Vanda Pharmaceuticals Inc has initiated a Phase III clinical trial to evaluate tasimelteon in patients with Non-24-Hour Sleep Wake Disorder (N24HSWD), a condition experienced primarily by totally blind individuals that results in abnormal night sleep patterns and chronic daytime sleepiness.

Tasimelteon binds to high affinity melatonin receptors located in the brain that are believed to regulate circadian rhythms, or sleep/wake cycles.

"Blind individuals with no light perception do not receive external light and darkness signals that synchronize our internal body clocks," said Mihael H. Polymeropoulos, MD, president and CEO of Vanda. "As a result, these individuals can live … in a constant state of circadian misalignment. Tasimelteon has the potential to be the first in the class of circadian regulators, drugs that may offer clinical benefits to patients with aberrant timing of the sleep/wake cycle."

The study is designed to investigate the efficacy and safety of 20 mg tasimelteon versus placebo in totally blind individuals with N24HSWD, with a target enrollment of 160 individuals. It includes a 6-month treatment period and an optional open-label extension. The primary endpoint of the study is improvement in Total Sleep Time (TST) during the night. The study will also measure parameters of daytime sleep and laboratory measures of the synchronization between the internal body clock and the 24-hour environmental light/dark cycle.

Vanda expects to report top-line results for this trial in the fourth quarter of 2011.