Axitinib (trade name Inlyta) is a small molecule tyrosine kinase inhibitor developed by Pfizer. It has been shown to significantly inhibit growth of breast cancer in animal (xenograft) models and has shown partial responses in clinical trials with renal cell carcinoma (RCC) and several other tumour types. Axitinib has been shown to inhibit receptor tyrosine kinases including vascular endothelial growth factor receptors (VEGFR)-1, VEGFR-2, and VEGFR-3 at therapeutic plasma concentrations. These receptors are implicated in pathologic angiogenesis, tumor growth, and cancer progression. VEGF-mediated endothelial cell proliferation and survival were inhibited by axitinib in vitro and in mouse models. It was approved by the U.S. Food and Drug Administration.

Lenvatinib, developed by Eisai Co., is a receptor tyrosine kinase (RTK) inhibitor that inhibits the kinase activities of vascular endothelial growth factor (VEGF) receptors VEGFR1 (FLT1), VEGFR2 (KDR), and VEGFR3 (FLT4). Lenvatinib also inhibits other RTKs that have been implicated in pathogenic angiogenesis, tumor growth, and cancer progression in addition to their normal cellular functions, including fibroblast growth factor (FGF) receptors FGFR1, 2, 3, and 4; the platelet derived growth factor receptor alpha (PDGFRα), KIT, and RET. These receptor tyrosine kinases (RTKs) located in the cell membrane play a central role in the activation of signal transduction pathways involved in the normal regulation of cellular processes, such as cell proliferation, migration, apoptosis and differentiation, and in pathogenic angiogenesis, lymphogenesis, tumour growth and cancer progression. In particular, VEGF has been identified as a crucial regulator of both physiologic and pathologic angiogenesis and increased expression of VEGF is associated with a poor prognosis in many types of cancers. Lenvatinib is indicated for the treatment of patients with locally recurrent or metastatic, progressive, radioactive iodine (RAI)-refractory differentiated thyroid cancer. Most patients with thyroid cancer have a very good prognosis with treatment (98% 5 year survival rate) involving surgery and hormone therapy. However, for patients with RAI-refractory thyroid cancer, treatment options are limited and the prognosis is poor, leading to a push for the development of more targeted therapies such as lenvatinib. Lenvatinib is marketed under the trade name Lenvima, it is indicated for the treatment of patients with locally recurrent or metastatic, progressive, radioactive iodine-refractory differentiated thyroid cancer.