Mureletecan is a water-soluble prodrug, consisting of camptothecin covalently linked to polymeric backbone methacryloylglycynamide, with potential antineoplastic activity. After entering tumor cells, the active moiety camptothecin is slowly released from mureletecan via hydrolysis of the ester linkage. Camptothecin, the active moiety, is an alkaloid isolatable from the Chinese tree Camptotheca acuminata. Camptothecin itself suffers from poor solubility, which is why it is often investigated with a solubilizing conjugate; such as in Mureletecan. Camptothecin binds to and stabilizes the topoisomerase I-DNA covalent complex producing potentially lethal double-stranded DNA breaks when encountered by DNA replication machinery. Camptothecin has also been shown to inhibit HIF1a. Camptothecin has been investigated with a number of solubilizing conjugates as a potential treatment in various forms of cancer.

Rebeccamycin analog (RA, Becatecarin/ BMS 181176, rebeccamycin derivative, NSC 655649) is an antitumor antibiotic with inhibitory activity against both topoisomerase I and II, and DNA-intercalating properties. The mechanism of action of becatecarin is not exactly known, but it is thought that by inhibiting (blocking) the function of topoisomerase enzymes, it will destroy cancer cells and slow down the growth of the tumour. On 25 July 2006, orphan designation (EU/3/06/388) was granted by the European Commission to Helsinn Birex Pharmaceuticals Ltd, Ireland, for becatecarin for the treatment of cancers of the biliary tree.

Dotarizine was developed as antimigraineur. Dotarizine inhibited the 5-HT2A response in a concentration-dependent manner. The mechanism of blockade by dotarizine of cerebral vessels contractility has three components: (i) presynaptic inhibition of noradrenaline release; (ii) blockade of postsynaptic vascular 5-HT receptors; (iii) blockade of Ca(2+)entry into the vascular smooth muscle cell cytosol. The compound does not affect the vascular receptors for noradrenaline, angiotensin II or prostaglandin F(2alpha). Dotarizine had a pronounced protective effect against electric seizures.

Carboxyamidotriazole (L651582) is a carboxyamide-amino-imidazole compound originally developed as a coccidiostat, an antiprotozoal agent that acts upon Coccidia parasites. Carboxyamidotriazole (L651582) is an orally-active agent with potential antineoplastic activity. Carboxyamidotriazole binds to and inhibits non-voltage-operated Ca2 channels, blocking both Ca2 influx into cells and Ca2 release from intracellular stores and resulting in the disruption of calcium channel-mediated signal transduction and inhibition of vascular endothelial growth factor (VEGF) signaling, endothelial proliferation, and angiogenesis. This agent may also inhibit tumor cell growth, invasion, and metastasis.

Safingol, the synthetic L-threo-stereoisomer of endogenous (D-erythro-) sphinganine, is an inhibitor of protein kinase C and sphingosine kinase in vitro, and in some cell types has been implicated in ceramide generation and induction of apoptosis. Safingol inhibits enzymatic activity and 3H-phorbol dibutyrate binding of purified rat brain PKC (IC50 = 37.5 uM and 31uM, respectively). Inhibits human PKCα, the major overexpressed isoenzyme in MCF-7 DOXR cells (IC50 = 40 uM). Safingol enhances the cytotoxic effect of the chemotherapeutic agent Mitomycin C (MMC) in gastric cancer cells by promoting drug-induced apoptosis. Safingol is an inhibitor of SphK (Sphingosine kinase). Safingol has been shown to act synergistically with other chemotherapeutic agents and may potentiate chemotherapy drug-induced apoptosis in vitro and in vivo.

Elesclomol (also known as STA-4783), originally identified in a cell-based phenotypic screen for pro-apoptotic activity, is a novel small-molecule that potently induces apoptosis of cancer cells through the rapid generation of reactive oxygen species (ROS) and the induction of unmanageable levels of oxidative stress. Elesclomol exhibits antitumor activity against a broad spectrum of types of cancer cell in human tumour xenograft models due to its excessive ROS production and elevated levels of oxidative stress leading to the death of cancer cells. Elesclomol is currently being studied as novel cancer therapeutic, in which it has demonstrated the ability to prolong progression-free survival in study subjects. Elesclomol induces oxidative stress by provoking a buildup of reactive oxygen species within cancer cells. Elesclomol requires a redox-active metal ion to function; the Cu(II) complex is 34 times more potent than the Ni(II) complex and 1040-fold more potent than the Pt(II) complex. Elesclomol is an HSP-90 Inhibitor with pro-apoptotic and potential antineoplastic activities. Elesclomol induces oxidative stress and triggers mitochondrial-induced apoptosis in cancer cells. Elesclomol is being developed by Synta Pharmaceuticals and GlaxoSmithKline as a chemotherapy adjuvant and has received both fast track and orphan drug status from the U.S. Food and Drug Administration for the treatment of metastatic melanoma. Synta Pharmaceuticals announced on February 26, 2009, the suspension of all clinical trials involving Elesclomol due to safety concerns. In March 2010, Synta announced that the FDA had approved resuming clinical development of elesclomol, and that they expected to initiate one or more clinical trials for elesclomol in the second half of the year. In a small, randomized phase II study, elesclomol was shown to significantly increase progression-free survival in people with metastatic melanoma when given in addition to paclitaxel (Taxol).

Tumor hypoxia remains one of the greatest challenges in the treatment of solid tumors, as cancer cells in these regions are resistant to killing by radiation therapy and most anticancer drugs. Tirapazamine (3-Amino-1,2,4-benzotriazine-1,4-dioxide or SR 4233) is a cytotoxic drug with selective toxicity towards hypoxic mammalian cells. Under both aerobic and hypoxic conditions, tirapazamine is reduced by an intracellular reductase to form a highly reactive radical, which can cause DNA single- and double-strand breaks. In addition, tirapazamine under hypoxic conditions reduces the activity of topoisomerase II and stabilizes DNA topoisomerase II cleavable complexes, and these complexes remain bound to DNA. Despite the very promising results obtained in various preclinical studies and early-Phase clinical trials, several Phase III trials have failed to demonstrate any survival benefit of adding tirapazamine to chemotherapy or radiation therapy of cancers.

Cevipabulin is a synthetic, water-soluble tubulin-binding agent with potential antineoplastic activity. Cevipabulin appears to bind at the vinca-binding site on tubulin but seems to act more similar to taxane-site binding agents in that it enhances tubulin polymerization and does not induce tubulin depolymerization. The disruption in microtubule dynamics may eventually inhibit cell division and reduce cellular growth.

Morazone is is a nonsteroidal anti-inflammatory drug (NSAID), originally developed by the German pharmaceutical company Ravensberg in the 1950s. Morazone was used as a moderately strong analgesic but was discontinued due to high abuse potential