Vanda Pharmaceuticals received notification from the US Food and Drug Administration (FDA) on Feb 4, regarding deficiencies in its supplemental new drug application (sNDA) for Hetlioz (tasimelteon) in treating insomnia, which hinders the discussion on labeling and post-marketing commitments. 

According to a release from Vanda, no deficiencies were disclosed by the FDA in the notification, and the FDA stated that the notification does not reflect a final decision on the information under review

In a letter to Vanda dated July 17, 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 sNDA.

Vanda notes in the release that it has “extensively” studied the efficacy of Hetlioz in the treatment of insomnia characterized by difficulties with sleep initiation. A phase III, multi-center, placebo-controlled, four-week trial evaluated patients with chronic primary insomnia. Two transient insomnia studies induced by phase advance of the sleep-wake cycle were also conducted with five-hour and eight-hour phase advance, which showed a significant effect on the first night in improving sleep parameters.

The FDA notification comes amidst ongoing legal challenges by Vanda against the FDA’s review process. 

Vanda says in the release that it believes that the timing of the FDA’s communication is part of an ongoing violation of the Federal Food, Drug, and Cosmetic Act (FDCA). The FDCA requires the FDA to either approve a new drug application or provide an opportunity for a hearing within 180 days after the filing of an application. 

Because Vanda submitted the sNDA on May 4, 2023, the FDA’s deadline under the FDCA was Oct 31. “The FDA has not complied with the statute and has not timely approved the application or provided an opportunity for a hearing within the statutorily prescribed timeframe,” according to the release from Vanda. 

The release also notes that Vanda is challenging the FDA’s approvals of several generic versions of Hetlioz, which have been marketed since 2023.