Anifrolumab - IFNAR1

Anifrolumab (anti-IFNAR1) is being tested in idiopathic inflammatory myopathies (IIM) because dermatomyositis (DM) in particular is strongly “type I interferon–driven,” making IFN-pathway blockade a biologically coherent target. However, for IIM itself there are not yet completed randomized efficacy trials, so the “established” evidence base is currently indirect—mainly the large SLE clinical program and post-marketing experience that define the key safety signals most relevant to myositis patients receiving background immunosuppression (notably respiratory infections and herpes zoster, including disseminated cases) [7].

Preliminary IIM (mostly DM) evidence is observational but increasingly substantive. The largest published experience to date is a multicenter retrospective compassionate-use study of 30 refractory systemic DM patients, with rapid improvement from month 1 across domains: median CDASI-A fell from 23 to 6, MMT-8 improved, and CK decreased/normalized in many patients; arthritis (n=3 active) remitted, and ILD cases (n=6) were reported as stabilized or improved by PFTs and/or CT. Steroid-sparing was prominent (dose reduced significantly; 50% discontinued glucocorticoids), adverse events were mostly mild (one pneumonia death in an 89-year-old), and discontinuation for loss of efficacy occurred in one patient [1]. Smaller published cohorts and case-based reports similarly emphasize robust cutaneous responses in recalcitrant DM/JDM and suggest possible extracutaneous benefit in selected patients (skin most consistent; muscle/joints/lung less certain because of confounding and small numbers) [2–4].

The key “true trial” test is the ongoing Phase III JASMINE study in IIM (polymyositis and dermatomyositis): a multinational, randomized, double-blind, placebo-controlled program evaluating subcutaneous anifrolumab added to standard of care with outcomes framed around overall disease activity [5,6]. AstraZeneca states JASMINE is expected to enroll ~240 adults (18–75) with moderate–severe IIM [6]. As of now, public efficacy results have not been reported, so the field is waiting for whether benefit extends beyond skin (strength/function, steroid-sparing, and organ involvement such as ILD where applicable) and whether infection risks familiar from SLE translate similarly in a heavily immunosuppressed myositis population [5–7].

References (linked)

1. Retuerto-Guerrero M, et al. Real-world experience of anifrolumab in 30 patients with refractory dermatomyositis: a multicentre–multidisciplinary retrospective study. Rheumatology. 2025. Oxford Academic (full text)
2. Shaw KS, et al. Anifrolumab in recalcitrant cutaneous dermatomyositis: a multicenter retrospective cohort study. J Am Acad Dermatol. 2024. PubMed
3. Ang PS, et al. Refractory dermatomyositis responsive to anifrolumab. JAAD Case Reports. 2023/2024. Full text
4. Patel S, et al. Improvement of recalcitrant multisystem disease in adult-onset dermatomyositis with anifrolumab (case series). 2025. PubMed
5. JASMINE (NCT06455449): Anifrolumab in adult IIM (PM/DM). ClinicalTrials.gov
6. AstraZeneca. Start of recruitment in Phase III JASMINE (IIM) and LAVENDER (CLE). Sept 19, 2024. Press release
7. FDA. SAPHNELO (anifrolumab-fnia) Prescribing Information. 2021 (label). PDF