Ixekizumab reduces erosion, increases backfill scores in radiographic axial SpA
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SAN DIEGO — Biologic-naïve patients with radiographic axial spondylarthritis who receive ixekizumab for 16 weeks demonstrate reduced erosion scores and increased backfill scores, according to data presented at ACR Convergence 2023.
“We do not have a good way of evaluating disease modification in spondyloarthritis,” Walter P. Maksymowych, MD, of the University of Alberta, in Edmonton, Canada, said told Healio.
He added that few data exist assessing the impact of ixekizumab (Taltz, Eli Lilly & Co.) on structural lesions in the sacroiliac joints of patients with radiographic axial SpA who have been evaluated using MRI.
“We currently do this using X-rays to see if the treatment we are testing has had any effect in preventing radiographic progression,” Maksymowych said. “But X-rays are not very sensitive, and a minimum of 2 years is required to reliably detect any change in spinal structural lesions in patients with this condition. So, we wondered if we could use MRI as a more sensitive tool to detect change in structural lesions in the sacroiliac joints.”
To examine the impact of ixekizumab, compared with placebo and adalimumab (Humira, Abbvie), on structural lesions in the sacroiliac joint, as assessed by MRI at week 16, in biologic-naïve patients with radiographic axial SpA, Maksymowych and colleagues conducted COAST V, a phase 3, multicenter, double-blind, placebo and active controlled study. Treatment groups, which were assigned in a 1:1:1:1 ratio, included 80 mg of subcutaneous ixekizumab every 2 weeks, subcutaneous ixekizumab 80 mg every 4 weeks, adalimumab 40 mg every 4 weeks, or placebo.
The full cohort included 341 patients. Baseline and week 16 MRI data were available for 325 patients.
According to the researchers, both ixekizumab doses yielded significant decreases in SPARCC sacroiliac joint structural score, with a –0.91 (SEM, 0.19) decrease reported in patients treated every 2 weeks. Both ixekizumab doses also were associated with an increase in SPARCC SSS backfill score, with the Q2W dose additionally leading to greater improvement.
Multiple subgroups showed particular improvement in SPARC SSS erosion score, including men treated with ixekizumab every 4 weeks (–0.731; SEM, 0.199) and every 2 weeks (–0.951; SEM, 0.207); HLAB27-positive patients in the ixekizumab Q4W (–0.607; SEM, 0.189) and Q2W (–0.779; SEM, 0.189) groups; and HLAB27-negative patients in the ixekizumab Q2W (–2.556; SEM, 0.656) group.
In addition, patients in both ixekizumab groups with SPARCC sacroiliac joint bone marrow edema scores of 4 or greater demonstrated improvement in SPARC SSS erosion. Moreover, men treated with ixekizumab every 2 weeks, HLAB27-negative patients treated with ixekizumab every 2 weeks, and those with SPARCC sacroiliac joint bone marrow edema scores of 4 or greater in both ixekizumab groups showed improvement in SPARC SSS backfill score.
“First, we can indeed reliably detect change in structural lesions on MRI and, in particular, we see there is significant improvement with ixekizumab or its active comparator adalimumab,” he said. “Second, the improvement continues right out to 52 weeks and is also noted in patients switching from placebo to ixekizumab at week 16. Third, the improvement is more noticeable in males, patients with the B27 gene, and those with more inflammation on MRI at baseline.”
Maksymowych added that it will be important to determine whether improvement on MRI in the sacroiliac joints also means that it is possible to prevent structural changes from occurring in the spine.
“This is true especially given that the MRI of the sacroiliac joints is a lead indicator of what might happen in the spine,” he said.
Maksymowych additionally urged ongoing communication with patients about these interventions.
“It may be helpful to inform patients that these drugs may do more than just improve symptoms,” he said. “We are increasingly using more sensitive tools such as MRI to study structural lesions and the impact of treatment. X-rays are increasingly becoming non-feasible for evaluating disease-modification. It is incumbent on rheumatologists to learn more about MRI.”
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Maksymowych W. Abstract 2549. Presented at: ACR Convergence 2023; Nov. 10-15, 2023; San Diego.
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