Fibroblast activation protein (FAP) has been extensively studied as a cancer biomarker for decades. Recently, small-molecule FAP inhibitors have been widely adopted as a targeting moiety of experimental theranostic radiotracers. Here we present a fast qPCR-based analytical method allowing FAP inhibition screening in a high-throughput regime. To identify clinically relevant compounds that might interfere with FAP-targeted approaches, we focused on a library of FDA-approved drugs. Using the DNA-linked Inhibitor Antibody Assay (DIANA), we tested a library of 2667 compounds within just a few hours and identified numerous FDA-approved drugs as novel FAP inhibitors. Among these, prodrugs of cephalosporin antibiotics and reverse transcriptase inhibitors, along with one elastase inhibitor, were the most potent FAP inhibitors in our dataset. In addition, by employing FAP DIANA in the quantification mode, we were able to determine FAP concentrations in human plasma samples. Together, our work expands the repertoire of FAP inhibitors, analyzes the potential interference of co-administered drugs with FAP-targeting strategies, and presents a sensitive and low-consumption ELISA alternative for FAP quantification with a detection limit of 50 pg/ml.

• MeSH
• Cephalosporins chemistry   pharmacology   MeSH
• Endopeptidases * metabolism   MeSH
• Small Molecule Libraries pharmacology   chemistry   MeSH
• Humans MeSH
• Membrane Proteins * antagonists & inhibitors   metabolism   MeSH
• Molecular Structure MeSH
• High-Throughput Screening Assays * MeSH
• Drug Approval MeSH
• Serine Endopeptidases * metabolism   MeSH
• United States Food and Drug Administration MeSH
• Dose-Response Relationship, Drug MeSH
• Structure-Activity Relationship MeSH
• Gelatinases * antagonists & inhibitors   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• United States MeSH