Myositis Clinical Trials

• Age 18-60 (age ≥18 years at first symptom onset), gender not limited;

• The diagnosis meets the criteria for IIM according to the 2017 EULAR/ACR criteria and is confirmed to be of the following subtype:

• a. Dermatomyositis: i. Presence of Gottron's rash or sunspot rash; ii. At least one serological result is positive: anti-transcriptional mediator (TIF1-gamma/P155) antibody, anti-matrix protein 2 (NXP2/P140) antibody, anti-Mi2 antibody, anti-melanoma differentiation-associated gene 5 (MDA5) antibody, anti-small ubiquitin-like modifier-1 activator (SAE1) antibody and/or SAE2 antibody, anti-histyl-tRNA synthetase (Jo-1) antibody, anti-alanyl-tRNA synthetase (PL-12) antibody, anti-threonyl-tRNA synthetase (PL-7) antibody, anti-glycyl-tRNA synthetase (EJ) antibody, anti-leucyl-tRNA synthetase (0J) antibody; b. Immune-mediated necrotizing myopathy: i. No characteristic skin manifestations of dermatomyositis were observed (i.e. Gottron's rash or sun-facing rash); ii. Muscle weakness characterized by IIM (e.g., symmetrical proximal muscle weakness of the upper/lower limbs; or more pronounced weakness of the neck flexors than the neck extensors; or more pronounced proximal muscle weakness of the lower limbs than distal muscle weakness).

• iii. At least one serological result must be positive: anti-human signal recognition particle (SRP) antibody, or trihydroxytrimethylcoenzyme A reductase (HMGCR) antibody; c. Antisynthetic enzyme syndrome: i. At least one of the following clinical manifestations must be present: Raynaud's phenomenon, arthritis, interstitial lung disease, fever (with no other cause of fever found), or technician's hand (thickened and cracked skin on the hands, especially the fingertips).

• ii. At least one serological result is positive: anti-histyl-tRNA synthetase (Jo-1) antibody, anti-threonyl-tRNA synthetase (PL-7) antibody, anti-alanyl-tRNA synthetase (PL-12) antibody, anti-glycyl-tRNA synthetase (EJ) antibody, anti-leucyl-tRNA synthetase (OJ) antibody, anti-aspartyl-tRNA synthetase (KS) antibody, anti-phenylalanyl-tRNA synthetase (Zo) antibody, anti-glutamyl-tRNA synthetase (JS) antibody, anti-lysyl-tRNA synthetase (SC) antibody, anti-tyrosyl-tRNA synthetase (YRS) antibody;

• Refractory IIM: At least one round of high-dose corticosteroid therapy and/or intravenous immunoglobulin, and at least two immunosuppressants (including but not limited to cyclophosphamide, mycophenolate mofetil, tacrolimus, cyclosporine, and azathioprine) have been used in adequate doses for more than 6 months;

• At the time of enrollment, participants must be receiving background medication at a stable dose, defined as: receiving background therapy with one oral glucocorticoid and/or one immunosuppressant at a stable dose for ≥ 12 weeks;

• Severity of enrollment met the following criteria:

‣ MMT-8 score ≤141 (out of 150);

⁃ Students must meet at least one of the following CSM numerical scale criteria based on abnormal visual analog scale (VAS) scores: Overall activity assessed by study participants ≥2; overall disease activity assessed by physicians ≥2; extra-muscular activity (MDAAT) ≥2; HAQ-DI ≥0.25;

⁃ At least one muscle enzyme level \>1.5 times ULN;

• Through examinations such as tumor markers, lung and abdominal CT scans, thyroid ultrasound, breast ultrasound, and gastroscopy and colonoscopy, possible potential tumors have been ruled out.