Study of YK012 in Primary Membranous Nephropathy

Inclusion Criteria: * Aged 18 to 80 years (inclusive), regardless of gender. * Kidney biopsy-confirmed diagnosis of primary (idiopathic) membranous nephropathy within the past 10 years. * Elevated 24-hour urine protein, meeting the pre-defined criteria. * Estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73m² as calculated by the CKD-EPI equation. * If currently taking an angiotensin-converting enzyme inhibitor (ACEi), angiotensin II receptor blocker (ARB), or sodium-glucose cotransporter-2 (SGLT-2) inhibitor, the dose must have been stable for at least 4 weeks prior to enrollment or since initiation of therapy. * Laboratory test results must meet the predefined criteria within 7 days prior to enrollment. * Capable of understanding and voluntarily participating in this clinical trial, having provided written informed consent, and able to comply with scheduled visits, treatments, examinations, and other study procedures as required. Exclusion Criteria: * Diagnosis of secondary membranous nephropathy. * Any prior receipt of protocol-specified pharmacological treatment for membranous nephropathy. * History of malignancy within 5 years prior to enrollment. * Poorly controlled hypertension at enrollment. * Severe renal dysfunction with prior dialysis or kidney transplantation within 6 months prior to enrollment. * Prior kidney biopsy-confirmed diagnosis of diabetic nephropathy. * History of severe or chronic infections within the 6 months before enrollment or current need for systemic antibiotic or antiviral therapy. * Cardiovascular or cerebrovascular events requiring hospitalization within 6 months prior to enrollment. * Severe or poorly controlled comorbidities that may affect protocol compliance or efficacy evaluation. * Active Tuberculosis (TB) with documented evidence of infection. * History of solid organ or bone marrow transplantation. * Live vaccination, major surgery, or participated in other clinical trials with investigational drug use within 28 days prior to enrollment. * HBsAg-positive, or HBcAb-positive with detectable HBV DNA above the normal range; HCV antibody-positive; HIV seropositive; Treponema pallidum antibody-positive. * CD4+ T lymphocyte count \<200 cells/μL * Known hypersensitivity to any component of YK012. * Pregnancy, breastfeeding, or positive pregnancy test at screening; or plans to become pregnant during the trial or within 12 months after study completion, or unwillingness to use physical contraceptive methods during the study and for 12 months thereafter. * Other conditions deemed by the investigator to make the subject unsuitable for participation in this study.