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- Laryea, Daniel
(författare)
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Preclinical Characterization in vivo and in vitro of Novel Agents for Cancer Chemotherapy : Studies on Benomyl, Carbendazim, Cryptolepine and Acriflavine
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Preclinical methods for the identification and characterization of molecules for development into new cancer drugs were investigated. Based on repurposing, i.e. the exploration of currently prescribed drugs for new indications, and as a result of a new high throughput screening (HTS) approach, the benzimidazoles benomyl and carbendazim, the alkaloid cryptolepine and the acridine acriflavine were found interesting to characterize using these methods. In mice the benzimidazoles inhibited 3H-thymidine incorporation in tissues with high cell renewal, with benomyl being more active than carbendazim. They were rapidly absorbed with highest amounts seen in the liver, kidneys and gastro-intestinal lumen as evidenced from distribution of 14C-labeled drugs. In human tumour cell lines, the benzimidazoles showed a similar activity pattern but benomyl was more potent. This was true also in tumour cells from patients but carbendazim was relatively more active against solid tumours. Analyses of drug activity cross-resistance patterns and of drug activity – gene expression correlations in a cell line panel suggested multiple mechanisms of action for the benzimidazoles. Cryptolepine was widely distributed to tissues in vivo in the mice. It was more potent than the benzimidazoles in tumour cells, with highest activity in haematological malignancies but some patient samples of breast, colon and non small-cell lung cancer were sensitive. Cross-resistance analysis indicated cryptolepine to be a topoisomerase II inhibitor whereas drug activity – gene expression correlations suggested additional mechanisms of action. HTS on 2 000 molecules in colon cancer cell lines and normal cells identified acriflavine as a hit molecule, subsequently shown to have unprecedented activity against colorectal cancer tumour cells in patient tumour samples. Connectivity map analysis, based on drug induced gene expression perturbation patterns in a tumour cell line, indicated acriflavine to be a topoisomerase inhibitor, subsequently confirmed in a plasmid relaxation assay. In conclusion, repurposing of drugs and HTS using stringent activity criteria followed by preclinical characterization might contribute to more efficient development of new cancer drugs.
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| 2. |
- von Heideman, Anne, 1956-
(författare)
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Exploring Cancer Drugs In Vitro and In Vivo : With Special Reference to Chemosensitivity Testing and Early Clinical Development
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of this thesis were to investigate the utility of in vitro drug sensitivity testing to optimize the use of cancer chemotherapy and to assess the properties of a new cancer drug in a phase I clinical trial. Tumour cells from patients were analysed with the short-term Fluorometric Microculture Cytotoxicity Assay (FMCA). In samples from a wide spectrum of tumour types, the effect of the drug combination FEC (5Fu-epirubicin-cyclophosphamide) was generally appropriately predicted from the effect of the best component drug. However, of samples intermediately sensitive to the best single drug, 45% converted to sensitive when testing the combination. Thus, combination testing may identify advantageous interactions and improve in vitro test performance. In tumour samples from peritoneal carcinomatosis, significant differences in drug sensitivity between diagnoses were observed, cross-resistance between most drugs was modest or absent, and the concentration-effect relationships for two drugs in individual samples varied considerably. Thus, for optimal selection of drugs for intraperitoneal chemotherapy, differences in drug sensitivity at the diagnosis and individual patient level should be considered. In samples from patients with ovarian carcinoma, drug sensitivity was related to tumour grade, histologic subtype and patient treatment status. In a homogeneous subset of patients, the FMCA predicted individual patient tumour response with high sensitivity and specificity. Thus, if carefully interpreted in the context of important clinical variables, in vitro testing could be of value for individualizing chemotherapy in ovarian cancer. Employing a once weekly dosing schedule in a phase I trial, the mechanistically new and preclinically promising NAD depleting drug CHS 828 produced dose limiting thrombocytopenia and gastrointestinal toxicity without clear evidence of anti-tumour efficacy. It is concluded that in vitro drug sensitivity testing could be a way to optimize the use of chemotherapy and that successful development of new cancer drugs needs improved strategies.
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