Evaluation of Long-Term Safety and Clinical Activity of Briquilimab in Patients with Chronic Urticaria: An Open-Label Extension Study

The primary objective of this Phase 2, open-label, extension study is to evaluate the **safety** and tolerability of **briquilimab** in participants with **Chronic Urticaria**. This is clinically relevant as it aims to ensure that the long-term administration of briquilimab does not result in adverse effects, thereby supporting its potential use as a therapeutic option for managing this condition. The secondary objective is to evaluate the clinical activity of briquilimab, which involves assessing its efficacy in alleviating symptoms associated with Chronic Urticaria. This evaluation is crucial for determining the therapeutic benefit of briquilimab in the long-term management of the disease.

The clinical trial involves a total of **45 participants** diagnosed with **Chronic Urticaria**. The study population includes both male and female subjects, with an age range that encompasses adults and older adults. Participants were selected based on their previous involvement in a Jasper-sponsored clinical trial, ensuring they had completed the prior study without any investigational product-related anaphylactic events. The trial population is characterized by a requirement for specific laboratory parameters to be within an acceptable range, and participants must adhere to certain lifestyle considerations, such as abstaining from blood donations during the trial period. Both male and female participants of childbearing potential are required to use highly effective contraceptive methods throughout the trial and for a specified period after the last dose of the investigational product. The study includes a vulnerable population, indicating additional ethical considerations in the trial design and execution.

The clinical trial is designed to evaluate the **safety** and tolerability of **briquilimab** in participants with **chronic urticaria**. This is a Phase 2, open-label, extension study involving participants who have previously completed a Jasper-sponsored clinical trial. The trial will assess the long-term safety and clinical activity of briquilimab, a humanized aglycosylated immunoglobulin G1 (IgG1) monoclonal antibody, administered via subcutaneous injection. The study is expected to commence recruitment on March 10, 2025, and conclude by December 7, 2029.

Participants will undergo a series of study visits, beginning with a screening visit to confirm eligibility based on specific inclusion criteria, such as the absence of investigational product-related anaphylactic events in prior studies and acceptable laboratory parameters. The trial will include regular follow-up visits to monitor the incidence and severity of adverse events, including serious adverse events, treatment-emergent adverse events, and adverse events of interest. Physical examination findings and standard clinical laboratory parameters will also be evaluated. The study will measure changes in urticaria activity scores and control tests over time, with a focus on both chronic inducible urticaria and chronic spontaneous urticaria.

The expected duration of participant involvement will vary, but the trial is structured to allow for comprehensive monitoring over an extended period. Participants must adhere to specific conditions, such as abstaining from blood donations and using effective contraceptive methods, to remain eligible throughout the study. Early termination from the study may occur if participants experience significant adverse events or fail to comply with trial requirements. The trial aims to provide valuable insights into the long-term effects of briquilimab in managing chronic urticaria, contributing to the broader understanding of its therapeutic potential.

The clinical trial involves the administration of **Briquilimab**, an experimental medication developed by Jasper Therapeutics Inc. **Briquilimab** is a humanized aglycosylated immunoglobulin G1 (IgG1) monoclonal antibody, classified under the pharmaceutical form of an **injection**. The active substance, **briquilimab**, is derived from a protein of other origin. The medication is administered via the **subcutaneous** route. The trial does not specify a maximum daily or total dose amount, indicating that dosing is likely determined based on individual participant needs or study protocol. The maximum treatment period is defined as one unit of time, though the specific unit is not detailed in the provided data. The study aims to evaluate the long-term safety and clinical activity of **Briquilimab** in participants from previous Jasper-sponsored chronic urticaria trials.

In this study, no non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatments are mentioned. The focus remains solely on the administration of **Briquilimab**. Participant compliance with the dosing schedule is monitored as per the study protocol, although specific compliance measures are not detailed in the provided data. The trial is designed to assess the safety and tolerability of **Briquilimab**, with no indication of pediatric formulation or orphan drug status. The study is conducted as an open-label extension, allowing for the observation of long-term effects in a real-world setting.

Efficacy in this clinical trial will be assessed through both primary and secondary endpoints. The primary endpoints focus on the incidence and severity of adverse events (AEs), including serious adverse events (SAEs), treatment-emergent adverse events (TEAEs), and adverse events of interest (AEIs). These will be evaluated alongside physical examination findings and standard clinical laboratory parameters.

Secondary endpoints are tailored to specific types of **chronic urticaria**. For participants with chronic inducible urticaria (CIndU), efficacy will be measured by changes from baseline in critical temperature threshold (CCT) and critical friction threshold (CFT) over time, as well as changes in the urticaria control test (UCT) over time. Additionally, the percentage of participants achieving complete response and well-controlled disease will be monitored. For those with chronic spontaneous urticaria (CSU), changes from baseline in the urticaria activity score over 7 days (UAS7), hive severity score over 7 days (HSS7), itch severity score over 7 days (ISS7), and UCT over time will be assessed. The percentage of participants with complete response and well-controlled disease will also be evaluated.