Considering the known effects of IVIg in idiopathic inflammatory myopathies (IIM), both as add-on therapy in refractory patients, as well as monotherapy in newly diagnosed IIM, we conducted a phase-2 double-blind placebo-controlled randomized trial to investigate the effect of add-on IVIg in patients with newly diagnosed IIM, who are treated with monotherapy prednisone.~Objective:~The primary aim of this trial is to examine whether the addition of early administered IVIg to standard therapy with prednisone in patients with newly diagnosed myositis leads to an improved clinical response after 12 weeks, compared to prednisone and placebo. Clinical response will be measured as the difference of the mean TIS after 12 weeks between intervention and control groups.~The secondary aims are to examine whether the intervention leads to a shorter time to improvement, and sustained positive effects on health-related quality of life, physical activity and fatigue, and a sustained reduction of muscle MRI abnormalities, as assessed up to 52 weeks.~Following a screening visit at the outpatient clinic, patients will be admitted to the neurology ward of the Amsterdam University Medical Center (AUMC) for the first infusion of study treatment. The remaining study medication will be administered at home, according to routine clinical practice for IVIg treatment in neuromuscular disorders in the Netherlands. A second and third study treatment will be administered at home after 4 and 8 weeks. At baseline and after 4, 8, 12, 26 and 52 weeks outcome assessments will be performed at the outpatient clinic. The outpatient study clinic visits at baseline and after 4, 12, 26 and 52 weeks will be combined with regular outpatient clinic visits.~The additional burden related to outcome assessments will consist of MRI muscle imaging after 12 weeks, blood sampling after 2, 4, 6, and 10 weeks and filling in questionnaires at baseline and after 4, 8, 12, 26 and 52 weeks. In addition, participants are asked to wear a watch three times in a period of 12 weeks and after 26 weeks.
In patients with myositis early immunomodulation by intensive treatment (hit-early/hit-hard principle) may induce faster reduction of disease activity and prevent chronic disability. Intravenous immunoglobulin (IVIg) in addition to standard treatment with glucocorticoids may be beneficial for this purpose: add-on IVIg improved symptoms in steroid-resistant myositis, and first-line monotherapy IVIg led to a fast and clinically relevant response in a pilot study in nearly 50% of patients with myositis.