RCT of Tocilizumab for Anti-MDA5+DM

Inclusion criteria

• All inclusion criteria must be met for eligibility:

• Age ≥ 18 years and < 65 years; no gender restriction; total body weight ≥ 45 kg;
• Diagnostic Criteria for Anti-MDA5-DM: Refer to the "2023 Chinese Expert Consensus on Diagnosis and Treatment of Anti-Melanoma Differentiation-Related Gene 5 Antibody-Positive Dermatomyositis in China." Dermatomyositis patients exhibiting one of the following manifestations-Gottron's papules, Gottron's rash, or erythema ab igne-along with positive serum anti-MDA5 antibodies, may be diagnosed with anti-MDA5-DM;
• If patients have concomitant ILD, the following conditions must be met: i) Pulse oxygen saturation (SpO₂) ≥ 90% or PaO₂ ≥ 60 mmHg; ii) Pulmonary function tests showing forced vital capacity percentage of predicted (FVC%) ≥ 60% and carbon monoxide diffusion capacity percentage of predicted (DLco%) ≥ 40%; iii) High-resolution chest CT demonstrating pulmonary interstitial lesions involving < 50% of lung fields;
• Patients must have received oral prednisone (< 1 mg/kg/day, or equivalent dose of other glucocorticoids) for ≥ 4 weeks prior to randomization;
• Patients must have received a stable dose of a calcineurin inhibitor (CNI, such as cyclosporine or tacrolimus) for ≥4 weeks prior to randomization; if immunosuppressive therapy was discontinued prior to the screening visit, a washout period of at least 4 weeks is required;
• Patients must receive prophylactic treatment with trimethoprim-sulfamethoxazole (TMP-SMZ, 400mg trimethoprim/80mg sulfamethoxazole) 1-2 tablets daily during treatment;
• Women of childbearing potential must have a negative pregnancy test at study entry. If sexually active, they must agree to use effective contraception throughout the study period and must not intend to become pregnant during the study.
• Patients voluntarily participate in this study and sign an informed consent form.

Exclusion criteria

• 1. Polymyositis, anti-synthetase syndrome, immune-mediated necrotizing myositis, or overlap myositis with other connective tissue diseases; 2. Patients with life-threatening complications, including but not limited to acute coronary syndrome (e.g., myocardial infarction, unstable angina) within 24 weeks prior to screening or any history of significant cerebrovascular disease; 3. Any of the following laboratory abnormalities at screening: white blood cell count <3.0×10⁹/L, neutrophil count <1.0×10⁹/L, lymphocyte count <0.5×10⁹/L, hemoglobin <90 g/L, platelet count <50×10⁹/L; severe hepatic impairment (ALT or AST ≥3 times ULN, total bilirubin ≥1.5 times ULN, excluding serum ALT or AST elevation due to dermatomyositis); severe renal impairment (creatinine clearance ≤45 mL/min); 4. Patients hospitalized for severe infection within 60 days prior to screening, or who received intravenous antibiotics (patients who used intravenous antibiotics must complete a five-half-life washout period and confirm absence of active infection before enrollment), but may receive empirical oral antibiotics or topical antibiotics; 5. Active tuberculosis infection that is untreated or inadequately treated; Latent tuberculosis infection (LTBI) requires at least 2 weeks of preventive antituberculosis therapy (including at least 2 antituberculosis drugs) prior to randomization, continuing through study completion. LTBI is defined as: Positive IGRA result (acceptable IGRA assays include: QFT-GIT, QFT-G, and T-spot® TB test); 6. Active viral hepatitis at screening: HBsAg-positive, HBeAg-positive, or HBV-DNA >10³ copies/L (HBV-DNA testing required if HBcAb-positive); HCVAb-positive; 7. Documented HIV infection, evidenced by positive serological test results or positive HIV serological test results at screening; 8. If the patient develops ILD-related clinical manifestations or progressive radiographic worsening within 4 weeks, RP-ILD should be considered. RP-ILD is defined as the presence of any one of the following four conditions within 1 month after the onset of respiratory symptoms: ① Acute and progressive worsening of dyspnea requiring hospitalization or supplemental oxygen; ② Decline in pulmonary function, manifested as a decrease in FVC% >10% with or without a decrease in DLco% >15%; ③ Increased interstitial abnormalities on chest HRCT scan >20%; ④ Decrease in arterial blood gas or partial pressure of oxygen >10 mmHg, indicating respiratory failure; and PaO₂/FiO₂≥200 mmHg.

• Allergy to the active ingredient tocilizumab or any of its excipients; 10. Patients with sulfonamide allergy; 11. Patients unable to complete pulmonary function testing at baseline; 12. Patients receiving prednisone at a dose exceeding 2 mg/kg/day prior to screening; 13. Patients receiving intravenous immunoglobulin (IVIG) prior to screening must discontinue treatment for at least 30 days; 14. Patients who used one or more of the following medications within the specified time window prior to screening:
• Rituximab within 6 months prior to screening;
• JAK inhibitors within 2 weeks prior to screening;
• Use of other biologics (including but not limited to anakinra, adalimumab, infliximab) or other immunosuppressive agents (including but not limited to methotrexate, azathioprine, mycophenolate mofetil) within 4 weeks prior to screening; 15. Patients with prior use of the study drug, other IL-6 inhibitors, or analogues; 16. Pregnant or lactating women, or women planning to become pregnant or initiate lactation; 17. History of malignant tumors within the past 5 years (excluding adequately treated basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or cervical carcinoma in situ with no evidence of recurrence within the preceding 5 years); 18. Other conditions deemed ineligible for study inclusion by the investigator.