Shionogi agrees to buy IntraBio for $2 billion, adding rare-disease drug Aqneursa

Shionogi & Co. agreed on Monday to buy IntraBio Inc., an Austin, Texas, drugmaker, for $2 billion, taking over Aqneursa, which on September 18 became the first drug the FDA approved for ataxia in patients with ataxia-telangiectasia, a rare inherited neurodegenerative disorder.

Shionogi's board approved the purchase on Monday, and the two companies signed the agreement the same day. Shionogi Inc., the group's U.S. subsidiary in New Jersey, will buy all of IntraBio's shares and pay its shareholders $2 billion upfront, or about ¥315.6 billion at the exchange rate Shionogi used in its Tokyo filing. The sellers were not named. Shionogi described them only as individuals, trusts and corporate entities that asked not to be identified. The announcement did not mention any milestone payments beyond the upfront amount, and it did not say how Shionogi will pay.

Nothing has changed hands yet. Shionogi expects to complete the purchase in November or December, once waiting periods under competition laws in each relevant country have expired and regulators have given their approvals and clearances. It said the effect on its results for the fiscal year ending in March 2027 is still under review.

What the FDA approved

Aqneursa is levacetylleucine, taken as an oral suspension. Its first U.S. approval came in September 2024, for the neurological manifestations of Niemann-Pick disease type C (NPC), an inherited lysosomal disorder that occurs in about one in 100,000 live births. That label covers adults and children who weigh at least 15 kilograms. The European Union followed in January 2026 with a narrower authorization: patients aged 6 and older who weigh at least 20 kilograms, taking the drug with miglustat, or alone when miglustat is not tolerated.

The second U.S. use is the newer one. On September 18 the FDA approved Aqneursa to treat ataxia, the progressive loss of muscle control and coordination, in adults and children with ataxia-telangiectasia (A-T) who weigh at least 15 kilograms. A-T is caused by mutations in the ATM gene and usually begins in early childhood. Shionogi puts its frequency at about one in 40,000 to 100,000 live births. The agency called Aqneursa the first treatment approved for ataxia in patients with the disease. Shionogi calls it the first and only drug approved for that use. "First" is the FDA's word; "only" is the company's.

The A-T approval rests on a randomized, double-blind, placebo-controlled crossover study of 73 patients aged 4 and older, each spending 12 weeks on the drug and 12 weeks on placebo. The measure was a modified version of a standard ataxia rating scale, scored from 0 to 16, that covers gait, sitting, stance and speech. Patients scored better while taking Aqneursa than while taking placebo, the FDA said; its announcement did not give the size of the difference. The most common side effects in the study were falls, skin lacerations and urinary tract infections. The drug may cause fetal harm, based on animal studies. The European Medicines Agency is still reviewing the A-T use.

What Shionogi is paying for

IntraBio is small. Founded in 2015, based in Austin and led by Chief Executive Mallory Factor, it reported net sales of $67.9 million in 2025, up from $3.5 million in 2024 and nothing in 2023, according to figures Shionogi published under U.S. accounting rules. It still lost money: its operating loss was $35.3 million last year, narrower than $56.2 million in 2024.

The price is more than 29 times last year's sales. Most of what Shionogi is buying, on that arithmetic, is what comes next: a U.S. A-T label that is less than three weeks old, a European A-T decision that has not been made, and global rights to the drug and related compounds, including the intellectual property. Shionogi also gets IntraBio's staff, and said their rare-disease experience would help its own programs in Pompe disease, Fragile X syndrome and Jordan's syndrome.

"The planned acquisition of IntraBio actively demonstrates Shionogi's solid commitment to building a leading global rare disease business," Chief Executive Isao Teshirogi said. Nathan McCutcheon, who runs Shionogi Inc., said the deal would help the company "deliver the first and only therapy for Ataxia-Telangiectasia to a community that has lived for many years without options."

A second rare-disease purchase in a year

Shionogi, which describes infectious disease as its area of leadership, has named rare disease as a strategic growth area, and it is paying to get there quickly. In December 2025 it agreed to pay Tanabe Pharma $2.5 billion for global rights to Radicava, the brand name for edaravone, a treatment for amyotrophic lateral sclerosis (ALS), plus possible royalties on future sales. That purchase closed in April, and Shionogi said it would add about $700 million in annual global sales. Its Tokyo filing says Shionogi will use the U.S. commercial base it built with Radicava to supply Aqneursa.

Between them, the two deals cost $4.5 billion before any Radicava royalties. Radicava came with roughly ten times the annual sales IntraBio reported for 2025.

How Tokyo took it

Shionogi's shares closed 4.5% lower in Tokyo on Monday at ¥2,661, after touching ¥2,649, their lowest price of the year. About 6.4 million shares changed hands, nearly twice Friday's volume. At the close the company was valued at about ¥2.37 trillion, so the IntraBio price equals roughly 13% of Shionogi's market value.

Goldman Sachs advised Shionogi, with Cleary Gottlieb Steen & Hamilton as legal counsel. Centerview Partners and Morgan Stanley advised IntraBio, with Kirkland & Ellis and DLA Piper as legal counsel.