Evaluation of [18F]Fluoro-PEG-Folate PET/CT Imaging in Active Giant Cell Arteritis Patients Pre- and Post-Standard Treatment

The primary objective of this study is to evaluate arterial **[18F]fluor-PEG-folate** uptake on PET/CT in patients with active, large vessel **giant cell arteritis** (GCA) and to assess the same patients after 9 months of standard treatment. This objective is clinically relevant as it aims to provide insights into the inflammatory activity within the arterial walls, which is crucial for understanding the disease progression and response to therapy in GCA. The study does not list any secondary objectives.

The clinical trial involves participants diagnosed with **giant cell arteritis** (GCA), focusing on individuals aged 50 years and older. Both male and female subjects are included in the study, with no specific vulnerable populations being targeted. The trial does not specify the total number of participants, as this information was not provided by the sponsor. Participants were selected based on the presence of clinical symptoms of large vessel GCA, such as constitutional symptoms, limb claudication, or symptoms of polymyalgia rheumatica, alongside imaging findings consistent with large vessel GCA. The study population is required to have an erythrocyte sedimentation rate (ESR) of 50 mm/hr or higher, or a C-reactive protein (CRP) level of 10 mg/L or more. Participants must be capable of adhering to study appointments and protocol requirements, and informed consent must be obtained prior to any study-related procedures. Lifestyle considerations such as diet, physical activity, or habits are not specified in the available data.

The clinical trial is designed to evaluate the arterial uptake of **[18F]fluoro-PEG-folate** on PET/CT in patients diagnosed with active giant cell arteritis (GCA) and to assess changes after nine months of standard treatment. This study is a Phase IV, non-low intervention trial, employing a controlled, observational design. The trial is expected to commence recruitment on January 1, 2024, and conclude by January 1, 2027. Participants will be administered **[18F]Fluor-PEG-Folate** via intravenous bolus, with a maximum daily dose of 200 MBq and a total dose not exceeding 400 MBq over the study period.

Participants will undergo a series of study visits, beginning with an inclusion (screening) visit to confirm eligibility based on criteria such as age (≥50 years), elevated erythrocyte sedimentation rate (ESR ≥50 mm/hr) or C-reactive protein (CRP ≥10 mg/L), and clinical symptoms consistent with large vessel GCA. Imaging findings supporting the diagnosis are also required. Following the screening, participants will attend follow-up visits to monitor arterial uptake and assess treatment response. The end-of-study visit will occur after nine months of treatment, where final assessments will be conducted.

The expected duration of participant involvement is approximately nine months, aligning with the treatment period. Conditions that may lead to early termination from the study include inability to adhere to study appointments, withdrawal of informed consent, or any adverse events that compromise participant safety. The primary endpoint is the measurement of arterial **[18F]fluoro-PEG-folate** uptake on PET/CT, both at baseline and after the treatment period. No secondary endpoints have been specified for this trial.

The clinical trial involves the use of **[18F]Fluor-PEG-Folate**, an experimental medication formulated as a **solution for injection**. This investigational product is administered via **intravenous bolus use**. The active substance, **[18F]Fluoro-PEG-Folate**, is a polymer-based compound. The dosing regimen for this trial specifies a maximum daily dose of 200 MBq (megabecquerels) and a maximum total dose of 400 MBq over the course of the study. The treatment period is limited to a maximum of 9 months. The investigational product is not a pediatric formulation and is not classified as an orphan drug.

In addition to the experimental treatment, participants will receive standard-of-care therapy for giant cell arteritis (GCA) as part of the study protocol. This standard treatment will be administered concurrently with the investigational product to evaluate the arterial uptake of **[18F]Fluor-PEG-Folate** on PET/CT imaging in patients with active, large vessel GCA. The study aims to assess the uptake both at baseline and after 9 months of standard treatment. Participant compliance with the dosing schedule will be monitored throughout the trial to ensure adherence to the protocol.

Efficacy in the clinical trial titled "[18F]fluor-PEG-folate PET/CT imaging in giant cell arteritis: a pilot study" will be assessed by evaluating the **arterial [18F]fluor-PEG-folate uptake** on PET/CT scans. This assessment will be conducted in patients diagnosed with active large vessel giant cell arteritis (GCA) and will be repeated in the same patients after a 9-month period of standard treatment. The primary endpoint of the study is the measurement of arterial uptake of the investigational product, [18F]fluor-PEG-folate, using PET/CT imaging. This imaging technique will provide quantitative data on the uptake levels, which will be used to determine the efficacy of the treatment over the specified period. The trial is designed to capture changes in uptake as a direct indicator of treatment response, thereby providing insights into the potential therapeutic benefits of the investigational product in managing large vessel GCA.