Dose-Escalated Upadacitinib for Refractory Myositis in Anti-Jo-1-Positive Antisynthetase Syndrome: A Case Report

Anti-Jo-1-positive antisynthetase syndrome (ASS) can follow a relapsing course during glucocorticoid tapering, and evidence for refractory myositis remains limited. We report a 33-year-old woman with anti-Jo-1-positive ASS with a dermatomyositis phenotype and recurrent myositis despite multiple immunosuppressants, biologics, and Janus kinase (JAK) inhibitors. Upadacitinib was increased from 15 to 30 mg/day during a flare, together with intravenous immunoglobulin and temporary prednisolone escalation. During follow-up, upadacitinib was withdrawn twice for fertility treatment; both withdrawals were followed by disease flares, and disease control was restored after reintroduction. Prednisolone was ultimately discontinued. This repeated withdrawal-rechallenge pattern suggests that dose-escalated upadacitinib may have contributed to sustained disease control.