Quiflapon Sodium (MK-0591; (3-[1-(4-chlorobenzyl)-3-(t-butylthio)-5-(quinolin-2-yl-methoxy)- indol-2-yl]-2,2-dimethyl propanoic acid, previously L-686,708) had been in phase II clinical studies for the treatment of inflammatory bowel disease, but the study was discontinued later, because in spite of MK-591 markedly inhibited Leukotrienes (LT) biosynthesis, it did not differ significantly from placebo in clinical efficacy. Also was discovered, that MK-0591 may modify the airway changes associated with bronchial hyper responsiveness, as well as offer symptomatic relief in asthma. MK-0591 is a selective and specific 5-Lipoxygenase-activating protein (FLAP) inhibitor with an IC50 value of 1.6 nM in a FLAP binding assay. In additional, recently was discovered, that MK591 possesses all major attributes of a standard anti-metastatic agent with significant cancer-selective effect, and suggest that MK591 may turn out to be an effective agent for therapy of castration-resistant, bone-metastatic prostate cancer. Though details of the molecular underpinnings of the anti-metastatic action of MK591 are unknown at this time, this finding gives an opportunity for further exploration to better understand the signaling mechanisms involved by in vitro and in vivo experiments.

Ganstigmine is an orally active, carbamate-based acetylcholinesterase (AChE) inhibitor developed for the treatment of Alzheimer's disease. It is a newer generation AChE than BChE inhibitor, derived from genserine, and has a long duration of action in vivo. Studies have shown it significantly prevented the progressive neuronal cell death due to growth factor deprivation and decreased neurodegeneration. Ganstigmine may be a suitable candidate for the treatment of cholinergic deficit in Alzheimer's disease because it was found to significantly increase basal extracellular concentrations of acetylcholine in rat prefrontal cortex, and does not affect the concentrations of serotonin, noradrenaline and levels of dopamine and metabolites. It is safe and well tolerated at 5–10 mg doses as the study conducted in Phase I randomized, double-blind, placebo-controlled clinical trial. It was dropped from phase II trials because of its adverse effects reported in some patients.

NMS-P937 is a selective PLK1 inhibitor. It was developed by Nerviano Medical Sciences and tested in phase I clinical trials.

Tanzisertib (CC-930) is a potent and selective inhibitor of JNK1/JNK2/JNK3 with IC50 values of 61 nM, 7 nM and 6 nM respectively. Tanzisertib had been in phase II clinical trials for the treatment of idiopathic pulmonary fibrosis and discoid lupus erythematosus. But this research was discontinued in 2012. In 2011, the compound was granted orphan drug designation in the U.S. and the E.U. for the treatment of idiopathic pulmonary fibrosis. The compound was co-developed by Celgene and Ligand.

Otsuka Pharmaceutical Co developed tetomilast, a thiazole derivative for the treatment of inflammatory bowel disease and chronic obstructive pulmonary disease. Tetomilast acts as a selective inhibitor of phosphodiesterase-4 results in increased intracellular levels of cyclic adenosine monophosphate (cAMP), and subsequent anti-inflammatory effects. Specifically, the release of pro-inflammatory mediators including TNF-a and IL-12 is suppressed, and there is stimulation of the release of anti-inflammatory mediators including IL-10 and prostaglandin E2. Unfortunately, tetomilast clinical trials in patients with ulcerative colitis failed to demonstrate superior efficacy compared to mesalamine and further development of tetomilast was discontinued.

Tolafentrine is phosphodiesterase 3/4 (PDE3/4) inhibitor. Treatment of endothelial cells with tolafentrine significantly decreased asymmetrical dimethylarginine-induced apoptosis via a cAMP/PKA-dependent pathway by induction of dimethylarginine dimethylaminohydrolase 2 (DDAH2). Chronic nebulization of PDE3/4 inhibitor significantly attenuated monocrotaline-induced hemodynamic, gas exchange abnormalities, vascular remodeling, and right heart hypertrophy. When chronically nebulized from day 28 to 42 (12 daily aerosol maneuvers), after full establishment of severe pulmonary hypertension, tolafentrine reversed about 60% of all hemodynamic abnormalities in rats, right heart hypertrophy and monocrotaline-induced structural lung vascular changes, including the proportion of pulmonary artery muscularization. Tolafentrine was developed as therapeutic agent for the treatment of asthma. However, this development was discontinued.

Lometrexol, formerly known as DDATHF; LY 264618; T-64 was the first glycinamide ribonucleotide formyl transferase (GARFT) inhibitor to be investigated clinically. Lometrexol had been in phase II clinical trial for the treatment non-small cell lung cancer (NSCLC). However, the studies have been discontinued by Tularik Inc, because Company had suggested, that drug would face competition from other companies in the indication

Barasertib (AZD1152) is a dihydrogen phosphate prodrug of a pyrazoloquinazoline Aurora kinase inhibitor [AZD1152–hydroxyquinazoline pyrazol anilide (HQPA)] and is converted rapidly to the active AZD1152-HQPA in plasma. AstraZeneca was developing the aurora kinase inhibitor, barasertib (AZD 1152) as a therapeutic for cancer. AZD1152-HQPA is a highly potent and selective inhibitor of Aurora B (Ki, 0.36nmol/L) compared with Aurora A (Ki, 1,369nmol/L) and has a high specificity versus a panel of 50 other kinases. Consistent with inhibition of Aurora B kinase, addition of AZD1152-HQPA to tumour cells in vitro induces chromosome misalignment, prevents cell division, and consequently reduces cell viability and induces apoptosis. Barasertib (AZD1152) potently inhibited the growth of human colon, lung, and haematologic tumour xenografts (mean tumour growth inhibition range, 55% to ≥100%; P < 0.05) in immunodeficient mice. Detailed pharmacodynamic analysis in colorectal SW620 tumour-bearing athymic rats treated i.v. with Barasertib (AZD1152) revealed a temporal sequence of phenotypic events in tumours: transient suppression of histone H3 phosphorylation followed by accumulation of 4N DNA in cells (2.4-fold higher compared with controls) and then an increased proportion of polyploid cells (>4N DNA, 2.3-fold higher compared with controls). Histologic analysis showed aberrant cell division that was concurrent with an increase in apoptosis in AZD1152-treated tumours. Bone marrow analyses revealed transient myelosuppression with the drug that was fully reversible following cessation of Barasertib (AZD1152) treatment. Barasertib (AZD1152) was in phase III for the treatment of Acute myeloid leukaemia, but later these studies were discontinued.

Indimitecan, also known as LMP776, is a novel topoisomerase I inhibitor. A substance being studied in the treatment of cancer. It blocks certain enzymes that break and rejoin DNA strands. These enzymes are needed for cells to divide and grow. Blocking them may cause cancer cells to die. Indimitecan (LMP776) also helps anticancer drugs kill cancers that are resistant to some other drugs. LMP776 is a type of indenoisoquinoline and a type of topoisomerase inhibitor. In vitro, LMP776 induces TOP 1 cleavage at unique genomic positions and causes cell cycle arrest in both S and G (2)-M phases. Protein linked DNA breaks were observed in cells treated with nanomolar concentrations of LMP776.

LAPISTERIDE is an inhibitor of 5alpha-reductase (5aR), converting testosterone to the more potent androgen dihydrotestosterone. It has dual inhibitory activity on both 5aR isoenzymes. It was under investigation for the treatment of benign prostatic hyperplasia and androgenic alopecia, but its development was discontinued.