Stage 1: there are 3 dose levels and 5 cohorts. The subjects will be followed up for up to 71 days after the IP administration.~Stage 2: the main period of the study (Weeks 0-24) is blinded; study subjects will receive levilimab with placebo. At Week 24 the study will become open-label and all subjects will continue to receive levilimab. At week 28 patients who achieved the RA remission at week 24 will be switched to maintenance therapy of levilimab and will receive it through Week 52. Subjects who do not achieve remission at Week 24, will continue to receive levilimab from Week 28 to Week 52 inclusive corresponding to their treatment group.
This is a two-stage study of efficacy, safety, pharmacokinetics, pharmacodynamics, and immunogenicity of various doses of levilimab when administered intravenously and subcutaneously to healthy subjects and subjects with active rheumatoid arthritis resistant to methotrexate monotherapy.~Aim of the Stage 1 is to study the tolerability, safety, immunogenicity, and main pharmacokinetic and pharmacodynamic parameters of levilimab after its single subcutaneous or intravenous administration at ascending doses to healthy subjects.~Aim of the Stage 2 is to confirm the efficacy and safety of levilimab 648 mg IV Q4W in combination with methotrexate and levilimab 324 mg SC Q2W in combination with methotrexate in subjects with active rheumatoid arthritis, resistant to methotrexate monotherapy.