FDA Reverses Course, Clearing Path for First Huntington's Disease Gene Therapy

In a landmark regulatory pivot, the U.S. Food and Drug Administration has cleared the path for what could become the first disease-modifying treatment for Huntington’s disease.[1][2]

The agency informed biotechnology company uniQure that it will accept existing three-year clinical data as the foundation for an accelerated approval application for AMT-130, an experimental gene therapy.[3][8]

The decision marks a dramatic reversal from the FDA’s stance just three months prior, when regulators demanded that uniQure conduct a new, double-blind trial featuring a sham-surgery control group.[2][3]

Huntington’s disease is a fatal, inherited neurodegenerative disorder that causes the progressive breakdown of nerve cells in the brain.[5]

It is caused by a single genetic mutation that produces a toxic, expanded version of the huntingtin protein, leading to severe motor, cognitive, and psychiatric decline.[4][6]

Currently, there are no approved treatments that slow or stop the disease; available medications only manage symptoms like involuntary movements.[1][5]

The core evidence supporting AMT-130 comes from a Phase I/II open-label trial involving 29 patients.[5][8]

According to uniQure’s data, patients receiving the high dose of the gene therapy demonstrated a 75% slowing of disease progression over 36 months, as measured by the composite Unified Huntington’s Disease Rating Scale (cUHDRS).[4][5]

Furthermore, the therapy slowed the decline in patients' total functional capacity by 60%, allowing them to maintain daily living skills longer than expected.[4][5]

Biomarker data also supported the clinical findings: levels of neurofilament light chain (NfL)—a protein released when brain cells are damaged—dropped below baseline in treated patients, suggesting a reduction in ongoing neurological injury.[4][6]

The mechanism behind AMT-130 represents a highly targeted approach to genetic medicine.[6][8]

The therapy uses a harmless adeno-associated virus (AAV5) as a delivery vehicle, or vector, to transport an engineered artificial microRNA directly into the brain.[6]

Once inside the neurons of the caudate and putamen, this microRNA binds to the messenger RNA responsible for creating the huntingtin protein, effectively silencing the gene and halting the production of the toxic mutant protein.[4][6]

Because the therapy cannot cross the blood-brain barrier effectively on its own, it must be administered via a one-time stereotactic neurosurgery, requiring surgeons to drill burr holes into the skull and infuse the vector deep into the brain tissue.[3][6]

This invasive delivery method was the crux of the recent regulatory dispute.[3][8]

In March 2026, the FDA had insisted that to prove efficacy, uniQure needed a control group of patients who would undergo the anesthesia and skull-drilling of the surgical procedure, but receive no active gene therapy.[2][3]

Patient advocates and European regulators widely condemned the sham-surgery requirement as unethical, arguing it subjected patients with a terminal illness to surgical risks for zero potential benefit.[3][8]

Following leadership changes at the FDA and continued negotiations, the agency relented, agreeing that uniQure's comparison of treated patients against an external "natural history" database of untreated Huntington's patients was sufficient for an accelerated pathway.[2][3]

Despite the regulatory green light, transparent uncertainties remain regarding the sheer magnitude of the drug's efficacy.[7][8]

Clinical skeptics note that open-label trials compared against historical controls often overestimate a drug's benefit, as patients receiving a highly invasive, novel surgery may experience a profound placebo effect or receive enhanced ancillary care.[7]

Some neurologists have cautioned that the 75% slowing figure should be interpreted carefully until a concurrent, standard-of-care control group can validate the exact trajectory of the disease modification.[7][8]

To address these evidentiary gaps, the FDA is requiring uniQure to design a confirmatory trial—likely using a concurrent standard-of-care control rather than a sham surgery—that will run simultaneously with the drug's potential market rollout.[2][4]

UniQure plans to submit its Biologics License Application in the third quarter of 2026, setting the stage for a potential landmark approval in 2027 that could fundamentally alter the landscape of neurodegenerative disease treatment.[1][2]