Shares of UniQure fell by double digits Thursday morning, after the Netherlands-based company affirmed that the path to approval for its closely watched gene therapy for Huntington’s disease will likely be longer and more difficult than previously expected.

In early November, UniQure disclosed that, during a meeting with the Food and Drug Administration a week prior, agency staff felt that the data collected so far probably wasn’t enough to support an approval filing. This position surprised analysts as well as UniQure’s leadership, considering that, earlier in the year, the company and the FDA seemed aligned on the data required to file. UniQure subsequently lost 65% of its value.

Now, the company has received final minutes from that meeting and is further convinced the FDA wouldn’t approve the application as it currently stands. The company said it’s “carefully evaluating the feedback and plans to urgently request a follow-up meeting” with the agency sometime in the first three months of next year.

UniQure’s share price was down more than 16%, to $21.25, at market’s open Thursday, though it had ticked back up to around $23 by mid-morning.

UniQure’s therapy, code-named AMT-130, is designed to shuttle a small piece of genetic material into brain cells, where it gums up the production of the mutated protein that causes Huntington’s. Results from a mid-stage clinical trial released in September show that, across 12 participants given a high dose of the therapy and followed for three years, signs of disease progression had slowed by 75% compared to an external control group.

“That means for one year of disease progression, they will have four years longer in terms of disease-free lives,” Sarah Tabrizi, director of the University College London Huntington’s Disease Center, said at the time. It’s a “huge effect size, and will have massive effects on patients’ lives.”

Encouraged by these results, UniQure had intended to file for approval in early 2026.

The latest update puts “many scenarios on the table,” according to Stifel analyst Paul Matteis. The FDA, perhaps moved by political pressure, could reverse its stance, or the two parties may be able to compromise by having that key trial enroll more patients and study them for longer.

However, there’s also the possibility of an “unfortunately challenging path forward,” where UniQure needs to run an entirely new trial. While there remains “some chance” the FDA opts to compromise or review the current filing, Thursday’s announcement suggests the “probability on this outcome is admittedly becoming more challenging,” Matteis wrote in a note to clients.

We “still do not know exactly what the FDA is concerned about, so it is difficult to speculate,” wrote Joseph Schwartz, an analyst at Leerink Partners, in his own note. Yet Schwartz and his team “remain cautiously optimistic that AMT-130 can find its way to market on the basis of the existing data to date in some form.”

“We consider [UniQure] a very resourceful company, and combined with the support they noted they have received from the HD community ... we think there could still be a way to carve out a path with the FDA, even if it takes a few meetings to hammer out,” he added.

In a statement, UniQure CEO Matt Kapusta said the company is “committed to collaborating with the FDA to advance AMT-130 to patients and their families as rapidly as possible.”