Study of YKST02 Alone or in Combination With YK012 in Patients With Active or Refractory Systemic Lupus Erythematosus

Inclusion Criteria: * Diagnosed with systemic lupus erythematosus (SLE) according to the 2019 EULAR/ACR classification criteria, with active disease defined as SLEDAI-2K ≥6 at screening, and considered to have inadequate response, intolerance, or ineligibility to standard therapy. * Have received standard therapy for SLE for at least 12 weeks prior to screening (including corticosteroids and at least one immunosuppressant and/or biologic agent), or are intolerant to or unsuitable for such therapies. * Receiving stable background therapy prior to enrollment, including stable doses of corticosteroids (within 2 weeks prior to enrollment), and/or antimalarial agents or one immunosuppressant (within 4 weeks prior to enrollment). * Positive for at least one lupus-related autoantibody at screening (e.g., anti-dsDNA, antinuclear antibody, or anti-Smith antibody). * Able and willing to provide written informed consent and comply with study procedures. Exclusion Criteria: * Known hypersensitivity to monoclonal antibodies, immunoglobulins, or any component of the study drug. * Prior treatment with B cell-depleting therapies, B cell-targeting biologics, or other biologic or targeted therapies within protocol-defined washout periods. * Receipt of intravenous immunoglobulin or plasma exchange within protocol-defined washout periods. * Receipt of live or attenuated vaccines within 4 weeks prior to enrollment. * Presence of other active autoimmune diseases or inflammatory conditions (exce…