1.Nitroimidazole drugs vary in their mode of action in the human parasite Giardia lamblia.
Leitsch D1, Schlosser S1, Burgess A2, Duchêne M1. Int J Parasitol Drugs Drug Resist. 2012 May 12;2:166-70. doi: 10.1016/j.ijpddr.2012.04.002. eCollection 2012.
Giardia lamblia (syn. duodenalis, intestinalis) is a globally occurring micro-aerophilic human parasite that causes gastrointestinal disease. Standard treatment of G. lamblia infections is based on the 5-nitroimidazole drugs metronidazole and tinidazole. In two other micro-aerophilic parasites, Entamoeba histolytica and Trichomonas vaginalis, 5-nitroimidazole drugs bind to proteins involved in the thioredoxin-mediated redox network and disrupt the redox equilibrium by inhibiting thioredoxin reductase and depleting intracellular thiol pools. The major aim of this study was to assess whether nitroimidazoles exert a similar toxic effect on G. lamblia physiology. The 5-nitroimidazoles metronidazole and tinidazole were found to bind to the same subset of proteins including thioredoxin reductase. However, in contrast to E. histolytica and T. vaginalis, none of the other proteins bound are candidates for being involved in the thioredoxin-mediated redox network.
2.A phase Ib/II translational study of sunitinib with neoadjuvant radiotherapy in soft-tissue sarcoma.
Lewin J1, Khamly KK1, Young RJ1, Mitchell C1, Hicks RJ2, Toner GC2, Ngan SY1, Chander S1, Powell GJ3, Herschtal A1, Te Marvelde L1, Desai J1, Choong PF3, Stacker SA4, Achen MG4, Ferris N1, Fox S1, Slavin J5, Thomas DM6. Br J Cancer. 2014 Dec 9;111(12):2254-61. doi: 10.1038/bjc.2014.537. Epub 2014 Oct 16.
BACKGROUND: Preoperative radiotherapy (RT) is commonly used to treat localised soft-tissue sarcomas (STS). Hypoxia is an important determinant of radioresistance. Whether antiangiogenic therapy can 'normalise' tumour vasculature, thereby improving oxygenation, remains unknown.
3.Design, synthesis, and preliminary biological evaluation of 6-O-glucose-azomycin adducts for diagnosis and therapy of hypoxic tumors.
Kumar P1, Shustov G, Liang H, Khlebnikov V, Zheng W, Yang XH, Cheeseman C, Wiebe LI. J Med Chem. 2012 Jul 12;55(13):6033-46. doi: 10.1021/jm2017336. Epub 2012 Jul 2.
Several 2-nitroimidazole-based molecules (NIs) are used as clinical hypoxic tumor radiodiagnostics, but they are not effective as radiosensitizers/radiochemotherapeutics. These NIs permeate tumor cells nonselectively via diffusion, and in therapy, where high doses are required, their dose limiting toxicities preclude success. The synthesis and preliminary in vitro evaluations of three glucoazomycins, members of a novel class of C6-O-glucose-linked-azomycin conjugates that are putative substrates of glucose transport proteins (GLUTs) and possess hypoxia-selective radiosensitization features, are now reported. The hypoxia-dependent upregulation of several GLUTs provides a rational basis to develop these glucoazomycins because more selective uptake in hypoxic cells would decrease systemic toxicities at effective doses. Calculated partition coefficients (ClogP, -1.70 to -2.99) predict rapid in vivo clearance for low systemic toxicity. In vitro experimental data show that glucoazomycins are radiosensitizers and that they competitively inhibit glucose uptake.