Vanda Pharmaceuticals Inc, a biopharmaceutical company focused on the development and commercialization of products for central nervous system disorders, announced that tasimelteon was shown for the first time to reset the body clock and to align it to a constant 24-hour day in patients suffering from non-24-hour sleep-wake disorder (non-24-hour disorder). Tasimelteon is a circadian regulator in development for the treatment of non-24-hour disorder in totally blind individuals with no light perception.

This observation was made in four patients during the initial run-in segment of the RESET study. RESET is a phase III study of the maintenance effect of tasimelteon in the treatment of non-24-hour disorder. Vanda intends to enroll a total of 20 tasimelteon responders in this study.

“We are extremely excited by this finding as it provides us with evidence that tasimelteon is able to reset the body clock in patients with non-24-hour disorder,” said Mihael H Polymeropoulos, MD, president and CEO of Vanda Pharmaceuticals.

Circadian regulation is necessary for the treatment of non-24-hour disorder and it is predictive of a beneficial effect on both nighttime sleep and daytime naps. While light resets the body clock in sighted individuals, keeping it synchronized with the 24-hour day, this effect is lost in totally blind individuals with no light perception.

Vanda is currently studying the efficacy of tasimelteon in non-24-hour disorder in two phase III studies, SET and RESET, which are ongoing and expected to be completed by the end of 2012.

RESET is a randomized withdrawal study designed to demonstrate the maintenance effect of 20 mg tasimelteon in the treatment of Non-24-Hour Disorder. Twenty totally blind individuals with no light perception and diagnosed as having a body clock period of greater than 24 hours, will be treated with tasimelteon for three months during a run-in phase.  Patients who respond to tasimelteon treatment during the run-in phase, as measured by the resetting and alignment of their body clock to the 24-hour day, will then be randomized either to receive placebo or to continue receiving tasimelteon for 2 months. During the post-randomization phase, patients will be re-evaluated.

Non-24-Hour Disorder is a chronic circadian rhythm sleep disorder that affects more than 50 percent of the totally blind individuals in the US, or 65,000 to 95,000 people. It occurs almost entirely in individuals who are totally blind and lack the light sensitivity necessary to reset the circadian clock. Without light perception, the brain's circadian rhythms, which guide many of the body's functions, including sleep, are not reset to a regular 24-hour cycle.

Tasimelteon is the first compound in development for the treatment of non-24-hour disorder. Tasimelteon is a specific and potent agonist of the human MT1 and MT2 receptors. Compounds that selectively bind to melatonin receptors are thought to be able to regulate the body clock, which may be useful to treat circadian rhythm disorders. Tasimelteon is being studied in both Non-24 and Major Depressive Disorder (MDD).