Conversion to brivaracetam monotherapy for the treatment of patients with focal seizures: Two double-blind, randomized, multicenter, historical control, Phase III studies

Abstract

Brivaracetam (BRV), a selective, high-affinity ligand for synaptic vesicle protein 2A, is a new antiepileptic drug (AED) approved for monotherapy (in the USA) and adjunctive treatment of focal (partial-onset) seizures in adults, at a dose range of 50–200 mg/day taken in two equal doses, with a recommended starting dose of 100 mg/day. Two Phase III, randomized, double-blind, multicenter, historical-controlled, conversion-to-monotherapy studies (N01276, NCT00698581; N01306, NCT00699283) were conducted to evaluate the efficacy, safety, and tolerability of conversion to BRV 50 mg/day monotherapy in adults with uncontrolled focal seizures. Patients aged 16–75 years, with 2–40 focal seizures per 4 weeks during an 8-week baseline, and on stable doses of 1–2 AEDs were enrolled. Patients were randomized to BRV 50 or 100 mg/day (3:1) in two equal doses without titration. The treatment period comprised 1-week BRV add-on, 8-week baseline AED tapering, and 8-week BRV monotherapy periods. Primary efficacy endpoint was Kaplan-Meier estimate of the cumulative exit rate due to pre-defined exit criteria at Day 112 (50 mg/day, efficacy population). The upper 95% confidence interval (CI) was compared with the historical control threshold (0.722). Safety and tolerability assessments included treatment-emergent adverse events (TEAEs; intent-to-treat population). After randomization of 150 patients (N01276: 88; N01306: 62), both studies were terminated due to the confounding effects of a higher-than-expected discontinuation rate. For BRV 50 mg/day, ≥1 exit criterion was met by 26/67 (38.8%) patients (study N01276) and 18/45 (40.0%) patients (study N01306). In both studies, the cumulative exit rate was lower than the historical control threshold (N01276: 0.487, 95% CI 0.347, 0.626; N01306: 0.474, 95% CI 0.310, 0.638). However, with maximum 10% censoring due to early withdrawal (sensitivity analysis), cumulative exit rates were above historical control (N01276: 0.652, 95% CI 0.532, 0.772; N01306: 0.704, 95% CI 0.563, 0.844). Overall incidence of TEAEs was 110/150, 73.3% (treatment period); 78/147, 53.1% (baseline AED tapering period); 41/84, 48.8% (BRV monotherapy period). In conclusion, BRV 50 mg/day monotherapy demonstrated an exit rate lower than historical control. Results should be interpreted with caution as, following termination of both studies, patient numbers were too low to evaluate the efficacy of BRV monotherapy. These are the first published safety and tolerability data for BRV monotherapy. Monotherapy was well tolerated, with a relatively low incidence of TEAEs, though this should be interpreted with the caveat that the majority of common TEAEs were likely to have occurred earlier in the course of treatment with BRV. No new safety concerns were identified, supporting the favorable safety profile of BRV observed in adjunctive studies.