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Since the problem of transporter-mediated multidrug resistance of tumor cells is becoming increasingly important in cancer therapy, it is necessary to modulate the activity of efflux transporters of the ABC family, among which P-glycoprotein is the best known. We consider the nucleotide binding domain, a universal fragment of these transporters, as a target for the rational design of small molecule compounds capable of preventing ATP-dependent drug efflux. Using various ATP mimetics, we showed that they suppress the efflux of fluorescent substrates and paclitaxel from the cells due to suppressing the ATPase activity of the transporters. The combined use of paclitaxel and ATP mimetics significantly increases its antitumor efficacy, including in cells with the multidrug resistance phenotype. The considered compounds are promising agents for the development of therapeutic efflux modulators, since they are not toxic at the given concentrations and do not induce the transporter overexpression. Moreover, the compounds overcome not only P-gp-mediated but also BCRP-mediated resistance of tumor cells.

Reduced delivery of the drug into the cell due to increased activity of specific transporter P-glycoprotein is one of the main mechanisms of drug resistance development. The inhibition of the activity of such a pump increases the intracellular concentration of the drug and contributes to cancer cell death. The combination of factors that allows one to overcome genetically determined resistance and to trigger apoptosis in one small molecule compound can lead to the development of new type of drugs for personalized therapy of chemoresistant tumors. In the course of work on optimization of MDM2 inhibitors based on indolinones and isoindolinones, we found fragments of the structure that can be modified with minimal risk of a decrease in the target activity. The combination of in silico and in vitro methods allowed the selection of compounds that showed strong binding to the target sites of P-glycoprotein and MDM2, and a good combination of solubility - membrane-active properties, which implies high bioavailability of the drug.