Glioblastomas belong to the most aggressive human cancers with short survival times. Due to the blood-brain barrier, they are mostly inaccessible to traditional chemotherapy. We have recently shown that doxorubicin bound to polysorbate-coated nanoparticles crossed the intact blood-brain barrier, thus reaching therapeutic concentrations in the brain. Here, we investigated the therapeutic potential of this formulation of doxorubicin in vivo using an animal model created by implantation of 101/8 glioblastoma tumor in rat brains. Groups of 5-8 glioblastoma-bearing rats (total n ‫؍‬ 151) were subjected to 3 cycles of 1.5-2.5 mg/kg body weight of doxorubicin in different formulations, including doxorubicin bound to polysorbate-coated nanoparticles. The animals were analyzed for survival (% median increase of survival time, Kaplan-Meier). Preliminary histology including immunocytochemistry (glial fibrillary acidic protein, ezrin, proliferation and apoptosis) was also performed. Rats treated with doxorubicin bound to polysorbate-coated nanoparticles had significantly higher survival times compared with all other groups. Over 20% of the animals in this group showed a long-term remission. Preliminary histology confirmed lower tumor sizes and lower values for proliferation and apoptosis in this group. All groups of animals treated with polysorbatecontaining formulations also had a slight inflammatory reaction to the tumor. There was no indication of neurotoxicity. Additionally, binding to nanoparticles may reduce the systemic toxicity of doxorubicin. This study showed that therapy with doxorubicin bound to nanoparticles offers a therapeutic potential for the treatment of human glioblastoma.

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In order to create an active pharmaceutical substance of the drug with prolonged action the modification of recombinant human granulocyte colony-stimulating factor GCSF (filgrastim) with polyethylene glycol (PEG, M 21.5 kDa) was conducted. A method for preparation of PEG-filgrastim designed for the development and scaling-up of the technological process of production was described. Modification of proteins with PEG was performed by selective covalent attachment of the molecule alpha-methyl-PEG-propionaldehyde to the alpha-amino group of the N-terminal methionine amino acid residue of the recombinant GCSF. The conditions of the reaction, which provide the desired product yield at least 85% of the total protein, also high protein concentration in the reaction mixture (more than 9 mg/mL) and reduce consumption of PEG in terms of terminal alpha-amino group of the protein was chosen. The data of RP HPLC and MALDI-mass spectrometry showed that the produced drug modified by the N-terminal residue and contains no more than 10% of products with a high degree of modification.

A new solubilization method of recombinant interferon beta-1b (IFNβ-1b) from the inclusion bodies was developed. This method allows to extract the target protein selectively in the solutions of different alcohols, such as ethanol, propanol and isopropanol. It was shown that the more effective IFNβ-1b solubilization was achieved in the 55% propanol solution. This method allowed to extract the target protein from inclusion bodies around 85-90%, and significantly reduced Escherichia coli content in the solubilizate, in comparison with standard methods.

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