We developed and described a new approach to vital analysis of functional activity of multidrug resistance markers (ABC transporters) in intact biopsy specimens from human solid tumors by the method of flow cytofluorometry. The algorithm of the study underwent revision, and the cell suspension was obtained in the final stage. Intensification of intracellular doxorubicin accumulation (fluorescence) and increase in the number of fluorescent cells and total fluorescence of doxorubicin-accumulating cells produced by ABC transporter inhibitor sodium azide served as the criteria of expression of these transporters in tumor tissue. Informative value of changes in various parameters of doxorubicin fluorescence is discussed. The increase in the count of fluorescent cells in the suspension of tumors cells after treatment with the inhibitor indicates the presence of tumor cells absolutely resistant to this preparation. The proposed method is technically simple, suitable for structurally different tumors, requires small amounts of the biopsy material and, therefore, can be used for routine analysis. The results of our analysis and spectrofluorometric assay of ABC transporters agree very closely, which suggest that this method is adequate for the purpose.

The N. Blokhin National Cancer Research Center is one of the few Russian scientific institutions in which hybridoma technology of monoclonal antibody (mAb) production has been successfully established. Using this technology, several dozens of mAbs to various antigens of human leukocytes have been elaborated. These mAbs are widely used for immune status evaluation and for differential diagnostics of leukemias. Two mAbs were used to develop therapeutic drugs. Imuteran is a pharmaceutical form of mAb ICO-25 against a mucin-like antigen of human milk fat globules and proposed for treatment of epithelial cell-originating cancers (breast, intestinal, ovarian, lung cancer, etc.). ThePhase II clinical study of this agent is now nearly completed, and preliminary results suggest Imuteran to be a promising anticancer agent with tumor-stabilizing activity, but patients should be carefully monitored for signs of allergic reactions. mAb ICO-90 against the CD3 antigen of human T lymphocytes was used to develop the therapeutic agent Atemonate proposed for treatment of acute transplant rejection. At present, the Phase II clinical study of this agent is over, and the results confirm the drug safety and efficacy for this indication. The drug is being registered at the Ministry of Healthcare and Social Development, and transfer to serial production is expected shortly.

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