Dazukibart in dermatomyositis: skin scores improved through 92 weeks in a small open-label extension

Design

Phase IIb open-label extension after a 24-week phase II double-blind study

Population

Adults with moderate-to-severe dermatomyositis (9 skin-predominant, 15 muscle-predominant, 16 pooled skin set)

Primary outcome

Treatment-emergent adverse events from week 24 to week 92

Effect

Adverse events mild 55%, moderate 38%, severe 7%; median CDASI-A change -24.0 (skin-predominant) at week 76

Dazukibart is an anti-interferon beta antibody being studied in dermatomyositis. Participants from a 24-week phase II double-blind study entered a 52-week open-label extension with a 16-week follow-up, for a total of 92 weeks. The extension analysed 9 people in a skin-predominant cohort, 15 in a muscle-predominant cohort and 16 in a pooled skin set.

Adverse events were mild in 55%, moderate in 38% and severe in 7%, with no treatment-related serious events or discontinuations. At week 76 the median change in CDASI-A from baseline was -24.0 in the skin-predominant cohort and -23.5 in the pooled skin set. The muscle-predominant cohort had a median Total Improvement Score of 65.0.

This is a phase II extension with no control arm and very small numbers, in a population that was mostly White and female. It supports interest in the mechanism, not a treatment decision.

• Treat this as early evidence; the drug is investigational.
• Open-label data without a control arm cannot separate drug effect from natural course.
• Interferon pathway targeting is a mechanism to watch in refractory dermatomyositis.
• Continue established therapy and specialist co-management in the meantime.

Why it matters

It adds long-term safety signal to an interferon-directed approach for a disease with limited targeted options.

Don't overread it

A phase II open-label extension in 40 or fewer people cannot show efficacy against a control.

The statistics, in plain English

Median changes with wide ranges in 9 to 16 people are descriptive. Without a comparison group, improvement after enrolment may partly reflect regression to the mean or concurrent treatment.

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