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.

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.

Inclusion Criteria:

• Adult patients (≥ 18 years) with IIM, according to diagnostic criteria:

  • Dermatomyositis
  • Polymyositis
  • Anti-synthetase syndrome
  • Immune mediated necrotizing myopathy
  • Overlap myositis

• Disease duration < 12 months

• Minimal disability defined as at least 10% loss on Manual Muscle Testing (MMT) and abnormal scores on two other Core Set Measures (CSMs) of the international Myositis Assessment and Clinical Studies (IMACS) group (see 'Primary and secondary outcomes').

• Patients are eligible for inclusion if they are treatment-naive, or if there is no clinical evident response (as carefully judged by the treating physician at a screening visit) to prior treatment with:

• High dosed glucocorticoids, such as dexamethasone (e.g. 40 mg per day up to 4 days) or intravenous methylprednisolone (e.g. 1000 mg daily for three days), within 1 week prior to screening visit.

• Daily dosed prednisone 1 mg/kg, or equivalent, used for up to 2 weeks prior to screening visit.

• Treatment with low-dosed prednisone (max 20 mg daily) up to three months prior to screening visit.

• Treatment with biologicals or other immunosuppressive or immunomodulatory treatment when meeting all of the following criteria:

  • Stable dose for the last 6 months
  • The biological or other immunosuppressive or immunomodulatory treatment has been approved for a non-muscular condition (e.g. hematological condition, eczema)
  • The biological or other immunosuppressive or immunomodulatory treatment is not known to induce inflammatory myopathy

• Signed informed consent

Exclusion Criteria:

A potentially eligible patient who meets any of the following criteria will be excluded from participation in this study:

• Severe muscle weakness (i.e. bedridden, severe dysphagia requiring a feeding tube, or respiratory muscle weakness (forced vital capacity below 50% of predicted in upright position)) necessitating more intensive treatment than standard glucocorticoids from the start.

• Related to IVIg:

  • History of thrombotic episodes within 10 years prior to enrolment
  • Known allergic reactions or other severe reactions to any blood-derived product
  • Known Immunoglobulin A (IgA) deficiency and IgA serum antibodies
  • Pregnancy or trying to conceive
  • Use of nephrotoxic medication

• Conditions that are likely to interfere with:

  • Compliance (legally incompetent and/or incapacitated patients are excluded), or,
  • Evaluation of efficacy (e.g. due to severe pre-existing disability as a result of any other disease than myositis or due to language barrier)

• Immunosuppressive medication or immunomodulatory treatment within the last 3 months (e.g. azathioprine, methotrexate, mycophenolate mofetil, tacrolimus, cyclophosphamide, cyclosporine, IVIg, biologicals, Janus kinase inhibitors, plasmapheresis).

Home-care nurse preparing study medication will be unblinded. Home-care nurse is not involved in outcome assessment.