Famitinib, an orally active, small molecule, is a tyrosine kinase inhibitor against multiple targets, including vascular endothelial growth factor receptor 2/3, platelet-derived growth factor receptor, and stem cell factor receptor (c-kit). Jiangsu Hengrui Medicine Co is developing famitinib against a wide variety of advanced-stage solid cancers. Famitinib is participating in phase III clinical trials to evaluate its safety and efficacy in patients with advanced colorectal adenocarcinoma. The other phase III clinical trial for patients with non-squamous non-small cell lung cancer was terminated because of the difficulty in recruitment. In addition, the drug is involved in phase II clinical trials for the treatment of cervical cancer, endometrial cancer, fallopian tube cancer, gastrointestinal stromal tumors, nasopharyngeal cancer, and neuroendocrine tumors.

Crenolanib is an orally active, highly selective, small molecule, next generation inhibitor of platelet-derived growth factor receptor (PDGFR) tyrosine kinase. Crenolanib, manufactured by Arog Pharmaceuticals in Dallas, is taken orally with chemotherapy. The compound is currently being evaluated for safety and efficacy in clinical trials for various types of cancer, including acute myeloid leukemia (AML), gastrointestinal stromal tumor (GIST), and glioma. Crenolanib is an orally bioavailable, selective small molecule inhibitor of type III tyrosine kinases with nanomolar potencies against platelet-derived growth factor receptors (PDGFR) (isoforms PDGFRα and PDGFRβ) and Fms-related tyrosine kinase 3 (FLT3). Besides PDGFR and FLT3, crenolanib does not inhibit any other known receptor tyrosine kinase (RTK) (e.g. VEGFR and FGFR) or any other serine/threonine kinase (e.g., Abl, Raf) at clinically achievable concentrations. Preclinical trials have shown Crenolanib to be active in inhibiting both wild-type and mutant FLT3. Crenolanib is cytotoxic to the FLT3/ITD-expressing leukemia cell lines Molm14 and MV411, with IC50s of 7 nM and 8 nM, respectively. In immunoblots, crenolanib inhibited phosphorylation of both the wild-type FLT3 receptor (in SEMK2 cells) and the FLT3/ITD receptor (in Molm14 cells) in culture medium with IC50s of 1-3 nM. Importantly, the IC50 of crenolanib against the D835Y mutated form of FLT3 was 8.8 nM in culture medium. Furthermore, crenolanib had cytotoxic activity against primary samples that were obtained from patients who had developed D835 mutations while receiving FLT3 TKIs. In vitro, the IC50 of crenolanib for inhibition of FLT3/ITD in plasma was found to be 34 nM, indicating a relatively low degree of plasma protein binding. From pharmacokinetic studies of crenolanib in solid tumor patients, steady state trough plasma levels of roughly 500 nM were found to be safe and tolerable, suggesting that crenolanib could potentially inhibit the target in vivo. Crenolanib has no significant activity against c-KIT, which may be an advantage in that myelosuppression can be avoided.1Furthermore, there was no evidence of QTc prolongation in patients treated with crenolanib. In summary, crenolanib offers a number of advantages over other FLT3 TKIs. Clinical trials of crenolanib in AML patients with FLT3 activating mutations are being planned.

Lestaurtinib (CEP-701, KT-5555) is an orally bio-available polyaromatic indolocarbazole alkaloid derived from K-252a. Lestaurtinib is a multi-targeted tyrosine kinase inhibitor which has been shown to potently inhibit FLT3 at nanomolar concentrations in preclinical studies, leading to its rapid development as a potential targeted agent for treatment of AML. Phase I studies have shown lestaturtinib to be an active agent particularly when used in combination with cytotoxic drugs. Currently, Phase II and Phase III studies are underway aiming to establish the future of this agent as a treatment option for patients with FLT3-ITD AML.

Filgotinib (GLPG0634) is a highly selective JAK1 inhibitor. GLPG0634 is a promising drug candidate for the future treatment of autoimmune and inflammatory disorders. It is in phase III clinical trials (initiated mid-2016) for the treatment of rheumatoid arthritis, Crohn's disease and ulcerative colitis. Most common adverse events observed were infections, gastrointestinal disorders and nervous system disorders.

BMS 911543 is a selective orally administered small molecule inhibitor of Janus kinase 2 (JAK2), developed by BristolMyers Squibb for the myelofibrosis treatment. BMS 911543 displayed potent antiproliferative effects in mutated JAK2expressing cell lines. A superior antiproliferative response occurred in primary progenitor cells isolated from patients with JAK2positive myeloproliferative disease (MPD) compared with those isolated from healthy volunteers. In vivo, a single oral dose of BMS 911543 resulted in durable JAK2phosphorylated STAT signalling pathway inhibition in multiple species. In a JAK2expressing xenograft model (SET2), BMS 911543 displayed a minimally effective dose of <2 mg/kg on phosphorylated STAT5 pathway inhibition.

Decernotinib is an oral JAK3 kinase inhibitor developed by Vertex for the treatment of rheumatoid arthritis. Although the drug demonstrated a good potency in vitro and in phases I and II of clinical trials, its development was terminated.

INCB-039110 (also known as Itacitinib) is an orally bioavailable inhibitor of Janus-associated kinase 1 (JAK1) with potential antineoplastic activity patented by Incyte Corporation for treatment of autoimmune disorders and cancer. Upon oral administration of NCB-039110, this agent selectively inhibits the phosphorylation and activity of JAK1, which may result in inhibition of JAK1-mediated signaling, induction of apoptosis, and reduction of cell proliferation in JAK1-expressing tumor cells. INCB-039110 in combination with nab-paclitaxel plus gemcitabine demonstrated an acceptable safety profile with clinical activity seen in patients with advanced solid tumors including pancreatic cancers. Based on the potential for additive or synergistic effects, NCB-039110 is currently being explored in combination with immunotherapeutic agents including the anti-programmed cell death protein 1 antibody and small molecule inhibitors.

Orantinib (SU-6668) is an orally bioavailable receptor tyrosine kinase inhibitor. Orantinib binds to and inhibits the autophosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR), thereby inhibiting angiogenesis and cell proliferation. Orantinib also inhibits the phosphorylation of the stem cell factor receptor tyrosine kinase c-kit, often expressed in acute myelogenous leukemia cells. Orantinib was in phase II clinical trials for the treatment of breast cancer. It was also in phase III clinical trials for the treatment of hepatocellular carcinoma. However, this research was terminated in 2014. The compound was originally developed by Sugen (subsidiary of Pfizer). In 1998, a co-development agreement took place between Sugen and Taiho for the compound.

Tesevatinib (EXEL-7647 or XL647) was optimized as an inhibitor of a spectrum of growth-promoting and angiogenic receptor tyrosine kinases (RTKs) to simultaneously block tumor growth and vascularization. In particular, Tesevatinib potently inhibits the EGF/ErbB2, VEGF, and ephrin RTK families. The drug is being developed by Kadmon Corporation under licence from Symphony Evolution (Symphony Capital Partners). Kadmon is developing tesevatinib for the treatment of autosomal polycystic kidney disease and solid cancers.

SU-14813 is an oral, multitargeted tyrosine kinase inhibitor (TKI) targeting vascular endothelial growth factor receptors (VEGFR), platelet-derived growth factor receptors (PDGFR), KIT, and fms-like tyrosine kinase 3 (FLT-3). SU-14813 was developed as a next-generation TKI agent following sunitinib (SU-11248) designed to demonstrate optimized pharmacokinetic (PK) and tolerability profiles. SU14813 demonstrated broad and potent antitumor activity equivalent to that of sunitinib, which resulted in tumor regression, growth arrest, growth delay, and prolonged survival in established xenograft cancer models in mice. A phase II trial of SU-14813 in patients with breast cancer was completed. However, according to the Pfizer pipeline development has been discontinued.