Nintedanib is an indolinone derivative and small molecule tyrosine-kinase inhibitor, inhibiting endothelial growth factor activity in enzymatic assays. It targets vascular endothelial growth factor receptor (VEGFR) 1-3, fibroblast growth factor receptor (FGFR), and platelet-derived growth factor receptor (PDGFR) α and β, which may result cell apoptosis, a reduction in tumor vasculature; and the inhibition of tumor cell proliferation and migration. This agent also inhibits some Src family of tyrosine kinases, including Src, Lck, Lyn, and FLT-3.