MILAN – About 80% of patients with gout who took the investigational selective uric acid transporter 1 (URAT1) inhibitor AR882 over 3 months reduced their serum uric acid levels to below recommended thresholds (below 5 or 4 mg/dL) for better flare and tophi reduction in a phase 2b study.
The drug was well tolerated, and patients with comorbidities did not require any adjustments in disease management.
At 75 mg, the highest tested dose of AR882, 73% of patients had serum uric acid levels < 5 mg/dL and 55% had < 4 mg/dL by week 12 of therapy in the intent-to-treat population, whereas in the per-protocol analysis, 82% had serum uric acid levels < 5 mg/dL and 63% < 4 mg/dL.
Becky McCall/MDedge News
Dr. Robert Keenan
“These efficacy results are not typically what you see with a once-daily oral medication, so it is really exciting,” Robert Keenan, MD, chief medical officer of Arthrosi Therapeutics, San Diego, said in presenting the results at the annual European Congress of Rheumatology.
“Regardless of whether you’re treating subclinical, hidden crystal deposition, versus clinically visible tophi, versus chronic, debilitating gout, we believe that AR882 has the potential to treat the entire gout spectrum with a once-daily monotherapy,” Dr. Keenan asserted.
“Currently, most gout patients around the world do not have a safe, effective, and easy to use alternative to allopurinol or febuxostat, which decrease the production of uric acid,” he said. “AR882 is a URAT1 inhibitor that goes to the root of the problem in over 90% of gout patients, helping the kidneys eliminate uric acid to levels similar to all those without hyperuricemia and gout.”
Abhishek Abhishek, MD, professor of rheumatology at the University of Nottingham (England), welcomed the study. “It’s a promising study and the reduction in uric acid was substantial. It was a small study and a larger phase 3 study is needed, but it does offer real hope for patients with gout as a third treatment option because we only have allopurinol and febuxostat, so if it is shown efficacious and safe and gets approved, then it’ll help more patients with gout.”
Anne-Kathrin Tausche, MD, a rheumatologist from University Clinic Dresden (Germany), said: “These results are really impressive. We’ve lost lesinurad now because Grünenthal no longer produces it, so this might be a good alternative for patients with severe gout.
“It is favorable with [few] side effects. With allopurinol, we have to titrate it in patients with poor renal function, but it doesn’t seem to be the case with this drug. I really hope they start phase 3 soon,” she added.
Phase 2 study, but promising results
Results of the global phase 2b, randomized, double-blind trial compared the safety, tolerability, and efficacy of AR882 against placebo in patients with gout.
A total of 140 patients with gout, aged 18-75 years with an estimated glomerular filtration rate (eGFR) > 30 mL/min, were recruited across the United States, Australia, and Taiwan. Patients received either once-daily AR882 50 mg (n = 46) for 12 weeks, AR882 50 mg for 2 weeks and then AR882 75 mg (n = 47) for 10 weeks, or matching placebo for 12 weeks (n = 47). Flare prophylaxis with daily colchicine started 10 days prior to the first dose and continued throughout the study.
“Patient characteristics were typical for gout trials except for having a very diverse population,” he said. The trial included 57.9% White, 27.9% Asian, and 15% Black patients. They had a mean age of 55 years, body mass index 31-32 kg/m2. There was a range of comorbidities including hypertension, hyperlipidemia, diabetes, and cardiovascular disease, evenly distributed across placebo and AR882 treatment groups.
The efficacy endpoints were the proportion of patients who reached serum uric acid below 6, 5, 4, and 3 mg/dL, at 6 weeks of therapy, while safety was also monitored throughout the study. Reductions in serum uric acid at weeks 2, 4, 6, 12 were exploratory endpoints.
The primary endpoint of the percentage of patients below < 6 mg/dL at 6 weeks in the intent-to-treat population was met by 66% with AR882 at the lower dose (50 mg) and 84% at the higher dose (75 mg).
With the 50-mg dose, serum uric acid was reduced at week 6 to < 5mg/dL by 41%, < 4mg/dL by 12%, and < 3mg/dL by 2%, whereas these percentages were 68%, 52%, and 23%, respectively, with the 75-mg dose.
Exploratory endpoints showed that by week 12, serum uric acid levels dropped from baseline 8.6 mg/dL to about 5.0 mg/dL with AR882 50 mg and from baseline 8.6 mg/dL to about 3.5 mg/dL with AR882 75 mg. Also at week 12, 55% and 23% reached serum uric acid levels of < 4mg/dL and < 3mg/dL in the intent-to-treat population. No change was observed in the placebo group.
All adverse events were mild to moderate, with the most prevalent being gout flares. There was little difference between doses. There were no clinically significant changes in a total of 778 post-dose measurements of alanine transaminase (ALT) and aspartate transaminase (AST) and 723 post-dose triplicated electrocardiogram (ECG) measurements.
Dr. Keenan is chief medical officer of Arthrosi Therapeutics. Dr. Tausche and Dr. Abhishek have no relevant financial relationships to disclose.