PBR28 PET and Inflammatory Arthritis

Study Overview
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Brief Summary
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The importance of the detection of early inflammatory arthritis is recognised as being essential to the prevention of permanent joint damage. Furthermore, drug development in inflammatory arthritis is in increasing need of imaging that is able to sensitively and accurately detect and quantify inflammation in a reproducible and objective manner. There is an increasing body of evidence to support the role of PET-CT for these indications. The PET tracer 11CPBR28 is specific to the translocator protein (TSPO) highly expressed on activated macrophages. In this proof of principle study, the investigators aim to ascertain whether or not the PET tracer 11CPBR28 is taken up in inflamed joints. The investigators also aim to explore the significance of TSPO to inflammatory arthritis, through blood and joint lining samples.

Detailed Description
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The investigators aim to recruit a minimum of 12 patients with known, active rheumatoid or psoriatic arthritis in the feet and ankles. Patients will first undergo a screening genotyping test; low affinity binders for PBR28 PET will be excluded from this pilot study. Those patients meeting inclusion criteria, will then undergo a PET-CT localised to feet and ankles that have been identified to be clinically inflamed (on examination and ultrasound at the screening visit). After PET-CT, patients will undergo synovial biopsy of one joint imaged. After 6 patients have undergone PET-CT, an interim analysis will be undertaken, to optimise PET scan duration and to alter the group of joints being imaged with CT.

Official Title
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Pilot Study to Evaluate the Feasibility of [11C]PBR28 PET-CT to Image Inflammation in the Joints of Arthritis Patients

Conditions
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Rheumatoid Arthritis, Psoriatic Arthritis

Intervention / Treatment
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* Other: this is not an interventional study


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with known rheumatoid arthritis or psoriatic arthritis, with at least one swollen joint, with evidence of joint inflammation in the feet and/or ankles (on clinical examination and/or ultrasound) Exclusion Criteria: pregnant and breastfeeding patients those with metalwork in feet/ankles patients unable to lie on their back Patient has been identified as a low affinity [11C]PBR28 binder according to peripheral blood genotyping assay The patient has any significant co-morbidity precluding participation as judged by the study doctor

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| this is a pilot study<br>All patients will undergo PET-CT with PBR28, with the CT being localised to one group of joints only | Other: this is not an interventional study<br>* this is not an interventional study; this is a pilot feasibility study to see whether or not 11CPR28 will be taken up in joints of those known to have active arthritis clinically<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| standardised uptake values (SUV) | Evidence of uptake of 11CPBR28 in the inflamed feet and/or ankle joints of patients with known rheumatoid or psoriatic arthritis as exhibited by SUV (standard uptake values) on the PET-CT images. | maximum duration of scan is 90 minutes |