A Prospective, Randomized, Open-Label, Blinded Endpoint (PROBE) Study to Evaluate the Efficacy of Rituximab as First Line Therapy Versus Conventional Immunosuppressants in Juvenile and Adult Patients with Idiopathic Inflammatory Myopathies (Polymyositis and Dermatomyositis)

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare systemic autoimmune diseases characterized by chronic inflammation primarily affecting skeletal muscles, though they frequently involve other organ systems including skin, lungs, joints, and heart. The treatment of IIM is challenging due to the rarity and wide phenotypic heterogeneity especially that of refractory myositis. Current treatment paradigms rely heavily on high-dose glucocorticoids as first-line therapy, typically combined with conventional immunosuppressive agents such as methotrexate, azathioprine, or mycophenolate mofetil. Rituximab is increasingly being used off label in the treatment of IIM, particularly refractory myositis.

Despite the individual efficacy of pulse methylprednisolone and rituximab, there remains limited evidence comparing their combined use against conventional therapy in IIM patients. The potential for synergistic effects between rapid corticosteroid-induced immunosuppression and B-cell depletion represents an attractive therapeutic strategy that warrants systematic investigation.

The current study aims to address this knowledge gap by comparing the efficacy of combination intravenous rituximab and pulse methylprednisolone therapy against conventional treatment with pulse corticosteroids followed by oral immunosuppressive therapy. The RCT will provide valuable insights into optimal treatment sequencing and the potential benefits of early aggressive immunosuppression in IIM management.