Whalen, Marisa

Abstract Introduction Jazz DUET (Develop hypersomnia Understanding by Evaluating low-sodium oxybate Treatment) is a phase 4, prospective, multicenter, single-arm, multiple-cohort, open-label study (NCT05875974) evaluating the effectiveness of low-sodium oxybate (LXB, Xywav®) treatment on outcomes including sleep quality (using polysomnography [PSG] and self-reported questionnaires) in participants with narcolepsy or idiopathic hypersomnia. Data reported here are from the narcolepsy cohort. Methods DUET included a screening period (with 2-week washout for current oxybate users), an 8-day baseline (BL) period, a 2- to 8-week LXB titration period, a 2-week stable-dose period (SDP), an 8-day end-of-treatment (EOT) period, and a 2-week safety follow-up. Participants underwent nocturnal PSG (ad libitum protocol) at BL and EOT. The Karolinska Sleepiness Scale (KSS) was administered 90 minutes post-awakening from PSG to measure situational sleepiness (9-point scale; 1=“extremely alert” to 9=“extremely sleepy, can’t keep awake”). Participants completed an electronic sleep diary (eDiary) daily during the BL and EOT periods, including questions regarding nightly sleep patterns, total sleep time (TST), sleep quality (5-point scale; “very good” to “very poor”), and how rested/refreshed the participant felt upon awakening (5-point scale; “very well” to “not at all”). Completion of ≥5 eDiary days during the 8-day assessment before PSG visits was required for analysis. eDiary and KSS data were analyzed in the completer set (enrolled participants who were dosed with LXB and completed SDP and PSG at EOT). Results Fifty-five participants with narcolepsy (type 1, n=26; type 2, n=29) enrolled (completer set, n=34). Most were female (40/55; 73%) and White (44/55; 80%); mean (SD) age was 33.4 (12.9) years. Mean (SD) self-reported nocturnal TST at BL (n=32) and EOT (n=20) was 8.1 (1.6) and 8.3 (0.9) hours, respectively. The percent of participants rating their sleep quality as “very good”/“good” increased from 15.6% (BL) to 70.0% (EOT). The percent of participants with rested sleep (“very well”/“well”/“somewhat” rested) increased from 46.9% (BL) to 90.0% (EOT). Likewise, mean (SD) rating of self-reported sleepiness decreased from 5.1 (2.0) at BL to 3.8 (1.9) at EOT. Conclusion Following open-label LXB treatment, participants with narcolepsy reported improvements in sleep quality and feeling more rested and less sleepy upon awakening. Support (if any) Jazz Pharmaceuticals