Zogenix data blunder trips up its FDA filing for epilepsy drug Fintepla

Last July, Zogenix was riding high on positive phase 3 data for Fintepla, its treatment for Dravet syndrome, a rare form of childhood epilepsy.

What a difference nine months can make. Now, the FDA has refused to consider Fintepla’s new drug application, not only because it was missing some studies but also because it included some clinical data that shouldn't have been there—a mistake that essentially stopped the review in its tracks.

In its refusal-to-file letter, the FDA said the application was missing nonclinical studies the agency needed to assess long-term administration of the drug, and it included the wrong version of a clinical data set. The FDA didn't ask for additional safety or efficacy studies, Zogenix said in a statement. 

Zogenix refused to say whether it has already conducted the nonclinical studies its application is missing or would need to start them from scratch.

"We understand that people want to know more about the non-clinical studies, but we can’t provide an update on this until we schedule and hold a Type A meeting with the FDA," the company said in an emailed statement. Its shares dropped 30% in after-hours trading on the news.

Fintepla, formerly known as ZX-008, is a low dose of fenfluramine, a drug that blocks the reuptake of serotonin. Zogenix is developing it for Dravet and Lennox-Gastaut syndromes, which tend to appear in childhood, have a higher mortality rate than other types of epilepsy and do not respond to many of the drugs typically used to treat seizures. These also happen to be the syndromes treated by GW Pharma’s Epidiolex, the first cannabis-based medicine to be approved in the U.S.

RELATED: Chasing GW, Zogenix scores a win in second Dravet phase 3

With its phase 3 data, though, Zogenix CEO Stephen Farr said he's unfazed by the news. “We remain highly confident in Fintepla's clinical profile demonstrated in the Phase 3 program in Dravet syndrome ... [and] are fully committed to working with the FDA as quickly as possible to address the open issues and clarify the path to successfully re-filing our application," Farr said in the statement.

Last July, Zogenix unveiled phase 3 data showing daily doses of Fintepla reduced monthly seizures by 55% compared with placebo. The study, which focused on 87 children and young adults with Dravet syndrome, also showed that 54% of patients in the Fintepla arm suffered half as many convulsive seizures a month after taking Fintepla.

Those efficacy data line up with the results of Zogenix’s first phase 3 trial, setting Fintepla up as a potential rival for GW Pharma’s Epidiolex. 

Though Fintepla’s path to the U.S. market may now be delayed, Zogenix says it expects the European Medicines Agency to recommend its approval as early as the first quarter of 2020.