Fibroblast Activation Protein Alpha (FAPα) as a Promising Target in the Diagnostics and Treatment of Cancer and Fibrotic Diseases: Recent Approaches to Imaging and Assessment of Functional Activity

Fibroblast activation protein alpha (FAPα) is a transmembrane serine peptidase and a well-known marker of activated fibroblasts that are formed during onco- and fibrogenesis and play an important role in the progression of cancer and fibrosis. Identification of FAPα-positive cells is widely used to visualize pathological changes in the stroma in the diagnosis and treatment of cancer diseases. Recent evidence suggests that FAPα itself contributes to the development of tumors and fibrosis-associated diseases through its enzymatic activity and other mechanisms. Various methods for visualization and evaluation of FAPα enzymatic activity are being developed, which are essential for deciphering the role of FAPα in the development of stromal pathologies. Here we discuss current approaches to visualization and regulation of FAPα enzymatic activity.