Tuberin Regulates Prostaglandin Receptor-Mediated Viability, via Rheb, in mTORC1-Hyperactive Cells.

Tuberous sclerosis complex (TSC) is a tumor-suppressor syndrome affecting multiple organs, including the brain, skin, kidneys, heart, and lungs. TSC is associated with mutations in TSC1 or TSC2, resulting in hyperactivation of mTOR complex 1 (mTORC1). Clinical trials demonstrate that mTORC1 inhibitors decrease tumor volume and stabilize lung function in TSC patients; however, mTOR inhibitors are cytostatic not cytocidal, and long-term benefits and toxicities are uncertain. Previously, we identified rapamycin-insensitive upregulation of cyclooxygenase 2 (PTGS2/COX2) and prostaglandin E2 (PGE2) production in TSC2-deficient cells and postulated that the action of excess PGE2 and its cognate receptors (EP) contributes to cell survival. In this study, we identify upregulation of EP3 (PTGER3) expression in TSC2-deficient cells, TSC renal angiomyolipomas, lymphangioleiomyomatosis lung nodules, and epileptic brain tubers. TSC2 negatively regulated EP3 expression via Rheb in a rapamycin-insensitive manner. The EP3 antagonist, L-798106, selectively suppressed the viability of TSC2-deficient cells in vitro and decreased the lung colonization of TSC2-deficient cells. Collectively, these data reveal a novel function of TSC2 and Rheb in the regulation of EP3 expression and cell viability.Implications: Therapeutic targeting of an aberrant PGE2-EP3 signaling axis may have therapeutic benefit for TSC patients and for other mTOR-hyperactive neoplasms. Mol Cancer Res; 15(10); 1318-30. ©2017 AACR.

Long-term treatment of epilepsy with everolimus in tuberous sclerosis.

OBJECTIVE: To evaluate the long-term benefit and safety of everolimus for the treatment of medically refractory epilepsy in patients with tuberous sclerosis complex (TSC). METHODS: Everolimus was titrated over 4 weeks and continued an additional 8 weeks in a prospective, open-label, phase I/II clinical trial design. Participants demonstrating initial benefit continued treatment until study completion (48 months). The primary endpoint was percentage of patients with a ≥50% reduction in seizure frequency compared to baseline. Secondary endpoints assessed absolute seizure frequency, adverse events (AEs), behavior, and quality of life. RESULTS: Of the 20 participants who completed the initial study phase, 18 continued extended treatment. Fourteen of 18 (78%) participants completed the study, all but 1 of whom reported ≥50% reduction in seizure frequency at 48 months. All participants reported at least 1 AE, the vast majority (94%) of which were graded mild or moderate severity. Improvements in behavior and quality of life were also observed, but failed to achieve statistical significance at 48 months. CONCLUSIONS: Improved seizure control was maintained for 4 years in the majority of patients with TSC with medically refractory epilepsy treated with everolimus. Long-term treatment with everolimus is safe and well-tolerated in this population. Everolimus may be a therapeutic option for refractory epilepsy in TSC. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with TSC with medically refractory epilepsy everolimus improves seizure control.

Everolimus for subependymal giant cell astrocytoma: 5-year final analysis.

OBJECTIVE: To analyze the cumulative efficacy and safety of everolimus in treating subependymal giant cell astrocytomas (SEGA) associated with tuberous sclerosis complex (TSC) from an open-label phase II study (NCT00411619). Updated data became available from the conclusion of the extension phase and are presented in this ≥5-year analysis. METHODS: Patients aged ≥ 3 years with a definite diagnosis of TSC and increasing SEGA lesion size (≥2 magnetic resonance imaging scans) received everolimus starting at 3mg/m(2) /day (titrated to target blood trough levels of 5-15ng/ml). The primary efficacy endpoint was reduction from baseline in primary SEGA volume. RESULTS: As of the study completion date (January 28, 2014), 22 of 28 (78.6%) initially enrolled patients finished the study per protocol. Median (range) duration of exposure to everolimus was 67.8 (4.7-83.2) months; 12 (52.2%) and 14 (60.9%) of 23 patients experienced SEGA volume reductions of ≥50% and ≥30% relative to baseline, respectively, after 60 months of treatment. The proportion of patients experiencing daily seizures was reduced from 7 of 26 (26.9%) patients at baseline to 2 of 18 (11.1%) patients at month 60. Most commonly reported adverse events (AEs) were upper respiratory tract infection and stomatitis of mostly grade 1 or 2 severity. No patient discontinued treatment due to AEs. The frequency of emergence of most AEs decreased over the course of the study. INTERPRETATION: Everolimus continues to demonstrate a sustained effect on SEGA tumor reduction over ≥5 years of treatment. Everolimus remained well-tolerated, and no new safety concerns were noted.

Everolimus treatment of refractory epilepsy in tuberous sclerosis complex.

OBJECTIVE: Epilepsy is a major manifestation of tuberous sclerosis complex (TSC). Everolimus is an mammalian target of rapamycin complex 1 inhibitor with demonstrated benefit in several aspects of TSC. We report the first prospective human clinical trial to directly assess whether everolimus will also benefit epilepsy in TSC patients. METHODS: The effect of everolimus on seizure control was assessed using a prospective, multicenter, open-label, phase I/II clinical trial. Patients≥2 years of age with confirmed diagnosis of TSC and medically refractory epilepsy were treated for a total of 12 weeks. The primary endpoint was percentage of patients with a ≥50% reduction in seizure frequency over a 4-week period before and after treatment. Secondary endpoints assessed impact on electroencephalography (EEG), behavior, and quality of life. RESULTS: Twenty-three patients were enrolled, and 20 patients were treated with everolimus. Seizure frequency was reduced by ≥50% in 12 of 20 subjects. Overall, seizures were reduced in 17 of the 20 by a median reduction of 73% (p<0.001). Seizure frequency was also reduced during 23-hour EEG monitoring (p=0.007). Significant reductions in seizure duration and improvement in parent-reported behavior and quality of life were also observed. There were 83 reported adverse events that were thought to be treatment-related, all of which were mild or moderate in severity. INTERPRETATION: Seizure control improved in the majority of TSC patients with medically refractory epilepsy following treatment with everolimus. Everolimus demonstrated additional benefits on behavior and quality of life. Treatment was safe and well tolerated. Everolimus may be a therapeutic option for refractory epilepsy in this population.

Everolimus long-term safety and efficacy in subependymal giant cell astrocytoma.

OBJECTIVE: To report long-term efficacy and safety data for everolimus for the treatment of subependymal giant cell astrocytoma (SEGA) in patients with tuberous sclerosis complex (TSC). METHODS: This was an open-label extension phase of a prospective, phase 1-2 trial (NCT00411619) in patients ≥3 years of age with SEGA associated with TSC. Patients received oral everolimus starting at 3 mg/m2 per day and subsequently titrated, subject to tolerability, to attain whole blood trough concentrations of 5-15 ng/mL. Change in SEGA volume, seizures, and safety assessments were the main outcome measures. RESULTS: Of 28 patients enrolled, 25 were still under treatment at the time of analysis. Median dose was 5.3 mg/m2/day and median treatment duration was 34.2 months (range 4.7-47.1). At all time points (18, 24, 30, and 36 months), primary SEGA volume was reduced by ≥30% from baseline (treatment response) in 65%-79% of patients. All patients reported ≥1 adverse event (AE), mostly grade 1/2 in severity, consistent with that previously reported, and none led to everolimus discontinuation. The most commonly reported drug-related AEs were upper respiratory infections (85.7%), stomatitis (85.7%), sinusitis (46.4%), and otitis media (35.7%). No drug-related grade 4 or 5 events occurred. CONCLUSION: Everolimus therapy is safe and effective for longer term (median exposure 34.2 months) treatment of patients with TSC with SEGA. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that everolimus, titrated to trough serum levels of 5-15 ng/mL, was effective in reducing tumor size in patients with SEGA secondary to TSC for a median of 34 months.