Fruquintinib is a highly selective small molecule drug candidate that has been shown to inhibit VEGFR 24 hours a day via an oral dose, with lower off-target toxicities compared to other targeted therapies. Mechanistically, Fruquintinib selectively blocks VEGF-mediated receptor autophosphorylation, thus inhibiting endothelial cell proliferation and migration. In preclinical in vitro studies using a 32P-ATP assay, Fruquintinib selectively inhibited the tyrosine kinase activity associated with VEGFR-1, VEGFR-2, and VEGFR-3 at concentrations in the nanomolar range, but showed little inhibition against a panel of 254 kinases related to cell cycle or cell proliferation, including cyclin-dependent kinase (CDK1, 2, 5), the epidermal growth factor receptor (EGFR), the mesenchymal-epithelial transition factor (c-Met), and platelet-derived growth factor receptor β (PDGFRβ) kinase. In cellular assays, Fruquintinib potently inhibited VEGF-stimulated VEGFR phosphorylation and proliferation in human umbilical vein endothelial cells. Fruquintinib demonstrated potent antiangiogenic effect and anti-tumor activity in xenograft models of colon adenocarcinoma (HT-29), non-small cell lung cancer (NSCLC; NCI-H460), renal clear cell carcinoma (Caki-1), and gastric carcinoma (BGC823) in mice treated for 3 weeks. Fruquintinib is currently under joint development in China by Chi-Med and its partner Eli Lilly and Company (“Lilly”). Chi-Med and Lilly jointly announced top-line results from the FRESCO CRC trial on March 3, 2017. In addition, Fruquintinib is being studied in China in Phase III pivotal trial in non-small cell lung cancer (“NSCLC”), known as FALUCA; and a Phase II study using Fruquintinib combined with Iressa® (gefitinib) in the first-line setting for patients with advanced or metastatic NSCLC.

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.

Nintedanib is a receptor tyrosine kinase inhibitor with potential antiangiogenic and antineoplastic activities. It is the only kinase inhibitor drug approved to treat idiopathic pulmonary fibrosis. that targets multiple receptor tyrosine kinases (RTKs) and non-receptor tyrosine kinases (nRTKs). Nintedanib inhibits the following RTKs: platelet-derived growth factor receptor (PDGFR) α and β, fibroblast growth factor receptor (FGFR) 1-3, vascular endothelial growth factor receptor (VEGFR) 1-3, and Fms-like tyrosine kinase-3 (FLT3). Among them, FGFR, PDGFR, and VEGFR have been implicated in IPF pathogenesis. Nintedanib binds competitively to the adenosine triphosphate (ATP) binding pocket of these receptors and blocks the intracellular signaling which is crucial for the proliferation, migration, and transformation of fibroblasts representing essential mechanisms of the IPF pathology.

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.

Pazopanib (VOTRIENT) is an orally bioavailable multi-targeted tyrosine kinase receptor inhibitor. Pazopanib inhibits vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, VEGFR-3, platelet-derived growth factor receptor (PDGFR)-α and -β, fibroblast growth factor receptor (FGFR) -1 and -3, cytokine receptor (Kit), interleukin-2 receptor inducible T-cell kinase (Itk), leukocyte-specific protein tyrosine kinase (Lck), and transmembrane glycoprotein receptor tyrosine kinase (c-Fms). In an vitro study, pazopanib exerted anti-tumor effect through mechanisms including the Raf-MAPK/ERK (MEK)-extracellular signal-regulated kinase (ERK) pathway. It has good oral exposure and inhibits angiogenesis and tumor growth in mice. Pazopanib (VOTRIENT) was developed by GlaxoSmithKline for the treatment of solid tumours and age-related macular degeneration. However, Novartis acquired all the rights to the drug from GlaxoSmithKline. Pazopanib (VOTRIENT) is indicated for the treatment of patients with advanced renal cell carcinoma and advanced soft tissue sarcoma.

Sunitinib (marketed as Sutent by Pfizer, and previously known as SU11248) is an oral, small-molecule, multi-targeted receptor tyrosine kinase inhibitor that was approved by the FDA for the treatment of renal cell carcinoma (RCC) and imatinib-resistant gastrointestinal stromal tumor. Sunitinib was evaluated for its inhibitory activity against a variety of kinases and was identified as an inhibitor of platelet-derived growth factor receptors (PDGFRa and PDGFRb), vascular endothelial growth factor receptors (VEGFR1, VEGFR2, and VEGFR3), stem cell factor receptor (KIT), Fms-like tyrosine kinase-3 (FLT3), colony-stimulating factor receptor Type 1 (CSF-1R), and the glial cell-line derived neurotrophic factor receptor (RET). Sunitinib adverse events are considered somewhat manageable and the incidence of serious adverse events low. The most common adverse events associated with sunitinib therapy are fatigue, diarrhea, nausea, anorexia, hypertension, yellow skin discoloration, hand-foot skin reaction, and stomatitis. In the placebo-controlled Phase III GIST study, adverse events which occurred more often with sunitinib than placebo included diarrhea, anorexia, skin discoloration, mucositis/stomatitis, asthenia, altered taste, and constipation. Dose reductions were required in 50% of the patients studied in RCC in order to manage the significant toxicities of this agent.

Telatinib (Bay-579352) developed by Bayer is an orally available and highly potent inhibitor of tyrosine kinases VEGFR2,VEGFR3, PDGFR and c-Kit. Telatinib is a potent inhibitor of angiogenesis. Telatinib caused a significant decrease in endothelium-dependent and endothelium-independent vasodilation. Telatinib demonstrates anti-tumor activity in various cancer models. Telatinib is ready for phase III clinical trials for the treatment of gastric cancer. In 2010, it has been granted orphan drug status by the FDA. Most frequent adverse events were pain, nausea, voice changes and fatigue.

Semaxanib is a potent and selective vascular endothelial growth factor (VEGF) receptor protein tyrosine kinase 1/2 inhibitor that also inhibits other tyrosine kinases KIT, MET, FLT3, and RET. Semaxanib inhibited cell migration of human vascular endothelial cells expressing both Flt-1 and KDR in response to VEGF and also inhibited the cell migration in response to placenta growth factor (PIGF), a specific ligand for Flt-1. Chemotaxis of monocytes expressing only Flt-1 was also inhibited by SU5416 in a dose-dependent manner. Semaxanib targets the VEGF pathway, and both in vivo and in vitro studies have demonstrated antiangiogenic potential. On February 2002, Pharmacia, the then-parent of Sugen, prematurely ended Phase III clinical trials of Semaxinib in the treatment of advanced colorectal cancer due to discouraging results.

Dovitinib is an orally active small molecule that exhibits potent inhibitory activity against multiple receptor tyrosine kinases (RTK) involved in tumor growth and angiogenesis. Dovitinib strongly binds to fibroblast growth factor receptor 3 (FGFR3) and inhibits its phosphorylation, which may result in the inhibition of tumor cell proliferation and the induction of tumor cell death. In addition, this agent may inhibit other members of the RTK superfamily, including the vascular endothelial growth factor receptor; fibroblast growth factor receptor 1; platelet-derived growth factor receptor type 3; FMS-like tyrosine kinase 3; stem cell factor receptor (c-KIT); and colony-stimulating factor receptor 1; this may result in an additional reduction in cellular proliferation and angiogenesis, and the induction of tumor cell apoptosis. There are several ongoing Phase I/III clinical trials for dovitinib.

BMS-690514 is a potent, reversible oral inhibitor of epidermal growth factor receptor (EGFR/HER-1), HER-2 and -4, and vascular endothelial growth factor receptors (VEGFRs)-1 to -3 offering targeted inhibition of tumour growth and vascularisation in a single agent. Bristol-Myers Squibb was developing BMS 690514, as an oral treatment for cancer. BMS-690514 had being in phase II for the treatment of breast cancer; non-small cell lung cancer, but later these studies were discontinued.