ИСТИНА

Introduction: Сombination chemotherapy using nanoscale delivery systems is a promising approach to chemotherapy of brain tumors. Besides the possibility to improve treatment results and reduce side effects, the co-delivery systems may enhance brain delivery of the antitumor drugs potentially active against brain tumors but unable to effectively cross the blood-brain barrier (BBB). The aim of this study was to develop the human serum albumin (HSA) based nanosystem for co-delivery of paclitaxel (PTX) and etoposide (, the cytotoxic agents with the limited penetration across the BBB. A hydrophobic etoposide derivative 4´-O-benzyloxycarbonyl-etoposide (ETP-сbz) was synthesized to enhance binding of etoposide to HSA. Methods: ETP-cbz was synthesized by a reaction of etoposide with benzyl chloroformate in tetrahydrofuran; the structure was confirmed by elemental analysis, FTIR, NMR spectroscopy and LC-MS assay. The nano-sized formulations of PTX and ETP-cbz (mono- and co-delivery) were obtained using the principles of nab™ technology. All nanoparticles (NPs) were thoroughly characterized regarding their size, size distribution and stability, ζ-potential, morphology, and contents of drugs and HSA. The rate of the ETP-cbz conversion to etoposide both for a substance and NPs was studied in the presence and absence of esterase at a molar ratio of 1:4 in the model medium (1% Tween® 80 in phosphate buffer solution at pH 7.4). The cytotoxicity (IC50) of the PTX/ETP-cbz co-delivery NPs compared to mono-formulations and free substances (solutions in DMSO) was evaluated in the Neuro-2a (mouse neuroblastoma) cell line using the MTT-test. Results:The ETP-cbz derivative exhibited high hydrophobicity that enabled formation of a stable HSA-based nanosuspension (drug content ≈ 2 mg/mL). Moreover, ETP-cbz was easily convertible into the parent drug in the presence of esterase, thus exhibiting the prodrug properties. The PTX/ETP-cbz NPs had a size of 90-150 nm and a negative surface potential (≈ -20 mV). The in vitro cytotoxicity study using the Neuro-2a cell line sensitive to both PTX and ETP-cbz demonstrated a synergistic effect of the PTX/ETP-cbz co-delivery formulation with a combination index of < 0.9. Conclusion: The developed dual drug-loaded nano-delivery system may serve for the improvement of the combination chemotherapy of brain tumors. To our knowledge this is the first report describing the non-cross-linked HSA-based nanosuspension containing two drugs that was prepared using the principles of nab™ technology. Acknowledgments: This work was supported by the Ministry of Science and Higher Education of Russian Federation (grant No 075-15-2020-792). The analytical studies were performed using the equipment of the D.I. Mendeleev Center for Collective Use of Scientific Equipments (Moscow, Russia).