Toceranib (toceranib phosphate) is an orally bioavailable small molecule inhibitor that blocks a variety of RTKs, including VEGFR2, PDGFRa and KIT. In non-clinical pharmacology studies, toceranib selectively inhibited the tyrosine kinase activity of several members of the split kinase receptor tyrosine kinase (RTK) family, some of which are implicated in tumor growth, pathologic angiogenesis, and metastatic progression of cancer. Toceranib inhibited the activity of Flk-1/KDR tyrosine kinase (vascular endothelial growth factor receptor, VEGFR2), platelet-derived growth factor receptor (PDGFR), and stem cell factor receptor (Kit) in both biochemical and cellular assays. Toceranib has been shown to exert an antiproliferative effect on endothelial cells in vitro. Toceranib treatment can induce cell cycle arrest and subsequent apoptosis in tumor cell lines expressing activating mutations in the split kinase RTK, ckit. Canine mast cell tumor growth is frequently driven by activating mutations in c-kit. Toceranib is a dog-specific anti-cancer drug approved by the U.S. Food and Drug Administration. It is marketed as Palladia as its phosphate salt, toceranib phosphate by Pfizer. PALLADIA (Toceranib) tablets are indicated for the treatment of Patnaik grade II or III, recurrent, cutaneous mast cell tumors with or without regional lymph node involvement in dogs.