Advances in managing medulloblastoma and intracranial primitive neuro-ectodermal tumors

MEK Inhibitors Reverse Growth of Embryonal Brain Tumors Derived from Oligoneural Precursor Cells

Malignant brain tumors are the leading cause of cancer-related deaths in children. Primitive neuroectodermal tumors of the CNS (CNS-PNETs) are particularly aggressive embryonal tumors of unknown cellular origin. Recent genomic studies have classified CNS-PNETs into molecularly distinct subgroups that promise to improve diagnosis and treatment; however, the lack of cell- or animal-based models for these subgroups prevents testing of rationally designed therapies. Here, we show that a subset of CNS-PNETs co-express oligoneural precursor cell (OPC) markers OLIG2 and SOX10 with coincident activation of the RAS/MAPK (mitogen-activated protein kinase) pathway. Modeling NRAS activation in embryonic OPCs generated malignant brain tumors in zebrafish that closely mimic the human oligoneural/NB-FOXR2 CNS-PNET subgroup by histology and comparative oncogenomics. The zebrafish CNS-PNET model was used to show that MEK inhibitors selectively eliminate Olig2⁺/Sox10⁺ CNS-PNET tumors in vivo without impacting normal brain development. Thus, MEK inhibitors represent a promising rationally designed therapy for children afflicted with oligoneural/NB-FOXR2 CNS-PNETs.

Challenges of Treating Childhood Medulloblastoma in a Country With Limited Resources: 20 Years of Experience at a Single Tertiary Center in Malaysia

PURPOSE

Pediatric medulloblastoma (MB) treatment has evolved over the past few decades; however, treating children in countries with limited resources remains challenging. Until now, the literature regarding childhood MB in Malaysia has been nonexistent. Our objectives were to review the demographics and outcome of pediatric MB treated at the University Malaya Medical Center between January 1994 and December 2013 and describe the challenges encountered.

METHODS

Fifty-one patients with childhood MB were seen at University Malaya Medical Center. Data from 43 patients were analyzed; eight patients were excluded because their families refused treatment after surgery.

RESULTS

Headache and vomiting were the most common presenting symptoms, and the mean interval between symptom onset and diagnosis was 4 weeks. Fourteen patients presented with metastatic disease. Five-year progression-free survival (± SE) for patients ≥ 3 years old was 41.7% ± 14.2% (95% CI, 21.3% to 81.4%) in the high-risk group and 68.6% ± 18.6% (95% CI, 40.3% to 100%) in the average-risk group, and 5-year overall survival (± SE) in these two groups was 41.7% ± 14.2% (95% CI, 21.3% to 81.4%) and 58.3% ± 18.6% (95% CI, 31.3% to 100%), respectively. Children younger than 3 years old had 5-year progression-free and overall survival rates (± SE) of 47.6% ± 12.1% (95% CI, 28.9% to 78.4%) and 45.6% ± 11.7% (95% CI, 27.6% to 75.5%), respectively. Time to relapse ranged from 4 to 132 months. Most patients who experienced relapse died within 1 year. Febrile neutropenia, hearing loss, and endocrinopathy were the most common treatment-related complications.

CONCLUSION

The survival rate of childhood MB in Malaysia is inferior to that usually reported in the literature. We postulate that the following factors contribute to this difference: lack of a multidisciplinary neuro-oncology team, limited health care facilities, inconsistent risk assessment, insufficient data in the National Cancer Registry and pathology reports, inadequate long-term follow-up, and cultural beliefs leading to treatment abandonment.

Pediatric Brain Tumors: Current Knowledge and Therapeutic Opportunities

Great progress has been made in many areas of pediatric oncology. However, tumors of the central nervous system (CNS) remain a significant challenge. A recent explosion of data has led to an opportunity to understand better the molecular basis of these diseases and is already providing a foundation for the pursuit of rationally chosen therapeutics targeting relevant molecular pathways. The molecular biology of pediatric brain tumors is shifting from a singular focus on basic scientific discovery to a platform upon which insights are being translated into therapies.

Clinical characteristics and abandonment and outcome of treatment in 67 Chinese children with medulloblastoma

OBJECT The purpose of this study was to explore the clinical features and outcome of medulloblastoma in Chinese children. The authors analyze the reasons that treatment is abandoned and attempt to provide evidence-based recommendations for improving the prognosis of medulloblastoma in this population. METHODS A total of 67 pediatric cases of newly diagnosed medulloblastoma were included in this study. All of the children were treated at Xinhua Hospital between January 2007 and June 2013. The authors retrospectively analyzed the clinical data, treatment modalities, and outcome. The male-to-female ratio was 2:1, and the patients' median age at diagnosis was 51.96 months (range 3.96-168.24 months). The median duration of follow-up was 32 months (range 3-70 months). RESULTS At the most recent follow-up date, 31 patients (46%) were alive, 30 (45%) had died, and 6 (9%) had been lost to follow-up. The estimated 3-year overall survival and progression-free survival, based on Kaplan-Meier analysis, were 55.1% ± 6.4% and 45.6% ± 6.7%, respectively. Univariate analysis showed that standard-risk group (p = 0.009), postoperative radiotherapy (RT) combined with chemotherapy (p < 0.001), older age (≥ 3 years) at diagnosis (p = 0.010), gross-total resection (p = 0.012), annual family income higher than $3000 (p = 0.033), and living in urban areas (p = 0.008) were favorable prognostic factors. Multivariate analysis revealed that postoperative RT combined with chemotherapy was an independent prognostic factor (p < 0.001). The treatment abandonment rate in this cohort was 31% (21 of 67 cases). CONCLUSIONS There was a large gap between the outcome of medulloblastoma in Chinese children and the outcome in Western children. Based on our data, treatment abandonment was the major cause of therapeutic failure. Parents' misunderstanding of medulloblastoma played a major role in abandonment, followed by financial and transportation difficulties. Establishment of multidisciplinary treatment teams could improve the prognosis of medulloblastoma in Chinese children.

Novel treatment of a central type, primitive neuroectodermal tumor of the ovary with postoperative pediatric medulloblastoma chemotherapy regimen: A case report and review of the literature

•Central type primitive neuroectodermal tumor (cPNET) of the ovary is difficult to treat.•Etoposide, cisplatin and cyclophosphamide is a pediatric medulloblastoma regimen.•Our case with cPNET responded to this combination chemotherapy.

SnapShot: Medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children, where one-third of patients succumb to their disease. This SnapShot describes the classification of MB subgroups, historically by histopathology and currently based on genomic information. Genomics-based classification has identified four major subgroups and provides greater opportunity for developing targeted therapies more successful than current conventional therapy.