Canadian Consensus for Treatment of BRAF V600E Mutated Pediatric and AYA Gliomas.

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.

Impact of trametinib on the neuropsychological profile of NF1 patients.

PURPOSE: The use of trametinib in the treatment of pediatric low-grade gliomas (PLGG) and plexiform neurofibroma (PN) is being investigated in an ongoing multicenter phase II trial (NCT03363217). Preliminary data shows potential benefits with significant response in the majority of PLGG and PN and an overall good tolerance. Moreover, possible benefits of MEK inhibitor therapy on cognitive functioning in neurofibromatosis type 1 (NF1) were recently shown which supports the need for further evaluation. METHODS: Thirty-six patients with NF1 (age range 3-19 years) enrolled in the phase II study of trametinib underwent a neurocognitive assessment at inclusion and at completion of the 72-week treatment. Age-appropriate Wechsler Intelligence Scales and the Trail Making Test (for children over 8 years old) were administered at each assessment. Paired t-tests and Reliable Change Index (RCI) analyses were performed to investigate change in neurocognitive outcomes. Regression analyses were used to investigate the contribution of age and baseline score in the prediction of change. RESULTS: Stable performance on neurocognitive tests was revealed at a group-level using paired t-tests. Clinically significant improvements were however found on specific indexes of the Wechsler intelligence scales and Trail Making Test, using RCI analyses. No significant impact of age on cognitive change was evidenced. However, lower initial cognitive performance was associated with increased odds of presenting clinically significant improvements on neurocognitive outcomes. CONCLUSION: These preliminary results show a potential positive effect of trametinib on cognition in patients with NF1. We observed significant improvements in processing speed, visuo-motor and verbal abilities. This study demonstrates the importance of including neuropsychological evaluations into clinical trial when using MEK inhibitors for patients with NF1.

Evidence-Based Recommendations for Education Provided to Patients and Families Regarding the Adverse Events of ALK and MEK Inhibitors: A Systematic Review From the Children's Oncology Group.

Background: Pediatric oncology patients receive multiple modalities of therapy to treat their malignancies. These modalities have the potential for acute toxicity and late effects. In the last decade, a new modality known as targeted biological therapy, has become an integral part of treatment for pediatric cancers. As targeted therapy use has increased, adverse events specific to these targeted agents have emerged, requiring a new effort focused on providing education to patients and families regarding how best to report, monitor, and manage these adverse events. Method: A clinical question was developed to guide the systematic literature review. Anaplastic lymphoma kinase (ALK) and mitogen-activated protein kinase kinase (MEK) inhibitors were selected for review due to their frequency of use in pediatric oncology. The search was conducted to identify relevant articles published between January 1, 2000 and May 5, 2020. Articles were screened by two team members for inclusion/exclusion criteria using the web-based systematic review tool, Rayyan. Results: Twenty-seven articles met the eligibility criteria for inclusion and were evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation criteria. Adverse events for ALK and MEK inhibitors included manifestations of the gastrointestinal, hematologic, dermatologic, musculoskeletal, neurological, cardiovascular, and ocular systems. Recommendations for patient/family education were made for ALK and MEK inhibitors based on the reported adverse events. Conclusions: Adverse events of ALK and MEK inhibitors differ from the more common adverse events experienced with conventional treatment modalities used in pediatric oncology. It is important for nurses to include information regarding potential adverse events in patient/family education for children receiving these targeted agents.

Time to dismiss boost? Outcomes of children with localized and metastatic germinoma.

PURPOSE: To determine long-term outcomes of a cohort of children with germinoma treated with chemotherapy and radiation therapy without primary tumor boost even in the absence of complete response to chemotherapy METHODS: This retrospective study analyzed the outcome of patients with germinoma consecutively diagnosed and treated at a tertiary care center from January 2000 to December 2021. MRIs were reviewed by two radiologists, blinded to patient data. Tumor location at diagnosis, tumor response to chemotherapy and at completion of radiation therapy and site of relapse were assessed. Tumor response was assessed radiologically by determining the tumor size and response on diffusion-weighted imaging, in addition to biochemical, cytological parameters and neurological status. RESULTS: Of 46 pediatric germinoma patients, 29 children (14 male; median age 12.8 years) received no primary tumor boost. Median follow-up was 63 months (range 9-187 months). Twenty-five children had localized disease and tumor location was suprasellar (n = 11), pineal (n = 10), bifocal (n = 3) and basal ganglia (n = 1) while 4 children had metastatic disease at presentation. All patients completed multi-agent chemotherapy followed by either ventricular irradiation (VI) (23.4 Gy) (n = 23), whole brain (WBI) (23.4 Gy) (n = 5) or craniospinal radiation (CSI) (23.4 Gy) (n = 1). Two children, who had localized disease at presentation and received VI after chemotherapy, relapsed 9 months and 32 months after completion of treatment respectively. No patient had a local relapse. Location of relapse was distant, outside (n = 1) and out- and inside (n = 1) the irradiation field. Five-year progression free survival (PFS) was 91% and overall survival (OS) was 100%. CONCLUSIONS: In this case series, excellent 5-year PFS and OS rates were achieved with chemotherapy followed by radiation therapy of 23.4 Gy delivered without primary tumor boost. No local relapse was observed despite omitting primary tumor boost in patients with localized and metastatic germinoma.

Outcomes of BRAF V600E Pediatric Gliomas Treated With Targeted BRAF Inhibition.

PURPOSE: Children with pediatric gliomas harboring a BRAF V600E mutation have poor outcomes with current chemoradiotherapy strategies. Our aim was to study the role of targeted BRAF inhibition in these tumors. PATIENTS AND METHODS: We collected clinical, imaging, molecular, and outcome information from patients with BRAF V600E-mutated glioma treated with BRAF inhibition across 29 centers from multiple countries. RESULTS: Sixty-seven patients were treated with BRAF inhibition (pediatric low-grade gliomas [PLGGs], n = 56; pediatric high-grade gliomas [PHGGs], n = 11) for up to 5.6 years. Objective responses were observed in 80% of PLGGs, compared with 28% observed with conventional chemotherapy (P < .001). These responses were rapid (median, 4 months) and sustained in 86% of tumors up to 5 years while receiving therapy. After discontinuation of BRAF inhibition, 76.5% (13 of 17) of patients with PLGG experienced rapid progression (median, 2.3 months). However, upon rechallenge with BRAF inhibition, 90% achieved an objective response. Poor prognostic factors in conventional therapies, such as concomitant homozygous deletion of CDKN2A, were not associated with lack of response to BRAF inhibition. In contrast, only 36% of those with PHGG responded to BRAF inhibition, with all but one tumor progressing within 18 months. In PLGG, responses translated to 3-year progression-free survival of 49.6% (95% CI, 35.3% to 69.5%) versus 29.8% (95% CI, 20% to 44.4%) for BRAF inhibition versus chemotherapy, respectively (P = .02). CONCLUSION: Use of BRAF inhibition results in robust and durable responses in BRAF V600E-mutated PLGG. Prospective studies are required to determine long-term survival and functional outcomes with BRAF inhibitor therapy in childhood gliomas.

Neuropsychological impact of trametinib in pediatric low-grade glioma: A case series.

Clinical trials of MEK inhibitors are underway in pediatric low-grade glioma (PLGG) with BRAF oncogene mutations and recurrent/refractory disease. Cognitive and behavioral impacts of MEK inhibitors, such as trametinib, are unknown as these outcomes have not yet been studied. This case series compared cognition and behavior in eight PLGG cases prior to and while on treatment with trametinib compared to four PLGG controls. Intelligence in the trametinib cases was mainly unchanged while on treatment, with mild decline in one of seven cases with complete data. Parent-reported depression symptoms increased in five of eight trametinib cases relative to one of four controls.

Pattern of Relapse and Treatment Response in WNT-Activated Medulloblastoma.

Over the past decade, wingless-activated (WNT) medulloblastoma has been identified as a candidate for therapy de-escalation based on excellent survival; however, a paucity of relapses has precluded additional analyses of markers of relapse. To address this gap in knowledge, an international cohort of 93 molecularly confirmed WNT MB was assembled, where 5-year progression-free survival is 0.84 (95%, 0.763-0.925) with 15 relapsed individuals identified. Maintenance chemotherapy is identified as a strong predictor of relapse, with individuals receiving high doses of cyclophosphamide or ifosphamide having only one very late molecularly confirmed relapse (p = 0.032). The anatomical location of recurrence is metastatic in 12 of 15 relapses, with 8 of 12 metastatic relapses in the lateral ventricles. Maintenance chemotherapy, specifically cumulative cyclophosphamide doses, is a significant predictor of relapse across WNT MB. Future efforts to de-escalate therapy need to carefully consider not only the radiation dose but also the chemotherapy regimen and the propensity for metastatic relapses.

Trametinib Toxicities in Patients With Low-grade Gliomas and Diabetes Insipidus: Related Findings?

Low-grade gliomas (LGG) represent the most common form of primary central nervous system tumor arising in childhood. There is growing evidence to support the role of the mitogen-activated protein kinase pathway in driving tumor growth and MEK inhibitors are being investigated in clinical trials for refractory and unresectable LGGs. As MEK inhibitors progress through clinical trials, drug toxicities have been identified. We report on 2 pediatric patients with LGG and known diabetes insipidus who developed severe hyponatraemia associated with significant decreases in desmopressin doses after starting trametinib. We review potential mechanisms for this sodium imbalance by examining the interaction between MEK inhibition and aquaporin channel physiology. We recommend close monitoring of serum sodium levels and clinical status in patients with diabetes insipidus who have optic-hypothalamic gliomas and are started on treatment with MEK inhibitors.

Therapeutic and Prognostic Implications of BRAF V600E in Pediatric Low-Grade Gliomas.

Purpose BRAF V600E is a potentially highly targetable mutation detected in a subset of pediatric low-grade gliomas (PLGGs). Its biologic and clinical effect within this diverse group of tumors remains unknown. Patients and Methods A combined clinical and genetic institutional study of patients with PLGGs with long-term follow-up was performed (N = 510). Clinical and treatment data of patients with BRAF V600E mutated PLGG (n = 99) were compared with a large international independent cohort of patients with BRAF V600E mutated-PLGG (n = 180). Results BRAF V600E mutation was detected in 69 of 405 patients (17%) with PLGG across a broad spectrum of histologies and sites, including midline locations, which are not often routinely biopsied in clinical practice. Patients with BRAF V600E PLGG exhibited poor outcomes after chemotherapy and radiation therapies that resulted in a 10-year progression-free survival of 27% (95% CI, 12.1% to 41.9%) and 60.2% (95% CI, 53.3% to 67.1%) for BRAF V600E and wild-type PLGG, respectively ( P < .001). Additional multivariable clinical and molecular stratification revealed that the extent of resection and CDKN2A deletion contributed independently to poor outcome in BRAF V600E PLGG. A similar independent role for CDKN2A and resection on outcome were observed in the independent cohort. Quantitative imaging analysis revealed progressive disease and a lack of response to conventional chemotherapy in most patients with BRAF V600E PLGG. Conclusion BRAF V600E PLGG constitutes a distinct entity with poor prognosis when treated with current adjuvant therapy.

Profound clinical and radiological response to BRAF inhibition in a 2-month-old diencephalic child with hypothalamic/chiasmatic glioma.

Infants with low-grade glioma (LGG) have a poor survival. BRAFV600E mutation has been identified in pediatric LGG; however, the use of BRAF inhibitors in infants has never been reported. A 2-month-old with V600E mutant hypothalamic/chiasmatic glioma progressed on chemotherapy resulting in profound visual loss, massive ascites, and diencephalic syndrome. Initiation of dabrafenib resulted in rapid and sustained disappearance of clinical symptoms and a profound sustained cytoreduction. BRAF inhibition was safely tolerated with dramatic clinicoradiological response, suggesting early targeted therapy is a viable option in infants with LGG. A re-evaluation of current management paradigms in this population is warranted to leverage the potential benefit of upfront-targeted therapies.