Vanda Pharmaceuticals Inc. (Nasdaq: VNDA) reported positive Phase III results for Hetlioz (tasimelteon) 20 mg in adults with Delayed Sleep-Wake Phase Disorder (DSWPD), with treatment advancing sleep onset by 37.1 minutes versus placebo (p=0.022).
DSWPD is a circadian rhythm disorder in which the internal biological clock is shifted later than conventional sleep and wake times, causing difficulty falling asleep and waking at socially required times. Adult prevalence has been estimated at 0.2% to 1.5%. No drug is currently FDA-approved specifically for DSWPD, although timed melatonin and behavioral or light-based approaches are used clinically.
Tasimelteon is a melatonin MT1/MT2 receptor agonist that acts on the circadian signaling system regulating sleep-wake timing. HETLIOZ is already FDA-approved for Non-24-Hour Sleep-Wake Disorder in adults and nighttime sleep disturbances in Smith-Magenis syndrome.
The multicenter, double-blind, randomized, placebo-controlled Phase III VP-VEC-162-3502 study (NCT04652882) evaluated once-daily oral tasimelteon 20 mg or placebo for 28 days in adults aged 18 to 75 years with confirmed DSWPD. Although more than 260 individuals were evaluated over more than five years, the primary efficacy analysis included 40 patients, 20 per treatment arm.
Mean sleep onset advanced by 42.5 minutes from baseline with tasimelteon versus 5.4 minutes with placebo, producing the 37.1-minute placebo-adjusted difference. In an exploratory responder analysis, 60% of tasimelteon-treated patients (12/20) advanced sleep onset by at least 30 minutes compared with 15% on placebo (3/20; p=0.008).