Evaluation of Baricitinib and Tocilizumab in Pediatric Patients with Systemic Juvenile Idiopathic Arthritis: A Randomized, Open-Label Study

The primary objective of this study is to evaluate the **efficacy** of **baricitinib** in children aged 1 to less than 18 years with **Systemic Juvenile Idiopathic Arthritis (sJIA)**. This is clinically relevant as sJIA is a severe form of juvenile arthritis characterized by systemic inflammation and joint involvement, and effective treatment options are crucial for managing symptoms and improving quality of life in affected children. The study includes a reference arm with **tocilizumab** to compare the safety, efficacy, and pharmacokinetics of baricitinib, providing a comprehensive assessment of its therapeutic potential in this pediatric population.

The clinical trial involves a total of **49 participants** diagnosed with **Systemic Juvenile Idiopathic Arthritis** (sJIA). The study population includes both male and female subjects, with an age range starting from 2 years old. Participants were selected based on specific criteria, including the onset of sJIA before the age of 16, the presence of arthritis in a joint, and fever lasting for at least two weeks. Additionally, participants must exhibit daily fever for three days and at least one of the following symptoms: evanescent erythematous rash, generalized lymph node enlargement, enlarged liver or spleen, or serositis. The trial population is considered vulnerable, and the selection process ensures that participants have at least two active joints. The study does not specify any particular lifestyle considerations such as diet or physical activity. The sponsor has not provided further information regarding the general health status or additional lifestyle factors of the participants.

The clinical trial is designed to evaluate the **efficacy** and safety of **baricitinib** in children aged 1 to less than 18 years with **Systemic Juvenile Idiopathic Arthritis** (sJIA). This is a randomized, open-label study with a reference arm using **tocilizumab**. The trial is structured to include a screening visit, multiple follow-up visits, and an end-of-study visit. The trial is expected to last until October 2025, with participant involvement spanning a maximum of 56 days. The study will commence with a screening visit to confirm eligibility based on specific inclusion criteria, such as a diagnosis of sJIA with onset before age 16, arthritis in a joint, and fever lasting two weeks. Participants must also exhibit at least two active joints. The primary endpoint is the percentage of participants achieving the adapted Pediatric American College of Rheumatology 30 (PediACR30) response criteria at week 12.

Participants will be randomly assigned to receive either **baricitinib** or **tocilizumab**, with **baricitinib** administered orally and **tocilizumab** via subcutaneous injection. The trial is not categorized as low intervention and is classified as a Phase III trial, aiming to confirm the safety and efficacy of **baricitinib** for a new indication. Follow-up visits will be conducted to monitor the participants' response to treatment and any adverse events. The end-of-study visit will assess the overall outcomes and gather final data. Participants may be withdrawn from the study early if they experience significant adverse effects or if they do not adhere to the study protocol. The trial's design ensures a rigorous evaluation of the treatment's impact on sJIA, contributing valuable data to the understanding of **baricitinib**'s therapeutic potential in this population.

The clinical trial involves the administration of **Baricitinib**, a **JAK1/JAK2 inhibitor**, which is provided in multiple pharmaceutical forms including film-coated tablets, capsules, and oral suspension. The active substance, **Baricitinib**, is of chemical origin. The film-coated tablet form is administered orally with a maximum daily dose of 4 mg and a total dose of 1568 mg over a treatment period of 56 days. The capsules and oral suspension are also administered orally, with the same dosing regimen. The investigational medicinal product (IMP) is specifically packaged for clinical trial use, with no commercial debossing on tablets, and is manufactured using the commercial drug substance with the same unit formula as Olumiant. The drug product and excipients may differ in facilities, specifications, methods, shelf-life, and packaging, all of which are appropriate for clinical trial use.

**Tocilizumab** is used as a comparator treatment in the trial. It is provided as a solution for injection and is administered via subcutaneous injection. The active substance, **Tocilizumab**, is a protein of other origin. The maximum total dose is 3888 mg, administered over a single treatment period. This formulation is not a pediatric formulation and is used to evaluate the safety and efficacy of Baricitinib in comparison.

Placebos are utilized in the study to match the active treatments. These include placebo tablets to match 1 mg, 2 mg, and 4 mg tablets, as well as a placebo to match a 2 mg/mL oral suspension. These placebos are designed to mimic the appearance and administration route of the active treatments but contain no active substance. The use of placebos is essential for maintaining the study's blinding and ensuring unbiased results.

Participant compliance with the dosing schedule is monitored throughout the trial. The trial aims to evaluate the efficacy of Baricitinib in children with systemic juvenile idiopathic arthritis, with a focus on safety, efficacy, and pharmacokinetics. The study is conducted in an open-label, randomized manner with a reference arm for Tocilizumab.

The efficacy of **baricitinib** in the treatment of Systemic Juvenile Idiopathic Arthritis (sJIA) in children will be assessed in this clinical trial. The primary endpoint for evaluating efficacy is the percentage of participants achieving the Adapted Pediatric American College of Rheumatology 30 (PediACR30) Response Criteria at Week 12. This endpoint is designed to measure the improvement in symptoms and overall response to the treatment. The trial will involve an open-label, randomized study design with a reference arm using **tocilizumab**. The efficacy assessments will be conducted at specified timepoints, with the primary evaluation occurring at Week 12. The trial aims to confirm the safety and efficacy of **baricitinib** in a pediatric population, with the study duration estimated to conclude by October 27, 2025.