Study of Single Doses of SBT777101 in Subjects With Rheumatoid Arthritis

This study will test the safety and effects of SBT777101 when given as a single dose to subjects with rheumatoid arthritis. It is the first study of this treatment being done in humans. Increasing dose levels will be given after the safety at lower dose levels is shown. Following completion of the initial single ascending dose cohorts, the study may evaluate alternative administration regimens of SBT777101, including split-dose administration. In the split-dose cohort, participants may receive two intravenous infusions of SBT777101 derived from a single manufacturing process, administered approximately 6 weeks apart. The study will continue to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical activity.

Inclusion Criteria: * Body mass index (BMI) \