Vanda Pharmaceuticals Announces Positive Phase III Results for HETLIOZ®(tasimelteon) in Delayed Sleep-Wake Phase Disorder

Sleep onset advanced at least 30 minutes in 60% of HETLIOZ participants versus 15% on placebo in an exploratory analysis.

Rhea-AI Summary

Vanda Pharmaceuticals (Nasdaq: VNDA) announced that its Phase III HETLIOZ study met the primary endpoint in adults with Delayed Sleep-Wake Phase Disorder.

The disorder shifts the body's sleep clock later. Over 28 days, HETLIOZ 20 mg moved sleep onset 42.5 minutes earlier, versus 5.4 minutes with placebo, a 37.1-minute difference (p=0.022). Sleep diaries measured the endpoint, with 20 participants analyzed per arm. An exploratory analysis found that 60% receiving HETLIOZ advanced sleep onset by at least 30 minutes, versus 15% on placebo (p=0.008). The trial enrolled 43 patients across 26 US and European sites over more than five years. No new safety signals were identified during the controlled period.

Vanda plans to discuss the data with the FDA and submit a supplemental New Drug Application seeking approval for this disorder. HETLIOZ is not currently approved for this use.

4 points · 1 major

PositiveiHow this balance works

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0 major · 2 points

Hollow bars mark forward-looking points. How the balance works

Positive

• Major pointPrimary endpoint met: sleep onset advanced 37.1 minutes earlier versus placebo over 28 days (p=0.022).
• Moderate point. Forward-looking: it has not happened yet and may not happen.Vanda plans FDA discussions and a supplemental application seeking HETLIOZ approval for Delayed Sleep-Wake Phase Disorder.
• Minor pointExploratory response: 60% advanced sleep onset at least 30 minutes versus 15% on placebo (p=0.008).
• Minor pointNo new safety signals identified during the 28-day controlled period; safety was consistent with the established label.

Negative

• Minor pointTrial size was limited: 43 patients enrolled; primary endpoint results included 20 participants per arm.
• Minor pointControlled treatment lasted 28 days, limiting the duration covered by the reported safety findings.

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Key Figures

Sleep-onset shift difference: 37.1 minutes vs placebo (p=0.022) Participants with at least 30-minute advance: 60% vs 15% (p=0.008) Patients enrolled: 43 patients

Sleep-onset shift difference

37.1 minutes vs placebo (p=0.022)

Phase III primary endpoint

Participants with at least 30-minute advance

60% vs 15% (p=0.008)

Exploratory responder analysis

Patients enrolled

43 patients

Phase III study

Previous Clinical trial Reports

1 past event · Latest: Jan 08

Same Type 1 event

1. Jan 08

   FDA decision

   24h Move

   -14.1%

   FDA declined HETLIOZ's jet-lag sNDA, citing trial protocols insufficiently analogous to real-world travel.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

snda, double-blind, placebo-controlled

3 terms

snda regulatory

"submit a supplemental New Drug Application (sNDA)"

A SNDA (Subordination, Non‑Disturbance and Attornment Agreement) is a legal pact among a property owner’s lender, the owner’s tenants, and sometimes the landlord that sets who keeps lease rights if the property is sold or a mortgage is enforced. Think of it as a rulebook that decides whether a tenant can stay and keep paying rent or must answer to a new owner after a foreclosure. For investors, an SNDA matters because it protects predictable rental income, clarifies who has priority on claims against a property, and therefore affects a property’s value and the security of related loans.

double-blind medical

"a multicenter, double-blind, randomized, placebo-controlled Phase III study"

A double-blind process means that neither the people conducting an activity nor the people involved know certain key details, such as who is receiving a treatment or a placebo. This approach helps prevent bias from influencing the results, making the outcome more trustworthy. For investors, it ensures that decisions or judgments are based on unbiased information rather than preconceived opinions or expectations.

placebo-controlled medical

"a multicenter, double-blind, randomized, placebo-controlled Phase III study"

"Placebo-controlled" describes a testing method where one group receives the actual treatment or intervention, while another group receives a harmless, inactive version called a placebo. This approach helps determine whether the real treatment has genuine effects beyond psychological expectations. For investors, understanding this ensures confidence that reported benefits are real and not influenced by bias or false perceptions.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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• Study met its primary endpoint: timing of sleep onset shifted 37.1 minutes earlier versus placebo (p=0.022)
• 60% of HETLIOZ^® treated participants shifted sleep at least 30 minutes earlier, compared to 15% of the placebo arm

WASHINGTON, Sept. 29, 2026 /PRNewswire/ -- Vanda Pharmaceuticals Inc. (Nasdaq: VNDA) today announced positive topline results from its pivotal Phase III study of HETLIOZ^® (tasimelteon) 20 mg in adults with Delayed Sleep-Wake Phase Disorder (DSWPD). Vanda intends to discuss these data with the U.S. 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 program would extend that same medicine, at the same 20 mg dose, to a third circadian sleep-wake disorder.

Delayed Sleep-Wake Phase Disorder (DSWPD)

DSWPD is a body-clock disorder, and not simply being a "night owl." In a typical night owl, late bedtimes are a preference. In DSWPD, the internal clock is stably set too late. People with the 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.¹ Estimated prevalence in adults is 0.2% to 1.5%, or roughly 0.5 to 4.1 million adults in the United States.^2,3 The condition is often comorbid with other common psychiatric disorders. ^4,5

Clinical Study results

VP-VEC-162-3502 (NCT04652882) was a multicenter, double-blind, randomized, placebo-controlled Phase III study.⁶ Adults 18 to 75 years of age with a confirmed clinical diagnosis of DSWPD received once-daily oral tasimelteon 20 mg or matching placebo for 28 days. The study evaluated over 260 individuals and enrolled a total of 43 patients with DSWPD across 26 clinical sites in the US and Europe for a period of over 5 years.

The study met its primary endpoint. HETLIOZ^® 20 mg (n=20) shifted the time of sleep onset 42.5 minutes earlier, compared with a 5.4-minute shift on placebo (n=20) — a 37.1-minute difference from placebo (p=0.022). The primary endpoint was the start time of the sleep episode, measured by sleep diary.

In an exploratory responder analysis, 60% of tasimelteon-treated participants (12/20) advanced their sleep timing onset by at least 30 minutes, compared with 15% on placebo (3/20) (p=0.008).

Endpoint	Placebo (N=20)	Tasimelteon 20 mg (N=20)	P-value
Sleep onset timing change, mean (min)*	5.4	42.5	0.022
≥30-minute sleep timing advance**	15% (3/20)	60% (12/20)	0.008

*Primary endpoint: change of sleep onset timing ( as compared to placebo. **Exploratory responder analysis defined as people with at least 30 minutes of advance of the sleep onset timing. P-value is from Fisher's exact test.

Safety over the 28-day controlled period was consistent with the established HETLIOZ^® label. No new safety signals were identified.

"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. "This study extends our knowledge of the clinical properties of HETLIOZ^® as a versatile circadian regulator. We look forward to discussing these data with the FDA and pursuing a new indication for HETLIOZ^® as the first ever approved treatment for DSWPD."

Vanda plans to file an sNDA for HETLIOZ^® in DSWPD. The application is expected to include this Phase III study together with Vanda's prior studies in related disorders and more than a decade of use in two approved circadian indications.

About HETLIOZ^® (tasimelteon)

HETLIOZ^® is a dual melatonin MT1 and MT2 receptor agonist. It is FDA-approved for the treatment of Non-24-Hour Sleep-Wake Disorder in adults (approved 2014) and for the treatment of nighttime sleep disturbances in Smith-Magenis Syndrome (approved 2020; capsules in patients 16 years and older and HETLIOZ LQ^® oral suspension in patients 3 to 15 years of age).⁷ It is not currently approved for DSWPD.

About Vanda Pharmaceuticals Inc.

Vanda is a leading biopharmaceutical company focused on the development and commercialization of innovative therapies to address high unmet medical needs and improve the lives of patients. For more on HETLIOZ^®, see the full Prescribing Information.

References

1. American Academy of Sleep Medicine. International Classification of Sleep Disorders, 3rd ed., Text Revision (ICSD-3-TR). Darien, IL: AASM; 2023.
2. Nesbitt AD. Delayed sleep-wake phase disorder. J Thorac Dis. 2018;10(Suppl 1):S103-S111.
3. US Census Bureau, Vintage 2025 population estimates, age 18 and older.
4. Takaesu Y, Inoue Y, Murakoshi A, et al. Prevalence of circadian rhythm sleep-wake disorders and associated factors in euthymic patients with bipolar disorder. PLoS One. 2016;11(7):e0159578. doi:10.1371/journal.pone.0159578 (PLOS One, PubMed 27442503)
5. Reis C, Paiva T. Sleep Sci. 2019;12(3):203-213.
6. ClinicalTrials.gov NCT04652882.
7. HETLIOZ^® Prescribing Information

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

Various statements in this press release, including but not limited to statements regarding Vanda's plans to submit an sNDA for HETLIOZ^® in DSWPD and the likelihood of receiving regulatory approval of HETLIOZ^® for the treatment of DSWPD are "forward-looking statements" under the securities laws. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. Forward-looking statements are based upon current expectations and assumptions that involve risks, changes in circumstances and uncertainties. Important factors that could cause actual results to differ materially from those reflected in Vanda's forward-looking statements include, among others, uncertainties relating to the timing and outcome of the regulatory approval process for HETLIOZ^® for the treatment of DSWPD. Therefore, no assurance can be given that the results or developments anticipated by Vanda will be realized or, even if substantially realized, that they will have the expected consequences to, or effects on, Vanda. Forward-looking statements in this press release should be evaluated together with the various risks and uncertainties that affect Vanda's business and market, particularly those identified in the "Cautionary Note Regarding Forward-Looking Statements", "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of Vanda's most recent Annual Report on Form 10-K, as updated by Vanda's subsequent Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and other filings with the U.S. Securities and Exchange Commission, which are available at www.sec.gov.

All written and verbal forward-looking statements attributable to Vanda or any person acting on its behalf are expressly qualified in their entirety by the cautionary statements contained or referred to herein. Vanda cautions investors not to rely too heavily on the forward-looking statements Vanda makes or that are made on its behalf. The information in this press release is provided only as of the date of this press release, and Vanda undertakes no obligation, and specifically declines any obligation, to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

Corporate Contact:

Kevin Moran
Senior Vice President, Chief Financial Officer and Treasurer
Vanda Pharmaceuticals Inc.
202-734-3400
pr@vandapharma.com 

Jim Golden / Jack Kelleher / Dan Moore
Collected Strategies
VANDA-CS@collectedstrategies.com 

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SOURCE Vanda Pharmaceuticals Inc.

FAQ

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What did Vanda's Phase III HETLIOZ trial show for Delayed Sleep-Wake Phase Disorder?

The study met its primary endpoint, with sleep onset moving 37.1 minutes earlier versus placebo (p=0.022). HETLIOZ 20 mg advanced sleep onset by 42.5 minutes, compared with 5.4 minutes on placebo over 28 days. Sleep diaries measured the endpoint.

What is Vanda's next step for HETLIOZ approval in Delayed Sleep-Wake Phase Disorder?

Vanda plans to discuss the results with the FDA and submit a supplemental New Drug Application seeking approval for Delayed Sleep-Wake Phase Disorder. HETLIOZ is not currently approved for this condition.

What evidence does Vanda expect to include in the HETLIOZ supplemental application?

Vanda expects the application to include this Phase III study, prior studies in related disorders and more than a decade of use in two approved circadian indications. Those existing indications are Non-24-Hour Sleep-Wake Disorder in adults and nighttime sleep disturbances in people with Smith-Magenis Syndrome.