Shares in Vanda Pharmaceuticals rocketed more than 70% after tasimelteon, its experimental drug designed to control circadian rhythms in the totally blind to help improve their sleep patterns, took a giant leap closer to US approval.

Documents posted on the US Food and Drug Administration's website, ahead of a meeting of experts on November 14, show that its advisory group consider the drug, which Vanda wants to call Hetlioz, safe and effective at treating non-24-hour disorder.

The serious but rare condition, in which the body's normal 24-hour circadian rhythm is disrupted, affects some 95,000 blind people in the US, and occurs almost entirely in individuals who lack the light sensitivity necessary to entrain the master clock in the brain with the normal day-night cycle.

Essentially, it means that in patients with the disorder the master body clock fails to reset every 24 hours and so continually delays, resulting in prolonged periods of misalignment between their circadian rhythms and the 24-hour day-night cycle.

There are currently no approves treatments for the disorder, so Vanda will be hoping to get the first to market, although some patients seem to benefit from taking the hormone melatonin. 

The FDA does not have to follow the advice of its advisory committee, but is expected to make a decision by January 31 next year, after a priority review that kicked off end of July.

This is particularly good news for Vanda, given that it earlier this year it was forced to withdraw an application to market its US-approved schizophrenia drug Fanaptum in Europe, following a negative opinion by advisors to the European Medicines Agency.