Echinomycin is a cyclic peptide of the family of quinoxaline antibiotics that was originally isolated from Streptomyces echinatus. It is thought to act as a bifunctional DNA intercalator. Echinomycin has a binding site size of four base pairs. The strong binding sites for echinomycin contain the central two-base-pair sequence 5'-CG-3'. Echinomycin interferes with HIF-1 DNA binding in a sequence-specific fashion. It was brought into clinical trials by the NCI 20 years ago based on its antitumor activity. It has been extensively tested in phase I-II clinical trials. Nausea, vomiting, reversible liver enzyme abnormalities, and allergic reactions were the most common toxicities encountered. However, minimal or no antitumor activity was found in phase II clinical trials.

ICI-118,551 is a selective subtype β2 adrenergic receptor (adrenoreceptor) antagonist. ICI-118,551 binds to the β2 subtype with at least 100 times greater affinity than to other subtypes of the beta adrenoceptor β1 or β3. Pharmacological experiments proved that the right shift of the norepinephrine dose-response curve by ICI-118,551 was mediated via a beta(2)-adrenoceptor/G(i/o) protein-dependent pathway enhancing NO production in the endothelium. These results were corroborated in beta-adrenoceptor and endothelial NO synthase knockout mice where ICI had no effect. ICI-118,551 increased vascular lumen diameter in lung sections and reduced pulmonary arterial pressure under normoxia and under hypoxia in the isolated perfused lung model. These effects were found to be physiologically relevant, because ICI-118,551 specifically decreased pulmonary but not systemic blood pressure in vivo. Thus, it has been suggested that ICI-118,551 is a pulmonary arterial-specific vasorelaxant and might be a potential novel therapeutic agent for the treatment of pulmonary arterial hypertension. It was also demonstrated that systemic topical administration of ICI 118,551 results in decreased intraocular pressure in both eyes of rabbits, indicating that at least part of the ocular hypotensive effect of topical ICI 118,551 is mediated through systemic absorption. However, ICI 118,551 did not lower blood pressure in hypertensive patients known to respond to therapy with atenolol or propranolol.

2-(4,6-DIMETHYLPYRIMIDIN-2-YL)-5-((2-FLUORO-6-(2H-1,2,3-TRIAZOL-2-YL)PHENYL)CARBONYL)OCTAHYDROPYRROLO(3,4-C)PYRROLE (Seltorexant, MIN 202), a small molecule, selective orexin receptor type-2 antagonist, is being developed by Minerva Neurosciences and Janssen Research & Development for the treatment of insomnia and major depressive disorder. Seltorexant has shown high in vitro affinity (affinity pKi =8.0 and 6.1 for OX2R and OX1R respectively) for the human OX2R and approximates two logs selectivity ratio versus its affinity for the OX1R. Seltorexant demonstrated a dose-dependent normalization of sleep and a trend towards improvement of subjective depressive symptoms in antidepressant-treated MDD patients with residual insomnia. Additionally, seltorexant’s favorable PK profile as a potential sedative-hypnotic drug was confirmed in a MDD population and did not demonstrate unacceptable adverse events or unwanted next-day CNS effects. Seltorexant is in phase II clinical trials for both insomnia and MDD.

1‐α‐D‐(5‐Fluoro‐5‐deoxyarabinofuranosyl)‐2‐nitroimidazole (fluoroazomycin arabinoside, FAZA) is a putative PET imaging agent when labelled with 18F. Fluoroazomycin arabinoside is essential in the generation of fluorine F 18-fluoroazomycin arabinoside (18F-FAZA), which is a radiofluorinated 2-nitroimidazole derivative with hypoxia (low oxygen)-specific tracer activity. 18F-FAZA is reduced under hypoxic conditions, forming highly reactive intermediates. In its reduced form, 18F-FAZA covalently binds to macromolecules, thereby accumulating in hypoxic cells (e.g. malignant tumors) and allowing radioisotopic imaging of these particular cells with positron emission tomography (PET).

CUDC-305, is a novel heat shock protein 90 (HSP90) inhibitor with strong affinity for HSP90 alpha/beta, high oral bioavailability and potent anti-proliferative activity against a broad range of cancer cell lines (with a mean IC50 of 220 nmol/L), including many non-small cell lung cancer (NSCLC) cell lines which are resistant to standard-of-care (SOC) agents. In both laboratory and animal testing, CUDC-305 demonstrated high potency in vitro and/or in vivo across a wide range of cancers. Most notably, Curis scientists observed complete tumor regression following oral administration of CUDC-305 in a mouse xenograft model of acute myelogenous leukemia (AML). Tumor regression has also been observed after treatment of CUDC-305 in mouse xenograft models of breast, non-small cell lung, gastric cancer and glioblastoma brain cancers. In this preclinical testing, the compound also demonstrated an ability to effectively cross the blood brain barrier, and demonstrated an ability to extend survival in an intracranial glioblastoma model. Early stage toxicity studies suggest that CUDC-305 appears to have a better therapeutic window than several leading Hsp90 inhibitors in clinical development.

SGX523 is a selective, ATP-competitive inhibitor of the MET receptor tyrosine kinase. SGX523 was able to inhibit HGF-induced cell migration and cell scatter. SGX523 inhibition of MET in vivo was associated with the dose-dependent inhibition of growth of tumor xenografts derived from human glioblastoma and lung and gastric cancers. The clinical development of SGX523, however, was discontinued at Phase I due to renal toxicity manifested by an early rise of serum blood urea nitrogen and creatinine.

TAK-960 is a novel, investigational, orally bioavailable, potent, and selective PLK1 inhibitor(IC50=1.5 nM) that has shown activity in several tumor cell lines, including those that express multidrug-resistant protein 1 (MDR1). In animal models, oral administration of TAK-960 increased pHH3 in a dose-dependent manner and significantly inhibited the growth of HT-29 colorectal cancer xenografts. Treatment with once daily TAK-960 exhibited significant efficacy against multiple tumor xenografts, including an adriamycin/paclitaxel-resistant xenograft model and a disseminated leukemia model. TAK-960 had been in phase I clinical trials by Takeda for the treatment of solid tumours. It had also been in preclinical trials for the treatment of acute myeloid leukaemia. However, these studies were discontinued.