ATLANTA – Adding ixekizumab (Taltz) to conventional background medications significantly improved the signs and symptoms of nonradiographic axial spondyloarthritis (axSpA) in the randomized, double-blind, placebo-controlled phase 3 COAST-X trial.
Sharon Worcester/MDedge News
Dr. Atul Deodhar
The high-affinity interleukin-17A monoclonal antibody ixekizumab “has shown efficacy in ankylosing spondylitis – also called radiographic axial spondyloarthritis – [and] it recently was approved by the [Food and Drug Administration] for the treatment of active ankylosing spondylitis,” said Atul Deodhar, MD, explaining that COAST-X sought to assess its efficacy in patients with active nonradiographic axSpA and objective evidence of inflammation. He presented the results of the trial at the annual meeting of the American College of Rheumatology.
Of 303 adults with an established diagnosis of axSpA who met Assessment of Spondyloarthritis International Society (ASAS) classification criteria and who were enrolled in the 52-week trial, 105 were randomized to receive background medications plus placebo, and 102 and 96 received background medications plus ixekizumab every 2 or 4 weeks, respectively. The primary endpoint of a 40% improvement in ASAS response criteria (ASAS 40) was reached at week 16 by 19% of the placebo-group patients and by 35% and 40% of the 2- and 4-week ixekizumab-group patients, and at week 52 by 13%, 30%, and 31% of the patients in the groups, respectively, Dr. Deodhar reported.
Additionally, “all major secondary endpoints were met for each ixekizumab regimen, both at week 16 and week 52,” said Dr. Deodhar, professor of medicine in the division of arthritis and rheumatic diseases at Oregon Health & Science University, Portland.
For example, Ankylosing Spondylitis Disease Activity Score (ASDAS) at week 16 declined by 0.6 with placebo, 1.3 with 2-week ixekizumab dosing, and 1.1 points with 4-week ixekizumab dosing; Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Functional Index changes were –1.5, –2.5, and –2.2, and –1.3, –2.3 and –2.0; Short Form–36 physical component score changes were 5.3, 8.0, and 8.1 points; and MRI sacroiliac joint Spondyloarthritis Research Consortium of Canada score changes were –0.3, –4.5 and –3.4, in the groups, respectively.
“ASDAS less than 2.1 – low disease activity – was achieved by 32% and 27% [in the 2- and 4-week ixekizumab groups] versus 12% in the placebo [group],” he said, noting that similarly significant results were seen at week 52.
Notably, the differences in ASAS 40 response rates between the treatment and placebo groups were observed beginning at week 1, and “a notable proportion” of patients who escaped to the open-label 2-week ixekizumab group, as allowed per study protocol starting at week 16, had an ASAS 40 response at the time of escape; the ASAS 40 response rates at that time were 6.5%, 16.7%, 25% in the groups, respectively, and the rates increased further on open-label ixekizumab, he said.
Study participants were adults diagnosed with axSpA by a physician and treated for at least 3 months. Inclusion criteria also included BASDAI score of at least 4, back pain score of at least 4, inflammation as evidenced by sacroiliitis on MRI or elevated C-reactive protein levels of greater than 5 mg/L, and inadequate response or intolerance to at least two NSAIDs.
Ixekizumab in both treatment groups was given at a dose of 80 mg, and changes to conventional background medications, including NSAIDs, conventional synthetic disease-modifying antirheumatic drugs, analgesics, and low-dose corticosteroids, were allowed, as was escape to open-label ixekizumab given every 2 weeks at investigators’ discretion after week 16.
Ixekizumab treatment was well tolerated; the frequency of serious adverse events and AEs leading to treatment discontinuation was low and similar across all arms, Dr. Deodhar said.
For example, treatment-emergent AEs occurred in 55.7%, 77.5%, and 65.6% of patients, serious AEs occurred in 1.0%, 1.0%, and 2.1%, and AE-related discontinuations occurred in 1.9%, 1.0%, and 1.0% or patients in the groups, respectively.
No deaths occurred and no new safety signals were identified.
“The results demonstrate, for the first time, that blocking IL-17A is a potential treatment option for patients with nonradiographic axSpA,” he concluded.
COAST-X was sponsored by Eli Lilly. Dr. Deodhar and most coauthors reported receiving research grants and/or honoraria for consulting or speaking from Eli Lilly and other pharmaceutical companies. Four authors are current employees and shareholders of Eli Lilly.
SOURCE: Deodhar A et al. Arthritis Rheumatol. 2019;71(suppl 10), Abstract 2729.