In vitro activity: SP-13786 (formerly known as FAP-IN-1) is a novel, potent and highly selective inhibitor of fibroblast activation protein (FAP) with IC50 of 3.2 nM; it also inhibits prolyl oligopeptidase (PREP) with an IC50 of 1.8 μM. Fibroblast activation protein (FAP) is a serine protease related to dipeptidyl peptidase IV (DPPIV). It has been convincingly linked to multiple disease states involving remodeling of the extracellular matrix. FAP inhibition is investigated as a therapeutic option for several of these diseases, with most attention so far devoted to oncology applications. The log D values, plasma stabilities, and microsomal stabilities of SP-13786 were found to be highly satisfactory. Pharmacokinetic evaluation in mice of SP-13786 demonstrated high oral bioavailability, plasma half-life, and the potential to selectively and completely inhibit FAP in vivo.

Kinase Assay: SP-13786 (formerly known as FAP-IN-1) is a novel, potent and highly selective inhibitor of fibroblast activation protein (FAP) with IC50 of 3.2 nM; it also inhibits prolyl oligopeptidase (PREP) with an IC50 of 1.8 μM.

Cell Assay: FAP-IN-1 is also found to have better FAP/PREP selectivity and a very proficient ligand efficiency of 0.34.