Abatacept Treatment in Polymyositis and Dermatomyositis
Condition: Polymyositis; Dermatomyositis
MeSH terms: Dermatomyositis; Polymyositis
Study type: Interventional
Phase: Phase 2

Summary: 
      The aim of this study is to investigate the efficacy and safety of abatacept in patients with
      Dermatomyositis (DM) and polymyositis (PM) refractory to conventional treatment using a
      randomised trial design with delayed start in one arm. Abatacept will be administered
      intravenously to participants at a dose based on body weight at the screening visit followed
      by six follow-up treatments (Active treatment arm). Abatacept will also be administered
      intravenously to participants at a dose based on body weight starting at 3 months followed by
      six follow-up treatments (Delayed-onset treatment arm). The International Myositis Assessment
      and Clinical Studies Group (IMACS) preliminary definition of improvement (DOI) will be used
      for assessment.
    

Detailed description: 
      This is a phase IIb pilot study with a randomised delayed treatment design. Half of the
      patients will be randomised to treatment with abatacept from week 0 (Active treatment arm)
      and half to start active treatment after 3 months (Delayed-onset treatment arm). The
      open-label study will not include placebo, but the efficacy outcome assessors will be blinded
      to treatment arm. The study will be conducted at three sites (Karolinska University Hospital
      Stockholm, Sweden; King's College Hospital National Health Service (NHS), London, United
      Kingdom (UK); and the Institute of Rheumatology Prague, Prague, Czech Republic).

      Patients will be eligible between ages 18 and 80 years and must have active disease after
      treatment with glucocorticoids (≥0.5 mg/kg/day for ≥1 month), in combination with at least
      one other immunosuppressive drug, methotrexate (minimum dose 15 mg/week) or azathioprine
      (minimum dose 100 mg/day) for at least 3 months. Concomitant methotrexate or azathioprine
      will be allowed, with stable doses for ≥1 month prior to inclusion in the study. Active
      disease is defined as persisting or worsening muscle weakness (Manual Muscle Test (MMT)-8
      bilaterally <150) or low endurance measured by Functional Index for myositis (FI-2) <20% of
      upper value,15 together with at least one other sign of active disease: elevated (above upper
      limit of normal) serum levels of muscle enzymes, inflammation in a recent muscle biopsy (<1
      month) or on Magnetic resonance imaging (MRI) findings consistent with inflammation, or
      active extramuscular disease.

      The primary endpoint will be the number of responders, defined according to the International
      Myositis Assessment and Clinical Studies Group (IMACS) preliminary definition of improvement
      (DOI),16 after treatment with abatacept for 6 months. IMACS DOI is defined as relative
      improvement by ≥20% in three of any six core set measures, with no more than two core set
      measures worsening by ≥25%, which cannot be MMT.

      Secondary objectives will include the number of responders in the delayed-onset arm compared
      with active treatment arm at 3 and 6 months, and the change in individual components of the
      IMACS core set measures for disease activity and in the muscle endurance as tested by FI-2,
      in the delayed-onset arm compared with active treatment arm at 3 and 6 months.
    

Intervention name(s): Abatacept Active Treatment; Abatacept Delayed-Onset Treatment
Intervention type(s): Drug; Drug
Intervention description(s): Participants will be treated with abatacept by intravenous infusions a total of seven times at week(s) 0, 2, 4, 8, 12, 16 and 20 weeks.; Participants will be treated with abatacept for 6 months and received a total of seven intravenous infusions at weeks 12, 14, 16, 20, 24, 28 and 32.
Other intervention name(s): Orencia; Orencia
Intervention MeSH terms: Abatacept
Allocation: Randomized
Intervention model: Sequential Assignment
Intervention model description: Delayed start design
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment