Etanidazole (also known as Radinyl) is a 2-nitroimidazole with radiosensitizing properties. Etanidazole exerts its therapeutic action by depleting glutathione and inhibiting glutathione S-transferase, thus enhancing the anticancer effects of radiation therapy. Etanidazole was tested in Phase III clinical trials in patients with advanced head and neck cancer, however, its development was stopped. A fluorinated etanidazole (EF5) may also be useful as an imaging agent for identification of hypoxic, drug-resistant regions of primary tumors and metastases.

Combretastatin A4 is a vascular disrupting agent (VDA) that targets tumor vasculature to inhibit angiogenesis. Combretastatin A4 is a tubulin-binding agent that binds at or near the colchicine binding site of β-tubulin and inhibits tubulin assembly. This tubulin-binding agent was originally isolated from an African shrub, Combretum caffrum. Combretastatin A4 is cytotoxic to umbilical-vein endothelial cells (HUVECs) and to a range of cells derived from primary tumors and these cytotoxicity profiles have been used to assess several novel analogs of the drug for future development. Combretastatin A4 has antitumor activity by inhibiting AKT function. The inhibited AKT activation causes decreased cell proliferation, cell cycle arrest, and reduced in vitro migration/invasiveness and in vivo metastatic ability. Several studies in mice have shown that a single administration of combretastatin A4 (100 mg/kg) does not significantly affect primary tumor growth. However, repeated administration (12.5 – 25.0mg/kg twice daily) for periods of 10 – 20 days resulted in approximately 50% retardation of growth of ectopic Lewis lung carcinoma and substantial growth delay of T138 spontaneous murine breast tumors. In clinical studies, Combretastatin A4 has been well tolerated in patients at doses up to 56 mg/m2, following a protocol of five daily 10-minute intravenous infusions every 21 days. The disodium combretastatin A4 phosphate prodrug is currently undergoing clinical trials in the UK and USA.

Exisulind (tentative trade name Aptosyn) is an antineoplastic agent, which was originally developed by Cell Pathways. This drug is an inhibitor of phosphodiesterase (PDE) isozymes: PDE5 and PDE4. Inhibition of PDE5 appears to be pharmacologically relevant, which leads to increase cGMP and activate protein kinase G at doses that induce apoptosis, whereas cyclic AMP levels were not changed. Exisulind has been in phase III clinical trials for the treatment of Non-Small Cell Lung Cancer and for the treatment of polyps in patients who have familial adenomatous polyposis (Colorectal Cancer and Small Intestine Cancer). In addition, this drug was in phase II/III for the treatment of Prostate Cancer, however, there studies have been discontinued.

Otenabant (CP-945,598) is Pfizer developed as a potent and selective cannabinoid receptor CB1 antagonist with Ki of 0.7 nM, which exhibits 10,000-fold greater selectivity against human CB2 receptor, for treatment of obesity. In clinical trial III Pfizer decided to discontinue the development program based on changing regulatory perspectives on the risk/benefit profile of the CB1 class and likely new regulatory requirements for approval.

Dexpramipexole (also known as KNS-760704/R-pramipexole) was originally developed by University of Virginia researchers to treat Amyotrophic Lateral Sclerosis and then was licensed to global biotechnology company Biogen Idec for further development. However, on phase III clinical trial the study of this drug was discontinued. Biogen said the drug neither slowed the loss of muscle function nor prolonged the lives of patients with ALS, often called Lou Gehrig’s disease. Nor did it show any efficacy in secondary endpoints of the clinical trial, or work in any sub-group of patients—about a big a failure as a company could have a Phase III trial. In addition, was discovered, that dexpramipexole was able to bind to beta-subunit of the mitochondrial F1/FO ATP synthase complex and increased its activity, thus reduced ischemic brain injury. These findings, together with the excellent brain penetration and favorable safety profile in humans, make dexpramipexole a drug with realistic translational potential for the treatment of stroke.

Amibegron (SR 58611A or SR 58611) is a highly selective agonist for atypical beta3-adrenoceptors. It stimulates neuronal activity in a specific area of the prefrontal cortex and also inhibits intestinal motility. Amibegron was in phase III trials worldwide for the treatment of depression and generalised anxiety disorder but development of the product was discontinued in 2008. Amibegron has been tested for its potential as a treatment for irritable bowel syndrome.

Eterobarb (Antilon) is a barbiturate derivative. It is an effective anticonvulsant as demonstrated in animal and clinical studies. Eterobarb possesses a unique and clinically intriguing feature-at therapeutically effective blood levels, the hypnotic side effects usually associated with barbiturates appear absent. Though effective against both electrically and chemically induced seizures in mice and rats, virtually no hypnotic effects were noted except at lethal doses. Double-blind cross-over studies have confirmed the anticonvulsant efficacy of eterobarb and several phase II and phase Ill studies show eterobarb to be an effective anticonvulsant with less hypnotic activity when compared with phenobarbital. Eterobarb had been NDA filed for the treatment of epilepsy in the US, UK, Switzerland and Canada. However, this research has been discontinued. The compound was originated by Colgate Palmolive, then licensed to MacroChem.

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.

Azeliragon is an orally bioavailable small molecule that inhibits the receptor for advanced glycation endproducts (RAGE). RAGE has been proposed to contribute to Alzheimer's disease pathology by promoting vascular leakage, promoting influx of peripheral amyloid beta into brain, mediating amyloid beta induced oxidative stress, mediating AGE induced hyperphosphorylation of tau and amyloid beta mediated neuronal death. Azeliragon is in Phase III clinical trial for the treatment of mild Alzheimer's disease.

Tarenflurbil (Flurizan or R-flurbiprofen) is the single enantiomer of the racemate NSAID flurbiprofen. Tarenflurbil is a first in class, selective amyloid-beta42 (A42) lowering agent (SALA), which acts by modulating the activity of gamma-secretase, an enzyme that converts amyloid precursor protein to amyloid-beta. The reduction of A42 may prevent the development of the amyloid plaques thought to be a key pathological process associated with Alzheimer’s disease. For several years, research and trials for the drug were conducted by Myriad Genetics, to investigate its potential as a treatment for Alzheimer's disease. In a brief statement issued June 30, Myriad Genetics reports that tarenflurbil (Flurizan) failed to have a significant effect in a phase 3 trial of patients with mild Alzheimer's disease (AD). The failure of Flurizan™ is generally attributed to its insufficient pharmacodynamics, i.e., inadequate ability to penetrate the brain and engage its target protein at doses sufficient to yield an effect. Two additional Phase 3 trials were terminated and further development of Flurizan™ was discontinued. Separate clinical development of Flurizan™ for prostate cancer has also been discontinued following negative Phase 2 results. Tarenflurbil activates c-Jun N terminal kinase, increases AP-1 binding to DNA, and downregulates cyclin D1 expression, resulting in the arrest of tumour cells in the G1 phase of the cell cycle and apoptosis. This agent also affects the expression of nuclear factor kappa B, a rapid response transcription factor that stimulates the immune response to tumour cells. Tarenflurbil does not inhibit the enzyme cyclooxygenase. The Fraunhofer Institute for Molecular Biology and Applied Ecology is currently developing tarenflurbil for the treatment of relapsing, remitting multiple sclerosis.