Sleep Well, Wake up Alert: Eisai and Purdue’s Lemborexant Positive in Phase III Trial for Insomnia


By Mark Terry


Eisai Co., based in Tokyo, and Purdue Pharma, headquartered in Stamford, Conn., announced topline results from their SUNRISE 2 Phase III clinical trial of lemborexant for sleep-wake disorders.

The clinical trial looked at more than 900 patients between the ages of 18 and 88 who had insomnia, characterized by difficulty falling asleep or staying asleep. The trial met the primary and key secondary efficacy objectives based on patient sleep diaries. At six months, 5 mg and 10 mg doses of lemborexant showed statistically significant improvement in subjective sleep onset latency compared to placebo.

Key secondary endpoints included improvement in sleep maintenance, including sleep efficiency and subjective wake after sleep onset.

The most common side effects were somnolence, headache, and influenza.

“As a clinician and researcher treating patients with insomnia and other sleep-wake disorders for 30 years, for me, successful treatment means that patients fall asleep fast, sleep well, and wake well, without functional impairment, or loss of effect over time,” said Russell Rosenberg, principal investigator in the trials and former chairman of the board of the National Sleep Foundation, in a statement. “The results of SUNRISE 2 are particularly encouraging for the many patients who suffer from chronic insomnia.”

Lemborexant acts on the orexin neurotransmitter system, which is believed to regulate sleep and wake cycles. The drug was discovered by Eisai and jointly developed by Eisai and Purdue. It is believed that in people with insomnia and sleeping problems, the orexin system is functioning abnormally. Lemborexant is a dual orexin receptor antagonist that inhibits orexin neurotransmission by binding to two subtypes of orexin receptors.

“Our aspiration for lemborexant is to bring to the millions of patients suffering from insomnia and other sleep-wake disorders an agent for sleep-wake regulation that improves their ability to fall asleep and stay asleep, and maintains efficacy over time,” said Lynn Kramer, Eisai’s chief clinical officer and chief medical officer, Neurology Business Group, in a statement. “In SUNRISE 2, lemborexant improved time to sleep onset and sleep maintenance over a six-month period. With these results, we now look forward to proceeding with regulatory submissions for lemborexant to bring to patients a long-term treatment option for treating the sleep-wake disorder, insomnia.”

Earlier studies have shown that the drug improves sleep with no “hangover effect” after waking up and “no grogginess” if the individual wakes up during the night.

At least one of the trials compared lemborexant head-to-head against an extended-release formulation of zolpidem, which is marketed under various brand names such as Ambien, Edluar and Intermezzo, as well as generic formulations. In that trial, lemborexant was more effective in keeping patients over the age of 55 asleep through the night.

In that study, “body sway” was evaluated. Patients using zolpidem had three times the level of body sway than would be seen if the individual had been drinking enough alcohol to place them close to the legal driving limit. The 5 mg dose of lemborexant had no clinically meaningful increase in body sway, but the 10 mg dose increased it “to just above the clinically meaningful threshold.”

On other factor studied was postural instability, which Kramer said at the time is “the single best predictor of falls” in older people. Noise threshold was studied as well, which is the amount of sound needed to wake patients up. There was no difference there, but patients receiving lemborexant fell asleep more easily.

Other studies that compared lemborexant to zopiclone, another sleeping medication sold as Imovane, Zimovane and Dopareel, evaluated the subjects’ driving ability in the morning after a bedtime dose of the drugs. Lemborexant patients didn’t show much difference, while those receiving zopiclone had significant increase what is called standard deviation of lateral position—weaving.



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