A Phase 1, Multicenter, Randomized, Placebo-Controlled, Participant-Blind, Single-Ascending Dose Study of LY4298445 in Healthy Participants and an Open-Label Single-Ascending Dose and Multiple-Ascending Dose Study of LY4298445 in Participants With Systemic Lupus Erythematosus or Rheumatoid Arthritis
The purpose of this study is to investigate the safety and tolerability of LY4298445 in healthy participants and in participants with systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA). Participation in the study will last up to approximately 52 weeks.
⁃ Healthy participants between the ages of 18 and 55 years.
• Have body weight of at least 50 kilograms (kg) and body mass index (BMI) between 18 and 32 kilogram per square meter (kg/m²), inclusive.
⁃ Participants with Systemic Lupus Erythematosus (SLE)
• Are 18 to 75 years of age, inclusive.
• Have body weight between 45 and 145 kg, inclusive, and BMI between 18 and 35 kg/m², inclusive.
• Have a clinical diagnosis of SLE according to the 2019 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria at least 6 months prior to screening.
⁃ Participants with Rheumatoid Arthritis (RA)
• Are 18 to 75 years of age, inclusive.
• Have body weight between 45 and 145 kg, inclusive, and BMI between 18 and 35 kg/m², inclusive.
• Have a diagnosis of adult-onset RA for at least 6 months prior to screening, as defined by the 2010 ACR/EULAR classification criteria
• Have Disease Activity Score in 28 joints (DAS28)-high-sensitivity C-reactive protein (hsCRP) greater than or equal to 4.4.
• Have positive test results for rheumatoid factor or anti-citrullinated peptide antibodies
• Have had a history of failure (an inadequate response, intolerance, or loss of response) to at least 2 advanced therapies (biological disease-modifying antirheumatic drug \[bDMARD\] or targeted synthetic DMARD \[tsDMARD\]) after failing a conventional synthetic DMARD (csDMARD).