Objective:

Once-nightly sodium oxybate (ON-SXB; FT218; LUMRYZ™) was investigated in patients with narcolepsy in the phase 3 REST-ON trial (NCT02720744). This post-hoc analysis assessed ON-SXB efficacy across participant subgroups.  

Background:

All tested doses of ON-SXB resulted in significant improvements (all P<0.001) for the coprimary endpoints of change from baseline in mean sleep latency on the Maintenance of Wakefulness Test (MWT), Clinical Global Impression-Improvement (CGI-I) rating of “much” or “very much” improved, weekly number of cataplexy attacks (NCA), and in the secondary endpoint Epworth Sleepiness Scale (ESS) score. 

Design/Methods:

Participants (≥16 years) with narcolepsy type 1 (NT1) or 2 (NT2) were randomized 1:1 to receive ON-SXB (4.5 g [1 week], 6 g [2 weeks], 7.5 g [5 weeks], and 9 g [5 weeks]) or placebo. Least squares mean differences (LSMD [95% CI]) in change from baseline with ON-SXB vs placebo for MWT, NCA, and ESS, and odds ratios (ORs) for CGI-I, across demographic and disease characteristic subgroups were calculated. Data from the modified intent-to-treat (mITT) population (all randomized participants with ≥1 efficacy measure after receiving the 6.0-g dose) were analyzed.  

Results:

The mITT population included 190 participants (ON-SXB, n=97; placebo, n=93). ON-SXB 9 g significantly improved mean sleep latency on the MWT (minutes; P<0.05) for age, sex, race, BMI, narcolepsy type, and alerting agent use subgroups (LSMD range: 4.0 – 10.0). ORs significantly favored ON-SXB 9 g on CGI-I (P<0.05) for low/high age, white/non-white race, alerting agent use, female sex, high BMI, and NT1 (range: 3.3–7.1). ON-SXB 9 g significantly improved NCA (P<0.05) for all subgroups (LSMD range: –5.5 to –7.6) except non-white and male. All subgroups showed significant improvements on ESS score with ON-SXB 9 g except NT2 (LSMD [95% CI]: –2.72 [–6.09, 0.65]). 

Conclusions:

These findings demonstrate the robust efficacy of once-at-bedtime ON-SXB  across participant subgroups.