Arthrosi drug trial in gout delivers for new owner Sobi

Sobi's $1.5 billion takeover of Arthrosi at the end of 2025 has started to pay off, with a positive phase 3 trial for gout therapy pozdeutinurad, the main asset in the deal.

The oral, once-daily URAT1 inhibitor has met its primary efficacy objectives in the first of two pivotal trials, REDUCE-2, in patients with gout that cannot be controlled with existing drugs. The other study, REDUCE-1, is due to generate results in the latter half of this year.

Pozdeutinurad, at both the doses tested in the REDUCE-2, led to a significant improvement in the proportion of patients achieving a serum uric acid (sUA) level of 6 mg/dl or less at six months. That endpoint was achieved in 69.2% of patients taking a 75 mg dose of the drug and 56.6% of those on a 50 mg dose, compared to 8.1% of the placebo group.

Targeting URAT1 is a tried-and-tested strategy to treat gout, an excruciatingly painful form of inflammatory arthritis caused by elevated levels of uric acid in the blood, resulting in crystals being deposited in and around joints.

Existing drugs in the class include probenecid, which has limited efficacy, a fairly high side-effect burden, and issues with drug interactions. Some years ago, Ironwood Pharma launched two more potent therapies – Zurampic (lesinurad) and Duzallo (lesinurad plus allopurinol) – but these failed commercially due to a complex dosing regimen and concerns about kidney side effects and were pulled from the market in 2019.

Sobi is confident pozdeutinurad can offer an improved therapeutic profile, particularly in terms of tolerability, as it made a hefty $950 million upfront payment for Arthrosi with another $550 million tied to potential clinical, regulatory, and sales milestones.

The Sweden-based company is developing a second therapy for uncontrolled gout – NASP (nano-encapsulated sirolimus plus pegadricase) – in an alliance with Selecta Biosciences, and filed the drug in the US last September with a verdict due next month.

Lydia Abad-Franch, Sobi's chief medical officer, said the company is "very encouraged" by the REDUCE-2 results, which point to sustained urate lowering and a favourable efficacy and tolerability profile.

The data "support the potential of pozdeutinurad to address a significant unmet need and provide a strong foundation for regulatory submissions," she added.

Other drugs coming through the URAT1 inhibitor pipeline include lingdolinurad from China's Atom Therapeutics, which in late-stage clinical testing and being offered out for licensing, and dotinurad, which is already sold by originator Fuji Yakuhin in Japan as Urece and is in phase 3 testing in the US by licensee Crystalys Therapeutics.

Photo by Marco Bianchetti on Unsplash