Fibroblast Activation Protein Inhibitors: Structural Evolution, Binding Mechanisms, and Theranostic Applications in Positron Emission Tomography/Computed Tomography Imaging
Year: 2026
Type: article
Abstract: α-Fibroblast activation protein (α-FAP) is overexpressed in cancer-associated fibroblasts within the tumor microenvironment of most epithelial cancers, making it an attractive target for cancer-specific imaging and therapy. This article summarizes the structural features, binding mechanisms, radiolabelling strategies, and clinical potential of FAP inhibitors (FAPIs). FAPI molecules generally consist of three functional modules: a quinoline-based core for target recognition, a linker, and a DOTA/NOTA chelator for radionuclide labelling. The interaction between FAPIs and α-FAP is primarily mediated by several amino acid residues, each engaging a specific structural module of the inhibitor, but residues involved are not fixed and may shift with structural variation among FAPI derivatives. The evolution from early boronic acid compounds to UAMC-1110 marks a transition from non-selective dipeptidyl peptidase inhibitors toward FAP-selective warheads, while later modifications (e.g., cyano to α-ketoamide) addressed the need for prolonged target residence. PET/CT is the combination of functional and structural scanning, increasing diagnostic accuracy. The same targeting principle also enables therapeutic applications when labelled with β-emitting radionuclides. The clear specificity of FAPI also helps overcome many limitations of 18 F-FDG.
Source: Theoretical and Natural Science
Author: Chuancheng Ju
Institution: Shanghai Jiao Tong University
Language: English
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W7221508559