Upadacitinib Trial for Polyarticular JIA

The purpose of this study is to see if a new investigational drug (Upadacitinib) is safe and well tolerated and also to determine the appropriate dose for subjects with polyarticular course juvenile arthritis (pcJIA). The study is a two part study; in Part 1 subjects will be categorized based on age group, and the dose administered for seven consecutive days will be based on four different body weight categories. Subjects who complete Part 1 and are benefiting from study drug with no ongoing adverse events of special interest or serious adverse events, based on investigator's clinical judgment and with subject/family's agreement, will have the option to enroll in Part 2 to receive open-label upadacitinib. Participants will remain in part 2 for up to 156 weeks. Researchers will also be testing the pharmacokinetics (PK) of the study drug, which looks at how the body processes a drug by measuring how quickly the drug is absorbed by the body, how quickly it is broken down by the body, and how long it remains in the body. Subjects will be asked to come into the Rheumatology clinic for blood and urine testing, a joint exam, and administration of study drug.