This study is a multicenter, randomized, double-blind, placebo-controlled Phase II clinical trial designed to evaluate the efficacy and safety of D-2570 in the treatment of active systemic lupus erythematosus.

Subjects who sign the informed consent form will enter the screening period, during which their eligibility will be assessed according to the inclusion and exclusion criteria. Eligible participants who meet the inclusion criteria and do not meet any exclusion criteria will be randomized. Participants will then be assigned to one of the following groups: Group A, Group B, Group C, or the placebo group. They will proceed to the treatment period, during which they will take the corresponding investigational product once daily for 48 consecutive weeks. After completing the treatment, subjects will undergo safety follow-up. Throughout the treatment period, both investigators and subjects will remain blinded. During the study, participants will be required to provide pharmacokinetic and pharmacodynamic blood samples at the time points specified in the trial protocol.

Inclusion Criteria:

• The patient voluntarily participates in this study after full informed consent.
• The age is 18 years ≤ age ≤ 70 years, regardless of gender.
• Diagnosed with Systemic Lupus Erythematosus (SLE) at least ≥ 24 weeks prior to screening.
• SLEDAI-2K total score ≥ 8.
• On stable treatment for systemic lupus erythematosus at least 4 weeks prior to randomization, and should remain at a stable dose throughout the trial period.

Exclusion Criteria:

• History of infection as defined in the protocol.
• Any of the medical diseases or disorders listed in the protocol.
• Significant, uncontrolled or unstable disease in any organ.