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Background: The treatment of BRAF V600E gliomas with BRAF inhibitors (BRAFis) and MEK inhibitors (MEKis) has been increasingly integrated into clinical practice for pediatric low-grade gliomas (PLGGs) and pediatric high-grade gliomas (HGGs). However, some questions remain unanswered, such as the best time to start targeted therapy, duration of treatment, and discontinuation of therapy. Given that no clinical trial has been able to address these critical questions, we developed a Canadian Consensus statement for the treatment of BRAF V600E mutated pediatric as well as adolescent and young adult (AYA) gliomas. Methods : Canadian neuro-oncologists were invited to participate in the development of this consensus. The consensus was discussed during monthly web-based national meetings, and the algorithms were revised until a consensus was achieved. Results : A total of 26 participants were involved in the development of the algorithms. Two treatment algorithms are proposed, one for the initiation of treatment and one for the discontinuation of treatment. We suggest that most patients with BRAF V600E gliomas should be treated with BRAFis ± MEKis upfront. Discontinuation of treatment can be considered in certain circumstances, and we suggest a slow wean. Conclusions: Based on expert consensus in Canada, we developed algorithms for treatment initiation of children and AYA with BRAF V600E gliomas as well as a discontinuation algorithm.

Replication repair deficiency (RRD) leading to hypermutation is an important driving mechanism of high-grade glioma (HGG) occurring predominantly in the context of germline mutations in RRD-associated genes. Although HGG presents specific patterns of DNA methylation corresponding to oncogenic mutations, this has not been well studied in replication repair-deficient tumors. We analyzed 51 HGG arising in the background of gene mutations in RRD utilizing either 450 k or 850 k methylation arrays. These were compared with HGG not known to be from patients with RRD. RRD HGG harboring secondary mutations in glioma genes such as IDH1 and H3F3A displayed a methylation pattern corresponding to these methylation subgroups. Strikingly, RRD HGG lacking these known secondary mutations clustered together with an incompletely described group of HGG previously labeled "Wild type-C" or "Paediatric RTK 1". Independent analysis of two comparator HGG cohorts showed that other RRD/hypermutant tumors clustered within these subgroups, suggesting that undiagnosed RRD may be driving some HGG clustering in this location. RRD HGG displayed a unique CpG Island Demethylator Phenotype in contrast to the CpG Island Methylator Phenotype described in other cancers. Hypomethylation was enriched at gene promoters with prominent demethylation in genes and pathways critical to cellular survival including cell cycle, gene expression, cellular metabolism, and organization. These data suggest that methylation arrays may provide diagnostic information for the detection of RRD HGG. Furthermore, our findings highlight the unique natural selection pressures in these highly dysregulated, hypermutant cancers and provide the novel impact of hypermutation and RRD on the cancer epigenome.

Infant gliomas have paradoxical clinical behavior compared to those in children and adults: low-grade tumors have a higher mortality rate, while high-grade tumors have a better outcome. However, we have little understanding of their biology and therefore cannot explain this behavior nor what constitutes optimal clinical management. Here we report a comprehensive genetic analysis of an international cohort of clinically annotated infant gliomas, revealing 3 clinical subgroups. Group 1 tumors arise in the cerebral hemispheres and harbor alterations in the receptor tyrosine kinases ALK, ROS1, NTRK and MET. These are typically single-events and confer an intermediate outcome. Groups 2 and 3 gliomas harbor RAS/MAPK pathway mutations and arise in the hemispheres and midline, respectively. Group 2 tumors have excellent long-term survival, while group 3 tumors progress rapidly and do not respond well to chemoradiation. We conclude that infant gliomas comprise 3 subgroups, justifying the need for specialized therapeutic strategies.

Background: There are very few studies about the role of repeat irradiation (RT2) for children with recurrent supratentorial high-grade glioma (HGG). It was the aim of this study to assess the effectiveness and safety of RT2 in this population., Procedure: This was a retrospective cohort study of 40 children age 18 years and under with recurrent supratentorial HGG who had received at least one course of RT. In-field reirradiation volumes included focal or whole brain RT, with doses ranging from 30 to 54 Gy. The primary endpoint was overall survival (OS) from the first day of RT2., Results: Fourteen patients underwent RT2. The median survival of these patients was 6.5 months. Patients with ≥12 months elapsed time between RT1 and RT2 experienced longer OS than patients who had < 12 months (P = 0.009). There was no difference in OS between patients with or without germline mutations (e.g., Lynch, Li-Fraumeni, or constitutional mismatch-repair deficiency, P = 0.20). Ten patients received RT2 that overlapped with RT1 volumes for locally recurrent disease. Of this group, 80% experienced clinical benefit from in-field RT2, defined as clinical/radiologic response or stable disease. Ninety-three percent completed the prescribed course of RT2, with one patient developing grade 3 radiation necrosis four months after RT2. When compared with 26 patients who were not offered reirradiation, those selected for RT2 had improved median survival from the time of first disease progression (9.4 vs 3.8 months, P = 0.005)., Conclusions: Reirradiation for children with recurrent supratentorial HGG is a safe, effective treatment that provides short-term disease control., (© 2019 Wiley Periodicals, Inc.)

In children under the age of 3, the most common solid tumours are brain tumors. Treatment for many of these patients includes surgery, chemotherapy and rarely radiation therapy. Many clinical trials have been performed in an attempt to establish the best treatment for these patients. Patients enrolled on clinical trials contribute to the establishment of the best therapy. We performed a national survey of all children less than the age of three with brain tumours and examined the contribution these patients made to clinical trials. A data bank was established using data collected from Canadian pediatric oncology centers on children less than age 3 diagnosed with brain tumours between 1990 and 2005. Data were collected on the use of adjunctive treatment after surgery, treatment on a protocol, reasons patients were not registered on a protocol, and reasons for discontinuation of therapy. From the 579 cases in the data bank, 302 (52%) patients were treated with further therapy after surgery. The use of further therapy after surgery was significantly higher in patients with cerebellar and brain stem tumors, patients who were over 1 year of age, patients with ependymal and embryonal tumors, and patients with high grade malignant tumors. Only 62 (21%) patients were enrolled on a protocol for therapy. No factor was significant for being enrolled on a protocol. Reasons for not being registered on a protocol were mainly that there was no open COG/POG/CCG study or the study was not open at the institution. The therapy was stopped because of completion of the protocol in 50% and because of disease progression in 34%. In Canada, about half of children under the age of 36 months with brain tumors are undergoing therapy following surgery for their malignancy but only a small fraction of them are enrolled on a clinical trial. There needs to be improved availability of clinical trials for these patients so that novel therapies can be evaluated and survival improved.

Background and Purpose: Reports of secondary high-grade glioma (HGG) in survivors of childhood cancer are scarce. The aim of this study was to review the pattern of diagnosis, the treatment, and outcome of secondary pediatric HGG., Patients and Methods: We performed a multi-center retrospective study among the 17 paediatric institutions participating in the Canadian Pediatric Brain Tumour Consortium (CPBTC)., Results: We report on 18 patients (14 males, 4 females) treated in childhood for a primary cancer, who subsequently developed a HGG as a second malignancy. All patients had previously received radiation therapy +/- chemotherapy for either acute lymphoblastic leukaemia (n=9) or solid tumour (n=9). All HGG occurred within the previous radiation fields. At the last follow-up, 17 patients have died and the median survival time is 9.75 months., Conclusion: Although aggressive treatment seems to provide sustained remissions in some patients, the optimal management is still to be defined. Further documentation of such cases is necessary in order to better understand the pathogenesis, the natural history and the prevention of these tumours.