Edatrexate (10-ethyl-10-deazaaminopterin or 10-EDAM) is an analog of methotrexate with improved pre-clinical antitumor activity, more selective cellular uptake, and with the more extensive formation of intracellular polyglutamate metabolites. This drug is a new dihydrofolate reductase inhibitor, which was studied in phase II clinical trial for the patients with different cancers. The studies were discontinued, for example, in advanced renal cell carcinoma edatrexate in the investigated dose and schedule had minimal activity and was toxic. In case of non-small-cell lung cancer, the dosing schedule of edatrexate did not appear to be improved compared to other chemotherapeutic regimens. In addition, edatrexate was involved in the experiment for the treatemnt of rheumatoid arthritis, but this study was also discontinued.

Nicainoprol, also known as RU-42924, is calcium channel antagonist and a putative class I antiarrhythmic agent. Nicainoprol was shown to be useful in the prevention and treatment of arrhythmias associated with acute myocardial infarction. Nicainoprol had been in phase II clinical trials for the treatment of arrhythmia. However, this research has been discontinued.

Mofegiline (MDL 72,974A or (E)-2-(4-fluorophenethyl)-3-fluoroallylamine, hydrochloride), is a selective and irreversible inhibitor of monoamine oxidase type B (MAO-B) both in vitro and in vivo. In addition, mofegiline inhibits semicarbazide-sensitive amine oxidase activity from human serum and saphenous vein. In phase II studies, MDL 72,974A is proving to be a useful adjunct to conventional therapy of Parkinson's disease. It seems mofegiline development was discontinued.

Dextofisopam, a non-serotonergic agent currently being evaluated for the treatment of irritable bowel syndrome (IBS), is the R-enantiomer of racemic tofisopam, a molecule marketed and used safely outside the United States for over three decades for multiple indications including IBS. Dextofisopam represents a novel, first-in-class opportunity with a positive proof-of-concept study in an arena where there are few compounds with unique approaches or positive efficacy results. By structure, Dextofisopam is a member of the homophthalazine class; Dextofisopam binds to specific receptors in areas of the brain affecting autonomic function, including gastrointestinal (GI) function. Unlike the two 5-HT3 or 5-HT4 mediated IBS therapies currently available, both with significant safety concerns, Dextofisopam novel non-serotonergic activity offers a unique and innovative approach to IBS treatment. Recent studies have indicated that dextofisopam binds to a novel binding site within the central nervous system that may be responsible for mediating its actions. This receptor has been characterized as the 2,3-benzodiazepine receptor, which is distinct from the classical 1,4 or 1,5-benzodiazepine receptor. Dextofisopam has no significant binding at other receptors or ion channels

Ciglitazone, 5-[4-(1-methylcyclohexylmethoxy) benzyl]-thiazolidine-2,4-dione, is a hypoglycemic agent and a thiazolidenedione derivative. Ciglitazone binds to the PPAR gamma receptor and possesses agonist activity. This drug was in clinical trials in Japan for the treatment Diabetes mellitus, but that study has been discontinued. Ciglitazone was able to decrease the production of vascular endothelial growth factor (VEGF) in an in vitro human granulosa cell model. That result together with the pivotal role of VEGF in ovarian hyperstimulation syndrome suggests that ciglitazone may have a high potential as a therapeutic agent.

Troxacitabine is a synthetic nucleoside analogue. It is a poor substrate for nucleoside transporters and gains entry into cells by passive diffusion. Intracellular conversion to its active triphosphate form is via deoxycytidine kinase. Incorporation of this metabolite into DNA results in immediate chain termination and apoptosis induction. It is the first nucleoside analog with anticancer activity that has an unnatural stereochemical configuration. The dose-limiting adverse reactions were stomatitis and hand–foot syndrome.

Alvocidib (also known as Flavopiridol or HMR-1275) is a flavonoid alkaloid CDK9 kinase inhibitor under clinical development for the treatment of acute myeloid leukemia, by Tolero Pharmaceuticals, Inc. As a broad spectrum CDK inhibitor, Alvocidib can inhibit cell cycle progression in either G1 or G2 and induces G1 arrest in either MCF-7 or MDA-MB-468 cells by inhibition of the CDK4 or CDK2 kinase activity. Alvocidib exhibits potent cytotoxicity against a wide variety of tumor cell lines (LNCAP, HCT116, A2780, K562, PC3, and Mia PaCa-2) with IC50 values ranging from 16 nM for LNCAP to 130 nM for K562. Administration of Alvocidib at 7.5 mg/kg for 7 days displays slight antitumor activity against P388 murine leukemia, and active against the human A2780 ovarian carcinoma implanted sc in nude mice). Alvocidib treatment at 1-2.5 mg/kg for 10 days significantly suppresses collagen-induced arthritis in mice in a dose-dependent manner, by inhibiting synovial hyperplasia and joint destruction, whereas serum concentrations of anti-collagen type II (CII) Abs and proliferative responses to CII are maintained. Tolero Pharmaceuticals Inc. announced that the FDA has granted orphan drug designation for Alvocidib, its cyclin-dependent kinase small molecule inhibitor, for the treatment of patients with acute myeloid leukemia.

An orally bioavailable imidazopyridazine and inhibitor of Janus kinase 2 mutant V617F (JAK2V617F), with potential antineoplastic activity. Upon oral administration, gandotinib selectively and competitively inhibits the activation of JAK2V617F, which may result in the inhibition of the JAK-STAT signaling pathway and the induction of apoptosis in JAK2V617F-expressing tumor cells. Gandotinib is in phase II clinical trials by Lilly for the treatment of myeloproliferative disorders.

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.