Huntington's Gene Therapy Reports Four-Year Data; Its Main Measure Missed Statistical Significance

The biotechnology company uniQure reported four-year results on Sept. 29 for 12 patients given a high dose of its experimental gene therapy for Huntington's disease. On the study's pre-chosen main measure, the company said decline was 44% slower than in a matched comparison group, a result that did not reach statistical significance.

Huntington's disease is inherited and progressive, and no approved treatment slows it. The therapy, ifezuntirgene inilparvovec, is given once, delivered by surgery directly into the brain, and is designed to silence the gene that causes the disease.

The analysis had no placebo group. The researchers compared the treated patients with controls matched from ENROLL-HD, an observational database of people with the disease. Total Functional Capacity is a scale of work, chores and self-care. On that measure the company's release reported 61% slowing, with a p-value it labels nominal, meaning it is not a formal significance test. The firm also said 53% of the matched control data was missing at the four-year point, and that patients who left the database had been declining faster than those who stayed, which it believes understated the therapy's measured effect.

The application already with regulators rests on three-year data, not these numbers. According to the company, the FDA told it at a June 2026 meeting that the three-year results from 12 high-dose patients would be acceptable as the primary basis for a biologics license application under accelerated approval. The company said the submission was made before these results and does not include them. An updated three-year analysis released the same day, covering 15 high-dose patients, showed 80% slowing on the main measure, the company said.

The team restated a previously disclosed safety finding: five high-dose participants had a treatment-related serious adverse event involving inflammation of the central nervous system, all of which resolved. It also reported one suicide, in a low-dose patient about five years after treatment, which the study investigator assessed as unrelated to the therapy; suicide occurs at substantially elevated rates in Huntington's disease. The company described the data clinically meaningful for patients and expects to present them at a scientific meeting. They have not been peer reviewed.