FDA rejects Zogenix' Dravet drug NDA

Shares of Zogenix (Nasdaq: ZGNX) plummeted 32.59% to $34.94 in after-hours trading on Monday, after the company disclosed that the US Food and Drug Administration has issued a Refusal to File (RTF) letter regarding its New Drug Application (NDA) for Fintepla (ZX008, fenfluramine hydrochloride) for the treatment of seizures associated with Dravet syndrome.

Upon its preliminary review, the FDA determined that the NDA, submitted on February 5, 2019, was not sufficiently complete to permit a substantive review. In the letter, the FDA cited two reasons for the RTF decision: first, certain non-clinical studies were not submitted to allow assessment of the chronic administration of fenfluramine; and, second, the application contained an incorrect version of a clinical dataset, which prevented the completion of the review process that is necessary to support the filing of the NDA. The FDA has not requested or recommended additional clinical efficacy or safety studies.

The company will seek immediate guidance, including a Type A meeting with the FDA, to clarify and respond to the issues identified in the RTF letter.