0640 Magnitude of Improvement in Excessive Daytime Sleepiness with the Once-at-Bedtime Oxybate for Narcolepsy

Abstract Introduction Safety and efficacy of once-nightly sodium oxybate (ON-SXB; LUMRYZ™) were investigated in the phase 3 REST-ON trial (NCT02720744). Results demonstrated statistically significant improvements in the secondary endpoint of excessive daytime sleepiness (EDS) measured using the Epworth Sleepiness Scale (ESS; P< 0.001 vs placebo) at all doses tested beginning at week 2 (post hoc analysis, ON-SXB 6 g vs placebo at week 2). The objective of this post hoc analysis was to assess the magnitude of improvement in the patient-reported outcome of EDS following treatment with ON-SXB. Methods Participants aged ≥16 years with narcolepsy type 1 (NT1) or 2 (NT2) were randomized 1:1 to ON-SXB or placebo. Doses were 4.5 g week 1; 6 g weeks 2−3; 7.5 g weeks 4−8; and 9 g weeks 9−13. Median (interquartile range [IQR]) ESS scores were assessed for each dosing period. Results Mean age of participants was 31.2 years, 68% were female, 75.5% were white, and 76.4% had NT1. The modified intent-to-treat population included 190 participants (ON-SXB, n=97; placebo, n=93). Baseline median (IQR) ESS scores were 17 (14−19) for ON-SXB and 18 (15−21) for placebo. At week 1, median (IQR) ESS scores were 16 (12−18) for ON-SXB 4.5 g vs 17 (13−20) for placebo. At week 3 (ON-SXB 6 g), median (IQR) ESS scores were 14 (10−18) vs 17 (14−20) for placebo. At week 8 (ON-SXB 7.5 g), median (IQR) ESS scores were 12 (8−16) vs 15.5 (12−20) for placebo. At week 13, median (IQR) ESS scores for ON-SXB 9.0 g were 9.5 (6.0−15.0) vs 15 (11−19) for placebo. Conclusion Treatment with ON-SXB resulted in clinically meaningful improvements in EDS with doses ≥6 g, as median ESS scores were within the range considered normal (≤10) at the end of the trial. ON-SXB is considered an effective intervention in treatment of EDS for patients with narcolepsy with a once-at-bedtime dose. Support (if any) Avadel Pharmaceuticals