Vanda Pharmaceuticals Faces FDA Setback on HETLIOZ® for Jet Lag Disorder Approval

In an unexpected turn of events, Vanda Pharmaceuticals Inc. (Nasdaq: VNDA) has announced it received a decision letter from the U.S. Food and Drug Administration (FDA) regarding its supplemental New Drug Application (sNDA) for HETLIOZ® (tasimelteon) targeted at treating jet lag disorder. The letter, issued on January 8, 2026, concludes that the application cannot be approved in its current format, raising significant concerns regarding the application's evidence of effectiveness.

Background of the Decision

The FDA's decision follows a re-review process initiated as part of a collaborative framework established between the agency and Vanda Pharmaceuticals in October 2025. This agreement allowed the FDA to re-evaluate the jet lag application after a previous set of refusals. In its latest correspondence, the FDA acknowledged the efficacy data submitted from controlled clinical trials conducted by Vanda but ultimately deemed them insufficient to support a claim of substantial effectiveness for jet lag disorder.

The FDA's primary concern rested on the comparison of controlled phase advance protocols used in the trials—consisting of 5-hour and 8-hour bedtime shifts—with actual jet travel experiences, which encompass additional complexities such as changes in oxygen levels, physical limitations during travel, and environmental factors like noise and lighting disturbances.

Vanda's Response

Vanda Pharmaceuticals expressed their disagreement with the FDA’s interpretation, reiterating that the phase advance models utilized in their research are accepted methodologies within circadian rhythm studies. According to the company, these models are reliable simulations of the core circadian misalignment that characterizes eastward jet lag, which they assert is the key contributor to the disorder's main symptoms based on the International Classification of Sleep Disorders, Third Edition (ICSD-3) criteria.

The company emphasizes that their studies, which included conditions of simulated and actual transatlantic travel, demonstrated significant benefits of tasimelteon in improving sleep duration, reducing latency to persistent sleep, and enhancing alertness the following day. Moreover, the safety profile of tasimelteon remains well-regarded, showcasing predominantly mild adverse effects and extensive usage over a decade in other approved conditions.

Procedural Updates

In light of a prior ruling from the D.C. Circuit Court in August 2025, which overturned a previous FDA denial of the HETLIOZ® jet lag application, Vanda remains determined to engage with the FDA constructively. The Court had previously noted the value and specificity in Vanda's evidence, criticizing the FDA's earlier reviews as cursory, particularly regarding the significant positive findings related to trial endpoints.

Vanda believes the current decision falls short of the collaborative intent and fails to adequately address the judicial concerns surrounding the agency's past conduct. The company is committed to exploring all pathways to achieve the approval of HETLIOZ® for jet lag treatment, addressing crucial unmet needs for travelers struggling with the disorder.

Conclusion

As the discourse between Vanda Pharmaceuticals and regulatory authorities continues, the company remains dedicated to substantiating the efficacy and safety of HETLIOZ® for jet lag disorder. This ongoing pursuit not only underscores the challenges inherent in drug approvals but also highlights Vanda's resolve to ensure the availability of innovative treatments for urgent medical needs. Stakeholders and patients alike will be keenly observing the developments surrounding the FDA's decision and Vanda's subsequent actions.

For more information on Vanda Pharmaceuticals and its initiatives, visit their official website at vandapharma.com.

_HETLIOZ® is approved in the United States for treating Non-24-Hour Sleep-Wake Disorder and sleeping disturbances linked to Smith-Magenis Syndrome, marking its importance in the broader scope of sleep-related therapeutic offerings._