Inclusion Criteria:  patients fulfilled the Bohan and Peter criteria; anti-MDA5 antibody positive; patients who were not receiving treatment, or previously diagnosed with anti- MDA5-positive DM, who did not use biological agents (including but not limited to rituximab, infliximab, adalimumab, etanercept, tofacitinib, etc.) at the time of screening, or who had stopped taking drugs for ≥3 months;  Exclusion Criteria:  patients if they had other connective tissue diseases, an underlying cancer, a concomitant infection, or a liver aminotransferase level greater than 2 times the upper limit of the normal range.