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04-12-2018 | Ankylosing spondylitis | News

Elevated CRP levels may point to better secukinumab response in AS patients

medwireNews: Ankylosing spondylitis (AS) patients with elevated C-reactive protein (CRP) levels may experience greater benefits from treatment with the interleukin (IL)-17A inhibitor secukinumab than those with lower levels of the inflammatory marker, researchers report.

However, Jürgen Braun (Ruhr-University Bochum, Herne, Germany) and co-investigators emphasize that “patients with normal baseline CRP levels also have a strong likelihood of experiencing a positive treatment response with IL-17A inhibition.”

In their post-hoc analysis, Braun and colleagues found that 63.5% of 392 patients who were treated with either secukinumab 150 mg or placebo every 4 weeks in the MEASURE 1 and 2 trials had elevated CRP levels (≥5 mg/L) at baseline.

They report that a significantly higher proportion of patients treated with secukinumab versus placebo achieved an ASAS20 response at week 16 in both the elevated and normal CRP groups, but “the magnitude of response [was] higher in patients with increased baseline CRP.”

Specifically, ASAS20 response rates with secukinumab versus placebo treatment were 63.2% versus 29.0% in the elevated CRP group, and 56.9% versus 28.2% in the normal CRP group. The corresponding ASAS40 response rates were 42.4% versus 15.3% and 34.7% versus 7.0%, and average improvements in BASDAI score were 2.4 versus 0.6 points and 2.2 versus 1.0 points, respectively.

When participants were categorized using a CRP cutoff of 10 mg/L, ASAS20 response rates were 72.4% for secukinumab-treated patients and 28.0% for placebo-treated patients among those with levels at or above this cutoff (45.9% of all participants), and were 51.8% and 29.4%, respectively, for those with levels below 10 mg/L.

The researchers also demonstrated an association between decreasing CRP levels and response to secukinumab treatment. Among the 168 patients who experienced at least a 50% reduction in CRP during the first 4 weeks of the study, those treated with secukinumab experienced significantly higher ASAS20 response rates than those given placebo (72.1 vs 35.7%). However, the difference in ASAS20 response rates between the secukinumab and placebo groups was no longer statistically significant among patients who did not experience a 50% decrease in CRP levels (33.3 vs 27.9%).

“To what extent those patients [without an early decrease in CRP levels] could benefit from an increased dose of secukinumab after week 4 is an open question,” write the study authors in RMD Open.

And they conclude: “Inclusion of prospectively planned analyses by baseline CRP level in future clinical trials would help guide treatment strategies for patients with AS with normal, as well as elevated, baseline CRP.”

By Claire Barnard

medwireNews is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group

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