Marimastat is a broad spectrum matrix metalloprotease (MMP) inhibitor. It is an angiogenesis and metastasis inhibitor. It mimics the peptide structure of natural MMP substrates and binds to matrix metalloproteases, thereby preventing the degradation of the basement membrane by these proteases. This antiprotease action prevents the migration of endothelial cells needed to form new blood vessels. Inhibition of MMPs also prevents the entry and exit of tumor cells into existing blood cells, thereby preventing metastasis. Marimastat has been in pivotal phase III trials in glioblastoma, breast, ovarian and small and non-small cell lung cancer, but these trials have all been discontinued because marimastat failed to show superior efficacy over either standard chemotherapy or placebo.

MKC-1 is an orally available cell cycle inhibitor with downstream targets that include tubulin and the importin-β family. MKC-1 has shown broad antitumor activity in preclinical models. MKC-1 and its metabolites inhibit tubulin polymerization, blocking the formation of the mitotic spindle, which may result in cell cycle arrest at the G2/M phase and apoptosis. In addition, this agent has been shown to inhibit the activities of the oncogenic kinase Akt, the mTOR pathway, and importin-beta, a protein essential to the transport of other proteins from the cytosol into the nucleus. MKC-1 had been in phase II clinical trials for the treatment of ovarian cancer, endometrial cancer, pancreatic cancer and breast cancer. This compound was originally discovered by Roche, then licensed to EntreMed (now CASI Pharmaceuticals) the exclusive worldwide rights to develop and commercialize. However, no recent development has been reported.

Tipifarnib is an oral farnesyltransferase (FTase) inhibitor which was developed by Janssen (J&J). Upon administration, tipifarnib inhibits FTase and thus suppresses the activity of downstream effectors. The drug reached phase III of clinical trials for such diseases as pancreatic cancer (terminated), colorectal cancer (terminated) and acute myeloid leukemia (in elderly patients).

R-etodolac (SDX-101) is the non-cyclooxygenase 2-inhibiting R-enantiomer of the non-steroid anti-inflammatory drug etodolac (1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid). The absolute configuration of the enantiomer is R-(-)-etodolac. R-etodolac specifically bound retinoid X receptor (RXRalpha), inhibited RXRalpha transcriptional activity, and induced its degradation by a ubiquitin and proteasome-dependent pathway. In addition R-etodolac can disrupt the beta-catenin signaling pathway. R-etodolac exerts antineoplastic properties. R-etodolac was in phase 2 studies for the treatment of hematologic malignancies however development was discontinued.

Rabusertib is a Chk1 kinase inhibitor which was developed by ICOS for the treatment of cancer. The drug was tested in phase II of clinical trials for pancreatic cancer and non small cell lung carcinoma, but its development was discontinued. Now the drug is undergoing phase I trial in Japanese patients with solid tumors.

Nefiracetam is a cyclic derivative of gamma-aminobutyric acid (GABA). It is thought to act by normalising dysfunctional acetylcholine, GABA and possibly monoamine neurotransmitter systems, but it may also facilitate N/L-type calcium channel opening. Nefiracetam has received attention as a treatment for seizures, depression, and dementia. Nefiracetam was found to be extremely testicular toxic in both rats and dogs; it was found to significantly decrease the levels of testicular testosterone leading to atrophy and malformation of sperm.

GV 150526A (gavestinel) is an investigational drug for a neuroprotective therapy of acute ischemic stroke within 6 hours of symptom onset. It is a potent and selective non-competitive antagonist at the glycine site of the N-methyl-D-aspartate receptor (NMDA) which reduces infarct volume in experimental stroke models. Gavestinel acts at the strychnine-insensitive glycine binding site of the NMDA receptor-channel complex with nanomolar affinity (pKi = 8.5), coupled with high glutamate receptor selectivity. Gavestinel displays higher than 1000-fold selectivity over NMDA, AMPA and kainate binding sites and is orally bioavailable and active in vivo. GV 150526A inhibited convulsions induced by NMDA in mice, when administered by both IV and po routes (ED50 = 0.06 and 6 mg/kg, respectively). The safety and efficacy of GV150526 were studied in two phase III randomized placebo-controlled clinical trials of acute ischemic stroke patients within 6 h from onset [The Glycine Antagonist in Neuroprotection (GAIN) International and GAIN Americas Trials] sponsored by GlaxoSmithKline. The results of these trials suggested that gavestinel was not of substantial benefit or harm to patients with primary intracerebral hemorrhage.

Idalopirdine (Lu AE58054) is a Serotonin 6 receptor (5-HT6) antagonist. Idalopirdine exrets good oral bioavailability and robust efficacy in a rat model of cognitive impairment in schizophrenia. In rats idalopirdine potentiates the effects of acetylcholinesterase inhibitor donepezil on two pharmacodynamic biomarkers associated with cognition, i.e. neuronal oscillations and extracellular ACh levels in the hippocampus. Such potentiation could contribute to the procognitive effects of idalopirdine observed in donepezil-treated Alzheimer's disease patients. The compound is being developed by Lundbeck as an adjunctive therapy with acetylcholinesterase inhibitor donepezil, and is in phase III development for the treatment of Alzheimer's disease in multiple countries worldwide. A phase II trial for the treatment of cognitive impairment associated with schizophrenia was conducted; however no recent reports of development for idalopirdine have been identified.

Sanguinarine is an extract of the bloodroot plant Sanguinaria canadensis, a member of the poppy family. It is an inhibitor of protein phosphatases PP1, PP2C and PP2B in vitro. Also inhibits mitogen-activated protein kinase phosphatase-1 (MKP-1) and other enzymes. Sanguinarine exerts a protective effect in cerebral ischemia, and this effect is associated with its anti-inflammatory and anti-apoptotic properties. It was clinically tested as an agent against gingivitis and tooth plaques.

18alpha-Glycyrrhetinic acid (18-GA), a derivative of enoxolone, is used to inhibit gap junctions and furthermore, it has anti-proliferative properties against various cancer types by affecting the cell cycle proteins. 18alpha-Glycyrrhetinic acid, is a non-selective inhibitor of 11beta-hydroxysteroid dehydrogenases isozymes and results in increased whole body insulin sensitivity and decreased glucose production.