Definition

An orally bioavailable inhibitor of the serine/threonine kinase, transforming growth factor (TGF)-beta receptor type 1 (TGFBR1), also known as activin receptor-like kinase 5 (ALK5), with potential antineoplastic activity. Upon oral administration, vactosertib inhibits the activity of TGFBR1 and prevents TGF-beta/TGFBR1-mediated signaling. This suppresses tumor growth in TGFBR1-overexpressing tumor cells. TGFBR1, which is overexpressed in a variety of tumor cell types, plays a key role in tumor cell proliferation. Expression of TGF-beta promotes tumor cell proliferation, enhances the migration of tumor cells and suppresses the response of the host immune system to tumor cells.