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# Vanda Hetlioz sNDA Not Approvable, FDA Says
- URL: https://www.fdaweb.com/vanda-hetlioz-snda-not-approvable-fda-says/
- Published: 2026-01-08T12:00:00.000Z
- Updated: 2026-09-14T15:30:12.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5160456

FDA has notified Vanda Pharmaceuticals that its sNDA for Hetlioz (tasimelteon) to treat jet lag disorder cannot be approved in its present form. A company [statement](https://news.google.com/read/CBMikgJBVV95cUxPeVJrRzdWRVJZYW82V1hIQ2piNVMxTUZDNXdRLXRab3RsSnFUVFNTUGJnajNWSUhGX20zbnJBNjZmQmIwbFZIbFp6LWxlTHNWNjRGREd6amh1bnotMmVId3hSbWRkdWZYLXdIYmI0dnJMZEl1UXRCck5lc3pjOEp1MHh0Zm9XM3RYRkhKTUNTOUt5UUNJN1pFeU1mLWNEenJzX05tbzhIOVcwdjloejhSMHpUZ0U3RHU2TzdUdk1DeG9iX0RRaTU5QU9NdkVyMVhxUU1aeHhCX1RSa283MmFJWmFWYlJDb2RKM2tPd2lWczlQN0VfZUVrc2MyMnRYQW9namR4dUhDSWxhaFJOOU9wcGFn?hl=en-US&gl=US&ceid=US%3Aen&ref=fdaweb.com) says the agency acknowledged positive efficacy from the company’s clinical trials, but said the data do not provide substantial evidence of efficacy for jet lag disorder, primarily because controlled phase advance protocols (five-hour and eight-hour bedtime shifts) are not sufficiently analogous to jet travel.

The agency letter indicated that jet travel involves additional factors such as reduced oxygen pressure, physical constraints, noise, and lighting changes.

Vanda says it “respectfully disagrees with this interpretation. Phase advance models are widely accepted in circadian rhythm research as valid and reliable surrogates for simulating the core circadian misalignment underlying eastward jet lag, the primary driver of the disorder’s hallmark symptoms…. These models reproducibly induce the essential features of jet lag without the confounders of variable travel conditions which are unrelated to jet lag. The convergent evidence from Vanda’s studies including simulated and actual transatlantic travel demonstrates tasimelteon’s meaningful benefits on sleep duration, latency to persistent sleep, and next-day alertness.”

The company says it maintains that the submitted dataset meets the statutory standard for substantial evidence of effectiveness on clinically relevant endpoints for jet lag disorder.

The FDA letter arises from a 10/2025 collaborative framework agreement between the company and the agency in which FDA committed to an expedited re-review of the sNDA by 1/7, including consideration of narrowed, sleep-focused indications. The agreement followed an 8/2025 DC Circuit Court [decision](https://www.fdaweb.com/court-orders-fda-to-reconsider-vanda-snda/) that set aside a prior FDA refusal to approve Hetlioz for jet lag disorder. In that decision, the court described Vanda’s evidence as “specific, reasoned, and rooted in evidence,” and said the agency review was “cursory.”

“Vanda appreciates FDA’s engagement,” the statement concludes, “but believes the current decision does not fully reflect the collaborative spirit or address the court’s concerns regarding meaningful engagement with the evidence. Vanda remains committed to working constructively with FDA while pursuing all appropriate avenues to advance approval of Hetlioz for jet lag disorder and make this important therapy available to travelers.”