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.

Pralsetinib (GAVRETO™, Blueprint Medicines Corporation) is an orally-administered, next-generation, small-molecule selective rearranged during transfection (RET) inhibitor being developed for the treatment of various solid tumours. RET is a well described proto-oncogene present in multiple cancers including non-small cell lung cancer (NSCLC), papillary thyroid cancer, and medullary thyroid carcinoma. Pralsetinib is a kinase inhibitor of wild-type RET and oncogenic RET fusions (CCDC6-RET) and mutations (RET V804L, RET V804M and RET M918T) with half maximal inhibitory concentrations (IC50s) less than 0.5 nM. In purified enzyme assays, pralsetinib inhibited DDR1, TRKC, FLT3, JAK1-2, TRKA, VEGFR2, PDGFRb, and FGFR1 at higher concentrations that were still clinically achievable at Cmax. In cellular assays, pralsetinib inhibited RET at approximately 14-, 40-, and 12-fold lower concentrations than VEGFR2, FGFR2, and JAK2, respectively. Pralsetinib is approved for the treatment of RET fusion-positive metastatic NSCLC. In the pivotal phase I/II ARROW trial, pralsetinib demonstrated rapid and durable anti-tumour activity in patients with advanced RET fusion-positive NSCLC who were previously treated with platinum-based chemotherapy or were treatment-naïve. Pralsetinib also showed clinical activity against intracranial metastases arising from NSCLC. Pralsetinib had a manageable tolerability profile, with the most common grade 3 treatment-related adverse events being neutropenia, hypertension, anaemia and decreased white blood cell count.

Ripretinib (DCC-2618) is an investigational, orally available switch control kinase inhibitor being developed for the treatment of gastrointestinal stromal tumors (GIST), advanced systemic mastocytosis (ASM), gliomas, and other solid tumors driven by tyrosine-protein kinase KIT (KIT) or platelet-derived growth factor alpha (PDGFRα) kinase. Ripretinib acts by forcing the activation loop (or activation "switch") of kinases into an inactive conformation and is a type II kinase inhibitor demonstrated to broadly inhibit activation loop mutations in KIT and PDGFRA, previously thought only achievable with type I inhibitor. Ripretinib is developed by the company Deciphera and is being investigated in phase 3 clinical trials for the treatment of GIST, ASM and other tumors.

Pexidartinib (PLX3397) is a small-molecule receptor tyrosine kinase (RTK) inhibitor with potential antineoplastic activity. Pexidartinib binds to and inhibits phosphorylation of stem cell factor receptor (KIT), colony-stimulating factor-1 receptor (CSF1R) and FMS-like tyrosine kinase 3 (FLT3), which may result in the inhibition of tumor cell proliferation and down-modulation of macrophages, osteoclasts and mast cells involved in the osteolytic metastatic disease. FDA has granted Breakthrough Therapy Designation to pexidartinib (PLX3397) for the treatment of tenosynovial giant cell tumor (TGCT) where surgical removal of the tumor would be associated with potentially worsening functional limitation or severe morbidity. In addition to Breakthrough Therapy Designation, pexidartinib (PLX3397) has been granted Orphan Drug Designation by FDA for the treatment of pigmented villonodular synovitis (PVNS) and giant cell tumor of the tendon sheath (GCT-TS). It also has received Orphan Designation from the European Commission for the treatment of TGCT.

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.

Regorafenib (trade name Stivarga) is an orally bioavailable small molecule with potential antiangiogenic and antineoplastic activities. Regorafenib binds to and inhibits vascular endothelial growth factor receptors (VEGFRs) 2 and 3, and Ret, Kit, PDGFR and Raf kinases, which may result in the inhibition of tumor angiogenesis and tumor cell proliferation. VEGFRs are receptor tyrosine kinases that play important roles in tumor angiogenesis; the receptor tyrosine kinases RET, KIT, and PDGFR, and the serine/threonine-specific Raf kinase are involved in tumor cell signaling. In in vivo models, regorafenib demonstrated anti-angiogenic activity in a rat tumor model, and inhibition of tumor growth as well as anti-metastatic activity in several mouse xenograft models including some for human colorectal carcinoma. Since 2009 it was studied as a potential treatment option in multiple tumor types. Stivarga is approved by FDA to treat two different tumor types: metastatic colorectal cancer in patients who have been previously treated with fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy, an anti-VEGF therapy, and, if KRAS wild type, an anti-EGFR therapy (approved in 2012) and to treat patients with locally advanced, unresectable or metastatic gastrointestinal stromal tumor who have been previously treated with imatinib mesylate and sunitinib malate (approved in 2013).

Cabozantinib (development code name XL184; marketed under the trade name Cometriq) is an orally bioavailable, small molecule receptor tyrosine kinase (RTK) inhibitor with potential antineoplastic activity. Cabozantinib strongly binds to and inhibits several RTKs, which are often overexpressed in a variety of cancer cell types, including hepatocyte growth factor receptor (MET), RET (rearranged during transfection), vascular endothelial growth factor receptor types 1 (VEGFR-1), 2 (VEGFR-2), and 3 (VEGFR-3), mast/stem cell growth factor (KIT), FMS-like tyrosine kinase 3 (FLT-3), TIE-2 (TEK tyrosine kinase, endothelial), tropomyosin-related kinase B (TRKB) and AXL. This may result in an inhibition of both tumor growth and angiogenesis, and eventually lead to tumor regression. Cabozantinib was granted orphan drug status by the U.S. Food and Drug Administration (FDA) in January 2011. It is currently undergoing clinical trials for the treatment of prostate, bladder, ovarian, brain, melanoma, breast, non-small cell lung, pancreatic, hepatocellular and kidney cancers.

Vandetanib, 4-anilinoquinazoline, is an anti-cancer drug that with the potential for use in a broad range of tumour types. In 2011 vandetanib (trade name Caprelsa) was approved by the FDA to treat nonresectable, locally advanced, or metastatic medullary thyroid cancer in adult patients. In vitro studies have shown that vandetanib inhibits the tyrosine kinase activity of the EGFR and VEGFR families, RET, BRK, TIE2, and members of the EPH receptor and Src kinase families. These receptor tyrosine kinases are involved in both normal cellular function and pathologic processes such as oncogenesis, metastasis, tumor angiogenesis, and maintenance of the tumor microenvironment. Vandetanib was shown to inhibit epidermal growth factor (EGF)-stimulated receptor tyrosine kinase phosphorylation in tumor cells and endothelial cells and VEGF-stimulated tyrosine kinase phosphorylation in endothelial cells. Vandetanib administration reduced tumor cell-induced angiogenesis, tumor vessel permeability, and inhibited tumor growth and metastasis in mouse models of cancer.