US pharmaceutical company Vanda Pharmaceuticals Inc (Nasdaq:VNDA) on Tuesday reported positive topline results from its pivotal Phase III study of HETLIOZ (tasimelteon) 20mg in adults with Delayed Sleep-Wake Phase Disorder (DSWPD).

People with DSWPD, a body-clock disorder, often cannot fall asleep until the early morning hours even when they get into bed at a conventional time, then cannot wake for work, school, or family life the next morning, even if they allow a full night in bed. Estimated prevalence in adults is 0.2% to 1.5%, or around 0.5 to 4.1 million adults in the United States. The condition is often comorbid with other common psychiatric disorders.

The Phase III study met its primary endpoint, with timing of sleep onset shifted 37.1 minutes earlier versus placebo. Of those treated with HETLIOZ, 60% shifted sleep at least 30 minutes earlier, compared to 15% of the placebo arm.

Vanda intends to discuss the results data with the US Food and Drug Administration (FDA) and to submit a supplemental New Drug Application (sNDA) seeking approval of HETLIOZ for DSWPD. If approved, HETLIOZ would be the first FDA-approved medicine indicated for this condition.

HETLIOZ is already an approved circadian regulator. The FDA first approved it in 2014 to treat Non-24-Hour Sleep-Wake Disorder in adults, and in 2020 to treat nighttime sleep disturbances in people with Smith-Magenis Syndrome. The DSWPD indication would extend the same medicine, at the same 20mg dose, to a third circadian sleep-wake disorder.