Vanda Pharmaceuticals Inc. announced positive top-line results from a phase III trial showing that investigational drug candidate, tasimelteon (VEC-162), a novel melatonin agonist, met the primary endpoint of the trial and significantly improved sleep in adult patients with chronic insomnia.

We are excited that the results of this phase III chronic insomnia study demonstrate the clinical utility of tasimelteon and the ability of the compound to treat sleep disorders over a period of four weeks. The mechanism of action of tasimelteon as a circadian regulator gives Vanda the opportunity to explore its use for the treatment of circadian rhythm sleep disorders as well as chronic primary insomnia, stated Paolo Baroldi, MD, PhD, Vanda's chief medical officer.

This phase III, multi-centre, placebo-controlled, four -week trial evaluated 322 patients with chronic primary insomnia. Patients were randomized to receive either 20 mg or 50 mg of tasimelteon or placebo over the course of four weeks. The primary endpoint consisted of the evaluation of the immediate and short-term ability of tasimelteon to improve sleep onset as measured by Latency to Persistent Sleep (LPS) through polysomnography (PSG). Secondary endpoints evaluated tasimelteon's ability to maintain improvements on sleep onset after long-term (average of Nights 22 and 29) use of the compound as well as measures of sleep duration and sleep maintenance. Patients were eligible for the study if symptoms of insomnia were chronic and LPS was greater than 30 minutes.

Analysis of the baseline PSG data revealed that the sleep disruption in this patient population occurred primarily during the first third of the 8-hour night. This is not unexpected given that the entry criteria in the study focused upon recruiting subjects with difficulty falling asleep and that there was no WASO entry criterion. At baseline, sleep efficiency during the first, second and last thirds of the night were 50.7%, 79.4% and 74.5%, respectively. Therefore, Vanda evaluated the effect of tasimelteon on sleep maintenance parameters in the first third of the night, when the sleep disruption was greatest in this population of chronic primary insomnia patients.