Sobi® (STO:SOBI) has entered into a definitive agreement to acquire Arthrosi Therapeutics, Inc. (Arthrosi), a private late-stage biotechnology company focused on developing a next-generation treatment for gout. The acquisition strengthens Sobi's gout franchise by adding pozdeutinurad (AR882), an investigational next-generation, once-daily oral URAT1 inhibitor currently being evaluated in two fully recruited global Phase 3 clinical studies for the potential management of progressive and tophaceous gout and expected to read out in 2026. Pozdeutinurad complements Sobi's pipeline by adding a potentially best-in-class URAT1 inhibitor for patients sub-optimally treated with first-line therapies. Today's announcement reflects Sobi's commitment to advancing treatment options for people living with gout.

"The acquisition of Arthrosi allows us to expand our gout pipeline with a highly differentiated new asset", said Guido Oelkers, President and CEO of Sobi. "Pozdeutinurad has the potential to become the therapy of choice for patients who have progressive gout with persistent and unresolved symptoms despite first-line therapy. The product has the potential to materially accelerate our growth until the mid 2030s, and beyond. We welcome all members of the talented Arthrosi team and are looking forward to working closely together to be able to offer this therapy to patients as soon as possible."

"We are thrilled to join forces with Sobi and look forward to working together to ensure a seamless transition as they advance pozdeutinurad towards pivotal data and potential regulatory filings. We believe that Sobi's global expertise in commercialisation will accelerate our shared mission to deliver pozdeutinurad's potentially transformative benefits for individuals living with gout", stated Litain Yeh, Ph.D., Founder and CEO of Arthrosi Therapeutics.

Transaction details

Under the terms of the agreement, Sobi will pay USD 950 million (approximately SEK 9.1 billion) upfront in cash to acquire Arthrosi, together with up to USD 550 m (approximately SEK 5.3 billion) in cash in clinical, regulatory and sales milestones.

The transaction is subject to the satisfaction of customary closing conditions and is expected to close in H1 2026.

Sobi plans to fund the upfront payment mainly through debt in the form of existing credit facilities and a new credit facility provided by Handelsbanken and Danske Bank.

The acquisition is expected to be highly accretive to Sobi's mid- to long-term growth and margin trajectory.

Barclays Bank PLC is acting as Sobi's financial advisor and McDermott, Will & Schulte is acting as legal advisor to Sobi on this transaction.

About Pozdeutinurad

Pozdeutinurad (AR882) is an investigational URAT1 inhibitor being developed for the treatment of progressive and tophaceous gout and has completed Phase 2 studies that demonstrated compelling efficacy with a sustained reduction of serum uric acid, dissolution of tophi and a well-tolerated safety profile.  It is currently being evaluated in two Phase 3 studies, REDUCE 1 and REDUCE 2, two twelve-month, randomized, double-blind, placebo-controlled studies to assess pozdeutinurad's ability to reduce sUA in patients with progressive and tophaceous gout. Both Phase 3 studies are now fully enrolled, and the pivotal data is expected in 2026.

About Arthrosi

Arthrosi Therapeutics, Inc., headquartered in San Diego, CA, is focused on developing pozdeutinurad, a potentially best-in-class, highly potent and selective next generation URAT1 inhibitor to reduce serum urate levels, flares and tophi in patients with progressive gout. The rights to pozdeutinurad in Greater China are held by ApicHope.

Invitation to conference call

Investors, analysts and media are invited to participate in a conference call which will include a presentation and a Q&A session on the 15th December at 08:00 CET.  The presentation can be followed live here or afterwards on sobi.com. The slides will be made available on sobi.com.

To participate in the conference call, please use the following dial-in details:

Sweden: +46 8 5051 0031

United Kingdom: +44 207 107 06 13

United States: +1 631 570 56 13

For other countries, please find the details here.

About Gout

Gout is the most common form of inflammatory arthritis. Gout is caused by high levels of uric acid in the body that accumulate around the joints and other tissues and can result in flares that cause intense pain. When gout is left untreated, it can become a progressive disease with serious consequences. Over time, frequent flares and persistent uric acid buildup can lead to chronic joint damage, reduced mobility, and the formation of tophi (hard deposits under the skin). While many patients with chronic gout are treated in first line with urate lowering therapy some are sub-optimally treated or do not respond to first line therapies and the disease progresses. In later lines, uncontrolled gout is associated with a higher risk of comorbidities such as kidney disease and cardiovascular complications, making early diagnosis and effective management critical. Despite available treatments, many patients struggle to achieve target uric acid levels, underscoring the need for innovative therapies to prevent long-term disability and improve quality of life.

Sobi®

Sobi is a global biopharma company unlocking the potential of breakthrough innovations, transforming everyday life for people living with rare diseases. Sobi has approximately 1,900 employees across Europe, North America, the Middle East, Asia and Australia. In 2024, revenue amounted to SEK 26 billion. Sobi's share (STO:SOBI) is listed on Nasdaq Stockholm. More about Sobi at sobi.com and LinkedIn.

Contacts

For details on how to contact the Sobi Investor Relations Team, please click here. For Sobi Media contacts, click here.

This information is information that Sobi is obliged to make public pursuant to the EU Market Abuse Regulation. The information was submitted for publication, through the agency of the contact person set out below, at 17:00 CET on 13 December 2025.

Gerard Tobin

Head of Investor Relations