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Tirapazamine (SR-[]) is an experimental anticancer drug that is activated to a toxic radical only at very low levels of oxygen (hypoxia). Such levels are common in human solid tumors, a phenomenon known as tumor hypoxia. Thus, tirapazamine is activated to its toxic form preferentially in the hypoxic areas of solid tumors. Cells in these regions are resistant to killing by radiotherapy and most anticancer drugs. Thus the combination of tirapazamine with conventional anticancer treatments is particularly effective. As of 2006 [update] , tirapazamine is undergoing phase III testing in patients with head and neck cancer and gynecological cancer, and similar trials are being undertaken for other solid tumor types.
Chemically it is an aromatic heterocycle di-N-oxide. Its full chemical name is 3-amino-1,2,4-benzotriazine-1,4 dioxide. Originally it was prepared in a program screening for new herbicides in 1972. Its clinical use was first described by Zeman et al. in 1986.While tirapazamine has had only limited effectiveness in clinical trials, it has been used as a lead compound to develop a number of newer compounds with improved anti-cancer properties.
An update of a Phase III trial (Tirapazamine, cisplatin, and radiation versus cisplatin and radiation for advanced squamous cell carcinoma of the head and neck (TROG 02.02, HeadSTART): a phase III trial of the Trans-Tasman Radiation Oncology Group) found no evidence that the addition of TPZ to chemoradiotherapy, in patients with advanced head and neck cancer not selected for the presence of hypoxia, improved overall survival.
Two possible molecular mechanisms of TPZ, for generating reactive oxygen species which causes DNA strand break, have been considered widely. In hypoxia, under bioreductive condition, it has been observed that TPZ primarily produces hydroxyl or and benzotriazinyl radicals as the DNA damaging reactive species.
A new clinical phase I trial of Tirapazamine combined with embolization in liver cancer has been received in June, 2014. This study will help to optimize the safe tolerable dose of TPZ, when it is administered with embolization in liver cancer. [ citation needed ]Treatment of solid tumors is complicated by the fact that these are often poorly provided with blood vessels, thus limiting their exposure to cytotoxic agents. Attempts have, however, been made to take advantage of the resulting hypoxic environment by designing drugs that are nonreactive until they are reduced to reactive species in oxygen-deficient tissues. This, it is hoped, will lead to enhanced selectivity. The azaquinoxaline dioxide function on the antineoplastic agent tirapazamine, for example, has been shown to give reactive nitroxide radicals on reduction.
The first step in the synthesis, condensation of 2-nitroaniline (1) with cyanamide, probably involves initial formation of a guanidine such as 2. This then cyclizes to the heterocycle 3. Oxidation with hydrogen peroxide then completes the preparation of tirapazamine (4).
Tumor hypoxia is the situation where tumor cells have been deprived of oxygen. As a tumor grows, it rapidly outgrows its blood supply, leaving portions of the tumor with regions where the oxygen concentration is significantly lower than in healthy tissues. Hypoxic microenvironements in solid tumors are a result of available oxygen being consumed within 70 to 150 μm of tumour vasculature by rapidly proliferating tumor cells thus limiting the amount of oxygen available to diffuse further into the tumor tissue. In order to support continuous growth and proliferation in challenging hypoxic environments, cancer cells are found to alter their metabolism. Furthermore, hypoxia is known to change cell behavior and is associated with extracellular matrix remodeling and increased migratory and metastatic behavior.
Irofulven or 6-hydroxymethylacylfulvene is an experimental antitumor agent. It belongs to the family of drugs called alkylating agents.
Cisplatin is a chemotherapy medication used to treat a number of cancers. These include testicular cancer, ovarian cancer, cervical cancer, bladder cancer, head and neck cancer, esophageal cancer, lung cancer, mesothelioma, brain tumors and neuroblastoma. It is given by injection into a vein.
Targeted therapy or molecularly targeted therapy is one of the major modalities of medical treatment (pharmacotherapy) for cancer, others being hormonal therapy and cytotoxic chemotherapy. As a form of molecular medicine, targeted therapy blocks the growth of cancer cells by interfering with specific targeted molecules needed for carcinogenesis and tumor growth, rather than by simply interfering with all rapidly dividing cells. Because most agents for targeted therapy are biopharmaceuticals, the term biologic therapy is sometimes synonymous with targeted therapy when used in the context of cancer therapy. However, the modalities can be combined; antibody-drug conjugates combine biologic and cytotoxic mechanisms into one targeted therapy.
The study of the tumor metabolism, also known as tumor metabolome describes the different characteristic metabolic changes in tumor cells. The characteristic attributes of the tumor metabolome are high glycolytic enzyme activities, the expression of the pyruvate kinase isoenzyme type M2, increased channeling of glucose carbons into synthetic processes, such as nucleic acid, amino acid and phospholipid synthesis, a high rate of pyrimidine and purine de novo synthesis, a low ratio of Adenosine triphosphate and Guanosine triphosphate to Cytidine triphosphate and Uridine triphosphate, low Adenosine monophosphate levels, high glutaminolytic capacities, release of immunosuppressive substances and dependency on methionine.
Triplatin tetranitrate is a platinum-based cytotoxic drug that underwent clinical trials for the treatment of human cancer. The drug acts by forming adducts with cellular DNA, preventing DNA transcription and replication, thereby inducing apoptosis. Other platinum-containing anticancer drugs include cisplatin, carboplatin, and oxaliplatin.
EF5 is a nitroimidazole derivative used in oncology research. Due to its similarity in chemical structure to etanidazole, EF5 binds in cells displaying hypoxia.
Satraplatin is a platinum-based antineoplastic agent that was under investigation as a treatment of patients with advanced prostate cancer who have failed previous chemotherapy. It has not yet received approval from the U.S. Food and Drug Administration. First mentioned in the medical literature in 1993, satraplatin is the first orally active platinum-based chemotherapeutic drug; other available platinum analogues—cisplatin, carboplatin, and oxaliplatin—must be given intravenously.
Evofosfamide. Is a compound being evaluated in clinical trials for the treatment of multiple tumor types as a monotherapy and in combination with chemotherapeutic agents and other targeted cancer drugs.
Efaproxiral (INN) is an analogue of the cholesterol drug bezafibrate developed for the treatment of depression, traumatic brain injury, ischemia, stroke, myocardial infarction, diabetes, hypoxia, sickle cell disease, hypercholesterolemia and as a radio sensitiser.
Taurolidine is an antimicrobial that is used to prevent infections in catheters. Side effects and the induction of bacterial resistance is uncommon. It is also being studied as a treatment for cancer.
Thymidylate synthase inhibitors are chemical agents which inhibit the enzyme thymidylate synthase and have potential as an anticancer chemotherapy. This inhibition prevents the methylation of C5 of deoxyuridine monophosphate (dUMP) thereby inhibiting the synthesis of deoxythymidine monophosphate (dTMP). The downstream effect is promotion of cell death because cells would not be able to properly undergo DNA synthesis if they are lacking dTMP, a necessary precursor to dTTP. Five agents were in clinical trials in 2002: raltitrexed, pemetrexed, nolatrexed, ZD9331, and GS7904L.
A radiosensitizer is an agent that makes tumor cells more sensitive to radiation therapy. It is sometimes also known as a radiation sensitizer or radio-enhancer.
Hydrazine sulfate, more properly hydrazinium hydrogensulfate, is a salt of the cation hydrazinium and the anion bisulfate (hydrogensulfate), with the formula N2H6SO4 or more properly [N2H5]+[HSO4]−. It is a white, water-soluble solid at room temperature.
NAMI-A is the imidazolium]] salt of the coordination complex [RuCl4(dmso)(C3N2H4)]− where dmso is dimethylsulfoxide and C3N2H4 is imidazole Together with KP1019 and BOLD-100, NAMI-A has been investigated as an anticancer agent.
Platinum-based antineoplastic drugs are chemotherapeutic agents used to treat cancer. Their active moieties are coordination complexes of platinum. These drugs are used to treat almost half of people receiving chemotherapy for cancer. In this form of chemotherapy, commonly used drugs include cisplatin, oxaliplatin, and carboplatin, but several have been proposed or are under development. Addition of platinum-based chemotherapy drugs to chemoradiation in women with early cervical cancer seems to improve survival and reduce risk of recurrence.
Dicycloplatin is a chemotherapy medication used to treat a number of cancers which includes the non-small-cell lung carcinoma and prostate cancer.
18F-FMISO or fluoromisonidazole is a radiopharmaceutical used for PET imaging of hypoxia. It consists of a 2-nitroimidazole molecule labelled with the positron-emitter fluorine-18.
PR-104 is a drug from the class of hypoxia-activated prodrugs (HAPs), which is being researched as a potential anti-cancer therapeutic agent. It is a phosphate ester “pre-prodrug” that is rapidly converted to the HAP PR-104A in the body. PR-104A is in turn metabolised to reactive nitrogen mustard DNA crosslinking agents in hypoxic tissues such as found in solid tumours. Following initial clinical studies, it was discovered that PR-104A is also activated by the enzyme AKR1C3, independently of hypoxia. Hypoxia in the bone marrow of patients with leukaemia, and high activity of AKR1C3 in some leukaemia subtypes has led to interest in clinical trials of PR-104 in relapsed refractory acute leukaemias.
KP1019, or indazole trans-[tetrachlorobis(1H-indazole)ruthenate(III)], is one of four ruthenium anti-cancer drugs to enter into phase I clinical trials, the others being BOLD-100, NAMI-A and TLD-1433. Research into ruthenium-based drugs has provided novel alternatives for platinum-based chemotherapeutics such as Cisplatin and its derivatives. KP1019 is useful for metastatic tumors and cis-platin resistant tumors. It exhibits potent cytotoxicity against primary tumors, particularly in colorectal cancer.