Misonidazole is a nitroimidazole with radiosensitizing and antineoplastic properties. Exhibiting high electron affinity, misonidazole induces the formation of free radicals and depletes radioprotective thiols, thereby sensitizing hypoxic cells to the cytotoxic effects of ionizing radiation. This single-strand breaks in DNA induced by this agent result in the inhibition of DNA synthesis. The drug also possesses a substantial cytotoxic effect, independent of radiation, which is selectively expressed in hypoxic cells. Misonidazole may be cytotoxic to the normal hypoxic tissues in the human body, making this became a major concern in the clinical application of the drug. Misonidazole leads to strand breaks in cellular DNA and those cells which fail to survive also fail to repair these strand breaks. Misonidazole depletes intracellular glutathione and is more toxic in glutathione depleted cells.

Nemorubicin, a doxorubicin derivative, is a DNA-intercalator, topoisomerase and RNA synthesis inhibitor that was undergoing development with Nerviano Medical Sciences (Nerviano MS; formerly Pharmacia Italia) for the treatment of solid tumours, specifically, the loco-regional treatment of primary liver tumours (hepatocellular carcinoma). The drug is active on tumors resistant to alkylating agents, topoisomerase II inhibitors and platinum derivatives. It works primarily through topoisomerase I inhibition. Of note, Nemorubicin is active in cells with upregulation of the nucleotide excision repair (NER) pathway, where current therapies fail. Nemorubicin is biotransformed in the liver into cytotoxic metabolites that may further contribute to render this drug highly active against primary liver tumors or liver metastases. Clinical trials were conducted in Europe, US and China with Nemorubicin given at different dose-schedules and by different routes of administration: as single agent by systemic IV route, oral route and by intra-hepatic artery (IHA) infusion alone or in combination with cisplatin.

Ethidium is a DNA intercalating agent first discovered as and used as a veterenary trypanocide. A bromide salt is commonly used as a fluorescent tag in molecular biology. The fluorescene of ethidium bromide increased 21 fold upon binding to double-stranded RNA, 25 fold upon binding double stranded DNA. Because of the binding to DNA, ethidium bromide is a powerful inhibitor of DNA polymerase.

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.

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.

BN-2629 (also known as SJG-136 and SG2000), a dimeric pyrrolobenzodiazepine that binds in the minor groove of DNA and produces G-G interstrand cross-links via reactive N(10)-C(11)/N(10')-C(ll') imine/carbinolamine moieties. This drug was investigated in phase II clinical trials in patients with epithelial ovarian, primary peritoneal, or fallopian tube cancer, however, these studied were terminated because of the slow accrual. In addition, BN-2629 participated in phase I/II trial in participants with advanced chronic lymphocytic leukemia and acute myeloid leukemia, but Spirogen also terminated these studies.

Spiroplatin is a metal drug and analog of the second generation for cisplatin, developed for the treatment of cancer. Spiroplatin induces DNA cross-linking, thereby inhibiting DNA replication and the synthesis of RNA and protein. Initial clinical trials of spiroplatin have shown that it can cause less nausea and vomiting than cisplatin, and can be administered without hydration due to less renal toxicity. However, with increasing doses, the marginal toxicity was both renal and hematologic. In addition, spiroplatin was devoid of significant antitumor effects in advanced ovarian cancer, a disease in which some response can be expected. Based on these data, further development was discontinued.

Mafosfamide is a synthetic oxazaphosphorine derivative with antineoplastic properties. Mafosfamide alkylates DNA, forming DNA cross-links and inhibiting DNA synthesis. The effects of mafosfamide on various types of cancer cells were determined during preclinical investigations and clinical trials. Its development has been discontinued.

Ormaplatin (NSC 363812, tetraplatin) is a stable platinum (IV) analog. Ormaplatin alkylates DNA, forming both inter- and intra-strand platinum-DNA crosslinks, which result in inhibition of DNA replication and transcription and cell-cycle nonspecific cytotoxicity. Ormaplatin showed marked antitumor activity both in vitro and vivo. The severe, cumulative and irreversible peripheral neurotoxicity observed in phase I studies resulted in termination of further clinical development of ormaplatin.

Cytochlor is a radio-sensitizing pyrimidine nucleoside with potential antineoplastic activity. Cytochlor is metabolized first to a phosphate derivative, CldCMP, by the enzyme deoxycytidine kinase and then to the active uracyl derivative, CldUMP, by the enzyme dCMP deaminase. CldUMP, the active metabolite, incorporates into DNA and, upon exposure to radiation, induces the formation of uracil radicals and double-strand DNA breaks. Cytochlor has been used in trials studying the treatment of Head and Neck Cancer and Brain and Central Nervous System Tumors.