Aqneursa Is the First Approved Treatment for Ataxia-Telangiectasia, Nearly 8 Months After the Disease's Biggest Trial Failed

A child with ataxia-telangiectasia usually walks on time. That is the cruel part. Somewhere around age 2 the walking starts to wobble, a little more each month, and the first doctor says cerebral palsy, because a toddler who lurches and has trouble with balance looks like cerebral palsy. Cerebral palsy does not get worse, though, and this does. By the time the eyes stop tracking properly and tiny red vessels appear on the whites of them, the diagnosis is usually clear, and a family learns that there is no treatment, that most children with this disease use a wheelchair by around age 10, and that the same broken gene that took their child's balance also weakens the immune system and raises the risk of leukemia and lymphoma many times over.

On January 29th of this year the A-T community absorbed the failure of the largest clinical trial ever run in the disease. On September 18th, not quite 8 months later, the FDA approved the first drug for it.

What Ataxia-Telangiectasia Is and Why One Gene Does So Much Damage

The gene is called ATM, and its job is to notice when a strand of DNA has broken and to direct the repair. A child with A-T inherits a non-working copy from each parent, neither of whom has symptoms, and is born without that sensor. Damage that other people's cells would fix quietly accumulates instead.

The cells that suffer first are the Purkinje cells of the cerebellum, the part of the brain that coordinates movement, and as they die the child loses balance, then hand control, then clear speech, then the ability to move the eyes quickly from one thing to another. Muscle strength stays for a long time; it is the control that goes. The immune system suffers because the cells that make antibodies have to cut and rejoin their own DNA to do it, and without ATM they do it badly, so most people with A-T have low antibody levels and repeated chest infections, which are the leading cause of death. The cancer risk follows from the same failure, since unrepaired DNA damage is how cancers begin, and the A-T Children's Project puts the risk of blood cancers at close to 1,000 times that of the general population. The last twist is that people with A-T are unusually sensitive to radiation, so the X-rays and radiotherapy that would be routine for anyone else can cause serious harm.

It affects somewhere between 1 in 40,000 and 1 in 100,000 people, boys and girls equally, in every population. The diagnosis is often slow because early A-T looks like something else; a raised alpha-fetoprotein level in the blood, which is present in nearly every child with the disease, is the clue that points a doctor toward the genetic test.

The story of this approval does not start with the drug that won. It starts with the one that did not. Quince Therapeutics spent years building a trial of a treatment called eDSP, in which a steroid, dexamethasone, is loaded into a child's own red blood cells and infused back, the idea being to deliver a small steady dose to the brain without the damage that daily steroids do to a growing body. The Phase 3 NEAT trial enrolled 105 participants, 83 of them aged 6 to 9, at academic centers in the US, the UK and Europe. It was the biggest thing A-T research had ever attempted.

On January 29th Quince announced that NEAT had missed its primary endpoint and its key secondary endpoints and that development was over. The treated children trended better than placebo, but not by enough to be sure it was real. The A-T Children's Project, the parent-founded foundation that has funded much of the field's research, wrote to families the same day. The letter, written by an A-T father, did something rare for a foundation announcing a failure: it thanked the company, credited the trial with teaching the disease's clinical sites how to run a large study properly, and told families those sites were now far better prepared to test whatever came next.

“That's disappointing, but it's also how progress happens in rare disease drug development.”

A-T Children's Project, letter to families, January 29, 2026

What was already true when that letter went out was that a second trial had finished enrolling 7 months earlier and was close to reporting. IntraBio's study of levacetylleucine had recruited its last patient in June 2025 at 10 sites in Germany, Slovakia, Spain, Switzerland, the United Kingdom and the United States, and it had been designed in a way that gave a rare disease with 73 available patients its best possible chance of a clear answer.

What the Aqneursa Trial in Ataxia-Telangiectasia Actually Showed

The design was a crossover. Every one of the 73 patients, aged 4 to 50 and about two thirds of them children, took levacetylleucine for 12 weeks and a placebo for 12 weeks, in an order chosen at random and with nobody knowing which was which. Each patient therefore served as their own comparison, which is why a trial this small could produce a result this clean. 70 of the 73 finished both periods.

The measure was the SARA, a 40-point scale on which a clinician scores gait, standing, sitting, speech and limb coordination, with lower numbers meaning less ataxia. On the drug, scores improved by an average of 1.9 points. On placebo, they moved by 0.1. The difference, 1.88 points with a confidence interval running from 1.06 to 2.70, had less than a 1 in 10,000 chance of being a fluke. The FDA judged the application on a narrower version of the scale called the functional SARA, which covers only gait, sitting, stance and speech on a 16-point range, and there the difference was 0.6 points in the drug's favor. The improvement showed up within 12 weeks and was consistent in children and adults.

2 points on a 40-point scale is not a cure, and the trial's own investigators describe the result as an improvement in functioning rather than a change in the disease. What it means in a life is more specific than the number suggests. The SARA domains that moved are the ones a family sees every day: whether a child can sit without support, stand without holding on, walk across a room, and be understood when she speaks. A shift of that size, sustained, is the difference between needing a hand and not needing one for some of those tasks.

The safety picture was quieter than the disease itself. There were fewer adverse events on the drug than on placebo, 54 against 75, and none of the serious ones were judged related to treatment. The reactions the label calls out, occurring in at least 5% of patients and more often than on placebo, are falls, skin lacerations and urinary tract infections. Falls in a disease defined by loss of balance are hard to attribute to anything, and the trial did not attribute them to the drug.

Why a Drug Approved for Niemann-Pick C Works in A-T Too

Levacetylleucine is an odd molecule to be the first A-T drug. It is a modified form of leucine, an amino acid in every protein you eat, and it descends from an older European vertigo remedy. It does not touch the ATM gene. IntraBio says plainly that its precise target is unknown; the working theory is that it enters the metabolic pathways of nerve cells and normalizes how they use glucose, which correlates with better activity in the cerebellum, and that it improves the function of the cell's lysosomes and mitochondria along the way.

That is why the same packet of powder was approved in September 2024 for Niemann-Pick disease type C, a lysosomal disease with no genetic connection to A-T, and now for A-T itself. The 2 diseases share a symptom, cerebellar ataxia, rather than a cause, and the drug acts on the symptom's machinery. It is a different logic from the gene therapies and antisense drugs that have dominated rare disease approvals this month, and it comes with a different set of expectations: this is a treatment to be taken every day for as long as it helps, not a one-time correction.

Aqneursa Side Effects, Dosing, and the 15 kg Rule

The drug comes as 1-gram packets of powder that are stirred into 40 mL of water, orange juice, almond milk or yogurt and taken within 30 minutes, or mixed with water only and given through a G-tube. The dose depends on weight: a child between 15 and 25 kg takes 1 g morning and evening, a child between 25 and 35 kg takes 1 g three times a day, and anyone 35 kg or heavier takes 2 g in the morning and 1 g in the afternoon and evening. It can be taken with or without food.

The weight floor is the label's one hard limit. Both indications stop at 15 kg, roughly the weight of an average 3-year-old, and the A-T trial enrolled children from age 4. That leaves the youngest children, who have often just been diagnosed and whose parents are the most desperate for something to do, outside the approved use. There is no biological reason given in the label; it reflects who was studied. Ask the neurologist whether an off-label or expanded-access route exists for a smaller child, and expect the answer to depend on the insurer.

The label's main warning is about pregnancy: animal studies suggest the drug can harm a fetus, so a pregnancy test is required before starting in anyone who could become pregnant, with contraception during treatment and for 7 days after stopping. Two interactions matter. The DL form of acetyl-leucine is sold online as a supplement and must not be taken alongside the drug, because it interferes with it. Medicines carried by the P-glycoprotein transporter, which include some heart drugs, blood thinners and chemotherapy agents, may need closer monitoring. There are no contraindications. Report reactions to IntraBio at 1-833-306-9677 or to the FDA at 1-800-FDA-1088.

How to Get Aqneursa for Ataxia-Telangiectasia This Week

Most first-ever approvals come with a wait: a launch date, a specialty pharmacy that does not have stock yet, a support program still being staffed. This one is different, and it is the single most useful fact in this post. Aqneursa has been on the US market for 2 years. The packets a pharmacy dispenses for Niemann-Pick C are the same packets, at the same doses. What stands between an A-T patient and the drug is a prescription and an insurer, not a supply chain.

Ask the neurologist who manages the A-T, not a general pediatrician

The prescription needs to come from someone who can document the ataxia with a SARA score, because that is what the insurer will ask for and what will show whether the drug is working. If your child does not have an A-T-experienced neurologist, the A-T Children's Project keeps a list of clinics, and the A-T Clinical Center at Johns Hopkins is the main US referral center.

Get a baseline SARA score before the first dose

The trial's effect appeared within 12 weeks. A score taken before starting and again at 3 months gives you and the neurologist a real answer about whether to continue, instead of an impression.

Confirm the weight

15 kg is the line. A child at 14 kg is outside the label and a child at 16 kg is inside it, and the dose changes at 25 and 35 kg, so an accurate current weight belongs in the prescription.

Expect a prior authorization and file the appeal the same day it is denied

A new indication for an existing orphan drug will be reviewed case by case for the first few months, and first denials are routine while payer policies catch up. The FDA notice, the Lancet Neurology paper and the SARA scores are what an appeal letter is built from. Our guide to appealing a rare disease drug denial walks through the letter.

Keep everything else going

Immunoglobulin replacement, infection care and cancer surveillance do not change. A child who starts Aqneursa still has A-T; the drug addresses one part of it.

For the wider A-T community, the September 18th approval closes a loop that opened with the January failure. The clinical sites that learned to run a large A-T trial on eDSP are the same ones that will test the antisense and gene-based approaches now in earlier stages, and for the first time a new therapy will be measured against a treated baseline rather than against nothing. That is what a first drug does for a rare disease, beyond what it does for any one patient.