Eltanexor (KPT-8602) is an investigational second-generation Selective Inhibitor of Nuclear Export (SINE) compound that is designed to selectively block the nuclear export protein XPO1. Most of the key tumor suppressor proteins (TSPs), are cargos of XPO1 and inhibition of XPO1 by eltanexor is believed to sequester TSPs in the nucleus where they can carry out their normal functions. Karyopharm Therapeutics is developing eltanexor for the treatment of relapsed/refractory cancers.

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.

Seliciclib (CYC202, R-roscovitine) is a second-generation orally available cyclin-dependent kinases (CDKs) inhibitor that competes for ATP binding sites on these kinases. It is a direct inhibitor of cyclin CDK2/E, CDK2/A and it has inhibitory effects on cyclin H/CDK7, CDK5, and CDK9. CDKs are enzymes that are central to the process of cell division and cell cycle control and play pivotal roles in cancer cell growth and DNA damage repair. Seliciclib exerts an anti-proliferative effect via several key mechanisms: selective downregulation of proliferative and survival proteins and upregulation of p53, leading to growth arrest or apoptosis. The second one is decreasing phosphorylation of Rb and modulating E2F transcriptional activity leading to growth arrest or apoptosis. Seliciclib is currently in phase II clinical trial as a drug candidate for the treatment of Cushing's disease and as a potential therapeutic agent for the treatment of cystic fibrosis (CF). In addition, it is in Phase II trials for non-small cell lung cancer and nasopharyngeal carcinoma.

Nitecapone (3-(3,4-dihydroxy-5-nitrobenzylidine)-2,4- pentanedione, OR-462) is a selective, short-acting catechol-O-methyltransferase (COMT) inhibitor, whose main site of action is in the gastrointestinal tract. Nitecapone displays in vivo activity in peripheral tissues but does not penetrate the blood-brain barrier. The compound increases mechanical and thermal nociception and reduces neuropathic pain in diabetic rats and in a spinal nerve ligation model. Nitecapone has been shown to have a protective effect against ischemia-reperfusion injury in experimental heart transplantation and in Langendorff preparations. Nitecapone added to cardioplegia solution reduces cardiac neutrophil accumulation and transcoronary neutrophil activation during clinical cardiopulmonary bypass. Reflected by better left ventricular stroke volume, nitecapone treatment may be an additional way of reducing the deleterious effects of neutrophil activation during cardiopulmonary bypass. Nitecapone was patented as an antiparkinsonian agent but was never marketed.

Temelastine (also known as SK&F 93944) is a competitive histamine H1-receptor antagonist, which does not penetrate the central nervous system. This drug was studied as an anti-allergic agent. Experiments on animals have shown that the drug was efficacious vs. pharmacologic and antigen-induced bronchoconstriction.

Nitracrine (Ledakrin, C-283) is an acridine derivative with potential cytostatic and antitumor activities. Nitracrine induces the unwinding of supercoiled DNA and binds to the DNA through intercalation, forming drug-DNA adducts and DNA interstrand crosslinks. This inhibits RNA synthesis, protein production, cell growth, DNA replication and cell proliferation; altogether, this may promote apoptosis. Since cancer cells have increased metabolism and proliferate at an increased rate, nitracrine may induce tumor cell apoptosis. The drug was used in clinics in Poland for the treatment of ovarian, colon, lung and mammary carcinomas. Some undesirable effects observed in clinics: e.g. nausea, vomiting and toxicity and mutagenicity of the drug in S. typhimurium strongly limited the therapeutic use of nitracrine and promoted a search for more suitable analogues.

VX-702 is a highly selective inhibitor of p38α MAPK kinase, developed by Vertex Pharmaceuticals Inc in collaboration with Kissei Pharmaceuticals Co. Ltd for potential treatment of inflammation, rheumatoid arthritis and cardiovascular diseases. VX-702 was evaluated in two phase II clinical trials against rheumatoid arthritis, but its development was discontinued by Vertex.

Omipalisib, also known as GSK2126458, is a small-molecule pyridylsulfonamide inhibitor of phosphatidylinositol 3-kinase (PI3K) with potential antineoplastic activity. Omipalisib (GSK2126458, GSK458) is a highly selective and potent inhibitor of p110α/β/δ/γ, mTORC1/2 with Ki of 0.019 nM/0.13 nM/0.024 nM/0.06 nM and 0.18 nM/0.3 nM in cell-free assays, respectively. It is also a low picomolar inhibitor of the common activating mutants of p110a (E542K, E545K, and H1047R) found in human cancer. Omipalisib (GSK2126458) binds to and inhibits PI3K in the PI3K/mTOR signaling pathway, which may trigger the translocation of cytosolic Bax to the mitochondrial outer membrane, increasing mitochondrial membrane permeability and inducing apoptotic cell death. Bax is a member of the proapoptotic Bcl2 family of proteins. PI3K, often overexpressed in cancer cells, plays a crucial role in tumor cell regulation and survival. GlaxoSmithKline (GSK) is developing omipalisib, a phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) inhibitor as well as mTOR complex 1 and 2 inhibitor, for the potential oral treatment of cancer and idiopathic pulmonary fibrosis.

SAR-405838 is an inhibitor of the interaction between the oncoprotein murine double minute 2 (MDM2) and p53. SAR-405838 was investigated in phase I clinical trials in patients with locally advanced/metastatic solid tumor with wild-type TP53 or with TP53 mutation prevalence below 40%. SAR-405838 had an acceptable safety profile with limited activity in patients with advanced solid tumors.

Clevudine F18 is a radioconjugate comprised of the synthetic pyrimidine analog clevudine (1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)thymine, d-FMAU) labeled with the radioisotope fluorine F18. Upon administration, fluorine F18 clevudine is distributed and taken up by cells based on the rate of the cell’s DNA synthesis. The amount is then measured using positron emission tomography (PET). The compound is investigated as an imaging agent in prostate, breast cancers, and other malignant neoplasms.