Objectives: To evaluate the efficacy and safety of ustekinumab (UST) in a multicentre, randomised, double-blind, placebo-controlled trial in adult Japanese patients with active polymyositis (PM) and dermatomyositis (DM).
Methods: Fifty-one Japanese adults diagnosed with active PM/DM who did not respond adequately to one or more standard-of-care treatments were randomised 1:1 to receive UST (n=25) or placebo (n=26). Participants received body weight-range based intravenous administration of UST (6 mg/kg) or placebo at week 0 followed by 90 mg subcutaneous (SC) administration of UST or placebo every 8 weeks from week 8 to week 24. At week 24, placebo group crossed over to receive body weight-range based intravenous administration of UST, and thereafter, all participants received/were to receive SC administration of UST 90 mg every 8 weeks (week 32 through to week 72). The primary efficacy endpoint was the proportion of participants who achieved minimal improvement (≥20) in the International Myositis Assessment and Clinical Studies Total Improvement Score (IMACS TIS) at week 24.
Results: No statistically significant difference was seen in the proportion of participants who achieved minimal improvement (≥20) in IMACS TIS at week 24 between the treatment groups (UST 64.0% vs placebo 61.5%, p=0.94) based on the primary estimand of the primary endpoint analysis.
Conclusions: UST was safe and well tolerated but did not meet the primary efficacy endpoint in adult Japanese participants with active PM/DM based on the primary analysis at week 24 in the study.
Trial registration number: NCT03981744.
Keywords: dermatomyositis; inflammation; polymyositis.
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