Washington – September 30, 2026 -- Vanda Pharmaceuticals Inc. (Nasdaq: VNDA) reported positive topline results from a pivotal Phase III study of HETLIOZ® (tasimelteon) 20 mg in adults with Delayed Sleep-Wake Phase Disorder (DSWPD), setting up a supplemental New Drug Application (sNDA) filing with the U.S. Food and Drug Administration (FDA).
Trial meets primary endpoint with statistically significant sleep-timing shift
The study, VP-VEC-162-3502 (NCT04652882), shifted sleep onset 42.5 minutes earlier in the HETLIOZ® arm (n=20) versus 5.4 minutes on placebo (n=20), a 37.1-minute difference (p=0.022). In an exploratory responder analysis, 60% of tasimelteon-treated participants (12/20) advanced sleep onset by at least 30 minutes, compared with 15% on placebo (3/20) (p=0.008).
Multicenter design spanned five years and 26 clinical sites
The double-blind, randomized, placebo-controlled trial screened over 260 individuals and enrolled 43 patients with confirmed DSWPD diagnoses across 26 sites in the US and Europe. Participants received once-daily oral tasimelteon 20 mg or matching placebo for 28 days. Safety data over the controlled period matched the established HETLIOZ® label, with no new safety signals identified.
Approval would create the first FDA-sanctioned DSWPD treatment
HETLIOZ® already carries FDA approvals for Non-24-Hour Sleep-Wake Disorder (2014) and nighttime sleep disturbances in Smith-Magenis Syndrome (2020). A DSWPD indication would extend the same 20 mg formulation to a third circadian sleep-wake disorder, addressing a condition Vanda estimates affects 0.2% to 1.5% of US adults, or roughly 0.5 to 4.1 million people. Vanda plans to file an sNDA incorporating this Phase III study alongside prior studies in related disorders and more than a decade of commercial use in its two approved circadian indications.
"People with DSWPD often remain undiagnosed and undertreated especially because of the absence of a proven approved treatment," said Mihael H. Polymeropoulos, M.D., President, CEO and Chairman of the Board, adding that Vanda intends to pursue the new indication with the FDA.