FAPI‑74 PET/CT versus FDG PET/CT for inflammation in FUO, IgG4‑RD, and axial spondyloarthritis
Official title: Prospective Diagnostic Performance of PET/CT Using the Novel Fibroblast Imaging Tracer [18F]-AlF-FAPI-74 Versus Standard of Care [18F]-FDG in Inflammatory Disorders
Run by Universitaire Ziekenhuizen KU Leuven · NCT07535554 · Data updated 2026-11-12
This project will test whether [18F]-AlF-FAPI-74 PET/CT finds inflammation more accurately than standard [18F]-FDG PET/CT in people with fever of unknown origin, IgG4‑related disease, or axial spondyloarthritis.
Quick facts
| Phase | Phase2; Phase3 |
|---|---|
| Study type | Interventional |
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 140 (estimated) |
| Sponsor | Universitaire Ziekenhuizen KU Leuven Academic / other |
| Drugs / interventions | radiation |
| Locations | 1 site (Leuven) |
| Status | Recruiting |
| Started | September 17, 2025 |
| Main results expected | March 31, 2029 |
| Study ends | March 31, 2030 |
| Registry record updated | April 17, 2026 |
| Trial ID | NCT07535554 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates are adults with FUO lasting >3 weeks with recurrent fevers or elevated inflammatory markers and no clear diagnosis, patients with suspected or histologically confirmed IgG4‑RD who need whole‑body disease assessment, and patients with suspected axial spondyloarthritis based on inflammatory back pain and supporting clinical features.
✕Probably not a fit
Patients without active inflammatory disease, those whose condition is already clearly diagnosed by other tests, pregnant women, or people unable to undergo PET/CT may not receive direct benefit from participation.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This interventional study enrolls three patient cohorts—fever of unknown origin (FUO), IgG4‑related disease (IgG4‑RD), and axial spondyloarthritis (axSpA)—to compare diagnostic performance of [18F]-AlF-FAPI-74 PET/CT with standard [18F]-FDG PET/CT. Participants will undergo imaging with the novel FAPI tracer and with FDG, and scans will be reviewed for lesion detection, uptake intensity, and anatomical distribution. Primary outcomes include sensitivity and specificity for identifying sites of active inflammation and disease extent in each cohort, with secondary analyses of inter-reader agreement and lesion-level concordance with clinical and laboratory data. Imaging and interpretation are performed at University Hospital Leuven by experienced nuclear medicine physicians.
Why it matters
Potential benefit: If successful, this imaging method could detect active inflammation more precisely than FDG, improving diagnosis, disease staging, and treatment planning for these patients.
How similar studies have gone: [18F]-FAPI tracers have shown promising results in oncology and in small pilot studies of inflammatory and fibrotic conditions, but direct head‑to‑head comparison of [18F]-AlF-FAPI-74 with FDG across these three inflammatory indications is relatively novel.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria FUO: * An illness of more than 3 weeks' duration, * Temperature exceeding 38.3°C on \> 3 occasions, or elevated inflammatory markers on \> 3 occasions * Diagnosis uncertain despite appropriate first-line investigations. Inclusion criteria IgG4-RD: * High clinical suspicion of IgG4-RD by an experienced clinician of Internal Medicine, based on anamnesis, physical examination, first-line investigations and blood tests. * Patients with a new diagnosis of IgG4-RD on histopathology and need for further assessment of disease extent with PET/CT, * Relapse of diagnosed IgG4-RD on histopathology according to an experienced clinician of Internal Medicine Inclusion criteria AxSpA: * High clinical suspicion of axial spondyloarthropahy according to an experienced rheumatology (based on inflammary back pain \> 3 months, insidious onset, morning stifness, improvement with exercise and worsening in rest, pain worse at night, age at onset \<45 years of age, imaging findings). * Patient has persisting inflammatory back pain after 2 different types of NSAID's (tried for over 2-4 weeks), and is therefore eligible for biological DMARDS therapy. Exclusion Criteria: * Participant is mentally or legally incapacitated, doesn't understand the study design or is not willing or capable to undergo all study-specific procedures. * Any disorder or condition, which in the Investigator's opinion might jeopardise the participant's safety or compliance with the protocol. * Any prior or concomitant treatment(s) that might jeopardise the participant's safety or that would compromise the integrity of the Trial. * Female who is pregnant (urinary hCG test will be performed in every WOCBP), breast-feeding or intends to become pregnant or is of child-bearing potential and not using an adequate, highly effective contraceptive (with a relatively high Pearl Index: natural methods, minipill outside postpartum period, spermicides or condoms in monotherapy or no usage of contraception when sexually active are not accepted). * Participation in an interventional Trial with an investigational medicinal product (IMP) or device when the trial designs are not considered compatible by the study team. * Participation in a clinical scientific study in the last 12 months with a radiation exposure caused by the experimental procedures greater than 1 mSv. * Participant has a known hypersensitivity to \[18F\]AlF-FAPI-74 or the used excipients. * Active treatment has already commenced
Where it's running
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University Hospital Leuven
Leuven, Belgium Recruiting
Study contacts
- Study coordinator: Lennert Boeckxstaens, MD
- Email: lennert.boeckxstaens@uzleuven.be
- Phone: +0032 16 34 37 15
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.