3T Therapy in the Treatment of MDA5-positive Dermatomyositis

Inclusion Criteria: * Aged 18 or above at the time of screening * Diagnosis of MDA5-positive dermatomyositis (EULAR/ACR) during screening, and the following 3 items are met at the same time: 1. The MDA5 titer during screening is ++ or +++; 2. Mild or above decrease in pulmonary diffusing function at screening and baseline; 3. Interstitial extravasation seen on chest CT at screening and baseline * Agree to receive highly effective contraception or sterilized * Subjects are willing and able to comply with study visits and related procedures * Subjects have the ability to understand the research requirements and procedures, voluntarily participate in clinical trials and sign the ICF Exclusion Criteria: * Have received any drug in 3T treatment in the past, but had poor response (including treatment failure or unacceptable treatment-related adverse reactions) * Have received lenalidomide, cyclosporine, or other highly selective or pan-selective JAK inhibitors such as lenalidomide or cyclosporine or other highly selective or pan-selective JAK inhibitors such as baricitinib within 2 weeks before visit D1 or within 5 drug half-lives (if known) agent. * Have received treatment with an immune cell depleting agent (such as rituximab) within 6 months before the D1 visit. * Have received any investigational drug/treatment within 4 weeks or 5 drug half-lives (if known) before visit D1, whichever is longer. * Known or suspected history of immunosuppression/deficiency (including but not limited to invasive opportunistic infections such as aspergillosis, coccidioidomycosis, histoplasmosis, AIDS, listeriosis, even if the infection has resolved) within 6 months prior to visit D1, or there are unusually frequent recurring or persistent infections. * There is a history of malignant tumors within 5 years before the D1 visit (except for completely cured cervical carcinoma in situ or non-metastatic cutaneous squamous cell carcinoma or basal cell carcinoma or thyroid malignant tumors or other malignant tumors considered by the researcher to be amenable to 3T treatment). * Positive hepatitis B surface antigen (HBsAg) during screening; or positive hepatitis B core antibody (HBcAb) and positive HBV-DNA; or positive hepatitis C antibody and positive HCV ribonucleic acid (RNA) polymerase chain reaction; or human immune HIV-deficiency virus (HIV) serology was positive. * Subjects with active tuberculosis, latent tuberculosis, or a history of non-tuberculous mycobacterial infection at the time of screening. * Have a history of systemic hypersensitivity reaction to any drug or matrix or excipient in 3T therapy. * Have been vaccinated within 12 weeks before the D1 visit, or plan to receive a live (attenuated) vaccine during the study. * Pregnant or lactating women, or subjects who plan to become pregnant or lactating during the study. * Any other circumstances in which the researcher determines that it is not appropriate to participate in this study