A Study of QLS2404 Injection in Healthy Participants and Participants With Rheumatic Autoimmune Diseases

The Phase Ia single-dose ascending stage will include five dose groups. The study plans to enroll 40 adult healthy participants, with 8 participants in each dose group, who will be randomized in a 3:1 ratio to receive QLS2404 Injection or placebo. Dose escalation will be conducted sequentially from the initial dose to higher dose levels in accordance with the dose-escalation principle. During the study, a Safety Monitoring Committee (SMC), composed of the investigators, the sponsor, or sponsor-designated personnel, will review the safety data generated during the trial. After the last participant in each dose group has completed the 14-day tolerability observation period following dosing, the SMC will review the safety data of participants in each cohort and conduct an integrated assessment of the available pharmacokinetic (PK) and pharmacodynamic (PD) data. The SMC will then provide recommendations regarding dose escalation or, if necessary, adjustments to the dose-escalation scheme. The Phase Ib part will be a multiple ascending-dose study of subcutaneous QLS2404 Injection in participants with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS), designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of QLS2404 Injection. Three dose groups are planned, with approximately 24 participants to be enrolled in total and 8 participants in each dose group. All participants will receive three subcutaneous doses of QLS2404 Injection, administered at 4-week intervals. Each dose group must include at least 6 participants with SLE, and the study will be conducted in strict accordance with the dose-escalation principle.