Vanda Pharmaceuticals Inc announced it received a complete response letter from the US Food and Drug Administration (FDA) as part of its ongoing review of Vanda’s supplemental New Drug Application for Hetlioz (tasimelteon) in the treatment of insomnia characterized by difficulties with sleep initiation.

In July 2023, the FDA had assigned a Prescription Drug User Fee Act target date of March 4, 2024, for the completion of its review of the supplemental New Drug Application. 

As previously reported, on Feb 4, the FDA provided a notification stating that it identified deficiencies that precluded discussion of labeling and postmarketing requirements/commitments. At the time, Vanda stated that no deficiencies were disclosed by the FDA in the notification.

Consistent with that notification, the FDA has issued a complete response letter, indicating that the FDA cannot approve Vanda’s supplemental New Drug Application for Hetlioz in its present form.

Vanda is reviewing the complete response letter and evaluating its next steps, according to a release from the company. Vanda also previously filed suit in the US District Court for the District of Columbia challenging the FDA’s conduct in reviewing the insomnia sNDA. Vanda is asking the DC District Court to compel the FDA to adhere to the legally mandated 180-day review period for sNDAs and to declare as unlawful and void the regulations the FDA relies upon to issue complete response letters.

Hetlioz is already FDA-approved for the treatment of non-24-hour sleep-wake disorder and for sleep disturbances in Smith-Magenis Syndrome.

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