Vidupiprant, also known as AMG 853, is an orally bioavailable and potent dual antagonist of the D-prostanoid and chemoattractant receptor-homologous molecule expressed on T helper 2 cells receptors. Vidupiprant inhibits PGD2-induced down modulation of CRTH2 on CD16- granulocytes in human whole blood as well as PGD2-induced cAMP response in platelets. It inhibits PGD2-induced airway constriction in vivo. Also inhibits BRD4 (Kd = 170 nM). AMG 853 as an add-on to inhaled corticosteroid therapy demonstrated no associated risks but was not effective at improving asthma symptoms or lung function in patients with inadequately controlled moderate-to-severe asthma. AMG 853 has been discontinued due to poor efficacy.

Palosuran, also known as ACT-058362, a potent and specific antagonist of the human UT receptor. Urotensin inhibition with palosuran was a promising alternative in pulmonary arterial hypertension. Palosuran inhibits binding to primate UT receptors in cell membranes but demonstrates differential activity in intact cells and vascular tissues. Palosuran improves pancreatic and renal function in diabetic rats. Phase-II clinical trials for diabetic nephropathies and cardiovascular disorders were discontinued.

Firategrast (SB683699) is an orally bioavailable alpha4 beta1/alpha4 beta7 integrin antagonist designed to reduce trafficking of lymphocytes into the central nervous system (CNS), that had been studied in phase II trials at GlaxoSmithKline under a license from Mitsubishi Tanabe Pharma for the oral treatment of multiple sclerosis (MS) in Europe. GlaxoSmithKline and Tanabe Seiyaku (now Mitsubishi Tanabe Pharma) had been studying the drug candidate for the treatment of asthma, rheumatoid arthritis (RA) and Crohn’s disease, but these studies had being discontinued. Firategrast is a drug for the treatment of multiple sclerosis (MS) which is found to be caused by the migration of leucocytes (such as monocytes, T cells, B cells and dendritic cells) into CNS. And the integrin α4β1 is found to take participate in the migration through activating the leucocytes. Firategrast has a much shorter half-life than natalizumab with about 2.5 hours to 4.5 hours. It is found to inhibit the binding of the integrins to the associated ligands, including vascular cell adhesion protein 1 and mucosal addressin cell adhesion molecule 1. In CNS, firategrast treatment caused moderate decreases of total lymphocyte count, lymphocyte subset count and the ratio of CD4 to CD8. In peripheral blood, firategrast treatment resulted in the increases of total lymphocyte count, all lymphocyte subset count as well as the peripheral CD34+ early haematopoietic progenitor cell count. Firategrast was well tolerated at the maximum doses of 1200 mg for men and 900 mg for women. Firategrast showed no side effects, such as PML or JC-virus reactivation, at these doses. In Phase I clinical trials, the administration of firategrast significantly reduced the cumulative number of new gadolinium-enhancing lesions in patients with relapsing remitting MS.

Tarafenacin (also known as SVT-40776) was developed as muscarinic M3 receptor antagonist for the treatment of overactive bladder. The drug participated in phase II clinical trial in patients suffering from overactive bladder, where both dose levels of tarafenacin were well tolerated. However, information about the further development of tarafenacin is not available.

Luteolin, 3',4',5,7-tetrahydroxyflavone, is a common flavonoid that exists in many types of plants including fruits, vegetables, and medicinal herbs. Plants rich in luteolin have been used in Chinese traditional medicine for treating various diseases such as hypertension, inflammatory disorders, and cancer. Luteolin possesses a variety of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial and anticancer activities. Numerous studies have shown that luteolin possesses beneficial neuroprotective effects both in vitro and in vivo.

CK-101 is an orally available third-generation and selective inhibitor of certain epidermal growth factor receptor (EGFR) activating mutations, including the resistance mutation T790M, with potential antineoplastic activity. Activating mutations in the tyrosine kinase domain of EGFR are found in approximately 20% of patients with advanced Non-Small Cell Lung Cancer (NSCLC). Compared to chemotherapy, first-generation EGFR inhibitors significantly improved ORR and progression-free survival in previously untreated NSCLC patients carrying EGFR mutations. However, tumor progression could develop due to resistance mutations, often within months of treatment with first-generation EGFR inhibitors. CK-101 designed to be highly selective against the T790M mutation while sparing wild-type EGFR, thereby improving tolerability and safety profiles. Compared to some other EGFR inhibitors, CK-101 may have therapeutic benefits in tumors with T790M-mediated drug resistance. This agent shows minimal activity against wild-type EGFR (WT EGFR) and does not cause dose-limiting toxicities that occur during the use of non-selective EGFR inhibitors, which also inhibit WT EGFR.

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.

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.