Phase 1 Study of LY4213663 Given Under the Skin or Into a Vein to Assess Safety and Body Effects in Healthy Adults and Adults With Rheumatoid Arthritis

What this Trial Is About

Researchers are evaluating the safety, tolerability, and how the body processes LY4213663 in healthy adults and adults with rheumatoid arthritis RA. This Phase 1 study aims to understand potential side effects and how the drug behaves when given by injection under the skin or into a vein. The study includes both healthy participants and those diagnosed with RA, with a focus on basic science aspects of the treatment. The study involves several parts single-ascending doses a gradually increasing dose and multiple-ascending doses of LY4213663 or placebo given either subcutaneously or intravenously in healthy participants. In participants with RA, multiple doses of LY4213663 are given by these two methods. The study design includes randomized assignments to drug or placebo groups for the healthy participant parts, while the RA participant parts are open-label. The entire study lasts about 33 weeks, excluding screening. Participants will have blood tests to check drug levels and effects, as well as monitoring for any serious side effects related to the drug. Researchers will assess safety throughout the study by tracking adverse events. The study measures how much LY4213663 is in the blood over time and its maximum concentration. Participants will attend regular visits for dosing and assessments during the study period, which runs from screening through to the last follow-up around 33 weeks after dosing begins.

A Study of LY4213663 in Healthy Participants and Participants With Rheumatoid Arthritis