Investigational Gout Drugs Do Well in Clinical Trials
November 3, 2011 by Lynn.
Ardea Biosciences was the first to announce successful clinical trials of its experimental gout drug RDEA594, also known as Lesinurad. Lesinurad's mechanism of action is different from that of the commonly prescribed xanthine oxidase inhibitors gout medications (such as allopurinol and febuxostat), which decrease the production of uric acid.
Lesinurad is a URAT1 transporter inhibitor which increases elimination of uric acid through the kidneys. Lesinurad is also active against another important regulator of urate secretion, OAT4. OAT4 is thought to be responsible for the high uric acid levels in gouty arthritis patients whose condition is caused or worsened by diuretics.
The Lesinurad study involved 208 gout patients who had high blood urate levels for at least 6 months, even while taking the gout drug allopurinol. Patients continued on allopurinol and were randomly assigned to receive either a placebo or lesinurad at doses of 200 mg, 400 mg, or 600 mg for four weeks.
All three groups who were given lesinurad showed significantly lower uric acid levels at the end of the month. The percentage of patients who achieved the target for uric acid levels after treatment was 28% in the placebo group, 71% in the 200 mg group, 76% in the 400 mg group, and 87% in the 600 mg group.
More recently, shares of BioCryst Pharmaceuticals rose 12% upon the release of the results of its phase 2b randomized, double-blind, study of the investigational gout drug BCX4208. BCX4208 is a novel enzyme inhibitor that acts upstream of xanthine oxidase in the purine metabolism pathway to reduce serum uric acid (sUA).
Its mechanism of action complements xanthine oxidase inhibitors such as allopurinol and febuxostat in reducing uric acid production, and BCX4208 is intended as an add-on therapy for those gouty arthritis patients who don't respond well to current gout medication.
Like Lesinurad, BCX4208 was studied in gouty arthritis patients who had experienced high blood urate levels for at least 6 months, despite taking the gout drug allopurinol. The 279 study participants were randomly assigned to take BCX4208 at doses of either 5 mg, 10 mg, 20 mg, or 40 mg once daily for 12 weeks. One group of patients was given a placebo. All participants were also given allopurinal 300 mg once-daily.
All but one of the doses showed that BCX4208 was superior to the placebo when taken with allopurinol. The BCX4208 doses evaluated in the study showed response rates ranging from 33% to 49%, compared to 18% for those taking the placebo.
At this point, Lesinurad appears the more promising of the two gout medications, and the most likely to hit the market first. It outperformed BCX4208 in early clinical trials, and is farther ahead in the development and approval process. But individual responses to drugs vary, and gout patients will benefit from having two new approaches to relieving the symptoms of this painful condition.
Filed under: Gout Arthritis.
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