Reversibility of calcinosis in anti-NXP2-positive refractory dermatomyositis treated with TNF-α blockade: a brief report.

Background: Calcinosis cutis is one of the most refractory complications of dermatomyositis (DM), particularly in patients with anti-nuclear matrix protein 2 (NXP2) autoantibodies. Whether tumor necrosis factor-alpha (TNF-α) blockade is associated with regression of established calcinosis remains uncertain. Methods: We conducted a retrospective, single-center study of nine patients with refractory dermatomyositis or juvenile dermatomyositis treated with TNF-α inhibitors (infliximab or adalimumab). Myositis-specific autoantibodies, longitudinal muscle strength (MMT8, CMAS), glucocorticoid exposure, and serial imaging of calcinosis were evaluated. Calcinosis change was analyzed as an exploratory endpoint. Results: Three patients were anti-NXP2 positive, and six were negative for tested myositis-specific autoantibodies. TNF-α blockade was associated with sustained clinical improvement and a marked steroid-sparing effect, with median daily prednisolone dose decreasing from 40 mg at baseline to 5 mg at 12 months. Radiographic regression of calcinosis, defined Conclusion: In this small retrospective cohort, prolonged TNF-α blockade was associated with radiographic regression of calcinosis in a subset of anti-NXP2-positive patients, while calcinosis was absent at baseline in antibody-negative patients. These findings generate a hypothesis that antibody-defined subgroups may differ in calcinosis responsiveness and warrant prospective validation.