Vicriviroc or SCH 417690 is a potent and selective antagonist of the CCR5 receptor. vicriviroc binds specifically to the CCR5 receptor and prevents infection of target cells by CCR5-tropic HIV-1 isolates. In antiviral assays, vicriviroc showed potent, broad-spectrum activity against genetically diverse and drug-resistant HIV-1 isolates and was consistently more active than SCH-C in inhibiting viral replication. This compound demonstrated synergistic anti-HIV activity in combination with drugs from all other classes of approved antiretrovirals. Competition binding assays revealed that vicriviroc binds with higher affinity to CCR5 than SCH-C. Functional assays, including inhibition of calcium flux, guanosine 5'-[35S]triphosphate exchange, and chemotaxis, confirmed that vicriviroc acts as a receptor antagonist by inhibiting signaling of CCR5 by chemokines. Finally, vicriviroc demonstrated diminished affinity for the human ether a-go-go related gene transcript ion channel compared to SCH-C, suggesting a reduced potential for cardiac effects. Vicriviroc represented a promising new candidate for the treatment of HIV-1 infection. Vicriviroc for HIV treatment was previously in Phase III studies but has since been discontinued.

Zibotentan (ZD4054) is a potent and specific orally available endothelin A (ETA) receptor antagonist, with no measurable affinity for endothelin B receptor. Activation of the ETA receptor by ET-1 has emerged as an important factor promoting tumor cell proliferation, survival, angiogenesis, migration, invasion, and metastasis in several tumor types. Zibotentan inhibits endothelin-mediated mechanisms that promote tumour cell proliferation. Zibotentan was being developed by AstraZeneca as treatment for heart failure, hormone resistant prostate cancer and other cancers including non-small cell lung, ovarian and breast cancer. However, following disappointing results from a phase III trial in patients with advanced prostate cancer, AstraZeneca decided to discontinue the development of zibotentan as a potential treatment for cancer. AstraZeneca undertook preclinical studies in the UK with zibotentan to investigate its potential as a treatment for heart failure. However, development for this indication has been discontinued.

Entinostat (MS-275) is an orally active, highly selective, small-molecule histone deacetylase inhibitor (HDACi) derived from benzamide. Entinostat preferentially inhibited HDAC1 versus HDAC3 and had no inhibitory activity toward HDAC8. The time to maximum plasma concentration (tmax) of entinostat ranged from 0.5 to 60h (median of 2h). Elimination of the drug was bi-exponential, with a terminal half-life of 30-80h. Entinostat is a well-tolerated that demonstrates promising therapeutic potential in both solid and hematologic malignancies. Its efficacy does not appear directly dose-related, and as such, more relevant biomarkers are needed to adequately assess its activity.

5-Fluoro-2-deoxycytidine is a fluorinated pyrimidine analog antimetabolite with potential antineoplastic activity. As a prodrug, 5-fluoro-2-deoxycytidine is converted by intracellular deaminases to the cytotoxic agent 5-fluorouracil (5-FU). 5-FU is subsequently metabolized to active metabolites including 5-fluoro-2-deoxyuridine monophosphate (FdUMP) and 5-fluorouridine triphosphate (FUTP). FdUMP binds to and inhibits thymidylate synthase, thereby reducing the production of thymidine monophosphate, which leads to depletion of thymidine triphosphate and the inhibition of DNA synthesis and cell division. FUTP competes with uridine triphosphate (UTP) for incorporation into the RNA strand, which results in the inhibition of RNA and protein synthesis and cell proliferation. 5-Fluoro-2-deoxycytidine undergoing trials to test its effectiveness in treating cancer that has not responded to standard therapies.

Seocalcitol (EB 1089) is a vitamin D analog, and agonist of the vitamin D receptor. Antineoplastic activity of seocalcitol was tested in clinical trials against hepatocellular carcinoma, pancreatic, breast and colorectal cancer. Due to inconsistent results of clinical trials, development of seocalcitol was discontinued by Leo Pharma.

Nafoxidine is a nonsteroidal antiestrogen available as an investigational agent from the Investigational Drug Branch of the National Cancer Institute. It has been used effectively in the treatment of breast cancer patients. Nafoxidine competes with endogenous estrogen for binding to specific estrogen receptors. This agent also inhibits angiogenesis in some tissues by blocking the effects of fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF); paradoxically, it may enhance angiogenesis in uterine tissue. Nafoxidine also induces oxidative stress, protein kinase C and calcium signaling.

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.

Galunisertib is a potent inhibitor of TGF beta type 1 receptor. The drug is under clinical development for the treatment of different cancers: pancreatic, hepatocellular, breast, rectal, prostate etc. and reached phase 2/3 in patients with myelodysplastic syndromes.

CI 1040 is an inhibitor of the mitogen-activated protein (MAP) kinase signal transduction pathway and has been shown to specifically inhibit MAP kinase kinase (MEK). CI 1040 was being developed by Parke-Davis (formerly a division of WarnerLambert, Now Pfizer) as an anticancer agent. It was the initial MEK inhibitor to undergo clinical evaluation based on promising preclinical activity. However, its development has been discontinued.

Dactolisib is a dual inhibitor of phosphatidylinositol 3-kinase (P13K) and the downstream mammalian target of rapamycin (mTOR) by binding to the ATP-binding cleft of these enzymes (inhibitor of PI3K/Akt/mTOR cascade). It is being investigated as a possible anti-cancer cancer agent and drug against Influenza virus infections. Frequently reported adverse events included nausea, vomiting, diarrhoea, fatigue/asthenia, anaemia, and anorexia.