A Phase 3, Multicenter, Open-label, Basket, Long-term Extension Study of Ustekinumab in Pediatric Clinical Study Participants (2 to <18 Years of Age)

The primary objective of this Phase 3, multicenter, open-label, long-term extension study is to evaluate the **long-term safety** of **ustekinumab** in pediatric participants aged 2 to less than 18 years with conditions such as Juvenile Psoriatic Arthritis, Moderately to Severely Active Ulcerative Colitis, and Moderately to Severely Active Crohn's Disease. The clinical relevance of this objective lies in ensuring the sustained safety profile of ustekinumab, a critical factor for its continued use in pediatric populations with these chronic inflammatory conditions.

Secondary objectives include providing continued access to ustekinumab for participants from the primary study. This ensures that participants can maintain their treatment regimen, which is essential for managing their conditions effectively over the long term.

The clinical trial involves a total of **106 participants** diagnosed with **Juvenile Psoriatic Arthritis**, **Moderately to Severely Active Ulcerative Colitis**, or **Moderately to Severely Active Crohn's Disease**. The study population comprises both male and female subjects aged between 2 to less than 18 years. Participants were selected based on their completion of the dosing planned in the primary pediatric ustekinumab study and demonstrated benefit from continued ustekinumab therapy, such as a clinical response or remission. The trial includes a vulnerable population, as it involves children and adolescents. Participants' general health status is characterized by their specific medical conditions, and no additional lifestyle considerations such as diet or physical activity are specified. The selection process required informed consent from parents or legal guardians, with assent from children capable of understanding the study, typically those aged 7 and older.

The clinical trial is a **Phase 3**, multicenter, open-label, basket, long-term extension study designed to evaluate the long-term safety of **ustekinumab** in pediatric participants aged 2 to less than 18 years. The study targets individuals with **Juvenile Psoriatic Arthritis**, **Moderately to Severely Active Ulcerative Colitis**, and **Moderately to Severely Active Crohn's Disease**. The trial is structured to gather comprehensive safety data over an extended period, with the estimated end date set for December 15, 2027. Participants will receive **ustekinumab** via subcutaneous injection, with the maximum treatment period being 12 months.

The trial involves several key visits, beginning with an inclusion (screening) visit to confirm eligibility based on criteria such as age, completion of prior dosing in a primary pediatric **ustekinumab** study, and demonstrated benefit from continued therapy. Follow-up visits will be scheduled to monitor safety and efficacy, with assessments including adverse events (AEs), serious adverse events (SAEs), and clinical laboratory evaluations. The end-of-study visit will conclude the participant's involvement, summarizing the safety data collected throughout the trial.

Participant involvement is expected to last up to 12 months, with conditions for early termination including the occurrence of AEs leading to discontinuation, loss of response necessitating additional therapy, or any other safety concerns. The trial's primary endpoints focus on the incidence of AEs, SAEs, and injection-site reactions, while secondary endpoints are not specified. The study aims to provide valuable insights into the long-term safety profile of **ustekinumab** in the pediatric population across multiple conditions.

The clinical trial involves the administration of **STELARA** (ustekinumab), a **solution for injection** available in two formulations: a 90 mg solution in a pre-filled syringe and a 45 mg solution. Both formulations are intended for **subcutaneous use**. The 90 mg solution is provided in a pre-filled syringe equipped with the UltraSafe Passive Delivery System, a needle guard system that adheres to ISO standards. The active substance, ustekinumab, is a protein of non-specified origin, classified under the ATC code L04AC05. The maximum daily and total dose for both formulations is 90 mg, with a treatment period extending up to 12 months.

The 45 mg solution for injection is also administered subcutaneously. Like the 90 mg formulation, it contains ustekinumab as the active ingredient, a protein of non-specified origin. The dosing schedule and maximum treatment period are consistent with the 90 mg formulation, with a maximum daily and total dose of 90 mg over a 12-month period. Both formulations are manufactured by Janssen-Cilag International NV and are not designated as pediatric formulations. The trial does not include any non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatments. Participant compliance with the dosing schedule is monitored throughout the study to ensure adherence to the protocol.

Efficacy in this clinical trial will be assessed through the evaluation of primary endpoints, which include adverse events (AEs), serious adverse events (SAEs), AEs leading to discontinuation of the study intervention, and AEs of special interest as determined for each indication. Additionally, clinical laboratory assessments will be conducted, focusing on hematology and chemistry parameters. Injection-site reactions and AEs related to the worsening of the disease under study will also be monitored. The need for the addition of concomitant therapy due to loss of response will be considered as part of the efficacy assessment.