Assessment of the Value of FAPI and FDG-PET-CT in Diagnosis of Acute Phase Peyronie's Disease (Hippocrates)

The use of FAPI-PET/CT and FDG-PET/CT scan in acute or chronic phase Peyronie's disease for detection of active fibroblasts and inflammation in the penis - a pilot study

Rationale Peyronie's Disease (PD) causes curvature of the penis due to grow of fibroblasts, leading to an inflammatory reaction in the Tunica Albuginea. It's causing pain in the acute phase in 20-70% of men. New pharmaceutical therapies are being developed, but these are only suitable for the active phase of PD. It is difficult to differentiate between the active phase with inflammation and active fibrosis, and the chronic phase with end stage fibrosis. At this moment, this differentiation can only be done by taking the history of the patient and physical examination.

Having a diagnostic test that is able to distinguish between the active and chronic phase will be ground-breaking and will support the decision to prescribe the new pharmaceutical options in the future.

FAPI-PET/CT scan is able to show active fibroblasts in tumour tissue. Recent studies also showed that this imaging technique is able to detect active fibroblasts in benign diseases, like idiopathic retroperitoneal fibrosis.

FDG-PET/CT scan can visualise active fibroblasts and inflammation based on enhanced uptake of glucose inside the fibroblasts and other inflammatory cells

Objective To evaluate if FAPI-PET/CT and/or FDG-PET/CT scan is able to detect active fibroblast tissue and inflammation in patients with acute phase PD.

To evaluate if FAPI-PET/CT and/or FDG-PET/CT scan is able to show fibrotic tissue (chronic phase) in a different way to distinguish between acute phase PD and chronic phase PD.

Main trial endpoints Primary: Detection of active fibroblasts (uptake of FAPI) and/or inflammation (uptake of FDG) in the penis of PD patients with FAPI-PET/CT scan and FDG-PET/CT scan.

No detection of FAPI and/or FDG uptake in chronic fibrotic tissue.

Trial design Pilot study

Trial population Ten patients >18 years with PD diagnosis, new onset < 6 months, painful erections, curvature and palpable nodule. Ten patients diagnosed with chronic PD will be included.

Interventions FAPI-PET/CT scan and FDG-PET/CT.

Ethical considerations relating to the clinical trial including the expected benefit to the individual subject or group of patients represented by the trial subjects as well as the nature and extent of burden and risks Nature and extent of the burden and risks associated with participation, benefit and group relatedness: After diagnosis of PD a FAPI-PET/CT scan will be performed in UMCG and < 2 weeks, before or after this, a FDG-PET/CT scan in St. Antonius Hospital. The scans will be performed as soon as possible.

After diagnosis of PD in chronic phase a FAPI-PET/CT scan will be performed in UMCG and a FDG-PET/CT scan in St. Antonius Hospital.