What happened

After Zogenix (NASDAQ:ZGNX) announced it has submitted marketing applications in the U.S. and Europe for approval for Fintepla (formerly ZX008) for treatment of Dravet syndrome, shares gained 20.5% in February, according to S&P Global Market Intelligence.

So what

A low-dose formulation of fenfluramine, Fintepla has demonstrated a remarkable ability to reduce seizures in Dravet syndrome patients.

A young man and woman standing with light bulbs above their heads.

IMAGE SOURCE: GETTY IMAGES.

Dravet syndrome is historically tough to treat, and there's only one FDA-approved medication specifically targeting it: GW Pharmaceuticals' (NASDAQ:GWPH) Epidiolex.

In trials, Fintepla produced a 62.7% decline in monthly seizures, significantly outperforming the 1.2% decline witnessed in the placebo group.

There aren't any head-to-head studies comparing Epidiolex to Fintepla, but Fintepla appears to be more effective than Epidiolex. In two phase 3 studies, Epidiolex reduced convulsive seizures by between 39% and 49%, respectively.

Check out the latest earnings call transcript for Zogenix.

Now what

The FDA hasn't announced its acceptance of Fintepla's filing yet, but the EU application was accepted, setting the stage there for a decision early in 2020. If all the i's were dotted and t's crossed in the FDA application, then Fintepla could be on the market next year in both of these big markets.

There's no guarantee of approval, though. Regulators will undoubtedly review safety data carefully, because fenfluramine was the "fen" part of an obesity drug known as fen-phen that was pulled from the market in the 1990s for increasing cardiovascular risks. Fintepla's safety in these trials looks pretty solid, though.

Zogenix is also studying Fintepla in Lennox-Gastaut syndrome (LGS), another rare form of epilepsy that's inadequately controlled by existing therapies. Data that could support approval in LGS is expected in Q1, 2020. If the data is good, then Fintepla could be competing against Epidiolex in both Dravet syndrome and Lennox-Gastaut syndrome by 2021.