Long-term Safety, Tolerability, and Efficacy Evaluation of Subcutaneous Sonelokimab in Moderate to Severe Hidradenitis Suppurativa

The primary objective of this study is to evaluate the long-term **safety** and **tolerability** of subcutaneous sonelokimab in participants with moderate to severe **hidradenitis suppurativa** (HS). This is clinically relevant as it aims to ensure that the treatment is safe for prolonged use, which is crucial for managing a chronic condition like HS.

Secondary objectives include:

• Evaluating the long-term **efficacy** of sonelokimab in participants with moderate to severe HS.
• Assessing the long-term efficacy of sonelokimab in terms of participant-reported symptoms and quality of life. This is important for understanding the impact of the treatment on daily living and overall well-being of the patients.

The clinical trial involves a total of **317 participants** diagnosed with **hidradenitis suppurativa (HS)**, a chronic inflammatory skin condition. The study population includes both male and female subjects, with an age range encompassing adults and adolescents. Participants were selected based on their prior involvement in a parental study, having completed specific treatment phases and visits. The trial does not include a vulnerable population. Participants are required to adhere to specific lifestyle considerations, such as the use of effective contraception methods for women of childbearing potential and the use of condoms for male participants when sexually active with partners of childbearing potential. The trial aims to evaluate the long-term safety and tolerability of sonelokimab in individuals with moderate to severe HS.

The clinical trial is a Phase 3, multicenter, open-label extension study designed to evaluate the long-term safety, tolerability, and efficacy of **sonelokimab** administered via subcutaneous injection in participants with moderate to severe **hidradenitis suppurativa**. The trial is structured to follow participants who have completed a prior study involving sonelokimab, ensuring continuity in treatment and monitoring. The study is not randomized or blinded, as it is an extension of previous trials where participants have already been exposed to the investigational product. The trial is expected to commence recruitment on October 11, 2025, and conclude by June 13, 2028, with the overall duration of participant involvement extending up to 100 weeks.

Participants will undergo a series of study visits, beginning with an inclusion (screening) visit to confirm eligibility based on criteria such as recent completion of a parental study and adherence to contraceptive guidelines. The inclusion visit will also involve a negative pregnancy test for women of childbearing potential. Subsequent visits will be scheduled to monitor treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), and other safety parameters such as vital signs, ECG results, and laboratory tests. The end-of-study visit will mark the conclusion of the participant's involvement, where final assessments will be conducted to evaluate the long-term effects of the treatment.

Participants are expected to remain in the study for the full duration unless conditions arise that necessitate early termination, such as the occurrence of significant adverse events or non-compliance with the study protocol. The primary endpoints focus on the safety profile of sonelokimab, including the incidence of TEAEs, SAEs, and adverse events of special interest (AESIs). The study aims to provide comprehensive data on the long-term use of sonelokimab, contributing valuable insights into its safety and efficacy for individuals with hidradenitis suppurativa.

The clinical trial involves the administration of **Sonelokimab**, an experimental medication developed by Moonlake Immunotherapeutics AG. Sonelokimab is a **nanobody** that inhibits **IL-17A** and **IL-17F**, designed for the treatment of moderate to severe **hidradenitis suppurativa**. The pharmaceutical form of Sonelokimab is an **injection**, specifically administered via **subcutaneous injection**. The maximum daily dose is 120 mg/ml, with a total maximum dose of 3120 mg/ml over the course of the treatment period, which spans up to 100 days. The medication is not formulated for pediatric use and is not classified as an orphan drug.

In this study, no non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatments are specified. The focus is solely on evaluating the long-term safety, tolerability, and efficacy of Sonelokimab. Participant compliance with the dosing schedule will be monitored throughout the trial to ensure adherence to the prescribed regimen. The trial is structured as a Phase 3, multicenter, open-label extension study, emphasizing the collection of data on the long-term effects of Sonelokimab in the target patient population.

The efficacy of the clinical trial involving **Sonelokimab** for the treatment of moderate to severe hidradenitis suppurativa will be assessed through a series of predefined endpoints. The primary endpoints focus on safety and tolerability, including treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), TEAEs leading to study withdrawal, adverse events of special interest (AESIs), as well as vital signs, ECG results, and abnormal laboratory parameters such as hematology and clinical chemistry. These parameters will be systematically measured and collected throughout the study duration to ensure comprehensive monitoring of the participants' responses to the treatment.