulloblastoma patients after radiotherapy

BackgroundHigh-dose chemotherapy combined with autologous stem cell rescue (HDCT+ASCR) has been used to treat newly diagnosed medulloblastoma (MB), but there was no high-level evidence to support its efficacy. MethodsDatabases were retrieved, and patients were divided into two 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), total survival (OS) and toxicities data were extracted. Results22 clinical trials met the inclusion criteria, 416 in group A and 2331 in group B. There was no difference in CBR between two groups (80.0% vs. 71.5%, P=0.262). The 3-year PFS (3-y PFS) of group A was significantly better than group B (79.0% vs. 69.5%, P=0.004). The analysis found that there was no difference between the two 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% vs.75.6%, P=0.004). Comparison of 3-y OS and 5-y OS between two groups of all MB patients showed no difference (P=0.086; P=0.507), stratified analysis was the same result. The gastrointestinal toxicity in group A was significantly higher than that in group B (P=0.016), and the level 3/4 ototoxicity in high-risk group A was higher than that in group B (P<0.001). ConclusionsHDCT+ASCR was not recommended for newly diagnosed high-risk MB patients. The clinical significance of HDCT+ASCR at the time of initiation in the standard risk group remains to be further explored. Legal entity responsible for the studyThe Second Hospital of Hebei Medical University. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

Improved therapy for medulloblastoma: targeting hedgehog and PI3K-mTOR signaling pathways in combination with chemotherapy.

Aberrant activation and interactions of hedgehog (HH) and PI3K/AKT/mTOR signaling pathways are frequently associated with high-risk medulloblastoma (MB). Thus, combined targeting of the HH and PI3K/AKT/mTOR pathways could be a viable therapeutic strategy to treat high-risk patients. Therefore, we investigated the anti-MB efficacies of combined HH inhibitor Vismodegib and PI3K-mTOR dual-inhibitor BEZ235 together or combined individually with cisplatin against high-risk MB. Using non-MYC- and MYC-amplified cell lines, and a xenograft mouse model, the in vitro and in vivo efficacies of these therapies on cell growth/survival and associated molecular mechanism(s) were investigated. Results showed that combined treatment of Vismodegib and BEZ235 together, or with cisplatin, significantly decreased MB cell growth/survival in a dose-dependent-fashion. Corresponding changes in the expression of targeted molecules following therapy were observed. Results demonstrated that inhibitors not only suppressed MB cell growth/survival when combined, but also significantly enhanced cisplatin-mediated cytotoxicity. Of these combinations, BEZ235 exhibited a significantly greater efficacy in enhancing cisplatin-mediated MB cytotoxicity. Results also demonstrated that the MYC-amplified MB lines showed a higher sensitivity to combined therapies compared to non-MYC-amplified cell lines. Therefore, we tested the efficacy of combined approaches against MYC-amplified MB growing in NSG mice. In vivo results showed that combination of Vismodegib and BEZ235 or their combination with cisplatin, significantly delayed MB tumor growth and increased survival of xenografted mice by targeting HH and mTOR pathways. Thus, our studies lay a foundation for translating these combined therapeutic strategies to the clinical setting to determine their efficacies in high-risk MB patients.

Hippocampal Sparing During Craniospinal Irradiation: What Did We Learn About the Incidence of Perihippocampus Metastases?

To identify the incidence of patients with perihippocampal metastases to assess the risk of brain relapse when sparing the hippocampal area. Medulloblastoma (MB) represents 20% of pediatric brain tumors. For high-risk MB patients, the 3- to 5-year event-free survival rate has recently improved from 50% to >76%. Many survivors, however, experience neurocognitive side effects. Several retrospective studies of patients receiving whole brain irradiation (WBI) have suggested a relationship between the radiation dose to the hippocampus and neurocognitive decline. The hippocampal avoidance-WBI (HA-WBI) approach could partially reduce neurocognitive impairment in children treated for high-risk MB. From 2008 to 2011, 51 patients with high-risk MB were treated according to the French trial primitive neuroectodermal tumor HR+5. Hippocampal contouring was manually generated on 3-dimensional magnetic resonance images according to the Radiation Therapy Oncology Group 0933 atlas. The distribution of metastases was assessed relative to the hippocampus: 0 to 5mm for the first perihippocampal area and 5 to 15mm for the rest of the perihippocampal area. The median patient age was 8.79years (33% female). After a follow-up of 2.4years, 43 patients were alive; 28 had had brain metastasis at diagnosis and 2 at relapse, with 16% in the first perihippocampal area and 43% in the rest of the perihippocampal area. Of the 18 patients without brain metastases at diagnosis, including M1 patients, none developed secondary lesions within the first or the rest of the perihippocampal area, after receiving 36Gy. No clinical or biological factor was significantly associated with the development of perihippocampal metastases. Our results suggest the HA-WBI strategy should be evaluated for the subgroup of high-risk MB patients without metastatic disease.

PDCT-01. TOXICITY AND OUTCOME IN ADOLESCENT AND YOUNG ADULTS TREATED FOR MEDULLOBLASTOMA AND PRIMITIVE NEUROECTODERMAL TUMORS ON STUDIES COG-A9961 AND CCG-99701: A REPORT FROM THE CHILDREN’S ONCOLOGY GROUP (COG)

Adolescent and young adults (AYA) with cancer have inferior outcomes compared with younger patients. We explored whether treatment-related toxicity and survival were associated with age in patients with medulloblastoma (MB) and primitive neuroectodermal tumor (PNET) enrolled on children’s oncology group (COG) studies COG-A9961 and CCG-99701. A retrospective analysis was conducted to compare the outcomes between AYA (15-21 years) vs. younger patients (3-14 years). On CCG-99701, 161 patients (16 AYA) with high-risk MB/PNET were treated with chemoradiotherapy followed by six cycles of maintenance chemotherapy cyclophosphamide/cisplatin/vincristine). On A9961 study, 379 patients with standard-risk MB (25 AYA) received chemoradiotherapy followed by eight cycles of maintenance chemotherapy (cisplatin/CCNU/vincristine). On CCG-99701, estimated 5-year event-free survival (EFS) and overall survival (OS) rates were lower for AYA patients (EFS: 37.5% versus 60.3%, p=0.05; OS: 50.0% versus 70.8%, p=0.005). On multivariate analysis, the observed difference in EFS was not statistically significant (p=0.12) but was still consistent with poorer outcome in older patients (HR 1.75, 95% CI 0.89-3.45) after adjustment for extent of resection and pathology. This difference was mainly due to poorer survival for AYA patients with PNET compared to patients 3-14 years of age (55.7% versus 9.1%; p=.002) as there was no significant difference in survival for high-risk medulloblastoma patients (p=0.26). Peripheral neuropathy was higher among AYA as well. On A9961, there was no difference in EFS or OS between AYA and younger patients. Interestingly, the AYA group experienced less hearing loss. Future studies examining the age-related differences in pharmacokinetics of chemotherapy and differences in tumor molecular biology are necessary.

MB-20 * EVALUATING THE ONCOGENIC POTENTIAL OF TSC1/2 MUTATIONS AND EFFICACY OF MTOR INHIBITORS IN HIGH RISK PEDIATRIC MEDULLOBLASTOMA

Medulloblastoma is the most common malignant pediatric brain tumor. Molecular profiling recently enabled the classification of medulloblastoma into four distinct subgroups, of which Group 3 patients have the worst prognosis. To identify targetable molecular vulnerabilities in Group 3 medulloblastoma, we utilized a high-throughput kinase inhibitor screening assay against the Group 3-like medulloblastoma cell line D341. Comparing inhibitor sensitivities of D341 to other medulloblastoma cell lines, >400 primary leukemia samples and >100 established human cancer cell lines, we found pronounced susceptibility to inhibitors of the PI3K/AKT/MTOR pathway as reflected by nanomolar IC50 values. We found this sensitivity to be biochemically correlated with increased phospho-MTOR as well as phosphorylation of MTOR effectors in the D341 cells when compared to the medulloblastoma cell lines exhibiting weaker or no MTOR inhibitor sensitivity. Exposure of D341 cells to the FDA-approved MTOR inhibitor everolimus resulted in a dose-dependent decrease in MTOR pathway activation and increase in cell death markers. Exome sequencing of D341 revealed a TSC2 A415V point mutation, which we found has significantly diminished TSC1-interaction potential in a heterologous expression system. Loss-of-function of the TSC1:TSC2 A415V complex concomitantly increased activation of the MTOR pathway. In silico mining of previously published exome sequencing data from primary patient samples unveils a subset of medulloblastoma tumors harboring TSC1 and TSC2 mutations in regions predicted to result in loss of function. We tested the functional consequence of these mutations using a heterologous model system and found they resulted in loss of the TSC1:TSC2 complex. Taken together, these findings corroborate that a subset of high risk medulloblastoma patients may have functionally relevant mutations in the MTOR pathway leading to oncogenic addiction to the pathway and susceptibility to MTOR inhibitors. In vitro response to an FDA-approved MTOR inhibitor may suggest a potentially promising adjunct treatment for a subgroup of medulloblastoma patients.

The KDM1A histone demethylase is a promising new target for the epigenetic therapy of medulloblastoma

BackgroundMedulloblastoma is a leading cause of childhood cancer-related deaths. Current aggressive treatments frequently lead to cognitive and neurological disabilities in survivors. Novel targeted therapies are required to improve outcome in high-risk medulloblastoma patients and quality of life of survivors. Targeting enzymes controlling epigenetic alterations is a promising approach recently bolstered by the identification of mutations in histone demethylating enzymes in medulloblastoma sequencing efforts. Hypomethylation of lysine 4 in histone 3 (H3K4) is also associated with a dismal prognosis for medulloblastoma patients. Functional characterization of important epigenetic key regulators is urgently needed.ResultsWe examined the role of the H3K4 modifying enzyme, KDM1A, in medulloblastoma, an enzyme also associated with malignant progression in the closely related tumor, neuroblastoma. Re-analysis of gene expression data and immunohistochemistry of tissue microarrays of human medulloblastomas showed strong KDM1A overexpression in the majority of tumors throughout all molecular subgroups. Interestingly, KDM1A knockdown in medulloblastoma cell lines not only induced apoptosis and suppressed proliferation, but also impaired migratory capacity. Further analyses revealed bone morphogenetic protein 2 (BMP2) as a major KDM1A target gene. BMP2 is known to be involved in development and differentiation of granule neuron precursor cells (GNCPs), one potential cell of origin for medulloblastoma. Treating medulloblastoma cells with the specific KDM1A inhibitor, NCL-1, significantly inhibited growth in vitro.ConclusionWe provide the first evidence that a histone demethylase is functionally involved in the regulation of the malignant phenotype of medulloblastoma cells, and lay a foundation for future evaluation of KDM1A-inihibiting therapies in combating medulloblastoma.

Long-term results of combined preradiation chemotherapy and age-tailored radiotherapy doses for childhood medulloblastoma

To reduce the sequelae of craniospinal irradiation (CSI) in children under 10 (≥3) years old and to improve the prognosis for high-risk medulloblastoma in adolescents, we adjusted postoperative chemotherapy and CSI doses to patients' stage and age. From 1986 to 1995, 73 patients entered the study. Children under 10 and adolescents with metastases, residual disease (RD) or stage >T3 received postoperative IV vincristine and high-dose (HD) ± intrathecal (IT) methotrexate, while standard-risk adolescents were given IV vincristine and IT methotrexate. Chemotherapy was followed by CSI (19.8 Gy for children <10; 36 Gy for adolescents), with a 54-Gy posterior fossa boost. Maintenance chemotherapy with lomustine and vincristine was administered for a year afterwards. A total of 39 children were under 10 of whom 20 had metastases. Response to chemotherapy was recorded in 70%, but 5-year EFS and OS were only 48 and 56%, respectively. Results were significantly worse for metastatic cases, patients under 10, those with RD, and those staged without MRI (unavailable early in the study). Efforts to preserve survivors' quality of life did not pay off, and most patients over 30 still depended on their parents' income and had severe cognitive/endocrine disabilities. In conclusion, despite a very high response rate with this preradiation HD methotrexate schedule, the outcome for high-risk medulloblastoma patients did not improve (especially when lower CSI doses were used) and patients still developed severe morbidities.

Biological and clinical heterogeneity of MYCN-amplified medulloblastoma

Focal high-level amplifications of MYC (or MYCC) define a subset of high-risk medulloblastoma patients. However, the prognostic role of MYCN oncogene amplification remains unresolved. We aimed to evaluate the prognostic value of this alteration alone and in combination with biological modifiers in 67 pediatric medulloblastomas with MYCN amplification (MYCN-MB). Twenty-one MYCN-MB were examined using gene expression profiling and array-CGH, whereas for 46 tumors immunohistochemical analysis and FISH were performed. All 67 tumors were further subjected to mutational analyses. We compared molecular, clinical, and prognostic characteristics both within biological MYCN-MB groups and with non-amplified tumors. Transcriptomic analysis revealed SHH-driven tumorigenesis in a subset of MYCN-MBs indicating a biological dichotomy of MYCN-MB. Activation of SHH was accompanied by variant-specific cytogenetic aberrations including deletion of 9q in SHH tumors. Non-SHH MB were associated with gain of 7q and isochromosome 17q/17q gain. Among clinically relevant variables, SHH subtype and 10q loss for non-SHH tumors comprised the most powerful markers of favorable prognosis in MYCN-MB. In conclusion, we demonstrate considerable heterogeneity within MYCN-MB in terms of genetics, tumor biology, and clinical outcome. Thus, assessment of disease group and 10q copy-number status may improve risk stratification of this group and may delineate MYCN-MB with the same dismal prognosis as MYC amplified tumors. Furthermore, based on the enrichment of MYCN and GLI2 amplifications in SHH-driven medulloblastoma, amplification of these downstream signaling intermediates should be taken into account before a patient is enrolled into a clinical trial using a smoothened inhibitor.

P53 expression predicts dismal outcome for medulloblastoma patients with metastatic disease

Medulloblastoma (MB) is the most common malignant primary brain tumour in childhood. Metastatic disease (M+) at diagnosis is the most important negative prognostic clinical marker and, despite craniospinal irradiation and intensive chemotherapy, it remains one of the leading causes of treatment failure. To date, few clinical and biological data have been evaluated to obtain an additional prognostic profile for these high-risk patients. In this study, 169 patients with metastatic MB registered in the multicentre HIT2000 trial of the German Society of Pediatric Oncology and Haematology (GPOH) have been investigated to determine the importance of p53 protein expression in predicting survival. At a median follow-up of 4.1 years, 159 patients with p53-negative tumours had significantly better four-year event-free survival (EFS) and progression-free survival (PFS) (56 ± 11, 59 ± 4%) than 10 patients with p53-positive tumours (40 ± 16, 40 ± 16%; P = 0.018 for EFS, P = 0.007 for PFS, respectively). Furthermore, four-year overall survival (OS) of children with p53-negative tumours was higher than for children with p53-positive tumours (72 ± 4 vs. 35 ± 18%, P = 0.05). Three of the p53-positive MBs harbored a point mutation in the TP53 gene. p53 protein assessment by immunohistochemistry may be a useful tool for sub-stratification of metastatic high-risk MB patients.

A Literature Review of the Recent Radiotherapy Clinical Trials in Pediatric Brain Tumors

Primary central nervous system neoplasms are the second malignancy in children following leukemia. Despite developments in neurosurgery and new drugs in chemotherapy, irradiation is an essential part of the management in most of pediatric brain tumors. A good treatment strategy should consider not only survival but also the quality of life. The new approach of radiotherapy and importance of new drugs in combined treatment are recently considered. This article summarizes the recent clinical trials conducted in pediatric brain tumors management. Results of randomized study of pre-irradiation chemotherapy versus radiotherapy alone for medulloblastoma were presented by SIOP/UKCCSG PNET-3. The French M-SFOP 98 protocol considered hyper-fractionated radiotherapy with reduced boost volume, without chemotherapy and estimated impact on early relapses and intellectual function. The influence of radiotherapy quality on survival in high-risk medulloblastoma patients was evaluated in POG Trial 9031. In the treatment of low-grade glioma in children the effectiveness of novel combination chemotherapy was considered. Role of new drugs as temozolamid, topotecan and RMP-7 was investigated in pediatric high grade glioma and brain stem tumors. Impact of combined treatment on outcome of intracranial germ-cell tumors was investigated as well.

Treatment of high risk medulloblastomas in children above the age of 3 years: A SFOP study

Aim Improvement of EFS of children older than 3 years with high risk medulloblastoma. Methods Between 1993 and 1999, 115 patients (3–18 years, mean 8 years) with high risk medulloblastoma were included. After surgery treatment consisted of chemotherapy (‘8in1’ and etoposide/carboplatin) before and after craniospinal radiotherapy. Results Patients were staged using Chang-criteria (PF residue only, M1 and M2/M3) by local investigator as well as by central review panel (82.4% concordance). Chemotherapy was well tolerated without major delays in radiotherapy. With a mean follow up of 81 months (9–119), 5-year EFS was 49.8% and OS 60.1%. In detail according to subgroups EFS was 68.8% for PF residue only, 58.8% for M1 disease and 43.1% for M2/M3. Conclusion M1 patients are legitimate high risk patients. Survival rates are still very low for high risk medulloblastoma patients and future trials should therefore focus on more intensive (chemotherapy/radiotherapy) treatment.