Post-hoc analysis supports further investigation of ustekinumab in PsA-associated spondylitis
medwireNews: Treatment with ustekinumab may be beneficial for some patients with psoriatic arthritis (PsA) and spondylitis, suggests a post-hoc subgroup analysis of the PSUMMIT 1 and 2 trials.
Speaking to medwireNews, Lianne Gensler (University of California, San Francisco, USA) who presented the findings in a late-breaking poster at the 2018 ACR/ARHP Annual Meeting in Chicago, Illinois, USA, explained that axial disease and psoriatic spondylitis are “pretty prevalent” in PsA patients, with up to half having axial involvement.
“The question is, do those patients with axial involvement also see benefit from the treatments that we use for their peripheral disease?” she added.
The post-hoc analysis included 223 tumor necrosis factor (TNF) inhibitor-naïve PsA patients with peripheral arthritis and physician-reported spondylitis who participated in PSUMMIT 1 and 2, two randomized placebo-controlled trials of ustekinumab for the treatment of PsA.
In this subgroup of patients, those who were randomly assigned to receive treatment with ustekinumab at a dose of 45 mg or 90 mg (given at baseline, week 4, and every 12 weeks thereafter) experienced a numerically greater improvement in modified BASDAI score from baseline to week 12 than patients treated with placebo, with mean decreases of 1.81 and 1.78 versus 0.52 points, respectively.
Similarly, average improvements in modified BASDAI score from baseline to week 24 were numerically greater in the ustekinumab 45 mg and 90 mg groups compared with the placebo group (1.73 and 2.41 vs 0.59 points). The differences did not reach statistical significance at either timepoint, however.
Gensler and team also found that a significantly greater proportion of patients treated with ustekinumab 45 mg or 90 mg versus placebo achieved inactive disease according to an ASDAS score below 1.3 points by week 24 (6.3 and 11.6 vs 0.0%), as well as a clinically important improvement in ASDAS score, defined as a decrease of at least 1.1 points (43.5 and 55.1 vs 12.7%).
“Approximately half of [ustekinumab]-treated peripheral arthritis with physician-reported spondylitis patients attained meaningful improvements in ASDAS by Week 24,” concluded the researchers.
Gensler cautioned, however, that “the major limitation of this study is that […] axial involvement was defined by physician diagnosis, so we did not have imaging [tests]” to confirm the diagnosis.
And she said that future research should involve randomized controlled trials of ustekinumab in patients with PsA and spondylitis, as well as translational studies to investigate the response “at a very granular level.”
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