11:14 AM EST, 12/23/2024 (MT Newswires) -- XBiotech ( XBIT ) shares were down over 25% Monday after the company said it is pausing its rheumatology clinical program due to irregularities in the phase II study of its candidate drug Natrunix for rheumatoid arthritis.

The study, which included about 230 participants with moderate to severe rheumatoid arthritis, did not achieve its primary endpoint of an American College of Rheumatology response rate after 12 weeks, the company said.

XBiotech ( XBIT ) said it found irregularities at the top enrolling clinical sites, including multiple enrollments of the same subjects, which raised concerns about data validity. As a result, the company has paused further planned studies in arthritis and ankylosing spondylitis while it evaluates the findings.

Price: 4.78, Change: -1.60, Percent Change: -25.08