Phase 1a/b Tolerability of NTR-1011 in Healthy Adults and Adult Patients With SLE and RA

The goal of this clinical trial is to inform the safety and tolerability of NTR-1011 in treating adult patients diagnosed with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). It will also learn about the safety of NTR-1011 in healthy adult volunteers. The main questions it aims to answer are: * What is the highest dose of NTR-1011 that is safe and well tolerated, when given under the skin or into a vein? * How does the body process NTR-1011, and how does NTR-1011 affect the body? * Does the body develop an immune response to NTR-1011? * Are there early signs that NTR-1011 may benefit patients with SLE or RA when added to their current standard-of-care treatment? In the first part of the study (Phase 1a, now complete), researchers compared single doses of NTR-1011 to a placebo (a look-alike substance that contains no drug) in 48 healthy volunteers to see how the body tolerates and processes the drug. In the current part of the study (Phase 1b, actively recruiting), all participants receive NTR-1011 in addition to their usual SLE or RA treatment; there is no placebo group. Up to 24 participants with moderate-to-severe SLE or RA will: * Receive five weekly doses of NTR-1011 given directly into a vein (intravenous) * Continue their current standard-of-care treatment throughout the study * Be monitored for 4 weeks after their last dose * Be assigned to either the SLE group or the RA group (up to 12 patients each)