Cityview: PET-Based Imaging to Evaluate the Distribution of Radiolabeled CIT-013 in Patients with Inflammatory Mediated Immune Disease

The primary objective of this trial is to evaluate the **distribution** of **radiolabeled CIT-013** in patients with **inflammatory mediated immune diseases (IMIDs)**. This assessment is clinically relevant for understanding the **biodistribution** and tissue localization of the investigational agent using **PET-based imaging**, which may inform therapeutic targeting and dosing strategies in this patient population.

The secondary objectives include:

• Evaluate the **safety** and **tolerability** of CIT-013 in patients with IMIDs.

• Characterize the **pharmacokinetic profile** of CIT-013 in patients with IMIDs.

The sponsor did not provide information regarding the total number of participants enrolled in this clinical trial. The study population includes both **male** and **female** participants aged **60 to 85 years**, with females required to be of non-childbearing potential. Participants are diagnosed with **inflammatory mediated immune diseases**, specifically **rheumatoid arthritis** (RA) or **hidradenitis suppurativa** (HS). For RA participants, the diagnosis must have been established at least 6 months prior to screening according to the 2010 ACR/EULAR classification criteria, with subgroups including those with active disease (DAS28-CRP ≥ 4.2 with at least one swollen and one tender joint) and those in remission (DAS28-CRP ≤ 2.6 with no swollen or tender joints). HS participants must have disease duration of at least 6 months, an IHS4 score of ≥ 7, and at least one draining tunnel at screening. Male participants with female partners of childbearing potential are required to use adequate contraception and refrain from sperm donation during the trial and for 6 months following investigational product administration. All participants must be willing and able to provide written informed consent.

This clinical trial evaluates the distribution of radiolabeled **CIT-013** in patients with **inflammatory mediated immune diseases** using **PET-based imaging**. The trial is designed as a **Phase II** study to assess the biodistribution of the investigational product **[89Zr]Zr-DFO-CIT-013**, which is administered as a concentrate for solution for infusion via **intravenous injection**. The active substance is a protein-based compound radiolabeled with zirconium-89. The maximum daily dose and maximum total dose are both 20 mg, administered over a treatment period of 1 day. The trial includes distinct patient cohorts, specifically individuals diagnosed with **rheumatoid arthritis** (RA) and **hidradenitis suppurativa** (HS), allowing for comparison of uptake patterns across different disease states.

The primary objective is to evaluate the distribution of radiolabeled CIT-013 in patients with inflammatory mediated immune diseases through whole body **PET-CT imaging** performed 24 hours after investigational product administration. Visual assessment and quantitative analysis of [89Zr]-DFO-CIT-013 uptake per organ and organ system will be conducted. In vivo distribution profiles will be evaluated within each cohort to determine ranges of uptake per organ system and compared between cohorts to assess differences in uptake across various inflammatory mediated immune diseases. Secondary objectives include assessment of the frequency and severity of **treatment-emergent adverse events** throughout the trial period, including clinically relevant findings and **anti-drug antibodies** (ADAs), as well as evaluation of **pharmacokinetic** levels throughout the trial per cohort.

The trial enrolls female participants of non-childbearing potential or male participants between 60 and 85 years of age (inclusive). For the rheumatoid arthritis cohort, participants must have been diagnosed according to the 2010 classification criteria of the **American College of Rheumatology** (ACR) and the **European League Against Rheumatism** (EULAR) at least 6 months prior to screening based on medical records. The active RA subgroup requires a **Disease Activity Score 28** (DAS28) **C-Reactive Protein** (CRP) score of 4.2 or greater with at least 1 swollen joint and at least 1 tender joint at screening. The RA in remission subgroup requires a DAS28-CRP score of 2.6 or less with no swollen or tender joints at screening. For the hidradenitis suppurativa cohort, participants must have HS of at least 6 months duration based on medical records, an **International Hidradenitis Suppurativa Severity Score System** (IHS4) score of 7 or greater, and at least 1 draining tunnel at screening. Male participants with female partners of childbearing potential must adhere to adequate contraception and refrain from donating sperm prior to trial entry and for 6 months after investigational product administration. All participants must be willing and able to provide written informed consent.

The estimated recruitment start date is November 1, 2025, with an estimated trial end date of September 30, 2026. Participant involvement includes a screening visit to assess eligibility criteria, followed by investigational product administration on Day 1. The primary imaging assessment occurs on Day 2, 24 hours post-administration, when whole body PET-CT imaging is performed. Additional follow-up visits are conducted to monitor safety parameters, collect pharmacokinetic samples, and assess for treatment-emergent adverse events and anti-drug antibodies throughout the trial period. The end-of-study visit marks the completion of participant involvement. Conditions that may lead to early termination from the study are not explicitly detailed in the available trial information.

The experimental medication under investigation is **[89Zr]Zr-DFO-CIT-013**, a radiolabeled compound containing the active substance [89Zr]Zr-DFO-CIT-013, which is classified as a protein of other origin. The investigational product is supplied as a **concentrate for solution for infusion** and is administered via **intravenous injection**. The maximum daily dose is 20 mg, with a maximum total dose of 20 mg over the treatment period. The treatment duration is limited to 1 day. This radiolabeled agent is designed to enable **PET-based imaging** for the evaluation of drug distribution in patients with **inflammatory mediated immune diseases**.

The primary objective is evaluated through whole body PET-CT imaging performed 24 hours after investigational product administration. The assessment includes visual evaluation of the distribution of radiolabeled CIT-013 in patients with inflammatory mediated immune diseases. Uptake of [89Zr]-DFO-CIT-013 is quantified per organ and organ system. In vivo distribution profiles are analyzed per cohort to determine ranges of uptake per organ and organ system, and comparisons are made between cohorts to evaluate uptake differences in different inflammatory mediated immune diseases.

Secondary efficacy assessments include the evaluation of frequency and severity of treatment-emergent adverse events throughout the trial period, incorporating clinically relevant findings and anti-drug antibodies. Pharmacokinetic levels are measured throughout the trial on a per cohort basis.