The primary outcome will be change in calcinosis activity visual analogue scale score from week 0 to week 10 on therapy, compared to the baseline change in calcinosis activity visual analogue scale score from week -10 to week 0 pre-treatment. Secondary measures will evaluate safety and changes in components of the Calcinosis Assessment Tool, clinical assessments of calcinosis, Mawdsley Calcinosis Questionnaire, quality of life, functional disability, muscle testing (manual and quantitative), laboratory parameters (muscle enzymes, inflammatory markers, and endothelial activation markers), gene expression, calcification pathogenesis, time to improvement, and imaging. Myositis disease activity and damage will also be assessed by validated measures.