Paediatric Sarcoma, Hybrid Imaging & FAPI - Raising the Diagnostic Standard for Paediatric Sarcoma Patients, Combining Novel Radiotracer FAPI and Whole-body PET/MRI

NCT07861217 — Phase 2, Not yet recruiting, 40 participants, Copenhagen University Hospital, Rigshospitalet

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Paediatric Sarcoma, Hybrid Imaging & FAPI - An Investigator-initiated, Non-inferiority, Single-group, Phase II Clinical Trial, Evaluating FAPI WB PET/MRI at Primary Staging, Treatment Control and Relapse in Paediatric Sarcoma - The PsiFI Trial

Registry	NCT07861217, acronym PsiFI
Status	Not yet recruiting
Phase	Phase 2
Study type	Interventional; na, single group, masking: none, diagnostic
Enrollment	40 (Estimated)
Sponsor	Copenhagen University Hospital, Rigshospitalet (Other); collaborators: Department of Clinical Physiology and Nuclear Medicine, Rigshospitalet, Denmark, Department of Pediatrics and Adolescent Medicine, Rigshospitalet, Denmark, Department of Pathology, Rigshospitalet, Denmark, Department of Clinical Medicine, University of Copenhagen, Denmark
Conditions	Sarcoma
Interventions	FAPI tracer (Drug)
Dates	start 2026-12-01 (estimated), primary completion 2028-12-01 (estimated), completion 2029-06-01 (estimated), first posted 2026-10-06, last updated 2026-10-06
Locations	1 site in Denmark

-Summary

The goal of this clinical trial is to evaluate \[68Ga\]FAPI-46 whole-body PET/MRI as a diagnostic tool to improve tumour lesion examination at primary staging, during treatment control and at relapse in paediatric sarcoma patients.

The main questions the trial aim to answer are:

* Is \[68Ga\]FAPI-46 whole-body PET/MRI better at detecting malignancy in paediatric sarcoma patients compared to current standard of care imaging modalities?
* Is the overall diagnostic performance of \[68Ga\]FAPI-46 whole-body PET/MRI feasible to implement in clinical practice?

The intervention of \[68Ga\]FAPI-46 will be compared to current standard of care imaging modalities. All participants will receive their standard of care imaging protocol as rutinely scheduled, which includes:

* A localized MRI scan of the tumour region and
* An \[18F\]FDG whole-body PET/CT scan

In addition to the standard of care imaging protocol, all patients will receive the following experimental scans:

* An \[18F\]FDG whole-body PET/MRI
* A \[68Ga\]FAPI-46 whole-body PET/MRI
* A \[68Ga\]FAPI-46 whole-body PET/CT

All patients and legal guardians will fill out questionnaires on their experiences. Patients may undergo the entire trial imaging procedures, including the standard of care imaging protocol and the experimental scans, a maximum of five times.

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+Arms and interventions

Arm	Type	Interventions	Description
Experimental scans	Active comparator	Drug: FAPI tracer	Each patient is administered a radioactive dose of \[68Ga\]FAPI-46 and undergoes a whole-body PET/MRI followed by a whole-body PET/CT on the same dose administration.

FAPI tracer (Drug), also known as IMP: The patient is administered 2.0 MBq/kg of \[68Ga\]FAPI-46 radioactive tracer.

+Outcome measures

Primary outcomes

Endpoint for the primary objective [From recruitment, at the time of each participant's initial evaluation, until 6 months after completion of participant recruitment. The trial duration, from the start of recruitment to end of participation, is expected to last 2.5 years.]: The primary objective is to evaluate physicians' ability to accurately detect malignancy on \[68Ga\]FAPI-46 WB PET/MRI compared with standard-of-care imaging modalities. This will be assessed by calculating sensitivity, specificity, and positive and negative predictive values, using histopathology as the reference standard. If histopathology is unavailable, true positives may also be defined by consensus among the evaluating physicians, based on available imaging and the patient's electronic medical record during the 6-month follow up period.

Secondary outcomes

Endpoint of the secondary objective [From recruitment, at the time of each participant's initial evaluation, until 6 months after completion of participant recruitment. The trial duration, from the start of recruitment to end of participation, is expected to last 2.5 years.]: Tissue samples collected as part of routine clinical care, will be used for immunohistochemical (IHC ) analysis of FAP expression. The histological presence of FAP in the tissue samples will be correlated with the standardized uptake value (SUV) of the corresponding lesion identified on \[68Ga\]FAPI-46 PET/MRI. A standardardized questionnaire will be used to assess the experiences of the patient and/or parent(s). A final qualitative assessment of the technical feasibility of implementing this imaging modality in clinical practice will be conducted as part of the overall study evaluation. This assessment will consider any site-specific challenges associated with executing the experimental imaging protocol, the results of the image interpretation analyses, additional experiences gained during the study, and the time and costs associated with the protocol compared with current standard-of-care imaging modalities.

+Eligibility

Sex: All, ages: any to 17 Years

Inclusion Criteria:

* <18 years old.
* Referred to the Recruiting Department for evaluation of any type of sarcoma.
* The patient and/or parent(s) must be able to read and understand the Participant Information Sheet (PIS) in Danish and/or English and provide innformed consent by signing the Informed Consent Form (ICF).

Exclusion Criteria:

* Pregnancy or lactation.
* Considered unable by the referring department to comply with the study imaging procedures without sedation.
* Severe claustrophobia or any contraindication indentified through the MRI safety screening questionnaire.
* History of an allergic reaction due to compounds with a chemical composition similar to that of \[68Ga\]FAPI-46.

+Locations (1)

Facility	City	Country	Status
Dept. of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 CPH	Copenhagen	Denmark

+Funding

NIH grants: 2025