A Phase 2 Proof of Concept Study to Evaluate the Efficacy and Safety of Daxdilimab in Participants With Dermatomyositis (DM) or Anti-synthetase Inflammatory Myositis (ASIM)

The primary efficacy objective: To evaluate the effect of daxdilimab compared with placebo in reducing disease activity at Week 24. The secondary efficacy objectives include: 1. To evaluate the effect of daxdilimab compared with placebo in reducing disease activity at Week 24. 2. To evaluate the effect of daxdilimab compared with placebo on skin symptoms at Week 24. 3. To evaluate the effect of daxdilimab on decreasing the use of corticosteroid at Week 24. Other secondary objectives include: 1. To characterize the pharmacokinetics (PK) and immunogenicity of daxdilimab in participants. 2. To evaluate the safety and tolerability of daxdilimab in participants.