Eisai Co. Ltd. and Purdue Pharma LP said topline results from a late-stage study showed their experimental sleep-wake regulation treatment lemborexant helped insomnia patients fall asleep and stay asleep.

The phase 3 trial, called Sunrise 2, enrolled 971 adults with sleep disorders. At six months, lemborexant had met the main goals of the study. The trial, which will be going on for 12 months in total, evaluated lemborexant, given in 5-milligram and 10-mg doses, against placebo.

The patients recorded how long it took them to fall asleep and how long they slept without waking up — measures for the study's main goals. The results showed that patients taking lemborexant experienced significant improvements in all the measures compared to those taking placebo.

The drug also improved patients' daily functioning, as measured by the Insomnia Severity Index.

Discontinuation rates due to adverse events were comparable between lemborexant and placebo groups. Lemborexant led to higher discontinuation rates at the higher dose.

"With these results, we now look forward to proceeding with regulatory submissions for lemborexant," said Lynn Kramer, chief clinical officer and chief medical officer of Eisai's neurology business group.

Eisai and Purdue Pharma plan to present full 12-month data from Sunrise 2 in 2019. The companies reported data from a similar trial, called Sunrise 1, in March.

Lemborexant works by suppressing the neurotransmission of orexin — a signalling molecule linked to wakefulness.

Japan's Eisai discovered lemborexant and is jointly developing it with Stamford, Conn.-based Purdue Pharma. The companies are also conducting a midstage study of lemborexant in patients with irregular sleep-wake rhythm disorder and mild-to-moderate Alzheimer's dementia.