Advancements in FAPI Tracers: Translational Steps Towards Clinical Applications

FAPI tracers promise clearer lesion detection and a matched theranostic pathway—transforming PET-based staging and targeted radionuclide delivery across several solid tumors.

Emerging data show that FAPI tracers achieve high tumor-to-background uptake with rapid clearance from non-target tissues, producing excellent contrast in head‑and‑neck, pancreatic, breast, and metastatic disease. Compared with conventional metabolic tracers, this profile improves small‑lesion conspicuity and may change biopsy targeting, nodal staging, and early response assessment. Clinically, the most immediate role is high‑contrast staging and lesion detection in selected tumor types.

Theranostic strategies are attractive because radiolabelled FAPI constructs provide both PET visualization and the means to deliver therapeutic radionuclides to cancer‑associated fibroblasts. Because the tracer binds stromal fibroblasts common to many solid tumors, radiolabelled FAPI could offer palliation and local tumor control when paired with beta or alpha emitters—potentially improving symptomatic relief and lesion shrinkage. The translational opportunity is a single agent for matched imaging and targeted radiotherapy.

Dosimetry and biodistribution data remain essential for safe translation. Liver and renal uptake and whole‑body dose estimates should guide diagnostic versus therapeutic use. Consequently, organ‑specific uptake patterns and absorbed‑dose modeling must inform patient selection, administered activity, and repeat‑dosing intervals to limit off‑target exposure. Robust dosimetry protocols are a prerequisite before routine diagnostic or therapeutic deployment.

Actionable operational gaps include manufacturing scale‑up and radionuclide supply reliability, standardized imaging acquisition and interpretation, regulatory clarity for theranostic claims, and prospective trials linking imaging to clinical outcomes and dosimetry‑guided dosing. Multicenter dosimetry studies, harmonized PET protocols, early‑phase safety/efficacy trials, and coordinated radiopharmacy networks address these needs and enable broader implementation.