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Gemcitabine is quite effective in the treatment of brain tumors, although this drug has a limited ability to overcome the blood-brain barrier (BBB). Aim of study is to assess the therapeutic efficacy of gemcitabine and other drugs with different permeability of BBB in the model of intracranial tumor. The therapeutic activity of gemcitabine, carmustine, cyclophosphamide and cisplatin was studied in mice with intracranially implanted Ehrlich tumor, and also gemcitabine in various doses - with intramuscularly implanted tumor. On intracranial tumor model gemcitabine (25 mg/kg) increased the life span (ILS) by 60-89% (p<0.001), despite the fact that its permeability of the BBB is about 10%. Therapeutic activity of carmustine, cyclophosphamide and cisplatin (ILS were 44, 22 and 11%, respectively) corresponds with the BBB permeability for these drugs (90, 20 and 8%, respectively). On intramuscular tumor model, gemcitabine showed significant antitumor effect at both 25 and 2.5 mg/kg, indicating a wide range of therapeutic doses of this drug. Pronounced therapeutic effect of gemcitabine on intracranial tumor most likely is due to the small but sufficient concentration of the drug that overcomes the BBB., Competing Interests: The authors declare that there is no conflict of interest., (© Georg Thieme Verlag KG Stuttgart · New York.)

HER2-positive breast tumors are found in 25-30% of patients with breast cancer and are characterized by aggressive course and reduced sensitivity to both chemotherapy and hormone therapy. The aim of the work was to study the possibilities of enhancing the therapeutic effect of anti-estrogen drug toremifene by combining it with biguanide, metformin, on the HER2-positive breast cancer model in FVB/N HER-2/neu transgenic mouse. Male FBV/N mice with intramuscularly transplanted HER2-positive mammary gland tumor from a female mouse of the same strain have been given toremifene (30 mg/kg, orally daily) or metformin (100 mg/kg, orally daily) that had a moderate antitumor effect (decrease the area under the kinetic curve of tumor growth by 1.6 and 1.5 times, respectively, when compared with intact control). Co-administration of these drugs in the same doses had a more pronounced effect (the area under the kinetic curve of tumor growth decreased by 3.1 times compared to intact control; p<0.05). After 10 days, in group receiving toremifene all 10 mice developed inguinal-scrotal hernias, and in group that received toremifene plus metformin - only 5 of 10 (p=0.0325). By the 15 th day after the start of treatment, the hernias was also determined in all mice treated with the combination of toremifene and metformin, but the size of the hernial sac was significantly smaller than in those receiving only toremifene - 537 ± 96 mm 3 and 1309 ± 120 mm 3 , respectively (p=0.0001). A possible explanation is the manifestation of collagen-degrading effect of toremifene., Competing Interests: The authors declare that there is no conflict of interest., (© Georg Thieme Verlag KG Stuttgart · New York.)

Synthetic phenolic antioxidant β-(4-hydroxy-3,5-di-tert-butylphenyl) propionic acid, named phenozan, is a potential antiepileptic drug. In pre-clinical trials this substance did not manifest any toxicity, and also inhibited the development of some spontaneous tumors in animals. The purpose of this study was to evaluate inhibiting effect of phenozan on spontaneous carcinogenesis in rats and mice. In experiments with rats LIO and mice SHR of local breeding, with high spontaneous tumor incidence, phenozan was dissolved in sunflower oil and administered by gavage in therapeutic dose 5 mg/kg 3 times per week for 18 months. There were no any signs of toxicity and differences in weight of animals during the phenozan treatment compared with the control (sunflower oil). Phenozan significantly reduced the overall incidence and multiplicity of all tumors but only multiplicity of malignant tumors, compared with the control. Moreover a significant decrease of overall incidence and multiplicity was observed in pituitary and breast tumors in females and only overall multiplicity of tumors of pituitary and lymphoid tissue in males. In mice phenozan reduced overall incidence and multiplicity of lung tumors (in females) and also overall multiplicity of all tumors (in females) and only malignant tumors (in males). These findings allow us to classify phenozan as anticarcinogenic agent. Anticarcinogenic activity of phenozan is important because clinical study of this drug as the possible antiepileptic drug goes along and it is known that such drugs are designed for long-term use., (© Georg Thieme Verlag KG Stuttgart · New York.)