Vanda Pharmaceuticals Inc. reported that the FDA’s Center for Drug Evaluation and Research has issued a decision letter concluding that the company’s sNDA seeking to expand HETLIOZ (tasimelteon) to include treatment of jet lag disorder cannot be approved as submitted. The decision follows an agreed re-review of the application under an October 2025 collaborative framework, which committed the agency to an expedited assessment by early January 2026.
According to Vanda, the FDA acknowledged positive efficacy signals from controlled clinical trials but determined that the data do not provide substantial evidence of effectiveness for jet lag disorder. The agency cited concerns that the phase advance sleep protocols used in the studies, involving 5‑hour and 8‑hour bedtime shifts, are not sufficiently analogous to real-world air travel, which also involves reduced cabin oxygen pressure, physical constraints, noise and lighting changes.
Vanda stated that it respectfully disagrees with the FDA’s interpretation and continues to view phase advance models as valid surrogates for the circadian misalignment central to eastward jet lag. The company said it remains committed to engaging with the FDA and pursuing available pathways to advance potential approval of HETLIOZ for jet lag disorder
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