Response of subependymal giant cell astrocytoma with spinal cord metastasis to everolimus

The Putative Role of mTOR Inhibitors in Non-tuberous Sclerosis Complex-Related Epilepsy

Epilepsy affects ~5 out of every 10,000 children per year. Up to one-third of these children have medically refractory epilepsy, with limited to no options for improved seizure control. mTOR, a ubiquitous 289 kDa serine/threonine kinase in the phosphatidylinositol 3-kinase (PI3K)-related kinases (PIKK) family, is dysregulated in a number of human diseases, including tuberous sclerosis complex (TSC) and epilepsy. In cell models of epilepsy and TSC, rapamycin, an mTOR inhibitor, has been shown to decrease seizure frequency and duration, and positively affect cell growth and morphology. Rapamycin has also been shown to prevent or improve epilepsy and prolong survival in animal models of TSC. To date, clinical studies looking at the effects of mTOR inhibitors on the reduction of seizures have mainly focused on patients with TSC. Everolimus (Novartis Pharmaceuticals), a chemically modified rapamycin derivative, has been shown to reduce seizure frequency with reasonable safety and tolerability. Mutations in mTOR or the mTOR pathway have been found in hemimegalencephaly (HME) and focal cortical dysplasias (FCDs), both of which are highly correlated with medically refractory epilepsy. Given the evidence to date, a logical next step is to investigate the role of mTOR inhibitors in the treatment of children with medically refractory non-TSC epilepsy, particularly those children who have also failed resective surgery.

Treatment of Renal Angiomyolipoma and Other Hamartomas in Patients with Tuberous Sclerosis Complex

Tuberous sclerosis complex is an autosomal dominant genetic disease characterized by growth of benign tumors (hamartomas) in multiple organs, especially the kidneys, brain, heart, lungs, and skin. Tuberous sclerosis complex is usually caused by a mutation in either the tuberous sclerosis complex 1 or tuberous sclerosis complex 2 gene, resulting in constitutive activation of mammalian target of rapamycin signaling. Currently, mammalian target of rapamycin inhibitors are recommended in adult patients with tuberous sclerosis complex for the treatment of asymptomatic, growing renal angiomyolipoma that are >3 cm in diameter and pediatric or adult patients with brain lesions (subependymal giant cell astrocytoma) that either are growing or are not amenable to surgical resection. Clinical evidence suggests that systemic administration of a mammalian target of rapamycin inhibitor may provide concurrent improvements in multiple lesions and symptoms of tuberous sclerosis complex. With the major paradigm shift in consensus guidelines toward screening at diagnosis and ongoing monitoring and with the recent availability of an effective oral treatment, it is important that nephrologists have a thorough understanding of our role in the management of patients with tuberous sclerosis complex. Because the various manifestations of tuberous sclerosis complex typically emerge at different periods during patients' lifetimes, patients will need to be followed throughout their lives. Unlike brain and cardiac lesions, renal lesions are more likely to emerge as patients age and can grow at any time. Considerations regarding long-term medication administration for the potential control of multiple tuberous sclerosis complex manifestations will need to be addressed; these include the most appropriate starting dose, appropriate doses for tumor shrinkage versus prevention of regrowth, and management of adverse events. Best practices and potential obstacles for nephrologists treating patients with tuberous sclerosis complex who have multiple manifestations are considered.

Safety of Everolimus in Patients Younger than 3 Years of Age: Results from EXIST-1, a Randomized, Controlled Clinical Trial

OBJECTIVES

To assess the long-term safety of everolimus in young children with tuberous sclerosis complex (TSC)-associated subependymal giant cell astrocytoma (SEGA).

STUDY DESIGN

EXamining everolimus In a Study of Tuberous Sclerosis Complex-1 (EXIST-1) was a multicenter, randomized, double-blind phase 3 study with an open-label extension evaluating the efficacy and tolerability of everolimus in patients with TSC-associated SEGA. Everolimus was initiated at 4.5 mg/m(2)/day and titrated to blood trough levels of 5-15 ng/mL. Post hoc analysis of safety data (adverse events [AEs]) was performed in a subgroup of patients aged <3 years at everolimus initiation.

RESULTS

Eighteen patients (median age 1.82 years) were included; 16 were still receiving everolimus at the analysis cut-off date of January 11, 2013. Median everolimus exposure was 31.1 months (range, 11.5-39 months). One patient discontinued treatment because of AEs (ie, Acinetobacter bacteremia, increased blood alkaline phosphatase, and viral infection). AEs were reported in all patients, but events were mostly grade 1/2 in severity; 12 patients (66.7%) experienced grade 3 events, and 2 patients (11.1%) reported grade 4 events. The most common AEs were stomatitis, cough, pharyngitis, and pyrexia; no new safety issues were identified in this population. Serious AEs were reported in 50% of patients; these were suspected to be medication related in 4 patients (22.2%).

CONCLUSIONS

Everolimus appears to be a safe therapeutic option for patients aged <3 years with TSC-associated SEGA. The small sample size in this subpopulation limits interpretation of the results; additional studies in the pediatric population are needed and are underway.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00789828.

Use of the mTOR inhibitor everolimus in a patient with multiple manifestations of tuberous sclerosis complex including epilepsy

Tuberous sclerosis complex (TSC) is a genetic disease in which overactivation of mechanistic target of rapamycin (mTOR) signaling leads to the growth of benign hamartomas in multiple organs, including the brain, and is associated with a high rate of epilepsy and neurological deficits. The mTOR inhibitor everolimus has been used in the treatment of subependymal giant cell astrocytomas and renal angiomyolipomas in patients with TSC. This article describes the case of a 13-year-old girl with TSC-associated epilepsy with refractory generalized seizures who initiated treatment with everolimus and experienced subsequent improvement in several TSC manifestations, including a reduction in seizure frequency from clusters of two or three daily to one every 2 to 4 weeks after 1.5 years of treatment.

Long-Term Everolimus Treatment in Individuals With Tuberous Sclerosis Complex: A Review of the Current Literature

BACKGROUND

Tuberous sclerosis complex is a genetic disease usually caused by mutations to either TSC1 or TSC2, where its gene products are involved in the inhibition of the mammalian target of rapamycin pathway. Under normal cellular conditions, mammalian target of rapamycin (mTOR) regulates cell growth and proliferation in response to signals from nutrients or growth factors, but loss of TSC1 or TSC2 leads to overactivation of mTOR and uncontrolled cellular proliferation. Everolimus is an mTOR inhibitor approved for use in a number of indications where mTOR overactivation is implicated, including tuberous sclerosis complex.

METHODS AND PATIENTS

We conducted a literature search of PubMed to identify published articles about the long-term efficacy and safety of everolimus in patients with tuberous sclerosis complex.

RESULTS

The short-term efficacy and safety of everolimus in patients with tuberous sclerosis complex has been demonstrated in placebo-controlled trials, and open-label extension studies are ongoing to monitor long-term effects, including safety. Examples of regrowth following discontinuation of mTOR inhibitors suggest that everolimus needs to be given indefinitely to maintain suppression of subependymal giant cell astrocytoma and other tuberous sclerosis complex-associated disease manifestations. No additional safety concerns have been reported to date with long-term administration of everolimus, but published long-term data (>1 year treatment) are currently limited to a small open-label trial and case reports for this relatively rare condition.

CONCLUSIONS

From the limited data available, long-term administration of everolimus appears feasible with few safety concerns beyond those associated with short-term use. Further investigation is needed to determine the long-term efficacy and safety of everolimus in patients with tuberous sclerosis complex.