Evofosfamide, also formerly known as TH-302, is an investigational hypoxia-activated prodrug and is used to target cancerous cells under hypoxic conditions, which is a feature possessed by multiple solid tumors including glioblastoma and pancreatic cancer. Within regions of tumor hypoxia, evofosfamide releases bromo isophosphoramide mustard (Br-IPM), a potent DNA alkylating agent that kills tumor cells by forming DNA crosslinks. Once activated in hypoxic tissues, Br-IPM can also diffuse into surrounding oxygenated regions of the tumor and kill cells there via a “bystander effect”. Because of its preferential activation in the targeted hypoxic regions of solid tumors, evofosfamide may be less likely to produce broad systemic toxicity seen with untargeted cytotoxic chemotherapies.

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.

Batabulin or T138067 (2-fluoro-1-methoxy-4-pentafluorophenylsulfonamidobenzene) covalently and selectively modifies the beta1, beta2, and beta4 isotypes of beta-tubulin at a conserved cysteine residue, thereby disrupting microtubule polymerization. Cells exposed to batabulin become altered in shape, indicating a collapse of the cytoskeleton, and show an increase in chromosomal ploidy. Batabulin is equally efficacious in inhibiting the growth of sensitive and multidrug-resistant human tumor xenografts in athymic nude mice. Batabulin has been in clinical trials for the treatment of cancers (breast cancer, colorectal cancer, glioma, hepatocellular carcinoma, non-small cell lung cancer). It does not have clinical activity in the treatment of colorectal cancer and glioma. Batabulin development was discontinued.

ISOMETAMIDIUM (as a chloride salt) is widely used in tropical countries as an antiprotozoal agent to control animal trypanosomiasis. It is used principally in cattle but also in sheep, goats, buffalos, donkeys, horses, camels and dogs.

Cyprenorphine is a mixed agonist-antagonist of opioid receptors. In clinical trials, administration of cyprenorphine induced psychotomimetic effects in pre-operative patients.

Banoxantrone (formally known as AQ4N), a bioreductive drug that is irreversibly converted to AQ4, a stable DNA affinic cytotoxic compound. Banoxantrone is activated by haem-containing reductases such as inducible nitric oxide synthase (iNOS). In hypoxic cells, AQ4N is reduced to the topoisomerase II inhibitor AQ4. By inhibition of topoisomerase II within these hypoxic areas, AQ4N has been shown to sensitize tumors to existing chemo- and radiotherapy treatments. Novacea, the company which was responsible for clinical trials for banoxantrone had decided to scale back on its clinical development, including discontinuing the clinical trial in acute lymphoblastic leukemia and delaying the planned clinical trial in B-cell lymphoma. The company decided to continue enrollment in an ongoing Phase 1b/2a clinical trial in patients with glioblastoma multiforme. However, further information about these clinical trials are not available. Some recent experiments have shown that targeting hypoxic tumors with high levels of iNOS with a combination of AQ4N and radiotherapy could be a useful clinical therapeutic strategy.

Troxacitabine is a synthetic nucleoside analogue. It is a poor substrate for nucleoside transporters and gains entry into cells by passive diffusion. Intracellular conversion to its active triphosphate form is via deoxycytidine kinase. Incorporation of this metabolite into DNA results in immediate chain termination and apoptosis induction. It is the first nucleoside analog with anticancer activity that has an unnatural stereochemical configuration. The dose-limiting adverse reactions were stomatitis and hand–foot syndrome.

Rigosertib sodium (ON 01910.Na) is a small molecule inhibitor of critical pathways important in the growth and survival of cancer cells, being developed by Onconova Therapeutics ("Onconova") for the treatment of hematologic malignancies and solid tumors. Rigosertib (ON-01910) is a non-ATP-competitive inhibitor of PLK1 with IC50 of 9 nM in a cell-free assay. It shows 30-fold greater selectivity against Plk2 and no activity to Plk3. Extensive Phase I and Phase II studies with rigosertib have been conducted at leading institutions in the U.S. and abroad in more than 450 patients with solid tumors and hematological cancers, including MDS and AML. MDS and AML are blood disorders widely recognized as difficult to manage, with limited therapeutic options available for patients, especially those with drug-resistant disease. The multi-site Phase III ONTIME trial in MDS patients is under a Special Protocol Assessment (SPA) from the U.S. FDA and is being supported by an award from the Therapeutics Acceleration Program (TAP) of the Leukemia and Lymphoma Society (LLS). FDA has granted Orphan Drug Designation for the use of rigosertib in MDS. The clinical program in solid tumors is also advancing with initiation of the Phase II/III combination ONTRAC trial (ON 01910.Na TRial in Patients with Advanced Pancreatic Cancer) and Phase II single agent trial in ovarian cancer. In Japan, SymBio is developing rigosertib for the treatment of refractory/relapsed HR-MDS (IV form) and first-line LR-MDS (oral form).

Berubicin, an anthracycline derivative, is a DNA binding agent and potent topoisomerase II poison. Reata Pharmaceuticals were developing it as a treatment for brain cancer as it can breach the blood-brain barrier. It had also been in early clinical trials for the treatment of lung cancer and malignant gliomas. However, studies have been terminated. In October 2006, it was granted orphan drug designation from the FDA for the treatment of malignant gliomas. According to a CNS Pharmaceuticals media release in April 2018, berubicin will be studied for glioblastoma patients, these investigations will be funded in part by an equity crowdfunding campaign.

Vadimezan (5,6-dimethyl(xanthenone-4-acetic acid), ASA404, DMXAA) is a fused tricyclic analogue of flavone acetic acid with potential antineoplastic activity. In pre-clinical mouse tumour models it was demonstrated that administration of Vadimezan rapidly leads to disruption of the existing vasculature in the tumour and consequent haemorrhagic necrosis of the tumour. This was consistent with the finding that a single dose of Vadimezan induced a prolonged reduction in the growth of xenografted tumours in animal models. The ability to disrupt the vasculature in these pre-clinical models has been attributed to a rapid induction of cytokines, particularly TNFα (tumour necrosis factor α), serotonin and nitric oxide, resulting in hemorrhagic necrosis and a decrease in angiogenesis. Despite the fact that the molecular targets for the drug remained unknown, the promising pre-clinical results led to Vadimezan being selected for clinical development. Results of Phase I trials showed some restriction of tumour blood flow within 24 h of treatment, although this was not as dramatic as seen in pre-clinical models. Unlike the animal models, there was also very little evidence for the rapid death of blood vessels or for increases in TNFα levels in human tumors. No difference in antitumour activity, cytokine induction or toxicity was observed between two parallel Phase I trials, one dosed weekly and the other dosed every 3 weeks. Therefore the drug proceeded to Phase II clinical trials, dosed every 21 days in combination with chemotherapeutic agents. These trials indicated the drug had small benefits in the treatment of non-small-cell lung cancer and prostate cancer. However, a subsequent Phase III clinical trial was not able to reproduce this response and clinical development was halted.