UniQure N.V. (QURE) dropped some interesting gene therapy data on Friday that tells a familiar biotech story: promising efficacy results paired with safety concerns that need sorting out. The company presented updated results from its Phase 1/2a trial of AMT-191, an experimental treatment for Fabry disease, at the WORLD Symposium in San Diego.

What Fabry Disease Does and Why This Matters

Fabry disease is a rare genetic disorder where your body doesn't produce enough of an enzyme called α-galactosidase A (α-Gal A for short). Without this enzyme, lipids accumulate in your tissues, causing all sorts of problems. The traditional treatment involves regular enzyme replacement therapy, which is exactly what it sounds like: regular infusions to replace the missing enzyme.

UniQure's approach uses gene therapy to potentially solve the problem at its source, teaching the body to produce the enzyme itself.

The Efficacy Results Look Solid

Here's where things get encouraging. As of the January 8, 2026 data cutoff, all 11 patients across three dosing groups showed elevated α-Gal A activity. The trial tested three dose levels: low (2×10¹³ gc/kg), mid (4×10¹³ gc/kg), and high (6×10¹³ gc/kg).

The enzyme increases were dose-dependent and quite substantial. At the lowest dose, patients showed 0.34 to 82.2 times normal enzyme levels. The mid-dose cohort saw 1.6 to 312.52 times normal levels, while the highest dose produced 27.7 to 223.7 times normal enzyme activity.

Perhaps more importantly, these increases stuck around. The longest follow-up in the high-dose group exceeded a year, while even the shortest follow-up in the mid-dose group lasted four months. Six of the 11 patients were able to stop their enzyme replacement therapy entirely after meeting pre-specified criteria for elevated enzyme activity. That's the dream scenario for a gene therapy: one treatment replacing ongoing infusions.

Plasma lyso-Gb3 levels, a biomarker for disease severity, remained stable across all dose groups after treatment, regardless of whether patients continued enzyme replacement therapy.

But Then There's the Safety Profile

The safety picture is more mixed, which is why UniQure paused dosing at the mid and high levels pending further review.

The lowest dose cohort looked clean with no serious adverse events related to AMT-191. But two patients at the mid-dose level experienced asymptomatic Grade 3 liver enzyme elevations. An Independent Data Monitoring Committee confirmed these as dose-limiting toxicities, triggering the pause. The good news is both patients responded to corticosteroid therapy and remain in follow-up.

At the highest dose, things got a bit more complicated. Five serious adverse events occurred in two patients: two unrelated to the treatment (stroke and diplopia), two related (chest pain and increased troponin), and one possibly related (leptomeningeal enhancement). One patient at this dose level also experienced an asymptomatic Grade 3 liver enzyme elevation that fully resolved with a short course of corticosteroids.

The company described the overall safety profile as "manageable," which in biotech speak means there are issues but nothing catastrophic, and they think they can work through them.

Meanwhile, UniQure has other irons in the fire. In January, the company announced that the FDA scheduled a Type A meeting to review the data package for AMT-130, its gene therapy candidate for Huntington's disease.

UniQure shares climbed 6.10% to $26.01 on Friday following the data presentation.