Have a body mass index (BMI) of 18.0 to 32.0 kilogram per square meter (kg/m²), inclusive
Part C and D Only:
Have a body weight at least 50 kilograms and BMI within the range 18.0 to 40.0 kg/m² (inclusive) at screening
Have a diagnosis of adult-onset RA for at least 3 months prior to screening
You may not be if
Healthy Participants for SAD Part A and MAD Part B Only:
Have a history or presence of cardiovascular, respiratory, hepatic, ophthalmological, renal, gastrointestinal, endocrine, hematological, neurological, or psychiatric disorders capable of significantly altering the absorption, metabolism, or elimination of drugs
Participants with RA for Parts C and D Only:
Have Class 4 RA according to American College of Rheumatology (ACR) revised criteria
Have a 12-lead electrocardiogram (ECG) abnormality at screening
Have a current or recent acute active infection
Clareo Health | A Study of LY4213663 in Healthy Participants and Participants With Rheumatoid Arthritis
