Arthrosi Presents Positive Long-Term Safety and Efficacy Data for Pozdeutinurad (AR882) at the European Alliance of Associations for Rheumatology (EULAR) Congress 2025

Data demonstrates that pozdeutinurad alone or in combination achieves significant reduction in sUA levels in patients with tophaceous gout up to 18 months of treatment

Pozdeutinurad's long-term use was well tolerated and comparable to standard of care, with no incidences of elevated serum creatine or clinically significant liver function abnormalities

SAN DIEGO, June 12, 2025 /PRNewswire/ -- Arthrosi Therapeutics, Inc., a late-stage biotechnology company developing a potentially best-in-class, highly potent and selective next generation URAT1 inhibitor to reduce serum urate (sUA) levels, flares, and dissolve tophi in gout and tophaceous gout patients, today announced long term treatment data from the Phase 2 trial extension period evaluating patient outcomes up to 18 months of treatment with pozdeutinurad (formerly known as AR882). Detailed results will be presented at the European Alliance of Associations for Rheumatology (EULAR) Congress 2025 meeting, being held June 11-14, 2025, in Barcelona, Spain.

"The long-term data from our Phase 2 trial evaluating pozdeutinurad continues to build on the body of evidence differentiating it as a potentially transformative, best-in-class treatment option for patients with gout and tophaceous gout," said Arthrosi's Chief Medical Officer Robert T. Keenan, MD, MPH, MBA. "The significant and sustained reduction in sUA over 18 months observed in both the monotherapy and combination groups demonstrates better efficacy to standard of care alone. In addition, the high response rates of complete tophi resolution as well as rapid resolution of total urate crystal volume represent unprecedented quality of life improvements for patients living with gout. We have already fully enrolled the Phase 3 REDUCE 2 global trial and are rapidly enrolling patients in the ongoing Phase 3 REDUCE 1 trial."

The long term safety and efficacy data will be presented in both oral and poster presentations at EULAR.

New Clinical Data for Pozdeutinurad Show:

• Pozdeutinurad alone or in combination demonstrated high rates of complete resolution of target and non-target tophi in patients as early as 6 months of treatment and was associated with potent sUA lowering.
  • The average baseline sUA level ranged between 9.1-9.6 mg across groups.
  • Pozdeutinurad alone or in combination showed rapid and sustained resolution of urate crystal volume.
  • Patients receiving pozdeutinurad alone or in combination maintained a clinically significant reduction in sUA of <4 mg/dL or lower.
  • Pozdeutinurad alone and in combination achieved clinically meaningful complete dissolution of at least one target tophi.
• Pozdeutinurad's long-term use was well tolerated throughout the 18-month chronic treatment both as a monotherapy and in combination with allopurinol.
  • Treatment-emergent adverse events (TEAEs) were consistent with previous reports and mostly mild-to-moderate in severity.
  • No elevation of serum creatine was observed during treatment with pozdeutinurad, and pozdeutinurad alone showed no clinically significant liver function abnormalities.

Presentation Details:

Title: Sustained Efficacy of Pozdeutinurad (AR882): Long-Term Effect of a Novel and Selective URAT1 Inhibitor in Patients with Chronic Gouty Arthritis.
Presenting Author: Robert Keenan, M.D., Chief Medical Officer of Arthrosi Therapeutics
Format: Poster presentation
Abstract Number: POS1307
Date and Time: Saturday, June 14, 2025, 10:00am-3:00pm CEST

Title: Safety and Tolerability of Pozdeutinurad (AR882) Treatment following Long-term Dosing in Patients with Chronic Gouty Arthritis and Subcutaneous Tophi.
Presenting Author: Robert Keenan, M.D., Chief Medical Officer of Arthrosi Therapeutics
Format: Oral presentation
Abstract Number: OP0300
Date and Time: Friday, June 13, 2025, 10:30am CEST

About the AR882-203 Phase 2 Study:

The Phase 2 study of pozdeutinurad (AR882) in patients with tophaceous gout was a six-month 1:1:1 randomized, global, placebo-controlled study of 42 patients with subcutaneous tophi. The mean baseline sUA among the participants ranged between 9.1-9.6 mg/dL. In the main treatment period, patients received a once daily dose of either 75 mg AR882, 50mg AR882 + allopurinol, or allopurinol up to 300mg. Serum uric acid levels (< 6, <5, <4, or <3 mg/dL) were evaluated monthly through month 6 and continued evaluated up to Month 18, and safety and tolerability were assessed throughout the study. Tophi measurements with calipers were completed every 4 weeks for 6 months and throughout the study. Patients were also imaged using Dual-Energy Computed Tomography (DECT), DECT a specialized imaging technique that is able to differentiate and identify uric acid crystals in the joints and soft tissue, allowing for quantifying uric acid crystal deposition and tophi at baseline, 6, 12, and 18 months.

About Gout:

In the U.S., an estimated 13 million individuals are diagnosed with gout, ~2 million of which have tophaceous gout. Gout is a form of inflammatory arthritis that can significantly diminish mobility, functionality, and overall quality of life. Gout emerges from the crystallization of uric acid within the joints and soft tissue, instigating painful flare-ups and chronic symptoms. The kidneys play a pivotal role in the process, as they are responsible for filtering out and excreting uric acid from the body. In over 90% of gout patients, underexcretion of uric acid results in the imbalanced and elevated sUA levels that can lead to the deposition of uric acid crystals. It's essential to monitor and manage sUA levels as part of comprehensive gout treatment and prevention strategies.

About Arthrosi:

Arthrosi Therapeutics, Inc., headquartered in San Diego, CA, is focused on developing pozdeutinurad (AR882), a potentially best-in-class, highly potent and selective next generation URAT1 inhibitor to reduce serum urate levels, flares and tophi in patients with gout. Pozdeutinurad has demonstrated encouraging efficacy and safety compared to SOC in Phase 2 studies as well as impressive results in achieving complete resolution of tophi in a Phase 2b study. Arthrosi is currently advancing pozdeutinurad in a pivotal Phase 3 program.

Media Contact:
Shunqi Yan, PhD
Founder & Chief Operating Officer
[email protected]

Investor Contact:
Precision AQ
Alex Lobo
212-698-8802
[email protected] 

SOURCE Arthrosi Therapeutics