Myositis is a rare autoimmune disease in which the immune system mistakenly attacks the
patient's own peripheral muscles. This aggression manifests by muscle inflammation and
necrosis responsible for a motor deficit of varying severity.
The treatments available today are insufficient and are non-specific. Biological
criteria, issued from simple blood or muscle tests are missing, and they will help to
define the activity of the disease and the efficacy of treatments.
The MASC protocol will include patients with myositis, and investigators will collect
clinical, radiological, electrophysiological, histological and biological data to be used
for researches aiming at better understanding this entity. A biobank (muscle biopsy, DNA,
serum, plasma, PBMCs) will be acquired on this prospective cohort.
The study itself will be composed of a baseline visit and monthly to yearly follow-up
visits which will assess:
Clinical examination with an evaluation of the muscle strength and function
impairment/handicap, including but not limited to:
Manual testing of proximal axial and distal muscles on the five points Medical
Research Council (MRC) scale
Barré tests and Mingazzini tests, number of stand-up / sitting, leg crossing
Biometry, lab and radiological measurements: muscle enzymes (creatine phosphokinase
CPK, troponin, C-reactive protein, quantification of autoantibodies, muscle MRI,
muscle biopsy, thorax tomodensitometry, pulmonary test function
Extra-muscular evaluation: cardiac examination and work-up (echocardiography,
cardiac MRI and Positron Emission Tomography (PET) scanner, cardiac biopsies),
pulmonary evaluation, rheumatological and dermatological assessment, history of
thromboembolic disease and cancer
Patient activity assessment: evaluation of daily life activity by both patient and
physician using a Visual Analogue Scale
For each patient, the date of last visit or contact will be collected as well as
outcomes, particularly for the cause of death if relevant.
Data from the biobank MASC " Muscles DNA/RNA Serum and Cells " will be added to other
data. The biobank has been fully registered with local authorities and ethical committees
("Committee for Personal Protection (CPP)" CPP agreement). It contains peripheral blood
mononuclear cells (PBMC), serum, DNA and RNA from blood and muscular biopsies collected
at the diagnosis stage. The database contains immunological and genetical data.
This prospective study will also aim at:
Identify the differential pathophysiological processes between the different
subgroups of myositis
Identify prognostic factors, including the different treatment modalities used
Improve physiopathological knowledge (clinico-anatomobiological characteristics and
identification of other biomarkers through the biobank)
Improve the evaluation of the clinical outcomes/endpoints for future trials
Develop clinical trials for homogeneous subgroups of patients, based on their
pathophysiology and evaluated on the appropriate endpoints.