Impact of lemborexant treatment on insomnia severity: analyses from a 12-month study of adults with insomnia disorder.

Objective/background: Evaluate changes in insomnia severity in subjects with moderate to severe insomnia (Insomnia Severity Index [ISI] score ≥15) treated for 12 months nightly with lemborexant.

Patients/methods: This phase 3 randomized study comprised two 6-month treatment periods. In Period 1, 949 subjects were randomized to placebo, lemborexant 5 mg (LEM5) or 10 mg (LEM10). In Period 2, placebo subjects were rerandomized to LEM5 or LEM10; subjects initially randomized to lemborexant continued their assigned treatment. Insomnia severity was assessed using baseline ISI and 1-, 3-, 6-, 9-, and 12-month post-treatment scores.

Results: Mean ISI scores improved significantly across treatment groups and disease severities, with greater decreases from baseline in the LEM5 and LEM10 versus placebo groups at months 1 (-7.1, -7.2, -5.2, respectively), 3 (-8.6, -8.9, -6.1, respectively), and 6 (-9.9, -9.8, -7.2 respectively); ISI score improvements were maintained with LEM5 and LEM10 at months 9 (-11.1 and -11.2, respectively) and 12 (-11.5 and -11.2, respectively). At months 1, 3, and 6, significantly more treatment responders (≥7-point ISI score decrease from baseline) were observed with LEM5 (44%-57%) and LEM10 (44%-52%) versus placebo (30%-41%). At months 1, 3, and 6, more remitters (ISI total score <10 and < 8) were observed with LEM5 (30%-44% and 22%-34%, respectively) and LEM10 (31%-41% and 22%-31%, respectively) versus placebo (18%-28% and 11%-21%, respectively).

Conclusions: Lemborexant significantly reduced insomnia severity for 12 months and increased clinically meaningful response and remission rates versus placebo.

Clinical Trial Registration: ClinicalTrials.gov, NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39.