Prime Medicine, a US biotech company, said on October 5, 2026 that the first patient has received its experimental treatment for Wilson’s disease, a rare inherited illness in which copper builds up in the body.1 The treatment, called PM577a, is a single drip into a vein that is meant to repair a faulty gene directly inside the patient’s liver cells.1 The company described it as the first clinical study of an in-body treatment using its editing method, called prime editing, and the first human test of its liver programs.1
No results have been released. The company said it expects the first clinical data in 2027.1
What Wilson’s disease does
Wilson’s disease is caused by faulty copies of a gene called ATP7B, which normally helps the liver move extra copper out of the body.2 When the gene does not work, copper piles up in the liver and later affects other organs, including the brain, kidneys and the clear front surface of the eye.1 The illness often shows up in childhood and the teenage years, according to the company’s chief medical officer.1
Today’s treatments are drugs that pull copper out of the body, such as penicillamine and trientine, or zinc, which are taken every day for life.31 The company notes these drugs do not cure the disease and that some people find them hard to tolerate or to keep taking.1 A liver transplant is the only cure, but it depends on donor organs and carries real surgical risk.1
How the treatment is meant to work
Many different mutations can break the ATP7B gene. PM577a targets one of them, known as H1069Q, which the company says is the most common Wilson’s-causing mutation in North America and Europe.1 The goal is to correct that spelling error in the DNA of liver cells so they can handle copper normally again.4
The editing tool is packed into lipid nanoparticles (tiny fat bubbles that carry it through the blood) and given once by intravenous infusion, or drip.1 Prime editing is a newer form of gene editing. In an earlier Prime Medicine treatment for a different disease, the company described its approach as correcting a mutation without cutting through both strands of the DNA.5
This is different from the gene therapies already being tested for Wilson’s disease. Those deliver a new, working copy of the ATP7B gene to the liver rather than repairing the patient’s own copy.2
How the trial is set up
The study is an early-stage trial that combines a first safety test with a first look at whether the treatment helps (called Phase 1/2).4 According to the registry record, it plans to enroll about 42 people, started in September 2026, and is expected to finish its main data collection in November 2028.4 Its main goal is safety: how often side effects happen and how serious they are, tracked for 48 weeks after the infusion.4
- Who is eligible: adults and teenagers with Wilson’s disease who carry at least one copy of the H1069Q mutation.1 The study will start with adults who are stable on their usual treatment.1 A trial-listing site says people need to have been stable on their current medicines for at least six months, and that people who have had a liver transplant or are on the waiting list cannot join.3
- No dummy treatment: everyone in the study gets PM577a; there is no placebo group.3 The trial is “open-label,” meaning doctors and patients know what is being given.1
- Rising doses: the study tests increasing doses of the treatment.1
- What is measured: early signs of benefit may include how well copper leaves the liver on a special scan, blood levels of ceruloplasmin (a copper-carrying protein) and of loose copper not bound to it, and how much copper passes in the urine over 24 hours.1 The trial will also look at whether patients can stop their usual Wilson’s medicines.1
- Follow-up: after about 48 weeks of visits, participants are asked to join a separate long-term study.3
A trial-listing site showed the study recruiting at 3 locations.3
What this does not show yet
Dosing a first patient is a starting point, not a result. There is no human data yet on whether PM577a is safe, and no evidence in people that it corrects the gene or lowers copper.3 Earlier work was done in the lab: the Wilson Disease Association notes that Prime Medicine presented early lab data in 2024 and 2025 showing it could correct the faulty gene there.2
Several open questions remain. A small study without a comparison group cannot show how the treatment stacks up against daily drugs. It will take time to learn whether any correction lasts. And the first product covers only people with the H1069Q mutation. The company has a second candidate in lab development aimed at a different mutation, R778L, which it says is the most common in East Asian populations.1
Who is behind it
Prime Medicine, listed on the Nasdaq exchange, sponsors and pays for the trial.41 Its scientific co-founder is David Liu, the researcher behind prime editing.5 The company’s statements about the treatment’s promise come from its own executives. Chief executive Allan Reine said:
“Dosing the first patient with PM577a is a meaningful step toward our goal of delivering a transformative, one-time treatment for people living with Wilson disease.”1
The company also said the US Food and Drug Administration (FDA) gave the program a Rare Pediatric Disease designation, which is for serious diseases that mainly affect people up to 18 years old and affect fewer than 200,000 people in the US.1 If such a drug is later approved, its maker may qualify for a voucher that speeds up the FDA review of another drug, and the voucher can be sold to another company.1 That gives the company a possible financial benefit beyond the treatment itself.
The company’s priorities have shifted recently. In late 2025, Inside Precision Medicine reported that Prime Medicine had published the first results of prime editing in patients: two people with chronic granulomatous disease, an immune disorder, treated with stem cells edited outside the body.5 Under Reine, who became chief executive in May 2025, the company paused recruitment for that trial, citing a market too small to sustain the company, and made Wilson’s disease the lead program.5 PM577a works differently from that first treatment: it edits cells inside the body rather than in a lab dish.15
How it fits the field
Other one-time approaches to Wilson’s disease have had mixed fortunes. Ultragenyx is testing UX701, a gene therapy that delivers a working copy of the ATP7B gene to the liver.2 Its trial is no longer recruiting, plans for about 82 participants, and lists March 2029 for completing its main data collection.6 Vivet Therapeutics ended its gene therapy trial in October 2024 after treating four patients at two doses; the Wilson Disease Association reported that the treatment appeared safe but did not show a large enough effect, and moving to a higher dose would have needed more funding.2
Prime Medicine also ran a pre-screening study, called Prime-0211, which gave no treatment and gathered information on adults with Wilson’s disease to help guide future studies.2 The company says interest from patients and doctors puts it in a good position to enroll the new trial efficiently.1
What to watch next
The next milestone is the first clinical data, which the company expects in 2027.1 Key things to look for: any serious side effects, whether copper measures change, and whether any participant is able to stop daily Wilson’s medicines.1 Reine has also said that moving from one liver disease to another should make each later program cheaper and faster, so progress here may shape the company’s wider plans.5 Biohack will follow this trial as new results appear.
