Everolimus for treatment-refractory seizures in TSC: Extension of a randomized controlled trial

BackgroundEXamining everolimus In a Study of Tuberous sclerosis 3 (EXIST-3) demonstrated significantly reduced seizure frequency (SF) with everolimus vs placebo. In this study, we evaluate the long-term efficacy and safety of everolimus for tuberous sclerosis complex (TSC)-associated treatment-refractory seizures.MethodsAfter completion of the core phase, patients could enter an open-label extension phase and receive everolimus (target exposure, 3-15 ng/mL) for 48 weeks. Efficacy end points included change from baseline in average weekly SF expressed as response rate (RR, 50% reduction) and median percentage reduction (PR).ResultsOf 366 patients, 361 received everolimus in core/extension phases. The RR was 31% (95% CI, 26.2-36.1; N = 352) at week 18, 46.6% (95% CI, 40.9-52.5; N = 298) at 1 year, and 57.7% (95% CI, 49.7-65.4; N = 163) at 2 years. Median PR in SF was 31.7% (95% CI, 28.5-36.1) at week 18, 46.7% (95% CI, 40.2-54) at 1 year, and 56.9% (95% CI, 50-68.4) at 2 years. Ninety-five patients (26.3%) discontinued everolimus before 2 years; 103 (28.5%) had <2 years of follow-up at study cutoff, and 40% were exposed to everolimus for 2 years. An analysis classifying discontinued patients as nonresponders showed an RR of 30.2% (95% CI, 25.5-35.2; N = 361) at week 18, 38.8% (95% CI, 33.7-44.1; N = 358) at 1 year, and 41% (95% CI, 34.6-47.7; N = 229) at 2 years, suggesting sustained benefit over time. The incidence of grade 3/4 adverse events (AEs) (any cause) was 40.2%, and 13% discontinued because of AEs (pneumonia [1.7%] and stomatitis [1.4%]). Two deaths were suspected to be treatment-related (pneumonia and septic shock).ConclusionsSustained reductions in TSC-associated treatment-refractory seizures over time were achieved with adjunctive everolimus. The safety profile was consistent with the core phase with no new safety concerns.Classification of evidenceThis study provides Class IV evidence that long-term everolimus therapy reduces SF in patients with TSC-associated treatment-refractory seizures.