Safety, Pharmacokinetics, Immunogenicity BCD-256-1 and Divozilimab in Subjects With Systemic Lupus Erythematosus

The study is conducted in 2 stages which involve different subjects. Stage 1 of the study have a modified "3+3" design and involves dose escalation of BCD-256 in 1-3 cohorts with an interval of at least 14 days dose - limiting toxicicity (DLT) (DLT assessment period) between cohorts 1-3. In cohorts 4 and 5, the administration of divozilimab is carried out in parallel with cohorts 1-3. A decision on the possibility of starting Stage 2 and including new subjects in it will be made after approval by thethe Cohort Dosing Safety Committee (CDSC) of an interim report (for 12 weeks of therapy). Stage 2 of the study will involve the use of BCD-256 in combination with divozilimab in 4 cohorts, BCD-256 dose levels in cohorts will be determined based on the results of the main period of Stage 1 (for 12 weeks of therapy).