Presurgical Administration of mTOR Inhibitors in Patients with Large Subependymal Giant Cell Astrocytoma Associated with Tuberous Sclerosis Complex

Pediatric-Like Brain Tumors in Adults

Pediatric brain tumors are different to those found in adults in pathological type, anatomical site, molecular signature, and probable tumor drivers. Although these tumors usually occur in childhood, they also rarely present in adult patients, either as a de novo diagnosis or as a delayed recurrence of a pediatric tumor in the setting of a patient that has transitioned into adult services.Due to the rarity of pediatric-like tumors in adults, the literature on these tumor types in adults is often limited to small case series, and treatment decisions are often based on the management plans taken from pediatric studies. However, the biology of these tumors is often different from the same tumors found in children. Likewise, adult patients are often unable to tolerate the side effects of the aggressive treatments used in children-for which there is little or no evidence of efficacy in adults. In this chapter, we review the literature and summarize the clinical, pathological, molecular profile, and response to treatment for the following pediatric tumor types-medulloblastoma, ependymoma, craniopharyngioma, pilocytic astrocytoma, subependymal giant cell astrocytoma, germ cell tumors, choroid plexus tumors, midline glioma, and pleomorphic xanthoastrocytoma-with emphasis on the differences to the adult population.

Neoadjuvant Therapy with Everolimus for Subependymal Giant Cell Astrocytoma: A Case Report

Direct surgical resection remains to be the standard treatment for tuberous sclerosis complex (TSC) with subependymal giant cell astrocytoma (SEGA). Medical therapy with everolimus (mammalian target of rapamycin inhibitor or mTOR) serves as a second-line treatment for patients with SEGA who are determined to be ineligible for surgical resection. Some recent studies have reported that neoadjuvant therapy for SEGA may be a useful, novel treatment. In this study, we herein present a case of SEGA and demonstrate the efficacy of preoperative everolimus therapy. We have also examined the utility and safety of neoadjuvant therapy for SEGA and investigated four previously reported cases of preoperative administration of mTOR inhibitors. In these cases, everolimus was administered preoperatively to shrink the tumor although the duration of treatment varied. Afterward, gross total tumor removal was conducted in all the cases. No postoperative complications were reported during the follow-up period. These findings indicate that neoadjuvant therapy with an mTOR inhibitor can be a potential treatment for SEGA. The findings of this present study also suggested that a short administration period of about 2 months may be sufficient to achieve preoperative tumor reduction.

Subependymal Giant Cell Astrocytomas in Tuberous Sclerosis Complex-Current Views on Their Pathogenesis and Management

Introduction, Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder caused by mutations inactivating TSC1 or TSC2 genes and characterized by the presence of tumors involving many organs, including the brain, heart, kidneys, and skin. Subependymal giant cell astrocytoma (SEGA) is a slow-growing brain tumor almost exclusively associated with TSC.

STATE OF THE ART

Despite the fact that SEGAs are benign, they require well-considered decisions regarding the timing and modality of pharmacological or surgical treatment. In TSC children and adolescents, SEGA is the major cause of mortality and morbidity.

CLINICAL IMPLICATIONS

Until recently, surgical resection has been the standard therapy for SEGAs but the discovery of the role of the mTOR pathway and the introduction of mTOR inhibitors to clinical practice changed the therapeutic landscape of these tumors. In the current paper, we discuss the pros and cons of mTOR inhibitors and surgical approaches in SEGA treatment.

FUTURE DIRECTIONS

In 2021, the International Tuberous Sclerosis Complex Consensus Group proposed a new integrative strategy for SEGA management. In the following review, we discuss the proposed recommendations and report the results of the literature search for the latest treatment directions.

Subependymal giant-cell astrocytoma: a surgical review in the modern era of mTOR inhibitors

INTRODUCTION

Surgical removal has been the historical treatment for subependymal giant-cell astrocytoma (SEGA) in tuberous sclerosis complex (TSC) patients. In the past decade, mTOR inhibitors have shown efficacy in the treatment of SEGA, significantly reducing tumor size. The aim of this study was to assess the safety and efficacy of surgical treatment at a time when mTOR inhibitors have changed standard treatment.

MATERIAL AND METHODS

We conducted a single-center retrospective study including all patients treated by surgery for SEGA from October 2003 to September 2019, with a review of all SEGA surgical case series, following PRISMA guidelines. Research focused on demographics, surgical indications, surgical approach, use of CSF shunt, morbidity and mortality, resection quality, recurrence rate and treatment of recurrence, follow-up and long-term clinical status.

RESULTS

Eleven patients were included, with a median age at surgery of 16.0 years. Gross total resection was achieved in 8 patients (72%), with no permanent morbidity. One patient needed further surgery for tumor recurrence. Eighteen studies were reviewed, totaling 263 TSC patients affected by SEGA and 286 surgical procedures. Gross total resection was achieved in 81.1% of cases, mortality was 4.9% and permanent morbidity 6.1%. Tumor recurrence occurred in 11.5% of cases, and was secondary to partial tumor resection at first surgery in the majority of cases.

CONCLUSION

Surgical treatment of SEGA is still a valid and effective option. Morbidity is low and complete disappearance of SEGA can be achieved in selected cases.

Managing Headache Disorders Associated with Tuberous Sclerosis and Neurofibromatosis

PURPOSE OF REVIEW

Tuberous sclerosis complex (TSC) and neurofibromatosis (NF) are neurocutaneous disorders often encountered by neurologists in clinical practice. This article aims to familiarize adult and pediatric neurologists with common features of these disorders and headache specific evaluation and management.

RECENT FINDINGS

Non-malignant intracranial tumors in TSC include cortical tubers (glioneuronal hamartomas), subependymal nodules or subependymal giant-cell astrocytomas (SEGA). Headache disorders in TSC are largely secondary and can cause headaches due to increased intracranial pressure, mass effect, obstructive hydrocephalus, or hemorrhage. Neurosurgical intervention is typically required for management of large SEGAs; however, in patients with increased surgical risk, newer treatment modalities may be offered such as neoadjuvant therapy with an mTOR inhibitor (mTORi). Newer studies indicate headache disorders are more prevalent in neurofibromatosis type 1 (NF1). Primary headache disorders can include migraine and tension-type headache, while secondary headache disorders can be due to associated neoplasms such as optic pathway gliomas or brainstem gliomas, or less commonly vasculopathies such as moyamoya syndrome. Selumetinib is an oral, small molecule mitogen-activated protein kinase (MEK) agent with antineoplastic activity which is in ongoing trials for treatment of NF1-associated pediatric low-grade gliomas. NF1 stands out as having a higher association with primary headache disorders such as migraine. This association may be related to effects of mutation of the neurofibromin gene on pathways involved in pain and migraine genesis, however, warrants future study. Care should be taken when formulating a headache treatment plan to address comorbidities and avoid medications that may be contraindicated.

Pediatric and Adult Low-Grade Gliomas: Where Do the Differences Lie?

Two thirds of pediatric gliomas are classified as low-grade (LGG), while in adults only around 20% of gliomas are low-grade. However, these tumors do not only differ in their incidence but also in their location, behavior and, subsequently, treatment. Pediatric LGG constitute 65% of pilocytic astrocytomas, while in adults the most commonly found histology is diffuse low-grade glioma (WHO II), which mostly occurs in eloquent regions of the brain, while its pediatric counterpart is frequently found in the infratentorial compartment. The different tumor locations require different skillsets from neurosurgeons. In adult LGG, a common practice is awake surgery, which is rarely performed on children. On the other hand, pediatric neurosurgeons are more commonly confronted with infratentorial tumors causing hydrocephalus, which more often require endoscopic or shunt procedures to restore the cerebrospinal fluid flow. In adult and pediatric LGG surgery, gross total excision is the primary treatment strategy. Only tumor recurrences or progression warrant adjuvant therapy with either chemo- or radiotherapy. In pediatric LGG, MEK inhibitors have shown promising initial results in treating recurrent LGG and several ongoing trials are investigating their role and safety. Moreover, predisposition syndromes, such as neurofibromatosis or tuberous sclerosis complex, can increase the risk of developing LGG in children, while in adults, usually no tumor growth in these syndromes is observed. In this review, we discuss and compare the differences between pediatric and adult LGG, emphasizing that pediatric LGG should not be approached and managed in the same way as adult LCG.

Updated International Tuberous Sclerosis Complex Diagnostic Criteria and Surveillance and Management Recommendations

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disease affecting multiple body systems with wide variability in presentation. In 2013, Pediatric Neurology published articles outlining updated diagnostic criteria and recommendations for surveillance and management of disease manifestations. Advances in knowledge and approvals of new therapies necessitated a revision of those criteria and recommendations.

METHODS

Chairs and working group cochairs from the 2012 International TSC Consensus Group were invited to meet face-to-face over two days at the 2018 World TSC Conference on July 25 and 26 in Dallas, TX, USA. Before the meeting, working group cochairs worked with group members via e-mail and telephone to (1) review TSC literature since the 2013 publication, (2) confirm or amend prior recommendations, and (3) provide new recommendations as required.

RESULTS

Only two changes were made to clinical diagnostic criteria reported in 2013: "multiple cortical tubers and/or radial migration lines" replaced the more general term "cortical dysplasias," and sclerotic bone lesions were reinstated as a minor criterion. Genetic diagnostic criteria were reaffirmed, including highlighting recent findings that some individuals with TSC are genetically mosaic for variants in TSC1 or TSC2. Changes to surveillance and management criteria largely reflected increased emphasis on early screening for electroencephalographic abnormalities, enhanced surveillance and management of TSC-associated neuropsychiatric disorders, and new medication approvals.

CONCLUSIONS

Updated TSC diagnostic criteria and surveillance and management recommendations presented here should provide an improved framework for optimal care of those living with TSC and their families.

Targeting mTORs by omega-3 fatty acids: A possible novel therapeutic strategy for neurodegeneration?

Neurodegenerative diseases (NDs) such as Parkinson's (PD), Alzheimer's (AD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) cause significant world-wide morbidity and mortality. To date, there is no drug of cure for these, mostly age-related diseases, although approaches in delaying the pathology and/or giving patients some symptomatic relief have been adopted for the last few decades. Various studies in recent years have shown the beneficial effects of omega-3 poly unsaturated fatty acids (PUFAs) through diverse mechanisms including anti-inflammatory effects. This review now assesses the potential of this class of compounds in NDs therapy through specific action against the mammalian target of rapamycin (mTOR) signaling pathway. The role of mTOR in neurodegenerative diseases and targeted therapies by PUFAs are discussed.